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[CodeGen] Don't allow function alignment less than the target's minimum #90415

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[CodeGen] Don't allow function alignment less than the target's minimum #90415

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527872f
[llvm codegen] In AsmPrinter::emitAlignment, don't allow the possibly
Apr 25, 2024
33bcaec
Add test
Apr 29, 2024
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14 changes: 11 additions & 3 deletions llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3147,9 +3147,17 @@ void AsmPrinter::emitAlignment(Align Alignment, const GlobalObject *GV,

if (getCurrentSection()->getKind().isText()) {
const MCSubtargetInfo *STI = nullptr;
if (this->MF)
STI = &getSubtargetInfo();
else
if (this->MF) {
// Don't allow the possibly smaller alignment of the GV
// (e.g. 2 for a C++ method) to reduce a function's alignment
// below the target's minimum function alignment. (#90358)
const TargetSubtargetInfo *TSI = &MF->getSubtarget();
const Align MinAlign =
TSI->getTargetLowering()->getMinFunctionAlignment();
if (Alignment < MinAlign)
Alignment = MinAlign;
STI = TSI;
} else
STI = TM.getMCSubtargetInfo();
OutStreamer->emitCodeAlignment(Alignment, STI, MaxBytesToEmit);
} else
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19 changes: 19 additions & 0 deletions llvm/test/CodeGen/AArch64/func-alignment.ll
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@@ -0,0 +1,19 @@
; RUN: llc -mtriple=aarch64 -O0 -fast-isel < %s | FileCheck %s

; Verify that Clang's C++ ABI alignment for functions of 2 does not
; result in underaligned functions when they are in special sections.
; (#90415)

define void @noSection() align 2 {
; CHECK: .p2align 2
entry:
ret void
}

define void @withSection() section "__TEXT,__foo,regular,pure_instructions" align 2 {
; CHECK: .p2align 2
entry:
ret void
}


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