[llvm] 41455dd - [X86] Remove isTargetShuffleSplat and just use SelectionDAG::isSplatValue

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2022-06-19T11:22:57+01:00
New Revision: 41455dd1dcbbdf2f5fb34cc1f248bfd8d947dc52

URL: https://github.com/llvm/llvm-project/commit/41455dd1dcbbdf2f5fb34cc1f248bfd8d947dc52
DIFF: https://github.com/llvm/llvm-project/commit/41455dd1dcbbdf2f5fb34cc1f248bfd8d947dc52.diff

LOG: [X86] Remove isTargetShuffleSplat and just use SelectionDAG::isSplatValue

shuffle(splat(x)) -> splat(x), it doesn't have to be a target specific broadcast

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 1b4c9e173468..56e40806c4ac 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -5239,13 +5239,6 @@ static bool isTargetShuffleVariableMask(unsigned Opcode) {
   }
 }
 
-static bool isTargetShuffleSplat(SDValue Op) {
-  unsigned Opcode = Op.getOpcode();
-  if (Opcode == ISD::EXTRACT_SUBVECTOR)
-    return isTargetShuffleSplat(Op.getOperand(0));
-  return Opcode == X86ISD::VBROADCAST || Opcode == X86ISD::VBROADCAST_LOAD;
-}
-
 SDValue X86TargetLowering::getReturnAddressFrameIndex(SelectionDAG &DAG) const {
   MachineFunction &MF = DAG.getMachineFunction();
   const X86RegisterInfo *RegInfo = Subtarget.getRegisterInfo();
@@ -37637,12 +37630,13 @@ static SDValue combineX86ShuffleChain(ArrayRef<SDValue> Inputs, SDValue Root,
     }
   }
 
-  // If we are shuffling a broadcast (and not introducing zeros) then
-  // we can just use the broadcast directly. This works for smaller broadcast
-  // elements as well as they already repeat across each mask element
-  if (UnaryShuffle && isTargetShuffleSplat(V1) && !isAnyZero(BaseMask) &&
+  // If we are shuffling a splat (and not introducing zeros) then we can just
+  // use it directly. This works for smaller elements as well as they already
+  // repeat across each mask element.
+  if (UnaryShuffle && !isAnyZero(BaseMask) &&
+      V1.getValueSizeInBits() >= RootSizeInBits &&
       (BaseMaskEltSizeInBits % V1.getScalarValueSizeInBits()) == 0 &&
-      V1.getValueSizeInBits() >= RootSizeInBits) {
+      DAG.isSplatValue(V1, /*AllowUndefs*/ false)) {
     return CanonicalizeShuffleInput(RootVT, V1);
   }
 
@@ -41216,10 +41210,10 @@ bool X86TargetLowering::SimplifyDemandedVectorEltsForTargetNode(
     }
   }
 
-  // For broadcasts, unless we *only* demand the 0'th element,
+  // For splats, unless we *only* demand the 0'th element,
   // stop attempts at simplification here, we aren't going to improve things,
   // this is better than any potential shuffle.
-  if (isTargetShuffleSplat(Op) && !DemandedElts.isOne())
+  if (!DemandedElts.isOne() && TLO.DAG.isSplatValue(Op, /*AllowUndefs*/false))
     return false;
 
   // Get target/faux shuffle mask.