[clang] [Headers][X86] Use `__builtin_elementwise_ctlz` instead of avx512cd intrinsics. (PR #155089)

[Phoebe Wang via cfe-commits]

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@@ -42,35 +43,41 @@ __m512i test_mm512_maskz_conflict_epi32(__mmask16 __U, __m512i __A) {
 }
 __m512i test_mm512_lzcnt_epi32(__m512i __A) {
   // CHECK-LABEL: test_mm512_lzcnt_epi32
-  // CHECK: call <16 x i32> @llvm.ctlz.v16i32(<16 x i32> %{{.*}}, i1 false)
+  // CHECK: call <16 x i32> @llvm.ctlz.v16i32(<16 x i32> %{{.*}}, i1 true)
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phoebewang wrote:

It's incorrect here. The `is_zero_poison` argument needs to stay `false`. The same below.

https://github.com/llvm/llvm-project/pull/155089