[hwasan] Remove memory attrs from instrumented functions.

[eugenis]

HWASan instrumentation makes writeonly attribute on function parameters, as well as most memory(*) attributes invalid. This causes miscompilations with LTO, when more optimizations are run after the HWASan pass.

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

@llvm/pr-subscribers-llvm-transforms

Author: Evgenii Stepanov (eugenis)

Changes

HWASan instrumentation makes writeonly attribute on function parameters, as well as most memory(*) attributes invalid. This causes miscompilations with LTO, when more optimizations are run after the HWASan pass.

---

Full diff: https://github.com/llvm/llvm-project/pull/92974.diff

2 Files Affected:

• (modified) llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp (+4)
• (added) llvm/test/Instrumentation/HWAddressSanitizer/mem-attr.ll (+15)

diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 8d39217992c71..3b1a5fce85137 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -1589,6 +1589,10 @@ void HWAddressSanitizer::sanitizeFunction(Function &F,
 
   assert(!ShadowBase);
 
+  F.removeFnAttr(llvm::Attribute::Memory);
+  for (auto& A : F.args())
+    A.removeAttr(llvm::Attribute::WriteOnly);
+
   BasicBlock::iterator InsertPt = F.getEntryBlock().begin();
   IRBuilder<> EntryIRB(&F.getEntryBlock(), InsertPt);
   emitPrologue(EntryIRB,
diff --git a/llvm/test/Instrumentation/HWAddressSanitizer/mem-attr.ll b/llvm/test/Instrumentation/HWAddressSanitizer/mem-attr.ll
new file mode 100644
index 0000000000000..c0e370f20213a
--- /dev/null
+++ b/llvm/test/Instrumentation/HWAddressSanitizer/mem-attr.ll
@@ -0,0 +1,15 @@
+; Test that HWASan remove writeonly and memory(*) attributes from instrumented functions.
+; RUN: opt -S -passes=hwasan %s | FileCheck %s
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32"
+target triple = "aarch64-unknown-linux-android30"
+
+; CHECK: define dso_local void @test_writeonly(ptr nocapture noundef %p) local_unnamed_addr #0
+define dso_local void @test_writeonly(ptr nocapture noundef writeonly %p) local_unnamed_addr #0 {
+entry:
+  store i32 42, ptr %p, align 4
+  ret void
+}
+
+; CHECK: attributes #0 = { sanitize_hwaddress uwtable }
+attributes #0 = { sanitize_hwaddress memory(argmem: write) uwtable }

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[pcc]

Do we need to do the same thing for call sites?

[fmayer]

Please run clang-format

[eugenis]

I do not think call site attributes are possible before hwasan - at I least I'm not sure how to cause them.
clang-format applied.

[eugenis]

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