[clang] [llvm] Match bitsin(typeof(x)) - popcnt(x) to s_bcnt0_i32 on AMDGPU (PR #164847)

[via llvm-commits]

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@@ -625,3 +622,111 @@ if:
 endif:
   ret i32 1
 }
+
+define amdgpu_ps void @bcnt032_not_for_vregs(ptr addrspace(1) %out, ptr addrspace(1) %in) {
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LU-JOHN wrote:

s_cmp_0.ll was intended to test deleting redundant s_cmp* sX, 0 instructions.  These new bcnt0* tests should be in a different file.

https://github.com/llvm/llvm-project/pull/164847