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

[Jay Foad via cfe-commits]

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@@ -2359,6 +2359,12 @@ def int_amdgcn_mbcnt_hi :
   DefaultAttrsIntrinsic<[llvm_i32_ty], [llvm_i32_ty, llvm_i32_ty],
             [IntrNoMem]>;
 
+def int_amdgcn_bcnt32_lo :
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jayfoad wrote:

"Intrinsic" means the LLVM IR special function `llvm.amdgcn.bcnt32.lo()`. "Builtin" means the Clang/C++ special function `__builtin_amdgcn_bcnt32_lo()`.

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