[llvm] [FunctionAttrs] Switch readonly etc inference to use CaptureTracking (PR #201136)

[Antonio Frighetto via llvm-commits]

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@@ -480,7 +480,7 @@ define void @memcpy(ptr %p, ptr %p2) {
 define void @memcpy_volatile(ptr %p, ptr %p2) {
 ; CHECK: Function Attrs: nofree norecurse nosync nounwind memory(argmem: readwrite, inaccessiblemem: readwrite)
 ; CHECK-LABEL: define void @memcpy_volatile(
-; CHECK-SAME: ptr writeonly [[P:%.*]], ptr readonly [[P2:%.*]]) #[[ATTR2]] {
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antoniofrighetto wrote:

> But I'm also not sure if inferring writeonly/readonly here is actually correct, even if the fix is accidental. Note that we don't infer them for plain volatile ops: https://llvm.godbolt.org/z/sbbvhKbon

Right, I agree there should be consistency across volatile memory ops, though I feel like I haven't fully interiorized why readonly shouldn't hold for a volatile load as well (also, perhaps worth to add a test for volatile load here in initializes.ll too, together with the store).

https://github.com/llvm/llvm-project/pull/201136