[cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64 #127282

Closed
#127289
Closed
[cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64#127282
#127289
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max-charlamb
Labels
area-Diagnostics-cdac

Description

@max-charlamb
max-charlamb
opened on Apr 22, 2026

Description

CallingConventionInfo (#126408) in the cDAC cannot reliably distinguish Apple ARM64 (macOS/iOS) from Linux ARM64, because RuntimeInfoOperatingSystem only has Unix — which covers both platforms.

Apple ARM64 has different stack alignment rules than Linux ARM64 (Apple uses natural alignment for primitives and 4-byte alignment for float HFAs on the stack, while Linux uses 8-byte alignment for everything). Applying the wrong rules produces incorrect argument offset calculations in ArgIterator.

Current State

IsAppleArm64ABI is hardcoded to false to avoid applying Apple-specific rules on Linux. This means Apple ARM64 stack layout may be slightly incorrect for value types passed on the stack.

Proposed Fix

Add a reliable Apple platform discriminator to IRuntimeInfo (or add a new global/data descriptor), such as:

  • RuntimeInfoOperatingSystem.Apple or RuntimeInfoOperatingSystem.MacOS
  • A boolean global IsApplePlatform
  • Inferring from the target's OS name string

Then update CallingConventionInfo to set IsAppleArm64ABI = true only when the target is confirmed to be an Apple platform.

Files

  • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/CallingConvention/CallingConventionInfo.cs
  • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs

Note

This issue was created with AI assistance from Copilot.

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    , '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); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

    Skip to content
    [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64 #127282
    Closed
    #127289
    Closed
    [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64#127282
    #127289
    Assignees
    max-charlamb
    Labels
    area-Diagnostics-cdac
    Description
    @max-charlamb
    max-charlamb
    opened on Apr 22, 2026
    Description
    CallingConventionInfo (#126408) in the cDAC cannot reliably distinguish Apple ARM64 (macOS/iOS) from Linux ARM64, because RuntimeInfoOperatingSystem only has Unix — which covers both platforms.
    Apple ARM64 has different stack alignment rules than Linux ARM64 (Apple uses natural alignment for primitives and 4-byte alignment for float HFAs on the stack, while Linux uses 8-byte alignment for everything). Applying the wrong rules produces incorrect argument offset calculations in ArgIterator.
    Current State
    IsAppleArm64ABI is hardcoded to false to avoid applying Apple-specific rules on Linux. This means Apple ARM64 stack layout may be slightly incorrect for value types passed on the stack.
    Proposed Fix
    Add a reliable Apple platform discriminator to IRuntimeInfo (or add a new global/data descriptor), such as:
    • RuntimeInfoOperatingSystem.Apple or RuntimeInfoOperatingSystem.MacOS
    • A boolean global IsApplePlatform
    • Inferring from the target's OS name string
    Then update CallingConventionInfo to set IsAppleArm64ABI = true only when the target is confirmed to be an Apple platform.
    Files
    • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/CallingConvention/CallingConventionInfo.cs
    • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
    Note
    This issue was created with AI assistance from Copilot.
    Metadata
    Metadata
    Assignees
    Labels
    area-Diagnostics-cdac
    Type
    No type
    Projects
    No projects
      Milestone
      No milestone
      Relationships
      None yet
      Development
      No branches or pull requests
      Issue actions
      
, '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('^' + ".*" + '

      Skip to content
      [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64 #127282
      Closed
      #127289
      Closed
      [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64#127282
      #127289
      Assignees
      max-charlamb
      Labels
      area-Diagnostics-cdac
      Description
      @max-charlamb
      max-charlamb
      opened on Apr 22, 2026
      Description
      CallingConventionInfo (#126408) in the cDAC cannot reliably distinguish Apple ARM64 (macOS/iOS) from Linux ARM64, because RuntimeInfoOperatingSystem only has Unix — which covers both platforms.
      Apple ARM64 has different stack alignment rules than Linux ARM64 (Apple uses natural alignment for primitives and 4-byte alignment for float HFAs on the stack, while Linux uses 8-byte alignment for everything). Applying the wrong rules produces incorrect argument offset calculations in ArgIterator.
      Current State
      IsAppleArm64ABI is hardcoded to false to avoid applying Apple-specific rules on Linux. This means Apple ARM64 stack layout may be slightly incorrect for value types passed on the stack.
      Proposed Fix
      Add a reliable Apple platform discriminator to IRuntimeInfo (or add a new global/data descriptor), such as:
      • RuntimeInfoOperatingSystem.Apple or RuntimeInfoOperatingSystem.MacOS
      • A boolean global IsApplePlatform
      • Inferring from the target's OS name string
      Then update CallingConventionInfo to set IsAppleArm64ABI = true only when the target is confirmed to be an Apple platform.
      Files
      • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/CallingConvention/CallingConventionInfo.cs
      • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
      Note
      This issue was created with AI assistance from Copilot.
      Metadata
      Metadata
      Assignees
      Labels
      area-Diagnostics-cdac
      Type
      No type
      Projects
      No projects
        Milestone
        No milestone
        Relationships
        None yet
        Development
        No branches or pull requests
        Issue actions
        
, '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('^' + ".*" + '

        Skip to content
        [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64 #127282
        Closed
        #127289
        Closed
        [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64#127282
        #127289
        Assignees
        max-charlamb
        Labels
        area-Diagnostics-cdac
        Description
        @max-charlamb
        max-charlamb
        opened on Apr 22, 2026
        Description
        CallingConventionInfo (#126408) in the cDAC cannot reliably distinguish Apple ARM64 (macOS/iOS) from Linux ARM64, because RuntimeInfoOperatingSystem only has Unix — which covers both platforms.
        Apple ARM64 has different stack alignment rules than Linux ARM64 (Apple uses natural alignment for primitives and 4-byte alignment for float HFAs on the stack, while Linux uses 8-byte alignment for everything). Applying the wrong rules produces incorrect argument offset calculations in ArgIterator.
        Current State
        IsAppleArm64ABI is hardcoded to false to avoid applying Apple-specific rules on Linux. This means Apple ARM64 stack layout may be slightly incorrect for value types passed on the stack.
        Proposed Fix
        Add a reliable Apple platform discriminator to IRuntimeInfo (or add a new global/data descriptor), such as:
        • RuntimeInfoOperatingSystem.Apple or RuntimeInfoOperatingSystem.MacOS
        • A boolean global IsApplePlatform
        • Inferring from the target's OS name string
        Then update CallingConventionInfo to set IsAppleArm64ABI = true only when the target is confirmed to be an Apple platform.
        Files
        • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/CallingConvention/CallingConventionInfo.cs
        • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
        Note
        This issue was created with AI assistance from Copilot.
        Metadata
        Metadata
        Assignees
        Labels
        area-Diagnostics-cdac
        Type
        No type
        Projects
        No projects
          Milestone
          No milestone
          Relationships
          None yet
          Development
          No branches or pull requests
          Issue actions
          
, '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
          [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64 #127282
          Closed
          #127289
          Closed
          [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64#127282
          #127289
          Assignees
          max-charlamb
          Labels
          area-Diagnostics-cdac
          Description
          @max-charlamb
          max-charlamb
          opened on Apr 22, 2026
          Description
          CallingConventionInfo (#126408) in the cDAC cannot reliably distinguish Apple ARM64 (macOS/iOS) from Linux ARM64, because RuntimeInfoOperatingSystem only has Unix — which covers both platforms.
          Apple ARM64 has different stack alignment rules than Linux ARM64 (Apple uses natural alignment for primitives and 4-byte alignment for float HFAs on the stack, while Linux uses 8-byte alignment for everything). Applying the wrong rules produces incorrect argument offset calculations in ArgIterator.
          Current State
          IsAppleArm64ABI is hardcoded to false to avoid applying Apple-specific rules on Linux. This means Apple ARM64 stack layout may be slightly incorrect for value types passed on the stack.
          Proposed Fix
          Add a reliable Apple platform discriminator to IRuntimeInfo (or add a new global/data descriptor), such as:
          • RuntimeInfoOperatingSystem.Apple or RuntimeInfoOperatingSystem.MacOS
          • A boolean global IsApplePlatform
          • Inferring from the target's OS name string
          Then update CallingConventionInfo to set IsAppleArm64ABI = true only when the target is confirmed to be an Apple platform.
          Files
          • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/CallingConvention/CallingConventionInfo.cs
          • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
          Note
          This issue was created with AI assistance from Copilot.
          Metadata
          Metadata
          Assignees
          Labels
          area-Diagnostics-cdac
          Type
          No type
          Projects
          No projects
            Milestone
            No milestone
            Relationships
            None yet
            Development
            No branches or pull requests
            Issue actions
            
, '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('^' + ".*" + '

            Skip to content
            [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64 #127282
            Closed
            #127289
            Closed
            [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64#127282
            #127289
            Assignees
            max-charlamb
            Labels
            area-Diagnostics-cdac
            Description
            @max-charlamb
            max-charlamb
            opened on Apr 22, 2026
            Description
            CallingConventionInfo (#126408) in the cDAC cannot reliably distinguish Apple ARM64 (macOS/iOS) from Linux ARM64, because RuntimeInfoOperatingSystem only has Unix — which covers both platforms.
            Apple ARM64 has different stack alignment rules than Linux ARM64 (Apple uses natural alignment for primitives and 4-byte alignment for float HFAs on the stack, while Linux uses 8-byte alignment for everything). Applying the wrong rules produces incorrect argument offset calculations in ArgIterator.
            Current State
            IsAppleArm64ABI is hardcoded to false to avoid applying Apple-specific rules on Linux. This means Apple ARM64 stack layout may be slightly incorrect for value types passed on the stack.
            Proposed Fix
            Add a reliable Apple platform discriminator to IRuntimeInfo (or add a new global/data descriptor), such as:
            • RuntimeInfoOperatingSystem.Apple or RuntimeInfoOperatingSystem.MacOS
            • A boolean global IsApplePlatform
            • Inferring from the target's OS name string
            Then update CallingConventionInfo to set IsAppleArm64ABI = true only when the target is confirmed to be an Apple platform.
            Files
            • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/CallingConvention/CallingConventionInfo.cs
            • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
            Note
            This issue was created with AI assistance from Copilot.
            Metadata
            Metadata
            Assignees
            Labels
            area-Diagnostics-cdac
            Type
            No type
            Projects
            No projects
              Milestone
              No milestone
              Relationships
              None yet
              Development
              No branches or pull requests
              Issue actions
              
, '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('^' + ".*" + '

              Skip to content
              [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64 #127282
              Closed
              #127289
              Closed
              [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64#127282
              #127289
              Assignees
              max-charlamb
              Labels
              area-Diagnostics-cdac
              Description
              @max-charlamb
              max-charlamb
              opened on Apr 22, 2026
              Description
              CallingConventionInfo (#126408) in the cDAC cannot reliably distinguish Apple ARM64 (macOS/iOS) from Linux ARM64, because RuntimeInfoOperatingSystem only has Unix — which covers both platforms.
              Apple ARM64 has different stack alignment rules than Linux ARM64 (Apple uses natural alignment for primitives and 4-byte alignment for float HFAs on the stack, while Linux uses 8-byte alignment for everything). Applying the wrong rules produces incorrect argument offset calculations in ArgIterator.
              Current State
              IsAppleArm64ABI is hardcoded to false to avoid applying Apple-specific rules on Linux. This means Apple ARM64 stack layout may be slightly incorrect for value types passed on the stack.
              Proposed Fix
              Add a reliable Apple platform discriminator to IRuntimeInfo (or add a new global/data descriptor), such as:
              • RuntimeInfoOperatingSystem.Apple or RuntimeInfoOperatingSystem.MacOS
              • A boolean global IsApplePlatform
              • Inferring from the target's OS name string
              Then update CallingConventionInfo to set IsAppleArm64ABI = true only when the target is confirmed to be an Apple platform.
              Files
              • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/CallingConvention/CallingConventionInfo.cs
              • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
              Note
              This issue was created with AI assistance from Copilot.
              Metadata
              Metadata
              Assignees
              Labels
              area-Diagnostics-cdac
              Type
              No type
              Projects
              No projects
                Milestone
                No milestone
                Relationships
                None yet
                Development
                No branches or pull requests
                Issue actions
                
, '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); }
})();
})();

                Skip to content
                [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64 #127282
                Closed
                #127289
                Closed
                [cDAC] CallingConventionInfo cannot distinguish Apple ARM64 from Linux ARM64#127282
                #127289
                Assignees
                max-charlamb
                Labels
                area-Diagnostics-cdac
                Description
                @max-charlamb
                max-charlamb
                opened on Apr 22, 2026
                Description
                CallingConventionInfo (#126408) in the cDAC cannot reliably distinguish Apple ARM64 (macOS/iOS) from Linux ARM64, because RuntimeInfoOperatingSystem only has Unix — which covers both platforms.
                Apple ARM64 has different stack alignment rules than Linux ARM64 (Apple uses natural alignment for primitives and 4-byte alignment for float HFAs on the stack, while Linux uses 8-byte alignment for everything). Applying the wrong rules produces incorrect argument offset calculations in ArgIterator.
                Current State
                IsAppleArm64ABI is hardcoded to false to avoid applying Apple-specific rules on Linux. This means Apple ARM64 stack layout may be slightly incorrect for value types passed on the stack.
                Proposed Fix
                Add a reliable Apple platform discriminator to IRuntimeInfo (or add a new global/data descriptor), such as:
                • RuntimeInfoOperatingSystem.Apple or RuntimeInfoOperatingSystem.MacOS
                • A boolean global IsApplePlatform
                • Inferring from the target's OS name string
                Then update CallingConventionInfo to set IsAppleArm64ABI = true only when the target is confirmed to be an Apple platform.
                Files
                • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/CallingConvention/CallingConventionInfo.cs
                • src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
                Note
                This issue was created with AI assistance from Copilot.
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