[x86] use VPMOVMSK to replace memcmp libcalls for 32-byte equality

Follow-up to:
https://reviews.llvm.org/rL298775

llvm-svn: 298933

2 files changed, 13 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 25523e52af1..9a4d44842ea 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6069,20 +6069,20 @@ bool SelectionDAGBuilder::visitMemCmpCall(const CallInst &I) {
   // supports the MVT we'll be loading or if it is small enough (<= 4) that
   // we'll only produce a small number of byte loads.
   MVT LoadVT;
-  switch (CSize->getZExtValue()) {
+  unsigned NumBitsToCompare = CSize->getZExtValue() * 8;
+  switch (NumBitsToCompare) {
   default:
     return false;
-  case 2:
+  case 16:
     LoadVT = MVT::i16;
     break;
-  case 4:
+  case 32:
     LoadVT = MVT::i32;
     break;
-  case 8:
-    LoadVT = hasFastLoadsAndCompare(64);
-    break;
-  case 16:
-    LoadVT = hasFastLoadsAndCompare(128);
+  case 64:
+  case 128:
+  case 256:
+    LoadVT = hasFastLoadsAndCompare(NumBitsToCompare);
     break;
   }
 
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 88e09cd56f8..eab398ac3bb 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -4646,8 +4646,12 @@ MVT X86TargetLowering::hasFastEqualityCompare(unsigned NumBits) const {
   if (NumBits == 128 && isTypeLegal(MVT::v16i8))
     return MVT::v16i8;
 
+  // VPMOVMSKB can handle this.
+  if (NumBits == 256 && isTypeLegal(MVT::v32i8))
+    return MVT::v32i8;
+
   // TODO: Allow 64-bit type for 32-bit target.
-  // TODO: 256- and 512-bit types should be allowed, but make sure that those
+  // TODO: 512-bit types should be allowed, but make sure that those
   // cases are handled in combineVectorSizedSetCCEquality().
 
   return MVT::INVALID_SIMPLE_VALUE_TYPE;