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[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions - #90739

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[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions#90739
carlossanlop merged 2 commits into
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Backport of #90694 to release/8.0

/cc @jakobbotsch

Customer Impact

Code that involves illegal reinterpretations of GC pointers in unreachable code paths can cause the JIT to generate code with incorrect GC reporting, even in the reachable paths.
For example, MemoryMarshal.Contains is a case. When value is a GC pointer, RuntimeHelpers.IsBitwiseEquatable<T>() will return false, but under some stress scenarios the JIT will still see the later Unsafe.As<T, long>(ref value). This can cause it to mistakenly reinterpret value as a long without any GC reporting, even outside the RuntimeHelpers.IsBitwiseEquatable<T>() branch.
For this particular case, in normal circumstances (no stress modes) the unreachable code is folded away early enough that the JIT does not see the reinterpretation, so no issue happens.

Testing

Verified that the failing test case now generates correct code and GC reporting, even when the stress variables are set.

Risk

Low. Targeted fix with no diffs in any of our own code (under non stress circumstances) that disables physical promotion when the case is detected.

@jakobbotsch
JIT: Disallow mismatched GC-ness for physical promotions
62946ee
Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.
Fix#90602
@jakobbotsch
Address feedback
ada908f
@ghostghost added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Aug 17, 2023
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Issue Details

Backport of #90694 to release/8.0

/cc @jakobbotsch

Customer Impact

Testing

Risk

IMPORTANT: If this backport is for a servicing release, please verify that:

  • The PR target branch is release/X.0-staging, not release/X.0.

  • If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.

Author:github-actions[bot]
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approved. please get a code review, you are good to merge

@build-analysisbuild-analysisBot mentioned this pull request Aug 17, 2023
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@carlossanlop

carlossanlop commented Aug 17, 2023

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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .

If you intended to send it to RC1, please retarget the PR to release/8.0-rc1 and send an email to Tactics requesting approval.

@jakobbotsch

jakobbotsch commented Aug 17, 2023

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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .

I think RC2 only is just fine.

@carlossanlopcarlossanlop added Servicing-consider Issue for next servicing release review Servicing-approved Approved for servicing release and removed Servicing-consider Issue for next servicing release review labels Aug 17, 2023
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carlossanlop merged commit 3ab4246 into release/8.0Aug 17, 2023
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@carlossanlop@jakobbotsch@EgorBo@jeffschwMSFT
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[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions by github-actions[bot] · Pull Request #90739 · dotnet/runtime · GitHub
Skip to content
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions - #90739
Merged
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
Aug 17, 2023
Merged
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions#90739
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
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Aug 17, 2023•

edited by jakobbotsch

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Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Code that involves illegal reinterpretations of GC pointers in unreachable code paths can cause the JIT to generate code with incorrect GC reporting, even in the reachable paths.

For example, MemoryMarshal.Contains is a case. When value is a GC pointer, RuntimeHelpers.IsBitwiseEquatable<T>() will return false, but under some stress scenarios the JIT will still see the later Unsafe.As<T, long>(ref value). This can cause it to mistakenly reinterpret value as a long without any GC reporting, even outside the RuntimeHelpers.IsBitwiseEquatable<T>() branch.

For this particular case, in normal circumstances (no stress modes) the unreachable code is folded away early enough that the JIT does not see the reinterpretation, so no issue happens.
Testing
Verified that the failing test case now generates correct code and GC reporting, even when the stress variables are set.
Risk
Low. Targeted fix with no diffs in any of our own code (under non stress circumstances) that disables physical promotion when the case is detected.
@jakobbotsch
JIT: Disallow mismatched GC-ness for physical promotions
62946ee
Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.
Fix#90602
@jakobbotsch
Address feedback
ada908f
@ghostghost
added
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CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Testing
Risk
IMPORTANT: If this backport is for a servicing release, please verify that:
  • The PR target branch is release/X.0-staging, not release/X.0.
  • If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.
Author:github-actions[bot]
Assignees:-
Labels:
area-CodeGen-coreclr
Milestone:-
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approved. please get a code review, you are good to merge
@build-analysisbuild-analysisBot
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
If you intended to send it to RC1, please retarget the PR to release/8.0-rc1 and send an email to Tactics requesting approval.
@jakobbotsch
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
I think RC2 only is just fine.
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[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions by github-actions[bot] · Pull Request #90739 · dotnet/runtime · GitHub
Skip to content
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions - #90739
Merged
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
Aug 17, 2023
Merged
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions#90739
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
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@github-actions
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commented
Aug 17, 2023•

edited by jakobbotsch

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Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Code that involves illegal reinterpretations of GC pointers in unreachable code paths can cause the JIT to generate code with incorrect GC reporting, even in the reachable paths.

For example, MemoryMarshal.Contains is a case. When value is a GC pointer, RuntimeHelpers.IsBitwiseEquatable<T>() will return false, but under some stress scenarios the JIT will still see the later Unsafe.As<T, long>(ref value). This can cause it to mistakenly reinterpret value as a long without any GC reporting, even outside the RuntimeHelpers.IsBitwiseEquatable<T>() branch.

For this particular case, in normal circumstances (no stress modes) the unreachable code is folded away early enough that the JIT does not see the reinterpretation, so no issue happens.
Testing
Verified that the failing test case now generates correct code and GC reporting, even when the stress variables are set.
Risk
Low. Targeted fix with no diffs in any of our own code (under non stress circumstances) that disables physical promotion when the case is detected.
@jakobbotsch
JIT: Disallow mismatched GC-ness for physical promotions
62946ee
Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.
Fix#90602
@jakobbotsch
Address feedback
ada908f
@ghostghost
added
the 
area-CodeGen-coreclr
CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Testing
Risk
IMPORTANT: If this backport is for a servicing release, please verify that:
  • The PR target branch is release/X.0-staging, not release/X.0.
  • If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.
Author:github-actions[bot]
Assignees:-
Labels:
area-CodeGen-coreclr
Milestone:-
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approved. please get a code review, you are good to merge
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
If you intended to send it to RC1, please retarget the PR to release/8.0-rc1 and send an email to Tactics requesting approval.
@jakobbotsch
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
I think RC2 only is just fine.
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merged commit 3ab4246
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[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions by github-actions[bot] · Pull Request #90739 · dotnet/runtime · GitHub
Skip to content
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions - #90739
Merged
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
Aug 17, 2023
Merged
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions#90739
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
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edited by jakobbotsch

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Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Code that involves illegal reinterpretations of GC pointers in unreachable code paths can cause the JIT to generate code with incorrect GC reporting, even in the reachable paths.

For example, MemoryMarshal.Contains is a case. When value is a GC pointer, RuntimeHelpers.IsBitwiseEquatable<T>() will return false, but under some stress scenarios the JIT will still see the later Unsafe.As<T, long>(ref value). This can cause it to mistakenly reinterpret value as a long without any GC reporting, even outside the RuntimeHelpers.IsBitwiseEquatable<T>() branch.

For this particular case, in normal circumstances (no stress modes) the unreachable code is folded away early enough that the JIT does not see the reinterpretation, so no issue happens.
Testing
Verified that the failing test case now generates correct code and GC reporting, even when the stress variables are set.
Risk
Low. Targeted fix with no diffs in any of our own code (under non stress circumstances) that disables physical promotion when the case is detected.
@jakobbotsch
JIT: Disallow mismatched GC-ness for physical promotions
62946ee
Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.
Fix#90602
@jakobbotsch
Address feedback
ada908f
@ghostghost
added
the 
area-CodeGen-coreclr
CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Testing
Risk
IMPORTANT: If this backport is for a servicing release, please verify that:
  • The PR target branch is release/X.0-staging, not release/X.0.
  • If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.
Author:github-actions[bot]
Assignees:-
Labels:
area-CodeGen-coreclr
Milestone:-
jeffschwMSFT
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approved. please get a code review, you are good to merge
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
If you intended to send it to RC1, please retarget the PR to release/8.0-rc1 and send an email to Tactics requesting approval.
@jakobbotsch
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
I think RC2 only is just fine.
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@carlossanlop@jakobbotsch@EgorBo@jeffschwMSFT

, 'i');
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// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
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cleanLinks();
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mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions by github-actions[bot] · Pull Request #90739 · dotnet/runtime · GitHub
Skip to content
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions - #90739
Merged
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
Aug 17, 2023
Merged
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions#90739
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
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Aug 17, 2023•

edited by jakobbotsch

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Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Code that involves illegal reinterpretations of GC pointers in unreachable code paths can cause the JIT to generate code with incorrect GC reporting, even in the reachable paths.

For example, MemoryMarshal.Contains is a case. When value is a GC pointer, RuntimeHelpers.IsBitwiseEquatable<T>() will return false, but under some stress scenarios the JIT will still see the later Unsafe.As<T, long>(ref value). This can cause it to mistakenly reinterpret value as a long without any GC reporting, even outside the RuntimeHelpers.IsBitwiseEquatable<T>() branch.

For this particular case, in normal circumstances (no stress modes) the unreachable code is folded away early enough that the JIT does not see the reinterpretation, so no issue happens.
Testing
Verified that the failing test case now generates correct code and GC reporting, even when the stress variables are set.
Risk
Low. Targeted fix with no diffs in any of our own code (under non stress circumstances) that disables physical promotion when the case is detected.
@jakobbotsch
JIT: Disallow mismatched GC-ness for physical promotions
62946ee
Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.
Fix#90602
@jakobbotsch
Address feedback
ada908f
@ghostghost
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Issue Details
Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Testing
Risk
IMPORTANT: If this backport is for a servicing release, please verify that:
  • The PR target branch is release/X.0-staging, not release/X.0.
  • If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.
Author:github-actions[bot]
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approved. please get a code review, you are good to merge
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
If you intended to send it to RC1, please retarget the PR to release/8.0-rc1 and send an email to Tactics requesting approval.
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
I think RC2 only is just fine.
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions by github-actions[bot] · Pull Request #90739 · dotnet/runtime · GitHub
Skip to content
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions - #90739
Merged
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
Aug 17, 2023
Merged
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions#90739
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
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@github-actions
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Aug 17, 2023•

edited by jakobbotsch

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Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Code that involves illegal reinterpretations of GC pointers in unreachable code paths can cause the JIT to generate code with incorrect GC reporting, even in the reachable paths.

For example, MemoryMarshal.Contains is a case. When value is a GC pointer, RuntimeHelpers.IsBitwiseEquatable<T>() will return false, but under some stress scenarios the JIT will still see the later Unsafe.As<T, long>(ref value). This can cause it to mistakenly reinterpret value as a long without any GC reporting, even outside the RuntimeHelpers.IsBitwiseEquatable<T>() branch.

For this particular case, in normal circumstances (no stress modes) the unreachable code is folded away early enough that the JIT does not see the reinterpretation, so no issue happens.
Testing
Verified that the failing test case now generates correct code and GC reporting, even when the stress variables are set.
Risk
Low. Targeted fix with no diffs in any of our own code (under non stress circumstances) that disables physical promotion when the case is detected.
@jakobbotsch
JIT: Disallow mismatched GC-ness for physical promotions
62946ee
Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.
Fix#90602
@jakobbotsch
Address feedback
ada908f
@ghostghost
added
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area-CodeGen-coreclr
CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Testing
Risk
IMPORTANT: If this backport is for a servicing release, please verify that:
  • The PR target branch is release/X.0-staging, not release/X.0.
  • If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.
Author:github-actions[bot]
Assignees:-
Labels:
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approved. please get a code review, you are good to merge
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
If you intended to send it to RC1, please retarget the PR to release/8.0-rc1 and send an email to Tactics requesting approval.
@jakobbotsch
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
I think RC2 only is just fine.
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merged commit 3ab4246
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@carlossanlop
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
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function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
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})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions by github-actions[bot] · Pull Request #90739 · dotnet/runtime · GitHub
Skip to content
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions - #90739
Merged
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
Aug 17, 2023
Merged
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions#90739
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
Conversation
@github-actions
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commented
Aug 17, 2023•

edited by jakobbotsch

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Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Code that involves illegal reinterpretations of GC pointers in unreachable code paths can cause the JIT to generate code with incorrect GC reporting, even in the reachable paths.

For example, MemoryMarshal.Contains is a case. When value is a GC pointer, RuntimeHelpers.IsBitwiseEquatable<T>() will return false, but under some stress scenarios the JIT will still see the later Unsafe.As<T, long>(ref value). This can cause it to mistakenly reinterpret value as a long without any GC reporting, even outside the RuntimeHelpers.IsBitwiseEquatable<T>() branch.

For this particular case, in normal circumstances (no stress modes) the unreachable code is folded away early enough that the JIT does not see the reinterpretation, so no issue happens.
Testing
Verified that the failing test case now generates correct code and GC reporting, even when the stress variables are set.
Risk
Low. Targeted fix with no diffs in any of our own code (under non stress circumstances) that disables physical promotion when the case is detected.
@jakobbotsch
JIT: Disallow mismatched GC-ness for physical promotions
62946ee
Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.
Fix#90602
@jakobbotsch
Address feedback
ada908f
@ghostghost
added
the 
area-CodeGen-coreclr
CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Testing
Risk
IMPORTANT: If this backport is for a servicing release, please verify that:
  • The PR target branch is release/X.0-staging, not release/X.0.
  • If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.
Author:github-actions[bot]
Assignees:-
Labels:
area-CodeGen-coreclr
Milestone:-
jeffschwMSFT
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Aug 17, 2023
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approved. please get a code review, you are good to merge
@build-analysisbuild-analysisBot
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
If you intended to send it to RC1, please retarget the PR to release/8.0-rc1 and send an email to Tactics requesting approval.
@jakobbotsch
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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
I think RC2 only is just fine.
@carlossanlopcarlossanlop
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@carlossanlop
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merged commit 3ab4246
into
release/8.0Aug 17, 2023
@carlossanlop
carlossanlop
deleted the

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August 17, 2023 17:27
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
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filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
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/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
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console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
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})();
})();
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions by github-actions[bot] · Pull Request #90739 · dotnet/runtime · GitHub
Skip to content
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions - #90739
Merged
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
Aug 17, 2023
Merged
[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions#90739
carlossanlop merged 2 commits into
release/8.0from 
backport/pr-90694-to-release/8.0
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@github-actions
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Aug 17, 2023•

edited by jakobbotsch

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Contributor
Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Code that involves illegal reinterpretations of GC pointers in unreachable code paths can cause the JIT to generate code with incorrect GC reporting, even in the reachable paths.

For example, MemoryMarshal.Contains is a case. When value is a GC pointer, RuntimeHelpers.IsBitwiseEquatable<T>() will return false, but under some stress scenarios the JIT will still see the later Unsafe.As<T, long>(ref value). This can cause it to mistakenly reinterpret value as a long without any GC reporting, even outside the RuntimeHelpers.IsBitwiseEquatable<T>() branch.

For this particular case, in normal circumstances (no stress modes) the unreachable code is folded away early enough that the JIT does not see the reinterpretation, so no issue happens.
Testing
Verified that the failing test case now generates correct code and GC reporting, even when the stress variables are set.
Risk
Low. Targeted fix with no diffs in any of our own code (under non stress circumstances) that disables physical promotion when the case is detected.
@jakobbotsch
JIT: Disallow mismatched GC-ness for physical promotions
62946ee
Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.
Fix#90602
@jakobbotsch
Address feedback
ada908f
@ghostghost
added
the 
area-CodeGen-coreclr
CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
Backport of #90694 to release/8.0
/cc @jakobbotsch
Customer Impact
Testing
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IMPORTANT: If this backport is for a servicing release, please verify that:
  • The PR target branch is release/X.0-staging, not release/X.0.
  • If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.
Author:github-actions[bot]
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area-CodeGen-coreclr
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jeffschwMSFT
jeffschwMSFT
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Aug 17, 2023
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approved. please get a code review, you are good to merge
@build-analysisbuild-analysisBot
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Aug 17, 2023

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@carlossanlop
carlossanlop
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Aug 17, 2023

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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
If you intended to send it to RC1, please retarget the PR to release/8.0-rc1 and send an email to Tactics requesting approval.
@jakobbotsch
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Aug 17, 2023

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FYI this is going into RC2 (release/8.0). If that's your intention, @jakobbotsch , then I can merge right away, since it has been signed-off and approved by @jeffschwMSFT .
I think RC2 only is just fine.
@carlossanlopcarlossanlop
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Issue for next servicing release review
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Aug 17, 2023
@carlossanlop
carlossanlop
merged commit 3ab4246
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release/8.0Aug 17, 2023
@carlossanlop
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backport/pr-90694-to-release/8.0

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August 17, 2023 17:27
@ghostghost
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Sep 16, 2023
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@EgorBoEgorBoEgorBo approved these changes
@jeffschwMSFTjeffschwMSFTjeffschwMSFT approved these changes

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area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIServicing-approvedApproved for servicing release

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@carlossanlop@jakobbotsch@EgorBo@jeffschwMSFT