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

[via llvm-commits]

================
@@ -2359,6 +2359,14 @@ def int_amdgcn_mbcnt_hi :
   DefaultAttrsIntrinsic<[llvm_i32_ty], [llvm_i32_ty, llvm_i32_ty],
             [IntrNoMem]>;
 
+def int_amdgcn_bcnt032_lo :
+  ClangBuiltin<"__builtin_amdgcn_bcnt032_lo">,
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LU-JOHN wrote:

Is "bcnt032_lo" the name we want to use?  For comparison:

```
  ClangBuiltin<"__builtin_amdgcn_sad_u8">,
  ClangBuiltin<"__builtin_amdgcn_msad_u8">,
```

follows the mnemonic without an initial "v_".


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