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

[Mariusz Borsa 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
+}
+
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wrotki wrote:

Still trying to wrap my head around this, I'm fresh to controlling optimizations by attributes

> so only HWAddressSanitizer removes writeonly

I feel uneasy with this - so is this change addressing the problem w. HWASAN , but not with ASAN, when the write only attribute is present? Or the opposite (the number of negations in the removal condition overwhelms me a bit, as the original `The API is `weird` comment suggests)?

In other words - if there's a function compiled with  (not HW) ASAN instrumentation, decorated with writeonly attribute, will it still be dropped?


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