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[WinEH] Take musttail calls into account when unlinking eh records #119702

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Merged
merged 2 commits into from
Dec 13, 2024
Merged

[WinEH] Take musttail calls into account when unlinking eh records #119702

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[WinEH] Take musttail calls into account when unlinking eh records
zmodem Dec 12, 2024
24568b0
use BB.getTerminatingMustTailCall()
zmodem Dec 12, 2024
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10 changes: 10 additions & 0 deletions llvm/lib/Target/X86/X86WinEHState.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -363,6 +363,16 @@ void WinEHStatePass::emitExceptionRegistrationRecord(Function *F) {
Instruction *T = BB.getTerminator();
if (!isa<ReturnInst>(T))
continue;

// Back up to any preceding musttail call, the de-facto terminator.
Instruction *Prev = T->getPrevNonDebugInstruction();
if (isa_and_present<BitCastInst>(Prev))
Prev = T->getPrevNonDebugInstruction();
if (CallInst *CI = dyn_cast_or_null<CallInst>(Prev)) {
if (CI->isMustTailCall())
T = CI;
}

Builder.SetInsertPoint(T);
unlinkExceptionRegistration(Builder);
}
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32 changes: 32 additions & 0 deletions llvm/test/CodeGen/WinEH/wineh-musttail-call.ll
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@@ -0,0 +1,32 @@
; RUN: llc < %s | FileCheck %s

target triple = "i386-pc-windows-msvc"

; Check that codegen doesn't fail due to wineh inserting instructions between
; the musttail call and return instruction.


define void @test() personality ptr @__CxxFrameHandler3 {
; CHECK-LABEL: test:

entry:
invoke void @foo() to label %try.cont unwind label %catch.dispatch

catch.dispatch:
%0 = catchswitch within none [label %catch] unwind to caller

catch:
%1 = catchpad within %0 [ptr null, i32 64, ptr null]
catchret from %1 to label %try.cont

try.cont:
; CHECK: movl %{{[a-z0-9]+}}, %fs:0
; CHECK: jmp _bar

musttail call void @bar()
ret void
}

declare i32 @__CxxFrameHandler3(...)
declare void @foo()
declare void @bar()
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