[X86][SSE] Improved blend+zero target shuffle combining to use combined shuffle mask directly

We currently only combine to blend+zero if the target value type has 8 elements or less, but this was missing a lot of cases where the combined mask had been widened.

This change makes it so we use the combined mask to determine the blend value type, allowing us to catch more widened cases.

llvm-svn: 272003

1 files changed, 11 insertions, 7 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index d976c57ac0f..8856532ceed 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -24602,23 +24602,27 @@ static bool combineX86ShuffleChain(SDValue Input, SDValue Root,
   }
 
   // Attempt to blend with zero.
-  if (VT.getVectorNumElements() <= 8 &&
+  if (NumMaskElts <= 8 &&
       ((Subtarget.hasSSE41() && VT.is128BitVector()) ||
        (Subtarget.hasAVX() && VT.is256BitVector()))) {
     // Convert VT to a type compatible with X86ISD::BLENDI.
     // TODO - add 16i16 support (requires lane duplication).
-    MVT ShuffleVT = VT;
+    bool FloatDomain = VT.isFloatingPoint();
+    MVT ShuffleVT = FloatDomain ? MVT::getFloatingPointVT(MaskEltSizeInBits)
+                                : MVT::getIntegerVT(MaskEltSizeInBits);
+    ShuffleVT = MVT::getVectorVT(ShuffleVT, NumMaskElts);
+
     if (Subtarget.hasAVX2()) {
-      if (VT == MVT::v4i64)
+      if (ShuffleVT == MVT::v4i64)
         ShuffleVT = MVT::v8i32;
-      else if (VT == MVT::v2i64)
+      else if (ShuffleVT == MVT::v2i64)
         ShuffleVT = MVT::v4i32;
     } else {
-      if (VT == MVT::v2i64 || VT == MVT::v4i32)
+      if (ShuffleVT == MVT::v2i64 || ShuffleVT == MVT::v4i32)
         ShuffleVT = MVT::v8i16;
-      else if (VT == MVT::v4i64)
+      else if (ShuffleVT == MVT::v4i64)
         ShuffleVT = MVT::v4f64;
-      else if (VT == MVT::v8i32)
+      else if (ShuffleVT == MVT::v8i32)
         ShuffleVT = MVT::v8f32;
     }