[llvm] [SelectionDAG] Preserve volatile undef stores. (PR #99918)

[Matt Arsenault via llvm-commits]

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@@ -16,7 +16,6 @@ declare hidden i32 @strcmp(ptr nocapture, ptr nocapture) #1
 define amdgpu_kernel void @test_memcmp(ptr addrspace(1) %x, ptr addrspace(1) %y, ptr nocapture %p) #0 {
 entry:
   %cmp = tail call i32 @memcmp(ptr addrspace(1) %x, ptr addrspace(1) %y, i64 2)
-  store i32 %cmp, ptr addrspace(1) undef
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arsenm wrote:

Should preserve the dummy use and make volatile, or store to non-undef 

https://github.com/llvm/llvm-project/pull/99918