[llvm] [AddressSanitizer] Remove memory effects from functions (PR #130495)

[Guy David via llvm-commits]

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@@ -0,0 +1,23 @@
+; Remove possible memory effects from functions that are invalidated by
+; AddressSanitizer instrumentation.
+
+; RUN: opt < %s -passes=asan -asan-use-after-scope -S | FileCheck %s
+
+target datalayout = "e-i64:64-f80:128-s:64-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK: @foo(ptr) #[[ATTRS_FOO:[0-9]+]]
+declare void @foo(ptr) memory(argmem: write)
+
+; CHECK: @bar() #[[ATTRS_BAR:[0-9]+]]
+define void @bar() sanitize_address {
+entry:
+  %x = alloca i32, align 4
+  call void @llvm.lifetime.start.p0(i64 4, ptr %x)
+  call void @foo(ptr %x)
+  call void @llvm.lifetime.end.p0(i64 4, ptr %x)
+  ret void
+}
+
----------------
guy-david wrote:

It's a portion from common code which ASan does not require. HWASan, however, when short granules are used, might read from the memory pointed by via pointer arguments.
To summarize, ASan will not drop `writeonly`.

https://github.com/llvm/llvm-project/pull/130495