[PATCH] D54513: [X86] Allow pmulh to be formed from narrow vXi16 vectors under -x86-experimental-vector-widening-legalization

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: RKSimon, spatel.

Narrower vectors will be widened to 128 bits without changing the element size. And generic type legalization can already handle widening mulhu/mulhs.


https://reviews.llvm.org/D54513

Files:
  lib/Target/X86/X86ISelLowering.cpp
  test/CodeGen/X86/pmulh.ll


Index: test/CodeGen/X86/pmulh.ll
===================================================================
--- test/CodeGen/X86/pmulh.ll
+++ test/CodeGen/X86/pmulh.ll
@@ -24,11 +24,6 @@
 ; SSE2-WIDEN-LABEL: mulhuw_v4i16:
 ; SSE2-WIDEN:       # %bb.0:
 ; SSE2-WIDEN-NEXT:    pmulhuw %xmm1, %xmm0
-; SSE2-WIDEN-NEXT:    pxor %xmm1, %xmm1
-; SSE2-WIDEN-NEXT:    punpcklwd {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1],xmm0[2],xmm1[2],xmm0[3],xmm1[3]
-; SSE2-WIDEN-NEXT:    pshuflw {{.*#+}} xmm0 = xmm0[0,2,2,3,4,5,6,7]
-; SSE2-WIDEN-NEXT:    pshufhw {{.*#+}} xmm0 = xmm0[0,1,2,3,4,6,6,7]
-; SSE2-WIDEN-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[0,2,2,3]
 ; SSE2-WIDEN-NEXT:    retq
 ;
 ; SSE41-PROMOTE-LABEL: mulhuw_v4i16:
@@ -42,11 +37,7 @@
 ;
 ; SSE41-WIDEN-LABEL: mulhuw_v4i16:
 ; SSE41-WIDEN:       # %bb.0:
-; SSE41-WIDEN-NEXT:    pmovzxwd {{.*#+}} xmm2 = xmm0[0],zero,xmm0[1],zero,xmm0[2],zero,xmm0[3],zero
-; SSE41-WIDEN-NEXT:    pmovzxwd {{.*#+}} xmm0 = xmm1[0],zero,xmm1[1],zero,xmm1[2],zero,xmm1[3],zero
-; SSE41-WIDEN-NEXT:    pmulld %xmm2, %xmm0
-; SSE41-WIDEN-NEXT:    psrld $16, %xmm0
-; SSE41-WIDEN-NEXT:    packusdw %xmm0, %xmm0
+; SSE41-WIDEN-NEXT:    pmulhuw %xmm1, %xmm0
 ; SSE41-WIDEN-NEXT:    retq
 ;
 ; AVX-LABEL: mulhuw_v4i16:
@@ -82,11 +73,6 @@
 ; SSE2-WIDEN-LABEL: mulhw_v4i16:
 ; SSE2-WIDEN:       # %bb.0:
 ; SSE2-WIDEN-NEXT:    pmulhw %xmm1, %xmm0
-; SSE2-WIDEN-NEXT:    pxor %xmm1, %xmm1
-; SSE2-WIDEN-NEXT:    punpcklwd {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1],xmm0[2],xmm1[2],xmm0[3],xmm1[3]
-; SSE2-WIDEN-NEXT:    pshuflw {{.*#+}} xmm0 = xmm0[0,2,2,3,4,5,6,7]
-; SSE2-WIDEN-NEXT:    pshufhw {{.*#+}} xmm0 = xmm0[0,1,2,3,4,6,6,7]
-; SSE2-WIDEN-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[0,2,2,3]
 ; SSE2-WIDEN-NEXT:    retq
 ;
 ; SSE41-PROMOTE-LABEL: mulhw_v4i16:
@@ -101,11 +87,7 @@
 ;
 ; SSE41-WIDEN-LABEL: mulhw_v4i16:
 ; SSE41-WIDEN:       # %bb.0:
-; SSE41-WIDEN-NEXT:    pmovsxwd %xmm0, %xmm2
-; SSE41-WIDEN-NEXT:    pmovsxwd %xmm1, %xmm0
-; SSE41-WIDEN-NEXT:    pmulld %xmm2, %xmm0
-; SSE41-WIDEN-NEXT:    psrld $16, %xmm0
-; SSE41-WIDEN-NEXT:    packusdw %xmm0, %xmm0
+; SSE41-WIDEN-NEXT:    pmulhw %xmm1, %xmm0
 ; SSE41-WIDEN-NEXT:    retq
 ;
 ; AVX-LABEL: mulhw_v4i16:
Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -37552,9 +37552,11 @@
   if (!Subtarget.hasSSE2())
     return SDValue();
 
-  // Only handle vXi16 types that are at least 128-bits.
+  // Only handle vXi16 types that are at least 128-bits unless they will be
+  // widened.
   if (!VT.isVector() || VT.getVectorElementType() != MVT::i16 ||
-      VT.getVectorNumElements() < 8)
+      (!ExperimentalVectorWideningLegalization &&
+       VT.getVectorNumElements() < 8))
     return SDValue();
 
   // Input type should be vXi32.


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