[X86][SSE] Add combine-pmadd.ll for PMADDWD/VPMADDUBSW combines

Pre-commit for D108522 to show failure to fold multiply by zero operands

Author: RKSimon

llvm/test/CodeGen/X86/combine-pmadd.ll

@@ -0,0 +1,73 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+sse4.1 | FileCheck %s --check-prefix=SSE
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx | FileCheck %s --check-prefixes=AVX
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx2 | FileCheck %s --check-prefixes=AVX
+
+declare <4 x i32> @llvm.x86.sse2.pmadd.wd(<8 x i16>, <8 x i16>) nounwind readnone
+declare <8 x i16> @llvm.x86.ssse3.pmadd.ub.sw.128(<16 x i8>, <16 x i8>) nounwind readnone
+
+define <4 x i32> @combine_pmaddwd_zero(<8 x i16> %a0, <8 x i16> %a1) {
+; SSE-LABEL: combine_pmaddwd_zero:
+; SSE:       # %bb.0:
+; SSE-NEXT:    pxor %xmm1, %xmm1
+; SSE-NEXT:    pmaddwd %xmm1, %xmm0
+; SSE-NEXT:    retq
+;
+; AVX-LABEL: combine_pmaddwd_zero:
+; AVX:       # %bb.0:
+; AVX-NEXT:    vpxor %xmm1, %xmm1, %xmm1
+; AVX-NEXT:    vpmaddwd %xmm1, %xmm0, %xmm0
+; AVX-NEXT:    retq
+  %1 = call <4 x i32> @llvm.x86.sse2.pmadd.wd(<8 x i16> %a0, <8 x i16> zeroinitializer)
+  ret <4 x i32> %1
+}
+
+define <4 x i32> @combine_pmaddwd_zero_commute(<8 x i16> %a0, <8 x i16> %a1) {
+; SSE-LABEL: combine_pmaddwd_zero_commute:
+; SSE:       # %bb.0:
+; SSE-NEXT:    pxor %xmm1, %xmm1
+; SSE-NEXT:    pmaddwd %xmm1, %xmm0
+; SSE-NEXT:    retq
+;
+; AVX-LABEL: combine_pmaddwd_zero_commute:
+; AVX:       # %bb.0:
+; AVX-NEXT:    vpxor %xmm1, %xmm1, %xmm1
+; AVX-NEXT:    vpmaddwd %xmm0, %xmm1, %xmm0
+; AVX-NEXT:    retq
+  %1 = call <4 x i32> @llvm.x86.sse2.pmadd.wd(<8 x i16> zeroinitializer, <8 x i16> %a0)
+  ret <4 x i32> %1
+}
+
+define <8 x i16> @combine_pmaddubsw_zero(<16 x i8> %a0, <16 x i8> %a1) {
+; SSE-LABEL: combine_pmaddubsw_zero:
+; SSE:       # %bb.0:
+; SSE-NEXT:    pxor %xmm1, %xmm1
+; SSE-NEXT:    pmaddubsw %xmm1, %xmm0
+; SSE-NEXT:    retq
+;
+; AVX-LABEL: combine_pmaddubsw_zero:
+; AVX:       # %bb.0:
+; AVX-NEXT:    vpxor %xmm1, %xmm1, %xmm1
+; AVX-NEXT:    vpmaddubsw %xmm1, %xmm0, %xmm0
+; AVX-NEXT:    retq
+  %1 = call <8 x i16> @llvm.x86.ssse3.pmadd.ub.sw.128(<16 x i8> %a0, <16 x i8> zeroinitializer)
+  ret <8 x i16> %1
+}
+
+define <8 x i16> @combine_pmaddubsw_zero_commute(<16 x i8> %a0, <16 x i8> %a1) {
+; SSE-LABEL: combine_pmaddubsw_zero_commute:
+; SSE:       # %bb.0:
+; SSE-NEXT:    pxor %xmm1, %xmm1
+; SSE-NEXT:    pmaddubsw %xmm0, %xmm1
+; SSE-NEXT:    movdqa %xmm1, %xmm0
+; SSE-NEXT:    retq
+;
+; AVX-LABEL: combine_pmaddubsw_zero_commute:
+; AVX:       # %bb.0:
+; AVX-NEXT:    vpxor %xmm1, %xmm1, %xmm1
+; AVX-NEXT:    vpmaddubsw %xmm0, %xmm1, %xmm0
+; AVX-NEXT:    retq
+  %1 = call <8 x i16> @llvm.x86.ssse3.pmadd.ub.sw.128(<16 x i8> zeroinitializer, <16 x i8> %a0)
+  ret <8 x i16> %1
+}
+