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[Codegen][X86] Fix /hotpatch with clang-cl and inline asm #87639

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Merged
merged 2 commits into from
Apr 9, 2024
Merged

[Codegen][X86] Fix /hotpatch with clang-cl and inline asm #87639

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455c4e5
[Codegen][X86] Fix /hotpatch with clang-cl and inline asm
aganea Apr 4, 2024
29f40cb
Change nop for int3 in test
aganea Apr 8, 2024
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4 changes: 3 additions & 1 deletion llvm/lib/Target/X86/X86MCInstLower.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -980,8 +980,10 @@ void X86AsmPrinter::LowerPATCHABLE_OP(const MachineInstr &MI,
SmallString<256> Code;
unsigned MinSize = MI.getOperand(0).getImm();

if (NextMI != MI.getParent()->end()) {
if (NextMI != MI.getParent()->end() && !NextMI->isInlineAsm()) {
// Lower the next MachineInstr to find its byte size.
// If the next instruction is inline assembly, we skip lowering it for now,
// and assume we should always generate NOPs.
MCInst MCI;
MCIL.Lower(&*NextMI, MCI);

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17 changes: 17 additions & 0 deletions llvm/test/CodeGen/X86/patchable-prologue.ll
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Expand Up @@ -193,3 +193,20 @@ do.body: ; preds = %do.body, %entry
do.end: ; preds = %do.body
ret void
}


; Test that inline asm is properly hotpatched. We currently don't examine the
; asm instruction when printing it, thus we always emit patching NOPs.

; 64: inline_asm:
; 64-NEXT: # %bb.0:
; 64-NEXT: xchgw %ax, %ax # encoding: [0x66,0x90]
; 64-NEXT: #APP
; 64-NEXT: nop # encoding: [0x90]
; 64-NEXT: #NO_APP

define dso_local void @inline_asm() "patchable-function"="prologue-short-redirect" {
entry:
call void asm sideeffect "nop", "~{dirflag},~{fpsr},~{flags}"()
ret void
}