[browser][coreCLR] Loading WebCIL - 2nd attempt - #124904

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pavelsavara merged 26 commits into
dotnet:mainfrom
pavelsavara:loading_webcil2
Mar 13, 2026
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[browser][coreCLR] Loading WebCIL - 2nd attempt#124904
pavelsavara merged 26 commits into
dotnet:mainfrom
pavelsavara:loading_webcil2

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@pavelsavarapavelsavara commented Feb 26, 2026•
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Enable Webcil loading in CoreCLR for Browser/WASM

Summary

Adds native Webcil container format support to the CoreCLR runtime, enabling CoreCLR-on-WASM to load .wasm-wrapped assemblies directly — previously only supported by the Mono runtime. Removes the WasmEnableWebcil=false override that was forcing CoreCLR browser builds to use raw .dll files.

Changes

CoreCLR Webcil decoder (src/coreclr/)

  • New WebcilDecoder class (webcildecoder.h, webcildecoder.cpp) — standalone reader for the Webcil container format with full RVA/offset translation, COR header resolution, metadata access, section validation, IL method checking, debug directory support, and DAC enumeration.
  • FEATURE_WEBCIL cmake gate enabled for CLR_CMAKE_TARGET_BROWSER (clrfeatures.cmake, clrdefinitions.cmake).

PEImageLayout composition refactor (src/coreclr/vm/)

  • PEImageLayout no longer inherits from PEDecoder; instead holds m_peDecoder (and conditionally m_webcilDecoder) as members with an ImageFormat discriminator (FORMAT_PE/FORMAT_WEBCIL).
  • ~160 inline forwarding methods in peimagelayout.inl dispatch to the active decoder via DECODER_DISPATCH/DECODER_CHECK/PE_OR_WEBCIL macros.
  • PEDecoder public API split: methods needed by PEImageLayout forwarding stay public; PE-internal helpers (GetHeaders, GetDirectoryEntry, CheckDirectoryEntry, relocation/TLS/strong-name internals, etc.) moved to a private section accessible only via friend class PEImageLayout.
  • FlatImageLayout constructor detects Webcil magic and initializes both decoders (Webcil for format operations, PE decoder for base/size/flags used by cDAC).
  • New HasHeaders() abstraction on PEImageLayout and PEImage — returns HasWebcilHeaders() or HasNTHeaders() depending on format. Callers in peassembly.cpp, peimage.cpp, eventtrace.cpp updated from HasNTHeaders() to HasHeaders().
  • debugdebugger.cpp: switched from PEDecoder* to PEImageLayout* and uses format-agnostic GetDirectoryEntryData instead of raw GetDirectoryEntry+GetDirectoryData.
  • ceeload.cpp: same PEDecoder* → PEImageLayout* fix for IJW host lookup.
  • peassembly.cpp: accept IMAGE_FILE_MACHINE_UNKNOWN (Webcil machine type) for IL-only validation; guard 32-bit NT header check with HasNTHeaders().
  • assemblybindercommon.cpp: treat IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL.

cDAC diagnostics (src/native/managed/cdac/)

  • PEImageLayout data descriptor gains Format field (datadescriptor.inc, PEImageLayout.cs).
  • Loader_1.cs: Webcil-aware RvaToOffset path that reads the Webcil section table directly from the target memory when IsWebcilFormat is set.

Build/infrastructure

  • Removed WasmEnableWebcil=false from CoreCLR browser build properties (WasmApp.InTree.props, tests.browser.targets).
  • MSBuild task renames: WebCilCandidates→WebcilCandidates, IsWebCilEnabled→IsWebcilEnabled, _WasmBuildWebCilPath→_WasmBuildWebcilPath and related properties.
  • Test infrastructure: BuildEnvironment.cs removes CoreCLR Webcil exclusion; env var WasmEnableWebCil→WasmEnableWebcil.

@pavelsavarapavelsavara added this to the 11.0.0 milestone Feb 26, 2026
@pavelsavarapavelsavara self-assigned this Feb 26, 2026
CopilotAI review requested due to automatic review settings February 26, 2026 14:56
@pavelsavarapavelsavara added arch-wasm WebAssembly architecture area-AssemblyLoader-coreclr only use for closed issues os-browser Browser variant of arch-wasm labels Feb 26, 2026
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Pull request overview

Enables CoreCLR-on-Browser/WASM to load assemblies packaged in the Webcil container format (i.e., .wasm-wrapped assemblies), aligning CoreCLR behavior with existing Mono Webcil support and removing prior build/test overrides that forced raw .dll usage.

Changes:

  • Adds CoreCLR-side Webcil decoding and wires it into PEImageLayout via format-dispatched forwarding to either PEDecoder (PE) or WebcilDecoder (Webcil).
  • Updates the Webcil tooling pipeline (converter/reader/wrapper + MSBuild tasks/targets) including 16-byte section alignment and property renames (WebCil* → Webcil*).
  • Extends cDAC contracts/readers and WASM test infrastructure to understand and exercise Webcil images.

Reviewed changes

Copilot reviewed 35 out of 35 changed files in this pull request and generated 6 comments.

Show a summary per file
FileDescription
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilWasmWrapper.csImproves wrapper error message for payload offset validation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.csUpdates to PascalCase header fields and adds bounds checking in RVA translation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilHeader.csRenames Webcil header fields to PascalCase for consistency.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.csImplements 16-byte section alignment, debug directory translation, and related validations.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.csRenames output item list to WebcilCandidates.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.csRenames task property to IsWebcilEnabled and updates usage.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.csAdds Format field to contract + helper to detect Webcil format.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.csAdds Webcil-aware RVA-to-offset logic by reading Webcil section table from target memory.
src/mono/wasm/features.mdDocumentation update: “WebCIL” → “Webcil”.
src/mono/wasm/Wasm.Build.Tests/Common/BuildEnvironment.csRemoves CoreCLR Webcil exclusion; renames env var WasmEnableWebcil.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targetsRenames MSBuild properties/items/parameters from WebCil → Webcil.
src/mono/cmake/options.cmakeDocumentation string update for ENABLE_WEBCIL.
src/mono/cmake/config.h.inComment update for ENABLE_WEBCIL.
src/mono/browser/debugger/BrowserDebugProxy/DebugStore.csDocumentation wording update for Webcil handling.
src/mono/browser/build/WasmApp.InTree.propsRemoves CoreCLR WasmEnableWebcil=false override.
src/coreclr/vm/peimagelayout.inlAdds decoder-dispatch forwarding methods; introduces format-agnostic header checks.
src/coreclr/vm/peimagelayout.hRefactors PEImageLayout to composition with PEDecoder/WebcilDecoder and ImageFormat discriminator.
src/coreclr/vm/peimagelayout.cppInitializes Webcil decoder on detection; updates PEDecoder init/reset call sites; DAC enumeration dispatch.
src/coreclr/vm/peimage.inlAdds PEImage::HasHeaders() helper.
src/coreclr/vm/peimage.hDeclares HasHeaders() in PEImage.
src/coreclr/vm/peimage.cppUses HasHeaders() instead of HasNTHeaders() in metadata/debug-directory paths.
src/coreclr/vm/peassembly.cppAccepts IMAGE_FILE_MACHINE_UNKNOWN for IL-only validation; guards 32-bit header check.
src/coreclr/vm/eventtrace.cppSwitches checks from NT headers to format-agnostic headers.
src/coreclr/vm/debugdebugger.cppSwitches from PEDecoder* to PEImageLayout* and uses GetDirectoryEntryData.
src/coreclr/vm/datadescriptor/datadescriptor.incAdds Format field to PEImageLayout’s cDAC data descriptor.
src/coreclr/vm/ceeload.cppUpdates IJW lookup to use PEImageLayout* (post-inheritance refactor).
src/coreclr/utilcode/webcildecoder.cppAdds CoreCLR Webcil decoding/validation implementation and DAC enumeration support.
src/coreclr/utilcode/CMakeLists.txtAdds webcildecoder.cpp to utilcode build.
src/coreclr/inc/webcildecoder.hAdds Webcil structures and WebcilDecoder API.
src/coreclr/inc/pedecoder.hMakes PEImageLayout a friend and restricts PE-internal APIs to PEImageLayout usage.
src/coreclr/clrfeatures.cmakeEnables FEATURE_WEBCIL for browser builds.
src/coreclr/clrdefinitions.cmakeAdds FEATURE_WEBCIL compile definition when enabled.
src/coreclr/binder/assemblybindercommon.cppTreats IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL in binder logic.
eng/testing/tests.browser.targetsRemoves CoreCLR WasmEnableWebcil=false override for browser tests.
docs/design/mono/webcil.mdUpdates spec text for alignment and PascalCase field names + naming consistency.

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp Outdated
Comment threadsrc/coreclr/vm/peimagelayout.inl
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs Outdated
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp Outdated
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
CopilotAI review requested due to automatic review settings February 26, 2026 15:12
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Pull request overview

Copilot reviewed 35 out of 35 changed files in this pull request and generated 4 comments.

Comments suppressed due to low confidence (1)

src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.cs:354

  • New exceptions in TranslateRVA use nameof(_stream) as the parameter name. Since _stream is a private field (not a parameter), this produces a less helpful ParamName than nameof(stream) (constructor parameter) or omitting the param name entirely. Consider aligning with the earlier constructor exceptions which use nameof(stream).

Comment threadsrc/coreclr/vm/peimagelayout.inl Outdated
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs Outdated
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs Outdated
CopilotAI review requested due to automatic review settings February 26, 2026 15:24
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Pull request overview

Copilot reviewed 35 out of 35 changed files in this pull request and generated 2 comments.

Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs Outdated
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pavelsavara marked this pull request as ready for review February 26, 2026 17:55
@pavelsavarapavelsavara mentioned this pull request Feb 26, 2026
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Pull request overview

Copilot reviewed 33 out of 33 changed files in this pull request and generated 6 comments.

Comments suppressed due to low confidence (1)

src/coreclr/utilcode/CMakeLists.txt:1

  • webcildecoder.cpp is added unconditionally to UTILCODE_COMMON_SOURCES. When FEATURE_WEBCIL is off this compiles an effectively empty translation unit, which is small but avoidable build work. Consider conditionally appending webcildecoder.cpp only when FEATURE_WEBCIL is enabled (or CLR_CMAKE_TARGET_BROWSER), to keep non-browser builds slightly leaner.
set(CMAKE_INCLUDE_CURRENT_DIR ON)

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment threadsrc/coreclr/inc/cordecoderhelpers.h
CopilotAI review requested due to automatic review settings March 12, 2026 23:29
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Pull request overview

Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.

Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs Outdated
@pavelsavara
Potential fix for pull request finding
c69c839
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
CopilotAI review requested due to automatic review settings March 13, 2026 00:35
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Pull request overview

Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.

Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs Outdated
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
CopilotAI review requested due to automatic review settings March 13, 2026 01:39
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Pull request overview

Copilot reviewed 34 out of 34 changed files in this pull request and generated 6 comments.

Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp Outdated
Comment threaddocs/design/datacontracts/Loader.md Outdated
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
This was referenced Mar 13, 2026
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Looks good to me from a cDAC perspective. Thanks for keeping the cDAC up to date 👍

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/ba-g unrelated CI failures

@pavelsavara
pavelsavara merged commit 41ac7d5 into dotnet:mainMar 13, 2026
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[browser][coreCLR] Loading WebCIL (#124904)
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@adamperlinadamperlinadamperlin approved these changes
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arch-wasmWebAssembly architecturearea-AssemblyLoader-coreclronly use for closed issuesos-browserBrowser variant of arch-wasm

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@pavelsavara@max-charlamb@jkotas@adamperlin@AaronRobinsonMSFT@radekdoulik
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
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var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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[browser][coreCLR] Loading WebCIL - 2nd attempt - #124904
Merged
pavelsavara merged 26 commits into
dotnet:mainfrom 
pavelsavara:loading_webcil2
Mar 13, 2026
Merged
[browser][coreCLR] Loading WebCIL - 2nd attempt#124904
pavelsavara merged 26 commits into
dotnet:mainfrom 
pavelsavara:loading_webcil2
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Enable Webcil loading in CoreCLR for Browser/WASM
Summary
Adds native Webcil container format support to the CoreCLR runtime, enabling CoreCLR-on-WASM to load .wasm-wrapped assemblies directly — previously only supported by the Mono runtime. Removes the WasmEnableWebcil=false override that was forcing CoreCLR browser builds to use raw .dll files.
Changes
CoreCLR Webcil decoder (src/coreclr/)
  • New WebcilDecoder class (webcildecoder.h, webcildecoder.cpp) — standalone reader for the Webcil container format with full RVA/offset translation, COR header resolution, metadata access, section validation, IL method checking, debug directory support, and DAC enumeration.
  • FEATURE_WEBCIL cmake gate enabled for CLR_CMAKE_TARGET_BROWSER (clrfeatures.cmake, clrdefinitions.cmake).
PEImageLayout composition refactor (src/coreclr/vm/)
  • PEImageLayout no longer inherits from PEDecoder; instead holds m_peDecoder (and conditionally m_webcilDecoder) as members with an ImageFormat discriminator (FORMAT_PE/FORMAT_WEBCIL).
  • ~160 inline forwarding methods in peimagelayout.inl dispatch to the active decoder via DECODER_DISPATCH/DECODER_CHECK/PE_OR_WEBCIL macros.
  • PEDecoder public API split: methods needed by PEImageLayout forwarding stay public; PE-internal helpers (GetHeaders, GetDirectoryEntry, CheckDirectoryEntry, relocation/TLS/strong-name internals, etc.) moved to a private section accessible only via friend class PEImageLayout.
  • FlatImageLayout constructor detects Webcil magic and initializes both decoders (Webcil for format operations, PE decoder for base/size/flags used by cDAC).
  • New HasHeaders() abstraction on PEImageLayout and PEImage — returns HasWebcilHeaders() or HasNTHeaders() depending on format. Callers in peassembly.cpp, peimage.cpp, eventtrace.cpp updated from HasNTHeaders() to HasHeaders().
  • debugdebugger.cpp: switched from PEDecoder* to PEImageLayout* and uses format-agnostic GetDirectoryEntryData instead of raw GetDirectoryEntry+GetDirectoryData.
  • ceeload.cpp: same PEDecoder* → PEImageLayout* fix for IJW host lookup.
  • peassembly.cpp: accept IMAGE_FILE_MACHINE_UNKNOWN (Webcil machine type) for IL-only validation; guard 32-bit NT header check with HasNTHeaders().
  • assemblybindercommon.cpp: treat IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL.
cDAC diagnostics (src/native/managed/cdac/)
  • PEImageLayout data descriptor gains Format field (datadescriptor.inc, PEImageLayout.cs).
  • Loader_1.cs: Webcil-aware RvaToOffset path that reads the Webcil section table directly from the target memory when IsWebcilFormat is set.
Build/infrastructure
  • Removed WasmEnableWebcil=false from CoreCLR browser build properties (WasmApp.InTree.props, tests.browser.targets).
  • MSBuild task renames: WebCilCandidates→WebcilCandidates, IsWebCilEnabled→IsWebcilEnabled, _WasmBuildWebCilPath→_WasmBuildWebcilPath and related properties.
  • Test infrastructure: BuildEnvironment.cs removes CoreCLR Webcil exclusion; env var WasmEnableWebCil→WasmEnableWebcil.
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added this to the 11.0.0 milestone
Feb 26, 2026
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self-assigned this
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Pull request overview
Enables CoreCLR-on-Browser/WASM to load assemblies packaged in the Webcil container format (i.e., .wasm-wrapped assemblies), aligning CoreCLR behavior with existing Mono Webcil support and removing prior build/test overrides that forced raw .dll usage.
Changes:
  • Adds CoreCLR-side Webcil decoding and wires it into PEImageLayout via format-dispatched forwarding to either PEDecoder (PE) or WebcilDecoder (Webcil).
  • Updates the Webcil tooling pipeline (converter/reader/wrapper + MSBuild tasks/targets) including 16-byte section alignment and property renames (WebCil* → Webcil*).
  • Extends cDAC contracts/readers and WASM test infrastructure to understand and exercise Webcil images.
Reviewed changes
Copilot reviewed 35 out of 35 changed files in this pull request and generated 6 comments.
Show a summary per file
FileDescription
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilWasmWrapper.csImproves wrapper error message for payload offset validation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.csUpdates to PascalCase header fields and adds bounds checking in RVA translation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilHeader.csRenames Webcil header fields to PascalCase for consistency.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.csImplements 16-byte section alignment, debug directory translation, and related validations.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.csRenames output item list to WebcilCandidates.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.csRenames task property to IsWebcilEnabled and updates usage.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.csAdds Format field to contract + helper to detect Webcil format.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.csAdds Webcil-aware RVA-to-offset logic by reading Webcil section table from target memory.
src/mono/wasm/features.mdDocumentation update: “WebCIL” → “Webcil”.
src/mono/wasm/Wasm.Build.Tests/Common/BuildEnvironment.csRemoves CoreCLR Webcil exclusion; renames env var WasmEnableWebcil.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targetsRenames MSBuild properties/items/parameters from WebCil → Webcil.
src/mono/cmake/options.cmakeDocumentation string update for ENABLE_WEBCIL.
src/mono/cmake/config.h.inComment update for ENABLE_WEBCIL.
src/mono/browser/debugger/BrowserDebugProxy/DebugStore.csDocumentation wording update for Webcil handling.
src/mono/browser/build/WasmApp.InTree.propsRemoves CoreCLR WasmEnableWebcil=false override.
src/coreclr/vm/peimagelayout.inlAdds decoder-dispatch forwarding methods; introduces format-agnostic header checks.
src/coreclr/vm/peimagelayout.hRefactors PEImageLayout to composition with PEDecoder/WebcilDecoder and ImageFormat discriminator.
src/coreclr/vm/peimagelayout.cppInitializes Webcil decoder on detection; updates PEDecoder init/reset call sites; DAC enumeration dispatch.
src/coreclr/vm/peimage.inlAdds PEImage::HasHeaders() helper.
src/coreclr/vm/peimage.hDeclares HasHeaders() in PEImage.
src/coreclr/vm/peimage.cppUses HasHeaders() instead of HasNTHeaders() in metadata/debug-directory paths.
src/coreclr/vm/peassembly.cppAccepts IMAGE_FILE_MACHINE_UNKNOWN for IL-only validation; guards 32-bit header check.
src/coreclr/vm/eventtrace.cppSwitches checks from NT headers to format-agnostic headers.
src/coreclr/vm/debugdebugger.cppSwitches from PEDecoder* to PEImageLayout* and uses GetDirectoryEntryData.
src/coreclr/vm/datadescriptor/datadescriptor.incAdds Format field to PEImageLayout’s cDAC data descriptor.
src/coreclr/vm/ceeload.cppUpdates IJW lookup to use PEImageLayout* (post-inheritance refactor).
src/coreclr/utilcode/webcildecoder.cppAdds CoreCLR Webcil decoding/validation implementation and DAC enumeration support.
src/coreclr/utilcode/CMakeLists.txtAdds webcildecoder.cpp to utilcode build.
src/coreclr/inc/webcildecoder.hAdds Webcil structures and WebcilDecoder API.
src/coreclr/inc/pedecoder.hMakes PEImageLayout a friend and restricts PE-internal APIs to PEImageLayout usage.
src/coreclr/clrfeatures.cmakeEnables FEATURE_WEBCIL for browser builds.
src/coreclr/clrdefinitions.cmakeAdds FEATURE_WEBCIL compile definition when enabled.
src/coreclr/binder/assemblybindercommon.cppTreats IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL in binder logic.
eng/testing/tests.browser.targetsRemoves CoreCLR WasmEnableWebcil=false override for browser tests.
docs/design/mono/webcil.mdUpdates spec text for alignment and PascalCase field names + naming consistency.
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Outdated

Comment threadsrc/coreclr/vm/peimagelayout.inl
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Copilot reviewed 35 out of 35 changed files in this pull request and generated 4 comments.
Comments suppressed due to low confidence (1)
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.cs:354
  • New exceptions in TranslateRVA use nameof(_stream) as the parameter name. Since _stream is a private field (not a parameter), this produces a less helpful ParamName than nameof(stream) (constructor parameter) or omitting the param name entirely. Consider aligning with the earlier constructor exceptions which use nameof(stream).
Comment threadsrc/coreclr/vm/peimagelayout.inl
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Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 2 comments.
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Copilot reviewed 33 out of 33 changed files in this pull request and generated 6 comments.
Comments suppressed due to low confidence (1)
src/coreclr/utilcode/CMakeLists.txt:1
  • webcildecoder.cpp is added unconditionally to UTILCODE_COMMON_SOURCES. When FEATURE_WEBCIL is off this compiles an effectively empty translation unit, which is small but avoidable build work. Consider conditionally appending webcildecoder.cpp only when FEATURE_WEBCIL is enabled (or CLR_CMAKE_TARGET_BROWSER), to keep non-browser builds slightly leaner.
set(CMAKE_INCLUDE_CURRENT_DIR ON)

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment threadsrc/coreclr/inc/cordecoderhelpers.h
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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@pavelsavara
Potential fix for pull request finding
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Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Copilot reviewed 34 out of 34 changed files in this pull request and generated 6 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threaddocs/design/datacontracts/Loader.md
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp

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Looks good to me from a cDAC perspective. Thanks for keeping the cDAC up to date 👍
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/ba-g unrelated CI failures
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[browser][coreCLR] Loading WebCIL (#124904)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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[browser][coreCLR] Loading WebCIL - 2nd attempt - #124904
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pavelsavara:loading_webcil2
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[browser][coreCLR] Loading WebCIL - 2nd attempt#124904
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pavelsavara:loading_webcil2
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Enable Webcil loading in CoreCLR for Browser/WASM
Summary
Adds native Webcil container format support to the CoreCLR runtime, enabling CoreCLR-on-WASM to load .wasm-wrapped assemblies directly — previously only supported by the Mono runtime. Removes the WasmEnableWebcil=false override that was forcing CoreCLR browser builds to use raw .dll files.
Changes
CoreCLR Webcil decoder (src/coreclr/)
  • New WebcilDecoder class (webcildecoder.h, webcildecoder.cpp) — standalone reader for the Webcil container format with full RVA/offset translation, COR header resolution, metadata access, section validation, IL method checking, debug directory support, and DAC enumeration.
  • FEATURE_WEBCIL cmake gate enabled for CLR_CMAKE_TARGET_BROWSER (clrfeatures.cmake, clrdefinitions.cmake).
PEImageLayout composition refactor (src/coreclr/vm/)
  • PEImageLayout no longer inherits from PEDecoder; instead holds m_peDecoder (and conditionally m_webcilDecoder) as members with an ImageFormat discriminator (FORMAT_PE/FORMAT_WEBCIL).
  • ~160 inline forwarding methods in peimagelayout.inl dispatch to the active decoder via DECODER_DISPATCH/DECODER_CHECK/PE_OR_WEBCIL macros.
  • PEDecoder public API split: methods needed by PEImageLayout forwarding stay public; PE-internal helpers (GetHeaders, GetDirectoryEntry, CheckDirectoryEntry, relocation/TLS/strong-name internals, etc.) moved to a private section accessible only via friend class PEImageLayout.
  • FlatImageLayout constructor detects Webcil magic and initializes both decoders (Webcil for format operations, PE decoder for base/size/flags used by cDAC).
  • New HasHeaders() abstraction on PEImageLayout and PEImage — returns HasWebcilHeaders() or HasNTHeaders() depending on format. Callers in peassembly.cpp, peimage.cpp, eventtrace.cpp updated from HasNTHeaders() to HasHeaders().
  • debugdebugger.cpp: switched from PEDecoder* to PEImageLayout* and uses format-agnostic GetDirectoryEntryData instead of raw GetDirectoryEntry+GetDirectoryData.
  • ceeload.cpp: same PEDecoder* → PEImageLayout* fix for IJW host lookup.
  • peassembly.cpp: accept IMAGE_FILE_MACHINE_UNKNOWN (Webcil machine type) for IL-only validation; guard 32-bit NT header check with HasNTHeaders().
  • assemblybindercommon.cpp: treat IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL.
cDAC diagnostics (src/native/managed/cdac/)
  • PEImageLayout data descriptor gains Format field (datadescriptor.inc, PEImageLayout.cs).
  • Loader_1.cs: Webcil-aware RvaToOffset path that reads the Webcil section table directly from the target memory when IsWebcilFormat is set.
Build/infrastructure
  • Removed WasmEnableWebcil=false from CoreCLR browser build properties (WasmApp.InTree.props, tests.browser.targets).
  • MSBuild task renames: WebCilCandidates→WebcilCandidates, IsWebCilEnabled→IsWebcilEnabled, _WasmBuildWebCilPath→_WasmBuildWebcilPath and related properties.
  • Test infrastructure: BuildEnvironment.cs removes CoreCLR Webcil exclusion; env var WasmEnableWebCil→WasmEnableWebcil.
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Pull request overview
Enables CoreCLR-on-Browser/WASM to load assemblies packaged in the Webcil container format (i.e., .wasm-wrapped assemblies), aligning CoreCLR behavior with existing Mono Webcil support and removing prior build/test overrides that forced raw .dll usage.
Changes:
  • Adds CoreCLR-side Webcil decoding and wires it into PEImageLayout via format-dispatched forwarding to either PEDecoder (PE) or WebcilDecoder (Webcil).
  • Updates the Webcil tooling pipeline (converter/reader/wrapper + MSBuild tasks/targets) including 16-byte section alignment and property renames (WebCil* → Webcil*).
  • Extends cDAC contracts/readers and WASM test infrastructure to understand and exercise Webcil images.
Reviewed changes
Copilot reviewed 35 out of 35 changed files in this pull request and generated 6 comments.
Show a summary per file
FileDescription
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilWasmWrapper.csImproves wrapper error message for payload offset validation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.csUpdates to PascalCase header fields and adds bounds checking in RVA translation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilHeader.csRenames Webcil header fields to PascalCase for consistency.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.csImplements 16-byte section alignment, debug directory translation, and related validations.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.csRenames output item list to WebcilCandidates.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.csRenames task property to IsWebcilEnabled and updates usage.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.csAdds Format field to contract + helper to detect Webcil format.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.csAdds Webcil-aware RVA-to-offset logic by reading Webcil section table from target memory.
src/mono/wasm/features.mdDocumentation update: “WebCIL” → “Webcil”.
src/mono/wasm/Wasm.Build.Tests/Common/BuildEnvironment.csRemoves CoreCLR Webcil exclusion; renames env var WasmEnableWebcil.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targetsRenames MSBuild properties/items/parameters from WebCil → Webcil.
src/mono/cmake/options.cmakeDocumentation string update for ENABLE_WEBCIL.
src/mono/cmake/config.h.inComment update for ENABLE_WEBCIL.
src/mono/browser/debugger/BrowserDebugProxy/DebugStore.csDocumentation wording update for Webcil handling.
src/mono/browser/build/WasmApp.InTree.propsRemoves CoreCLR WasmEnableWebcil=false override.
src/coreclr/vm/peimagelayout.inlAdds decoder-dispatch forwarding methods; introduces format-agnostic header checks.
src/coreclr/vm/peimagelayout.hRefactors PEImageLayout to composition with PEDecoder/WebcilDecoder and ImageFormat discriminator.
src/coreclr/vm/peimagelayout.cppInitializes Webcil decoder on detection; updates PEDecoder init/reset call sites; DAC enumeration dispatch.
src/coreclr/vm/peimage.inlAdds PEImage::HasHeaders() helper.
src/coreclr/vm/peimage.hDeclares HasHeaders() in PEImage.
src/coreclr/vm/peimage.cppUses HasHeaders() instead of HasNTHeaders() in metadata/debug-directory paths.
src/coreclr/vm/peassembly.cppAccepts IMAGE_FILE_MACHINE_UNKNOWN for IL-only validation; guards 32-bit header check.
src/coreclr/vm/eventtrace.cppSwitches checks from NT headers to format-agnostic headers.
src/coreclr/vm/debugdebugger.cppSwitches from PEDecoder* to PEImageLayout* and uses GetDirectoryEntryData.
src/coreclr/vm/datadescriptor/datadescriptor.incAdds Format field to PEImageLayout’s cDAC data descriptor.
src/coreclr/vm/ceeload.cppUpdates IJW lookup to use PEImageLayout* (post-inheritance refactor).
src/coreclr/utilcode/webcildecoder.cppAdds CoreCLR Webcil decoding/validation implementation and DAC enumeration support.
src/coreclr/utilcode/CMakeLists.txtAdds webcildecoder.cpp to utilcode build.
src/coreclr/inc/webcildecoder.hAdds Webcil structures and WebcilDecoder API.
src/coreclr/inc/pedecoder.hMakes PEImageLayout a friend and restricts PE-internal APIs to PEImageLayout usage.
src/coreclr/clrfeatures.cmakeEnables FEATURE_WEBCIL for browser builds.
src/coreclr/clrdefinitions.cmakeAdds FEATURE_WEBCIL compile definition when enabled.
src/coreclr/binder/assemblybindercommon.cppTreats IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL in binder logic.
eng/testing/tests.browser.targetsRemoves CoreCLR WasmEnableWebcil=false override for browser tests.
docs/design/mono/webcil.mdUpdates spec text for alignment and PascalCase field names + naming consistency.
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/vm/peimagelayout.inl
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 4 comments.
Comments suppressed due to low confidence (1)
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.cs:354
  • New exceptions in TranslateRVA use nameof(_stream) as the parameter name. Since _stream is a private field (not a parameter), this produces a less helpful ParamName than nameof(stream) (constructor parameter) or omitting the param name entirely. Consider aligning with the earlier constructor exceptions which use nameof(stream).
Comment threadsrc/coreclr/vm/peimagelayout.inl
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Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 2 comments.
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 6 comments.
Comments suppressed due to low confidence (1)
src/coreclr/utilcode/CMakeLists.txt:1
  • webcildecoder.cpp is added unconditionally to UTILCODE_COMMON_SOURCES. When FEATURE_WEBCIL is off this compiles an effectively empty translation unit, which is small but avoidable build work. Consider conditionally appending webcildecoder.cpp only when FEATURE_WEBCIL is enabled (or CLR_CMAKE_TARGET_BROWSER), to keep non-browser builds slightly leaner.
set(CMAKE_INCLUDE_CURRENT_DIR ON)

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment threadsrc/coreclr/inc/cordecoderhelpers.h
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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@pavelsavara
Potential fix for pull request finding
c69c839
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Pull request overview
Copilot reviewed 34 out of 34 changed files in this pull request and generated 6 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threaddocs/design/datacontracts/Loader.md
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp

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Looks good to me from a cDAC perspective. Thanks for keeping the cDAC up to date 👍
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/ba-g unrelated CI failures
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158 of 166 checks passed

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[browser][coreCLR] Loading WebCIL (#124904)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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[browser][coreCLR] Loading WebCIL - 2nd attempt - #124904
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pavelsavara merged 26 commits into
dotnet:mainfrom 
pavelsavara:loading_webcil2
Mar 13, 2026
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[browser][coreCLR] Loading WebCIL - 2nd attempt#124904
pavelsavara merged 26 commits into
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pavelsavara:loading_webcil2
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Enable Webcil loading in CoreCLR for Browser/WASM
Summary
Adds native Webcil container format support to the CoreCLR runtime, enabling CoreCLR-on-WASM to load .wasm-wrapped assemblies directly — previously only supported by the Mono runtime. Removes the WasmEnableWebcil=false override that was forcing CoreCLR browser builds to use raw .dll files.
Changes
CoreCLR Webcil decoder (src/coreclr/)
  • New WebcilDecoder class (webcildecoder.h, webcildecoder.cpp) — standalone reader for the Webcil container format with full RVA/offset translation, COR header resolution, metadata access, section validation, IL method checking, debug directory support, and DAC enumeration.
  • FEATURE_WEBCIL cmake gate enabled for CLR_CMAKE_TARGET_BROWSER (clrfeatures.cmake, clrdefinitions.cmake).
PEImageLayout composition refactor (src/coreclr/vm/)
  • PEImageLayout no longer inherits from PEDecoder; instead holds m_peDecoder (and conditionally m_webcilDecoder) as members with an ImageFormat discriminator (FORMAT_PE/FORMAT_WEBCIL).
  • ~160 inline forwarding methods in peimagelayout.inl dispatch to the active decoder via DECODER_DISPATCH/DECODER_CHECK/PE_OR_WEBCIL macros.
  • PEDecoder public API split: methods needed by PEImageLayout forwarding stay public; PE-internal helpers (GetHeaders, GetDirectoryEntry, CheckDirectoryEntry, relocation/TLS/strong-name internals, etc.) moved to a private section accessible only via friend class PEImageLayout.
  • FlatImageLayout constructor detects Webcil magic and initializes both decoders (Webcil for format operations, PE decoder for base/size/flags used by cDAC).
  • New HasHeaders() abstraction on PEImageLayout and PEImage — returns HasWebcilHeaders() or HasNTHeaders() depending on format. Callers in peassembly.cpp, peimage.cpp, eventtrace.cpp updated from HasNTHeaders() to HasHeaders().
  • debugdebugger.cpp: switched from PEDecoder* to PEImageLayout* and uses format-agnostic GetDirectoryEntryData instead of raw GetDirectoryEntry+GetDirectoryData.
  • ceeload.cpp: same PEDecoder* → PEImageLayout* fix for IJW host lookup.
  • peassembly.cpp: accept IMAGE_FILE_MACHINE_UNKNOWN (Webcil machine type) for IL-only validation; guard 32-bit NT header check with HasNTHeaders().
  • assemblybindercommon.cpp: treat IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL.
cDAC diagnostics (src/native/managed/cdac/)
  • PEImageLayout data descriptor gains Format field (datadescriptor.inc, PEImageLayout.cs).
  • Loader_1.cs: Webcil-aware RvaToOffset path that reads the Webcil section table directly from the target memory when IsWebcilFormat is set.
Build/infrastructure
  • Removed WasmEnableWebcil=false from CoreCLR browser build properties (WasmApp.InTree.props, tests.browser.targets).
  • MSBuild task renames: WebCilCandidates→WebcilCandidates, IsWebCilEnabled→IsWebcilEnabled, _WasmBuildWebCilPath→_WasmBuildWebcilPath and related properties.
  • Test infrastructure: BuildEnvironment.cs removes CoreCLR Webcil exclusion; env var WasmEnableWebCil→WasmEnableWebcil.
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added this to the 11.0.0 milestone
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Pull request overview
Enables CoreCLR-on-Browser/WASM to load assemblies packaged in the Webcil container format (i.e., .wasm-wrapped assemblies), aligning CoreCLR behavior with existing Mono Webcil support and removing prior build/test overrides that forced raw .dll usage.
Changes:
  • Adds CoreCLR-side Webcil decoding and wires it into PEImageLayout via format-dispatched forwarding to either PEDecoder (PE) or WebcilDecoder (Webcil).
  • Updates the Webcil tooling pipeline (converter/reader/wrapper + MSBuild tasks/targets) including 16-byte section alignment and property renames (WebCil* → Webcil*).
  • Extends cDAC contracts/readers and WASM test infrastructure to understand and exercise Webcil images.
Reviewed changes
Copilot reviewed 35 out of 35 changed files in this pull request and generated 6 comments.
Show a summary per file
FileDescription
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilWasmWrapper.csImproves wrapper error message for payload offset validation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.csUpdates to PascalCase header fields and adds bounds checking in RVA translation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilHeader.csRenames Webcil header fields to PascalCase for consistency.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.csImplements 16-byte section alignment, debug directory translation, and related validations.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.csRenames output item list to WebcilCandidates.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.csRenames task property to IsWebcilEnabled and updates usage.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.csAdds Format field to contract + helper to detect Webcil format.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.csAdds Webcil-aware RVA-to-offset logic by reading Webcil section table from target memory.
src/mono/wasm/features.mdDocumentation update: “WebCIL” → “Webcil”.
src/mono/wasm/Wasm.Build.Tests/Common/BuildEnvironment.csRemoves CoreCLR Webcil exclusion; renames env var WasmEnableWebcil.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targetsRenames MSBuild properties/items/parameters from WebCil → Webcil.
src/mono/cmake/options.cmakeDocumentation string update for ENABLE_WEBCIL.
src/mono/cmake/config.h.inComment update for ENABLE_WEBCIL.
src/mono/browser/debugger/BrowserDebugProxy/DebugStore.csDocumentation wording update for Webcil handling.
src/mono/browser/build/WasmApp.InTree.propsRemoves CoreCLR WasmEnableWebcil=false override.
src/coreclr/vm/peimagelayout.inlAdds decoder-dispatch forwarding methods; introduces format-agnostic header checks.
src/coreclr/vm/peimagelayout.hRefactors PEImageLayout to composition with PEDecoder/WebcilDecoder and ImageFormat discriminator.
src/coreclr/vm/peimagelayout.cppInitializes Webcil decoder on detection; updates PEDecoder init/reset call sites; DAC enumeration dispatch.
src/coreclr/vm/peimage.inlAdds PEImage::HasHeaders() helper.
src/coreclr/vm/peimage.hDeclares HasHeaders() in PEImage.
src/coreclr/vm/peimage.cppUses HasHeaders() instead of HasNTHeaders() in metadata/debug-directory paths.
src/coreclr/vm/peassembly.cppAccepts IMAGE_FILE_MACHINE_UNKNOWN for IL-only validation; guards 32-bit header check.
src/coreclr/vm/eventtrace.cppSwitches checks from NT headers to format-agnostic headers.
src/coreclr/vm/debugdebugger.cppSwitches from PEDecoder* to PEImageLayout* and uses GetDirectoryEntryData.
src/coreclr/vm/datadescriptor/datadescriptor.incAdds Format field to PEImageLayout’s cDAC data descriptor.
src/coreclr/vm/ceeload.cppUpdates IJW lookup to use PEImageLayout* (post-inheritance refactor).
src/coreclr/utilcode/webcildecoder.cppAdds CoreCLR Webcil decoding/validation implementation and DAC enumeration support.
src/coreclr/utilcode/CMakeLists.txtAdds webcildecoder.cpp to utilcode build.
src/coreclr/inc/webcildecoder.hAdds Webcil structures and WebcilDecoder API.
src/coreclr/inc/pedecoder.hMakes PEImageLayout a friend and restricts PE-internal APIs to PEImageLayout usage.
src/coreclr/clrfeatures.cmakeEnables FEATURE_WEBCIL for browser builds.
src/coreclr/clrdefinitions.cmakeAdds FEATURE_WEBCIL compile definition when enabled.
src/coreclr/binder/assemblybindercommon.cppTreats IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL in binder logic.
eng/testing/tests.browser.targetsRemoves CoreCLR WasmEnableWebcil=false override for browser tests.
docs/design/mono/webcil.mdUpdates spec text for alignment and PascalCase field names + naming consistency.
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Outdated

Comment threadsrc/coreclr/vm/peimagelayout.inl
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Outdated

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Outdated

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 4 comments.
Comments suppressed due to low confidence (1)
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.cs:354
  • New exceptions in TranslateRVA use nameof(_stream) as the parameter name. Since _stream is a private field (not a parameter), this produces a less helpful ParamName than nameof(stream) (constructor parameter) or omitting the param name entirely. Consider aligning with the earlier constructor exceptions which use nameof(stream).
Comment threadsrc/coreclr/vm/peimagelayout.inl
Outdated

Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 2 comments.
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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February 26, 2026 17:55
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 6 comments.
Comments suppressed due to low confidence (1)
src/coreclr/utilcode/CMakeLists.txt:1
  • webcildecoder.cpp is added unconditionally to UTILCODE_COMMON_SOURCES. When FEATURE_WEBCIL is off this compiles an effectively empty translation unit, which is small but avoidable build work. Consider conditionally appending webcildecoder.cpp only when FEATURE_WEBCIL is enabled (or CLR_CMAKE_TARGET_BROWSER), to keep non-browser builds slightly leaner.
set(CMAKE_INCLUDE_CURRENT_DIR ON)

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment threadsrc/coreclr/inc/cordecoderhelpers.h
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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@pavelsavara
Potential fix for pull request finding
c69c839
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Pull request overview
Copilot reviewed 34 out of 34 changed files in this pull request and generated 6 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Outdated

Comment threaddocs/design/datacontracts/Loader.md
Outdated

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp

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Looks good to me from a cDAC perspective. Thanks for keeping the cDAC up to date 👍
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/ba-g unrelated CI failures
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[browser][coreCLR] Loading WebCIL (#124904)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
[browser][coreCLR] Loading WebCIL - 2nd attempt - #124904
Merged
pavelsavara merged 26 commits into
dotnet:mainfrom 
pavelsavara:loading_webcil2
Mar 13, 2026
Merged
[browser][coreCLR] Loading WebCIL - 2nd attempt#124904
pavelsavara merged 26 commits into
dotnet:mainfrom 
pavelsavara:loading_webcil2
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Enable Webcil loading in CoreCLR for Browser/WASM
Summary
Adds native Webcil container format support to the CoreCLR runtime, enabling CoreCLR-on-WASM to load .wasm-wrapped assemblies directly — previously only supported by the Mono runtime. Removes the WasmEnableWebcil=false override that was forcing CoreCLR browser builds to use raw .dll files.
Changes
CoreCLR Webcil decoder (src/coreclr/)
  • New WebcilDecoder class (webcildecoder.h, webcildecoder.cpp) — standalone reader for the Webcil container format with full RVA/offset translation, COR header resolution, metadata access, section validation, IL method checking, debug directory support, and DAC enumeration.
  • FEATURE_WEBCIL cmake gate enabled for CLR_CMAKE_TARGET_BROWSER (clrfeatures.cmake, clrdefinitions.cmake).
PEImageLayout composition refactor (src/coreclr/vm/)
  • PEImageLayout no longer inherits from PEDecoder; instead holds m_peDecoder (and conditionally m_webcilDecoder) as members with an ImageFormat discriminator (FORMAT_PE/FORMAT_WEBCIL).
  • ~160 inline forwarding methods in peimagelayout.inl dispatch to the active decoder via DECODER_DISPATCH/DECODER_CHECK/PE_OR_WEBCIL macros.
  • PEDecoder public API split: methods needed by PEImageLayout forwarding stay public; PE-internal helpers (GetHeaders, GetDirectoryEntry, CheckDirectoryEntry, relocation/TLS/strong-name internals, etc.) moved to a private section accessible only via friend class PEImageLayout.
  • FlatImageLayout constructor detects Webcil magic and initializes both decoders (Webcil for format operations, PE decoder for base/size/flags used by cDAC).
  • New HasHeaders() abstraction on PEImageLayout and PEImage — returns HasWebcilHeaders() or HasNTHeaders() depending on format. Callers in peassembly.cpp, peimage.cpp, eventtrace.cpp updated from HasNTHeaders() to HasHeaders().
  • debugdebugger.cpp: switched from PEDecoder* to PEImageLayout* and uses format-agnostic GetDirectoryEntryData instead of raw GetDirectoryEntry+GetDirectoryData.
  • ceeload.cpp: same PEDecoder* → PEImageLayout* fix for IJW host lookup.
  • peassembly.cpp: accept IMAGE_FILE_MACHINE_UNKNOWN (Webcil machine type) for IL-only validation; guard 32-bit NT header check with HasNTHeaders().
  • assemblybindercommon.cpp: treat IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL.
cDAC diagnostics (src/native/managed/cdac/)
  • PEImageLayout data descriptor gains Format field (datadescriptor.inc, PEImageLayout.cs).
  • Loader_1.cs: Webcil-aware RvaToOffset path that reads the Webcil section table directly from the target memory when IsWebcilFormat is set.
Build/infrastructure
  • Removed WasmEnableWebcil=false from CoreCLR browser build properties (WasmApp.InTree.props, tests.browser.targets).
  • MSBuild task renames: WebCilCandidates→WebcilCandidates, IsWebCilEnabled→IsWebcilEnabled, _WasmBuildWebCilPath→_WasmBuildWebcilPath and related properties.
  • Test infrastructure: BuildEnvironment.cs removes CoreCLR Webcil exclusion; env var WasmEnableWebCil→WasmEnableWebcil.
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Pull request overview
Enables CoreCLR-on-Browser/WASM to load assemblies packaged in the Webcil container format (i.e., .wasm-wrapped assemblies), aligning CoreCLR behavior with existing Mono Webcil support and removing prior build/test overrides that forced raw .dll usage.
Changes:
  • Adds CoreCLR-side Webcil decoding and wires it into PEImageLayout via format-dispatched forwarding to either PEDecoder (PE) or WebcilDecoder (Webcil).
  • Updates the Webcil tooling pipeline (converter/reader/wrapper + MSBuild tasks/targets) including 16-byte section alignment and property renames (WebCil* → Webcil*).
  • Extends cDAC contracts/readers and WASM test infrastructure to understand and exercise Webcil images.
Reviewed changes
Copilot reviewed 35 out of 35 changed files in this pull request and generated 6 comments.
Show a summary per file
FileDescription
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilWasmWrapper.csImproves wrapper error message for payload offset validation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.csUpdates to PascalCase header fields and adds bounds checking in RVA translation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilHeader.csRenames Webcil header fields to PascalCase for consistency.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.csImplements 16-byte section alignment, debug directory translation, and related validations.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.csRenames output item list to WebcilCandidates.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.csRenames task property to IsWebcilEnabled and updates usage.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.csAdds Format field to contract + helper to detect Webcil format.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.csAdds Webcil-aware RVA-to-offset logic by reading Webcil section table from target memory.
src/mono/wasm/features.mdDocumentation update: “WebCIL” → “Webcil”.
src/mono/wasm/Wasm.Build.Tests/Common/BuildEnvironment.csRemoves CoreCLR Webcil exclusion; renames env var WasmEnableWebcil.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targetsRenames MSBuild properties/items/parameters from WebCil → Webcil.
src/mono/cmake/options.cmakeDocumentation string update for ENABLE_WEBCIL.
src/mono/cmake/config.h.inComment update for ENABLE_WEBCIL.
src/mono/browser/debugger/BrowserDebugProxy/DebugStore.csDocumentation wording update for Webcil handling.
src/mono/browser/build/WasmApp.InTree.propsRemoves CoreCLR WasmEnableWebcil=false override.
src/coreclr/vm/peimagelayout.inlAdds decoder-dispatch forwarding methods; introduces format-agnostic header checks.
src/coreclr/vm/peimagelayout.hRefactors PEImageLayout to composition with PEDecoder/WebcilDecoder and ImageFormat discriminator.
src/coreclr/vm/peimagelayout.cppInitializes Webcil decoder on detection; updates PEDecoder init/reset call sites; DAC enumeration dispatch.
src/coreclr/vm/peimage.inlAdds PEImage::HasHeaders() helper.
src/coreclr/vm/peimage.hDeclares HasHeaders() in PEImage.
src/coreclr/vm/peimage.cppUses HasHeaders() instead of HasNTHeaders() in metadata/debug-directory paths.
src/coreclr/vm/peassembly.cppAccepts IMAGE_FILE_MACHINE_UNKNOWN for IL-only validation; guards 32-bit header check.
src/coreclr/vm/eventtrace.cppSwitches checks from NT headers to format-agnostic headers.
src/coreclr/vm/debugdebugger.cppSwitches from PEDecoder* to PEImageLayout* and uses GetDirectoryEntryData.
src/coreclr/vm/datadescriptor/datadescriptor.incAdds Format field to PEImageLayout’s cDAC data descriptor.
src/coreclr/vm/ceeload.cppUpdates IJW lookup to use PEImageLayout* (post-inheritance refactor).
src/coreclr/utilcode/webcildecoder.cppAdds CoreCLR Webcil decoding/validation implementation and DAC enumeration support.
src/coreclr/utilcode/CMakeLists.txtAdds webcildecoder.cpp to utilcode build.
src/coreclr/inc/webcildecoder.hAdds Webcil structures and WebcilDecoder API.
src/coreclr/inc/pedecoder.hMakes PEImageLayout a friend and restricts PE-internal APIs to PEImageLayout usage.
src/coreclr/clrfeatures.cmakeEnables FEATURE_WEBCIL for browser builds.
src/coreclr/clrdefinitions.cmakeAdds FEATURE_WEBCIL compile definition when enabled.
src/coreclr/binder/assemblybindercommon.cppTreats IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL in binder logic.
eng/testing/tests.browser.targetsRemoves CoreCLR WasmEnableWebcil=false override for browser tests.
docs/design/mono/webcil.mdUpdates spec text for alignment and PascalCase field names + naming consistency.
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/vm/peimagelayout.inl
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 4 comments.
Comments suppressed due to low confidence (1)
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.cs:354
  • New exceptions in TranslateRVA use nameof(_stream) as the parameter name. Since _stream is a private field (not a parameter), this produces a less helpful ParamName than nameof(stream) (constructor parameter) or omitting the param name entirely. Consider aligning with the earlier constructor exceptions which use nameof(stream).
Comment threadsrc/coreclr/vm/peimagelayout.inl
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Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 2 comments.
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Copilot reviewed 33 out of 33 changed files in this pull request and generated 6 comments.
Comments suppressed due to low confidence (1)
src/coreclr/utilcode/CMakeLists.txt:1
  • webcildecoder.cpp is added unconditionally to UTILCODE_COMMON_SOURCES. When FEATURE_WEBCIL is off this compiles an effectively empty translation unit, which is small but avoidable build work. Consider conditionally appending webcildecoder.cpp only when FEATURE_WEBCIL is enabled (or CLR_CMAKE_TARGET_BROWSER), to keep non-browser builds slightly leaner.
set(CMAKE_INCLUDE_CURRENT_DIR ON)

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment threadsrc/coreclr/inc/cordecoderhelpers.h
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Potential fix for pull request finding
c69c839
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Pull request overview
Copilot reviewed 34 out of 34 changed files in this pull request and generated 6 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threaddocs/design/datacontracts/Loader.md
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp

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Looks good to me from a cDAC perspective. Thanks for keeping the cDAC up to date 👍
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/ba-g unrelated CI failures
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[browser][coreCLR] Loading WebCIL (#124904)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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[browser][coreCLR] Loading WebCIL - 2nd attempt - #124904
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pavelsavara:loading_webcil2
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[browser][coreCLR] Loading WebCIL - 2nd attempt#124904
pavelsavara merged 26 commits into
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pavelsavara:loading_webcil2
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Enable Webcil loading in CoreCLR for Browser/WASM
Summary
Adds native Webcil container format support to the CoreCLR runtime, enabling CoreCLR-on-WASM to load .wasm-wrapped assemblies directly — previously only supported by the Mono runtime. Removes the WasmEnableWebcil=false override that was forcing CoreCLR browser builds to use raw .dll files.
Changes
CoreCLR Webcil decoder (src/coreclr/)
  • New WebcilDecoder class (webcildecoder.h, webcildecoder.cpp) — standalone reader for the Webcil container format with full RVA/offset translation, COR header resolution, metadata access, section validation, IL method checking, debug directory support, and DAC enumeration.
  • FEATURE_WEBCIL cmake gate enabled for CLR_CMAKE_TARGET_BROWSER (clrfeatures.cmake, clrdefinitions.cmake).
PEImageLayout composition refactor (src/coreclr/vm/)
  • PEImageLayout no longer inherits from PEDecoder; instead holds m_peDecoder (and conditionally m_webcilDecoder) as members with an ImageFormat discriminator (FORMAT_PE/FORMAT_WEBCIL).
  • ~160 inline forwarding methods in peimagelayout.inl dispatch to the active decoder via DECODER_DISPATCH/DECODER_CHECK/PE_OR_WEBCIL macros.
  • PEDecoder public API split: methods needed by PEImageLayout forwarding stay public; PE-internal helpers (GetHeaders, GetDirectoryEntry, CheckDirectoryEntry, relocation/TLS/strong-name internals, etc.) moved to a private section accessible only via friend class PEImageLayout.
  • FlatImageLayout constructor detects Webcil magic and initializes both decoders (Webcil for format operations, PE decoder for base/size/flags used by cDAC).
  • New HasHeaders() abstraction on PEImageLayout and PEImage — returns HasWebcilHeaders() or HasNTHeaders() depending on format. Callers in peassembly.cpp, peimage.cpp, eventtrace.cpp updated from HasNTHeaders() to HasHeaders().
  • debugdebugger.cpp: switched from PEDecoder* to PEImageLayout* and uses format-agnostic GetDirectoryEntryData instead of raw GetDirectoryEntry+GetDirectoryData.
  • ceeload.cpp: same PEDecoder* → PEImageLayout* fix for IJW host lookup.
  • peassembly.cpp: accept IMAGE_FILE_MACHINE_UNKNOWN (Webcil machine type) for IL-only validation; guard 32-bit NT header check with HasNTHeaders().
  • assemblybindercommon.cpp: treat IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL.
cDAC diagnostics (src/native/managed/cdac/)
  • PEImageLayout data descriptor gains Format field (datadescriptor.inc, PEImageLayout.cs).
  • Loader_1.cs: Webcil-aware RvaToOffset path that reads the Webcil section table directly from the target memory when IsWebcilFormat is set.
Build/infrastructure
  • Removed WasmEnableWebcil=false from CoreCLR browser build properties (WasmApp.InTree.props, tests.browser.targets).
  • MSBuild task renames: WebCilCandidates→WebcilCandidates, IsWebCilEnabled→IsWebcilEnabled, _WasmBuildWebCilPath→_WasmBuildWebcilPath and related properties.
  • Test infrastructure: BuildEnvironment.cs removes CoreCLR Webcil exclusion; env var WasmEnableWebCil→WasmEnableWebcil.
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added this to the 11.0.0 milestone
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Pull request overview
Enables CoreCLR-on-Browser/WASM to load assemblies packaged in the Webcil container format (i.e., .wasm-wrapped assemblies), aligning CoreCLR behavior with existing Mono Webcil support and removing prior build/test overrides that forced raw .dll usage.
Changes:
  • Adds CoreCLR-side Webcil decoding and wires it into PEImageLayout via format-dispatched forwarding to either PEDecoder (PE) or WebcilDecoder (Webcil).
  • Updates the Webcil tooling pipeline (converter/reader/wrapper + MSBuild tasks/targets) including 16-byte section alignment and property renames (WebCil* → Webcil*).
  • Extends cDAC contracts/readers and WASM test infrastructure to understand and exercise Webcil images.
Reviewed changes
Copilot reviewed 35 out of 35 changed files in this pull request and generated 6 comments.
Show a summary per file
FileDescription
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilWasmWrapper.csImproves wrapper error message for payload offset validation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.csUpdates to PascalCase header fields and adds bounds checking in RVA translation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilHeader.csRenames Webcil header fields to PascalCase for consistency.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.csImplements 16-byte section alignment, debug directory translation, and related validations.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.csRenames output item list to WebcilCandidates.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.csRenames task property to IsWebcilEnabled and updates usage.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.csAdds Format field to contract + helper to detect Webcil format.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.csAdds Webcil-aware RVA-to-offset logic by reading Webcil section table from target memory.
src/mono/wasm/features.mdDocumentation update: “WebCIL” → “Webcil”.
src/mono/wasm/Wasm.Build.Tests/Common/BuildEnvironment.csRemoves CoreCLR Webcil exclusion; renames env var WasmEnableWebcil.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targetsRenames MSBuild properties/items/parameters from WebCil → Webcil.
src/mono/cmake/options.cmakeDocumentation string update for ENABLE_WEBCIL.
src/mono/cmake/config.h.inComment update for ENABLE_WEBCIL.
src/mono/browser/debugger/BrowserDebugProxy/DebugStore.csDocumentation wording update for Webcil handling.
src/mono/browser/build/WasmApp.InTree.propsRemoves CoreCLR WasmEnableWebcil=false override.
src/coreclr/vm/peimagelayout.inlAdds decoder-dispatch forwarding methods; introduces format-agnostic header checks.
src/coreclr/vm/peimagelayout.hRefactors PEImageLayout to composition with PEDecoder/WebcilDecoder and ImageFormat discriminator.
src/coreclr/vm/peimagelayout.cppInitializes Webcil decoder on detection; updates PEDecoder init/reset call sites; DAC enumeration dispatch.
src/coreclr/vm/peimage.inlAdds PEImage::HasHeaders() helper.
src/coreclr/vm/peimage.hDeclares HasHeaders() in PEImage.
src/coreclr/vm/peimage.cppUses HasHeaders() instead of HasNTHeaders() in metadata/debug-directory paths.
src/coreclr/vm/peassembly.cppAccepts IMAGE_FILE_MACHINE_UNKNOWN for IL-only validation; guards 32-bit header check.
src/coreclr/vm/eventtrace.cppSwitches checks from NT headers to format-agnostic headers.
src/coreclr/vm/debugdebugger.cppSwitches from PEDecoder* to PEImageLayout* and uses GetDirectoryEntryData.
src/coreclr/vm/datadescriptor/datadescriptor.incAdds Format field to PEImageLayout’s cDAC data descriptor.
src/coreclr/vm/ceeload.cppUpdates IJW lookup to use PEImageLayout* (post-inheritance refactor).
src/coreclr/utilcode/webcildecoder.cppAdds CoreCLR Webcil decoding/validation implementation and DAC enumeration support.
src/coreclr/utilcode/CMakeLists.txtAdds webcildecoder.cpp to utilcode build.
src/coreclr/inc/webcildecoder.hAdds Webcil structures and WebcilDecoder API.
src/coreclr/inc/pedecoder.hMakes PEImageLayout a friend and restricts PE-internal APIs to PEImageLayout usage.
src/coreclr/clrfeatures.cmakeEnables FEATURE_WEBCIL for browser builds.
src/coreclr/clrdefinitions.cmakeAdds FEATURE_WEBCIL compile definition when enabled.
src/coreclr/binder/assemblybindercommon.cppTreats IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL in binder logic.
eng/testing/tests.browser.targetsRemoves CoreCLR WasmEnableWebcil=false override for browser tests.
docs/design/mono/webcil.mdUpdates spec text for alignment and PascalCase field names + naming consistency.
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/vm/peimagelayout.inl
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 4 comments.
Comments suppressed due to low confidence (1)
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.cs:354
  • New exceptions in TranslateRVA use nameof(_stream) as the parameter name. Since _stream is a private field (not a parameter), this produces a less helpful ParamName than nameof(stream) (constructor parameter) or omitting the param name entirely. Consider aligning with the earlier constructor exceptions which use nameof(stream).
Comment threadsrc/coreclr/vm/peimagelayout.inl
Outdated

Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 2 comments.
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Copilot reviewed 33 out of 33 changed files in this pull request and generated 6 comments.
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src/coreclr/utilcode/CMakeLists.txt:1
  • webcildecoder.cpp is added unconditionally to UTILCODE_COMMON_SOURCES. When FEATURE_WEBCIL is off this compiles an effectively empty translation unit, which is small but avoidable build work. Consider conditionally appending webcildecoder.cpp only when FEATURE_WEBCIL is enabled (or CLR_CMAKE_TARGET_BROWSER), to keep non-browser builds slightly leaner.
set(CMAKE_INCLUDE_CURRENT_DIR ON)

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment threadsrc/coreclr/inc/cordecoderhelpers.h
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Potential fix for pull request finding
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Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Copilot reviewed 34 out of 34 changed files in this pull request and generated 6 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threaddocs/design/datacontracts/Loader.md
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp

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Looks good to me from a cDAC perspective. Thanks for keeping the cDAC up to date 👍
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[browser][coreCLR] Loading WebCIL (#124904)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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[browser][coreCLR] Loading WebCIL - 2nd attempt - #124904
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pavelsavara:loading_webcil2
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[browser][coreCLR] Loading WebCIL - 2nd attempt#124904
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Enable Webcil loading in CoreCLR for Browser/WASM
Summary
Adds native Webcil container format support to the CoreCLR runtime, enabling CoreCLR-on-WASM to load .wasm-wrapped assemblies directly — previously only supported by the Mono runtime. Removes the WasmEnableWebcil=false override that was forcing CoreCLR browser builds to use raw .dll files.
Changes
CoreCLR Webcil decoder (src/coreclr/)
  • New WebcilDecoder class (webcildecoder.h, webcildecoder.cpp) — standalone reader for the Webcil container format with full RVA/offset translation, COR header resolution, metadata access, section validation, IL method checking, debug directory support, and DAC enumeration.
  • FEATURE_WEBCIL cmake gate enabled for CLR_CMAKE_TARGET_BROWSER (clrfeatures.cmake, clrdefinitions.cmake).
PEImageLayout composition refactor (src/coreclr/vm/)
  • PEImageLayout no longer inherits from PEDecoder; instead holds m_peDecoder (and conditionally m_webcilDecoder) as members with an ImageFormat discriminator (FORMAT_PE/FORMAT_WEBCIL).
  • ~160 inline forwarding methods in peimagelayout.inl dispatch to the active decoder via DECODER_DISPATCH/DECODER_CHECK/PE_OR_WEBCIL macros.
  • PEDecoder public API split: methods needed by PEImageLayout forwarding stay public; PE-internal helpers (GetHeaders, GetDirectoryEntry, CheckDirectoryEntry, relocation/TLS/strong-name internals, etc.) moved to a private section accessible only via friend class PEImageLayout.
  • FlatImageLayout constructor detects Webcil magic and initializes both decoders (Webcil for format operations, PE decoder for base/size/flags used by cDAC).
  • New HasHeaders() abstraction on PEImageLayout and PEImage — returns HasWebcilHeaders() or HasNTHeaders() depending on format. Callers in peassembly.cpp, peimage.cpp, eventtrace.cpp updated from HasNTHeaders() to HasHeaders().
  • debugdebugger.cpp: switched from PEDecoder* to PEImageLayout* and uses format-agnostic GetDirectoryEntryData instead of raw GetDirectoryEntry+GetDirectoryData.
  • ceeload.cpp: same PEDecoder* → PEImageLayout* fix for IJW host lookup.
  • peassembly.cpp: accept IMAGE_FILE_MACHINE_UNKNOWN (Webcil machine type) for IL-only validation; guard 32-bit NT header check with HasNTHeaders().
  • assemblybindercommon.cpp: treat IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL.
cDAC diagnostics (src/native/managed/cdac/)
  • PEImageLayout data descriptor gains Format field (datadescriptor.inc, PEImageLayout.cs).
  • Loader_1.cs: Webcil-aware RvaToOffset path that reads the Webcil section table directly from the target memory when IsWebcilFormat is set.
Build/infrastructure
  • Removed WasmEnableWebcil=false from CoreCLR browser build properties (WasmApp.InTree.props, tests.browser.targets).
  • MSBuild task renames: WebCilCandidates→WebcilCandidates, IsWebCilEnabled→IsWebcilEnabled, _WasmBuildWebCilPath→_WasmBuildWebcilPath and related properties.
  • Test infrastructure: BuildEnvironment.cs removes CoreCLR Webcil exclusion; env var WasmEnableWebCil→WasmEnableWebcil.
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Pull request overview
Enables CoreCLR-on-Browser/WASM to load assemblies packaged in the Webcil container format (i.e., .wasm-wrapped assemblies), aligning CoreCLR behavior with existing Mono Webcil support and removing prior build/test overrides that forced raw .dll usage.
Changes:
  • Adds CoreCLR-side Webcil decoding and wires it into PEImageLayout via format-dispatched forwarding to either PEDecoder (PE) or WebcilDecoder (Webcil).
  • Updates the Webcil tooling pipeline (converter/reader/wrapper + MSBuild tasks/targets) including 16-byte section alignment and property renames (WebCil* → Webcil*).
  • Extends cDAC contracts/readers and WASM test infrastructure to understand and exercise Webcil images.
Reviewed changes
Copilot reviewed 35 out of 35 changed files in this pull request and generated 6 comments.
Show a summary per file
FileDescription
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilWasmWrapper.csImproves wrapper error message for payload offset validation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.csUpdates to PascalCase header fields and adds bounds checking in RVA translation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilHeader.csRenames Webcil header fields to PascalCase for consistency.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.csImplements 16-byte section alignment, debug directory translation, and related validations.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.csRenames output item list to WebcilCandidates.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.csRenames task property to IsWebcilEnabled and updates usage.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.csAdds Format field to contract + helper to detect Webcil format.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.csAdds Webcil-aware RVA-to-offset logic by reading Webcil section table from target memory.
src/mono/wasm/features.mdDocumentation update: “WebCIL” → “Webcil”.
src/mono/wasm/Wasm.Build.Tests/Common/BuildEnvironment.csRemoves CoreCLR Webcil exclusion; renames env var WasmEnableWebcil.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targetsRenames MSBuild properties/items/parameters from WebCil → Webcil.
src/mono/cmake/options.cmakeDocumentation string update for ENABLE_WEBCIL.
src/mono/cmake/config.h.inComment update for ENABLE_WEBCIL.
src/mono/browser/debugger/BrowserDebugProxy/DebugStore.csDocumentation wording update for Webcil handling.
src/mono/browser/build/WasmApp.InTree.propsRemoves CoreCLR WasmEnableWebcil=false override.
src/coreclr/vm/peimagelayout.inlAdds decoder-dispatch forwarding methods; introduces format-agnostic header checks.
src/coreclr/vm/peimagelayout.hRefactors PEImageLayout to composition with PEDecoder/WebcilDecoder and ImageFormat discriminator.
src/coreclr/vm/peimagelayout.cppInitializes Webcil decoder on detection; updates PEDecoder init/reset call sites; DAC enumeration dispatch.
src/coreclr/vm/peimage.inlAdds PEImage::HasHeaders() helper.
src/coreclr/vm/peimage.hDeclares HasHeaders() in PEImage.
src/coreclr/vm/peimage.cppUses HasHeaders() instead of HasNTHeaders() in metadata/debug-directory paths.
src/coreclr/vm/peassembly.cppAccepts IMAGE_FILE_MACHINE_UNKNOWN for IL-only validation; guards 32-bit header check.
src/coreclr/vm/eventtrace.cppSwitches checks from NT headers to format-agnostic headers.
src/coreclr/vm/debugdebugger.cppSwitches from PEDecoder* to PEImageLayout* and uses GetDirectoryEntryData.
src/coreclr/vm/datadescriptor/datadescriptor.incAdds Format field to PEImageLayout’s cDAC data descriptor.
src/coreclr/vm/ceeload.cppUpdates IJW lookup to use PEImageLayout* (post-inheritance refactor).
src/coreclr/utilcode/webcildecoder.cppAdds CoreCLR Webcil decoding/validation implementation and DAC enumeration support.
src/coreclr/utilcode/CMakeLists.txtAdds webcildecoder.cpp to utilcode build.
src/coreclr/inc/webcildecoder.hAdds Webcil structures and WebcilDecoder API.
src/coreclr/inc/pedecoder.hMakes PEImageLayout a friend and restricts PE-internal APIs to PEImageLayout usage.
src/coreclr/clrfeatures.cmakeEnables FEATURE_WEBCIL for browser builds.
src/coreclr/clrdefinitions.cmakeAdds FEATURE_WEBCIL compile definition when enabled.
src/coreclr/binder/assemblybindercommon.cppTreats IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL in binder logic.
eng/testing/tests.browser.targetsRemoves CoreCLR WasmEnableWebcil=false override for browser tests.
docs/design/mono/webcil.mdUpdates spec text for alignment and PascalCase field names + naming consistency.
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/vm/peimagelayout.inl
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 4 comments.
Comments suppressed due to low confidence (1)
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.cs:354
  • New exceptions in TranslateRVA use nameof(_stream) as the parameter name. Since _stream is a private field (not a parameter), this produces a less helpful ParamName than nameof(stream) (constructor parameter) or omitting the param name entirely. Consider aligning with the earlier constructor exceptions which use nameof(stream).
Comment threadsrc/coreclr/vm/peimagelayout.inl
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Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 2 comments.
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 6 comments.
Comments suppressed due to low confidence (1)
src/coreclr/utilcode/CMakeLists.txt:1
  • webcildecoder.cpp is added unconditionally to UTILCODE_COMMON_SOURCES. When FEATURE_WEBCIL is off this compiles an effectively empty translation unit, which is small but avoidable build work. Consider conditionally appending webcildecoder.cpp only when FEATURE_WEBCIL is enabled (or CLR_CMAKE_TARGET_BROWSER), to keep non-browser builds slightly leaner.
set(CMAKE_INCLUDE_CURRENT_DIR ON)

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment threadsrc/coreclr/inc/cordecoderhelpers.h
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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@pavelsavara
Potential fix for pull request finding
c69c839
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Pull request overview
Copilot reviewed 34 out of 34 changed files in this pull request and generated 6 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threaddocs/design/datacontracts/Loader.md
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp

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Looks good to me from a cDAC perspective. Thanks for keeping the cDAC up to date 👍
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/ba-g unrelated CI failures
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loading_webcil2

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[browser][coreCLR] Loading WebCIL (#124904)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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[browser][coreCLR] Loading WebCIL - 2nd attempt - #124904
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pavelsavara merged 26 commits into
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pavelsavara:loading_webcil2
Mar 13, 2026
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[browser][coreCLR] Loading WebCIL - 2nd attempt#124904
pavelsavara merged 26 commits into
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pavelsavara:loading_webcil2
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Enable Webcil loading in CoreCLR for Browser/WASM
Summary
Adds native Webcil container format support to the CoreCLR runtime, enabling CoreCLR-on-WASM to load .wasm-wrapped assemblies directly — previously only supported by the Mono runtime. Removes the WasmEnableWebcil=false override that was forcing CoreCLR browser builds to use raw .dll files.
Changes
CoreCLR Webcil decoder (src/coreclr/)
  • New WebcilDecoder class (webcildecoder.h, webcildecoder.cpp) — standalone reader for the Webcil container format with full RVA/offset translation, COR header resolution, metadata access, section validation, IL method checking, debug directory support, and DAC enumeration.
  • FEATURE_WEBCIL cmake gate enabled for CLR_CMAKE_TARGET_BROWSER (clrfeatures.cmake, clrdefinitions.cmake).
PEImageLayout composition refactor (src/coreclr/vm/)
  • PEImageLayout no longer inherits from PEDecoder; instead holds m_peDecoder (and conditionally m_webcilDecoder) as members with an ImageFormat discriminator (FORMAT_PE/FORMAT_WEBCIL).
  • ~160 inline forwarding methods in peimagelayout.inl dispatch to the active decoder via DECODER_DISPATCH/DECODER_CHECK/PE_OR_WEBCIL macros.
  • PEDecoder public API split: methods needed by PEImageLayout forwarding stay public; PE-internal helpers (GetHeaders, GetDirectoryEntry, CheckDirectoryEntry, relocation/TLS/strong-name internals, etc.) moved to a private section accessible only via friend class PEImageLayout.
  • FlatImageLayout constructor detects Webcil magic and initializes both decoders (Webcil for format operations, PE decoder for base/size/flags used by cDAC).
  • New HasHeaders() abstraction on PEImageLayout and PEImage — returns HasWebcilHeaders() or HasNTHeaders() depending on format. Callers in peassembly.cpp, peimage.cpp, eventtrace.cpp updated from HasNTHeaders() to HasHeaders().
  • debugdebugger.cpp: switched from PEDecoder* to PEImageLayout* and uses format-agnostic GetDirectoryEntryData instead of raw GetDirectoryEntry+GetDirectoryData.
  • ceeload.cpp: same PEDecoder* → PEImageLayout* fix for IJW host lookup.
  • peassembly.cpp: accept IMAGE_FILE_MACHINE_UNKNOWN (Webcil machine type) for IL-only validation; guard 32-bit NT header check with HasNTHeaders().
  • assemblybindercommon.cpp: treat IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL.
cDAC diagnostics (src/native/managed/cdac/)
  • PEImageLayout data descriptor gains Format field (datadescriptor.inc, PEImageLayout.cs).
  • Loader_1.cs: Webcil-aware RvaToOffset path that reads the Webcil section table directly from the target memory when IsWebcilFormat is set.
Build/infrastructure
  • Removed WasmEnableWebcil=false from CoreCLR browser build properties (WasmApp.InTree.props, tests.browser.targets).
  • MSBuild task renames: WebCilCandidates→WebcilCandidates, IsWebCilEnabled→IsWebcilEnabled, _WasmBuildWebCilPath→_WasmBuildWebcilPath and related properties.
  • Test infrastructure: BuildEnvironment.cs removes CoreCLR Webcil exclusion; env var WasmEnableWebCil→WasmEnableWebcil.
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added this to the 11.0.0 milestone
Feb 26, 2026
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Pull request overview
Enables CoreCLR-on-Browser/WASM to load assemblies packaged in the Webcil container format (i.e., .wasm-wrapped assemblies), aligning CoreCLR behavior with existing Mono Webcil support and removing prior build/test overrides that forced raw .dll usage.
Changes:
  • Adds CoreCLR-side Webcil decoding and wires it into PEImageLayout via format-dispatched forwarding to either PEDecoder (PE) or WebcilDecoder (Webcil).
  • Updates the Webcil tooling pipeline (converter/reader/wrapper + MSBuild tasks/targets) including 16-byte section alignment and property renames (WebCil* → Webcil*).
  • Extends cDAC contracts/readers and WASM test infrastructure to understand and exercise Webcil images.
Reviewed changes
Copilot reviewed 35 out of 35 changed files in this pull request and generated 6 comments.
Show a summary per file
FileDescription
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilWasmWrapper.csImproves wrapper error message for payload offset validation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.csUpdates to PascalCase header fields and adds bounds checking in RVA translation.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilHeader.csRenames Webcil header fields to PascalCase for consistency.
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.csImplements 16-byte section alignment, debug directory translation, and related validations.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.csRenames output item list to WebcilCandidates.
src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.csRenames task property to IsWebcilEnabled and updates usage.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.csAdds Format field to contract + helper to detect Webcil format.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.csAdds Webcil-aware RVA-to-offset logic by reading Webcil section table from target memory.
src/mono/wasm/features.mdDocumentation update: “WebCIL” → “Webcil”.
src/mono/wasm/Wasm.Build.Tests/Common/BuildEnvironment.csRemoves CoreCLR Webcil exclusion; renames env var WasmEnableWebcil.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targetsRenames MSBuild properties/items/parameters from WebCil → Webcil.
src/mono/cmake/options.cmakeDocumentation string update for ENABLE_WEBCIL.
src/mono/cmake/config.h.inComment update for ENABLE_WEBCIL.
src/mono/browser/debugger/BrowserDebugProxy/DebugStore.csDocumentation wording update for Webcil handling.
src/mono/browser/build/WasmApp.InTree.propsRemoves CoreCLR WasmEnableWebcil=false override.
src/coreclr/vm/peimagelayout.inlAdds decoder-dispatch forwarding methods; introduces format-agnostic header checks.
src/coreclr/vm/peimagelayout.hRefactors PEImageLayout to composition with PEDecoder/WebcilDecoder and ImageFormat discriminator.
src/coreclr/vm/peimagelayout.cppInitializes Webcil decoder on detection; updates PEDecoder init/reset call sites; DAC enumeration dispatch.
src/coreclr/vm/peimage.inlAdds PEImage::HasHeaders() helper.
src/coreclr/vm/peimage.hDeclares HasHeaders() in PEImage.
src/coreclr/vm/peimage.cppUses HasHeaders() instead of HasNTHeaders() in metadata/debug-directory paths.
src/coreclr/vm/peassembly.cppAccepts IMAGE_FILE_MACHINE_UNKNOWN for IL-only validation; guards 32-bit header check.
src/coreclr/vm/eventtrace.cppSwitches checks from NT headers to format-agnostic headers.
src/coreclr/vm/debugdebugger.cppSwitches from PEDecoder* to PEImageLayout* and uses GetDirectoryEntryData.
src/coreclr/vm/datadescriptor/datadescriptor.incAdds Format field to PEImageLayout’s cDAC data descriptor.
src/coreclr/vm/ceeload.cppUpdates IJW lookup to use PEImageLayout* (post-inheritance refactor).
src/coreclr/utilcode/webcildecoder.cppAdds CoreCLR Webcil decoding/validation implementation and DAC enumeration support.
src/coreclr/utilcode/CMakeLists.txtAdds webcildecoder.cpp to utilcode build.
src/coreclr/inc/webcildecoder.hAdds Webcil structures and WebcilDecoder API.
src/coreclr/inc/pedecoder.hMakes PEImageLayout a friend and restricts PE-internal APIs to PEImageLayout usage.
src/coreclr/clrfeatures.cmakeEnables FEATURE_WEBCIL for browser builds.
src/coreclr/clrdefinitions.cmakeAdds FEATURE_WEBCIL compile definition when enabled.
src/coreclr/binder/assemblybindercommon.cppTreats IMAGE_FILE_MACHINE_UNKNOWN as processor-agnostic MSIL in binder logic.
eng/testing/tests.browser.targetsRemoves CoreCLR WasmEnableWebcil=false override for browser tests.
docs/design/mono/webcil.mdUpdates spec text for alignment and PascalCase field names + naming consistency.
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Outdated

Comment threadsrc/coreclr/vm/peimagelayout.inl
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Outdated

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 4 comments.
Comments suppressed due to low confidence (1)
src/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilReader.cs:354
  • New exceptions in TranslateRVA use nameof(_stream) as the parameter name. Since _stream is a private field (not a parameter), this produces a less helpful ParamName than nameof(stream) (constructor parameter) or omitting the param name entirely. Consider aligning with the earlier constructor exceptions which use nameof(stream).
Comment threadsrc/coreclr/vm/peimagelayout.inl
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Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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Pull request overview
Copilot reviewed 35 out of 35 changed files in this pull request and generated 2 comments.
Comment threadsrc/tasks/Microsoft.NET.WebAssembly.Webcil/WebcilConverter.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
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February 26, 2026 17:55
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 6 comments.
Comments suppressed due to low confidence (1)
src/coreclr/utilcode/CMakeLists.txt:1
  • webcildecoder.cpp is added unconditionally to UTILCODE_COMMON_SOURCES. When FEATURE_WEBCIL is off this compiles an effectively empty translation unit, which is small but avoidable build work. Consider conditionally appending webcildecoder.cpp only when FEATURE_WEBCIL is enabled (or CLR_CMAKE_TARGET_BROWSER), to keep non-browser builds slightly leaner.
set(CMAKE_INCLUDE_CURRENT_DIR ON)

Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment threadsrc/coreclr/vm/peimagelayout.cpp
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment threadsrc/coreclr/inc/cordecoderhelpers.h
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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@pavelsavara
Potential fix for pull request finding
c69c839
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Pull request overview
Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
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Pull request overview
Copilot reviewed 34 out of 34 changed files in this pull request and generated 6 comments.
Comment thread...native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEImageLayout.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/native/managed/cdac/tests/LoaderTests.cs
Comment threadsrc/coreclr/utilcode/webcildecoder.cpp
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Comment threaddocs/design/datacontracts/Loader.md
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Comment threadsrc/coreclr/utilcode/webcildecoder.cpp

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Looks good to me from a cDAC perspective. Thanks for keeping the cDAC up to date 👍
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/ba-g unrelated CI failures
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[browser][coreCLR] Loading WebCIL (#124904)
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