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[AArch64] Bugfix when using execute-only and memtag sanitizer together #133084

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Merged
merged 1 commit into from
Apr 1, 2025
Merged

[AArch64] Bugfix when using execute-only and memtag sanitizer together #133084

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16 changes: 11 additions & 5 deletions llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -511,11 +511,17 @@ void AArch64TargetELFStreamer::finish() {
})) {
auto *Text =
static_cast<MCSectionELF *>(Ctx.getObjectFileInfo()->getTextSection());
for (auto &F : *Text)
if (auto *DF = dyn_cast<MCDataFragment>(&F))
if (!DF->getContents().empty())
return;
Text->setFlags(Text->getFlags() | ELF::SHF_AARCH64_PURECODE);
bool Empty = true;
for (auto &F : *Text) {
if (auto *DF = dyn_cast<MCDataFragment>(&F)) {
if (!DF->getContents().empty()) {
Empty = false;
break;
}
}
}
Comment on lines +514 to +522
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Can you use something like all_of(*Text, [](***) {return DF->getContents().empty();} here?

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I wanted to do that too, but I get the following error:

error: no matching function for call to '__iterator_category'
note: candidate template ignored: substitution failure [with _Iter = llvm::MCSection::iterator]: no type named 'iterator_category' in 'std::iterator_traits<llvm::MCSection::iterator>'

To me it looks like MCSection::iterator is not a proper iterator according to the standard library, so we can't use std::all_of (which llvm::all_of uses).

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Ok. Thanks for checking.

if (Empty)
Text->setFlags(Text->getFlags() | ELF::SHF_AARCH64_PURECODE);
}

MCSectionELF *MemtagSec = nullptr;
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18 changes: 18 additions & 0 deletions llvm/test/MC/AArch64/execute-only-memtag.ll
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@@ -0,0 +1,18 @@
; RUN: llc %s -mtriple=aarch64-linux-android31 -filetype=obj -o %t.o
; RUN: llvm-readelf -r %t.o | FileCheck %s

; CHECK: Relocation section '.rela.memtag.globals.static' at offset {{.*}} contains 1 entries:
; CHECK-NEXT: Type {{.*}} Symbol's Name
; CHECK-NEXT: R_AARCH64_NONE {{.*}} global

@global = global i32 1, sanitize_memtag

define void @foo() {
ret void
}

define void @bar() #0 {
ret void
}

attributes #0 = { "target-features"="+execute-only" }