[llvm] [LegalizeTypes] Use vector CTPOP for wide integer popcount on targets with VPOPCNTDQ (PR #182547)

[Timothy Herchen via llvm-commits]

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@@ -18,13 +19,43 @@ define i32 @test_ctpop_i128(i128 %a0) nounwind {
 ; CHECK-NEXT:    # kill: def $eax killed $eax killed $rax
 ; CHECK-NEXT:    retq
 ;
-; AVX512-LABEL: test_ctpop_i128:
-; AVX512:       # %bb.0:
-; AVX512-NEXT:    popcntq %rsi, %rcx
-; AVX512-NEXT:    popcntq %rdi, %rax
-; AVX512-NEXT:    addl %ecx, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    retq
+; AVX512F-LABEL: test_ctpop_i128:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    popcntq %rsi, %rcx
+; AVX512F-NEXT:    popcntq %rdi, %rax
+; AVX512F-NEXT:    addl %ecx, %eax
+; AVX512F-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512F-NEXT:    retq
+;
+; AVX512VL-LABEL: test_ctpop_i128:
+; AVX512VL:       # %bb.0:
+; AVX512VL-NEXT:    popcntq %rsi, %rcx
+; AVX512VL-NEXT:    popcntq %rdi, %rax
+; AVX512VL-NEXT:    addl %ecx, %eax
+; AVX512VL-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512VL-NEXT:    retq
+;
+; AVX512VPOPCNTDQ-LABEL: test_ctpop_i128:
+; AVX512VPOPCNTDQ:       # %bb.0:
+; AVX512VPOPCNTDQ-NEXT:    vmovq %rsi, %xmm0
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anematode wrote:

This seems pretty terrible compared to the standard impl?

https://github.com/llvm/llvm-project/pull/182547