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Ensure the Thumb bit is set for resumption stub relocs #125421

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Ensure the Thumb bit is set for resumption stub relocs #125421

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62c80b7
Revert "Just skip ARM32 instead of trying to get it all working all a…
jtschuster Mar 10, 2026
c558b8c
Jit format
jtschuster Mar 12, 2026
3695c42
Fix ARM32 SIGILL in R2R async resume stubs by preserving Thumb bit
jtschuster Mar 12, 2026
1970178
ARM32: pass Thumb bit via addlDelta instead of mutating handle
jtschuster Mar 13, 2026
09e1a1e
Move .Resume assignment back to original position
jtschuster Mar 13, 2026
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16 changes: 16 additions & 0 deletions src/coreclr/jit/emit.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8440,9 +8440,25 @@ void emitter::emitOutputDataSec(dataSecDsc* sec, AllocMemChunk* chunks)
BYTE* target = emitLoc->Valid() ? emitOffsetToPtr(emitLoc->CodeOffset(this)) : nullptr;
aDstRW[i].Resume = (target_size_t)(uintptr_t)emitAsyncResumeStubEntryPoint;
aDstRW[i].DiagnosticIP = (target_size_t)(uintptr_t)target;

#ifdef TARGET_ARM
// ARM32 requires the Thumb bit (bit 0) set on code pointers.
// For target (intra-code pointer), OR directly — findKnownBlock preserves it.
// For resumeStub (external handle), use addlDelta so the handle stays clean
// for HandleToObject's integer division in crossgen2.
Comment on lines +8447 to +8448
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@MichalStrehovsky MichalStrehovsky Mar 16, 2026

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Suggested change
// For resumeStub (external handle), use addlDelta so the handle stays clean
// for HandleToObject's integer division in crossgen2.
// For resumeStub (external handle), use addlDelta because we can't do math with handles.

if (target != nullptr)
{
target = (BYTE*)((size_t)target | 1);
}
Comment on lines 8440 to +8452
#endif

if (m_compiler->opts.compReloc)
{
#ifdef TARGET_ARM
emitRecordRelocationWithAddlDelta(&aDstRW[i].Resume, emitAsyncResumeStubEntryPoint, CorInfoReloc::DIRECT, 1);
#else
emitRecordRelocation(&aDstRW[i].Resume, emitAsyncResumeStubEntryPoint, CorInfoReloc::DIRECT);
#endif
if (target != nullptr)
{
emitRecordRelocation(&aDstRW[i].DiagnosticIP, target, CorInfoReloc::DIRECT);
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11 changes: 5 additions & 6 deletions ...ols/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunCodegenNodeFactory.cs
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Expand Up @@ -482,13 +482,12 @@ public IEnumerable<MethodWithGCInfo> EnumerateCompiledMethods(EcmaModule moduleT
foreach (IMethodNode methodNode in MetadataManager.GetCompiledMethods(moduleToEnumerate, methodCategory))
{
MethodDesc method = methodNode.Method;
// Async methods are not emitted in composite mode nor on ARM32
// The mutable module tokens emission is not well tested for composite mode and we should find a real solution for that problem
// ARM32 relocs require the thumb bit set, and the JIT/crossgen doesn't set it properly for the usages in async methods.
// Async methods are not emitted in composite mode.
// The mutable module tokens emission is not well tested for composite mode
// and we should find a real solution for that problem.
// https://github.com/dotnet/runtime/issues/125337
// https://github.com/dotnet/runtime/issues/125338
if ((CompilationModuleGroup.IsCompositeBuildMode || Target.Architecture == TargetArchitecture.ARM)
&& (method.IsAsyncVariant() || method.IsCompilerGeneratedILBodyForAsync()))
if (CompilationModuleGroup.IsCompositeBuildMode &&
(method.IsAsyncVariant() || method.IsCompilerGeneratedILBodyForAsync()))
{
continue;
}
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