[llvm] [AArch64] Fix #94909: Optimize vector fmul(sitofp(x), 0.5) -> scvtf(x, 2) (PR #141480)
David Green via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 25 02:57:04 PDT 2025
================
@@ -3952,6 +3960,119 @@ static bool checkCVTFixedPointOperandWithFBits(SelectionDAG *CurDAG, SDValue N,
return true;
}
+static bool checkCVTFixedPointOperandWithFBitsForVectors(SelectionDAG *CurDAG,
+ SDValue N,
+ SDValue &FixedPos,
+ unsigned FloatWidth,
+ bool IsReciprocal) {
+
+ SDValue ImmediateNode;
+ // N must be a bitcast or nvcast
+ if (N.getOpcode() == ISD::BITCAST || N.getOpcode() == AArch64ISD::NVCAST) {
+ ImmediateNode = N.getOperand(0);
+ } else {
+ return false;
+ }
+
+ EVT NodeVT = N.getValueType();
+ EVT InputVT = ImmediateNode.getValueType();
+ // The input must me a vector of int but N must be a floating point
+ if (!InputVT.isVector() || !InputVT.isInteger() || !NodeVT.isFloatingPoint())
+ return false;
+
+ bool IsSplatConfirmed = false;
+
+ if (ImmediateNode.getOpcode() == AArch64ISD::DUP ||
+ ImmediateNode.getOpcode() == ISD::SPLAT_VECTOR) {
+ // These opcodes inherently mean a splat.
+ IsSplatConfirmed = true;
+ } else if (ImmediateNode.getOpcode() == ISD::BUILD_VECTOR) {
+ // For BUILD_VECTOR, we must explicitly check if it's a constant splat.
+ BuildVectorSDNode *BVN = cast<BuildVectorSDNode>(ImmediateNode.getNode());
+ APInt SplatValue;
+ APInt SplatUndef;
+ unsigned SplatBitSize;
+ bool HasAnyUndefs;
+ if (BVN->isConstantSplat(SplatValue, SplatUndef, SplatBitSize,
+ HasAnyUndefs)) {
+ IsSplatConfirmed = true;
+ }
+ } else if (ImmediateNode.getOpcode() == AArch64ISD::MOVIshift) {
+ // This implies that the DAG structure was (DUP (MOVIshift C)) or
+ // (BUILD_VECTOR (MOVIshift C)).
----------------
davemgreen wrote:
I think this comment is old and can be removed?
https://github.com/llvm/llvm-project/pull/141480
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