diff options
Diffstat (limited to 'llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp')
-rw-r--r-- | llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp index 163ed52..51bec36 100644 --- a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp +++ b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp @@ -462,7 +462,7 @@ private: SDValue &Offset, SDValue &SignExtend, SDValue &DoShift); bool isWorthFoldingALU(SDValue V, bool LSL = false) const; - bool isWorthFoldingAddr(SDValue V) const; + bool isWorthFoldingAddr(SDValue V, unsigned Size) const; bool SelectExtendedSHL(SDValue N, unsigned Size, bool WantExtend, SDValue &Offset, SDValue &SignExtend); @@ -674,17 +674,22 @@ static bool isWorthFoldingSHL(SDValue V) { /// Determine whether it is worth to fold V into an extended register addressing /// mode. -bool AArch64DAGToDAGISel::isWorthFoldingAddr(SDValue V) const { +bool AArch64DAGToDAGISel::isWorthFoldingAddr(SDValue V, unsigned Size) const { // Trivial if we are optimizing for code size or if there is only // one use of the value. if (CurDAG->shouldOptForSize() || V.hasOneUse()) return true; - // If a subtarget has a fastpath LSL we can fold a logical shift into - // the addressing mode and save a cycle. - if (Subtarget->hasAddrLSLFast() && V.getOpcode() == ISD::SHL && - isWorthFoldingSHL(V)) + + // If a subtarget has a slow shift, folding a shift into multiple loads + // costs additional micro-ops. + if (Subtarget->hasAddrLSLSlow14() && (Size == 2 || Size == 16)) + return false; + + // Check whether we're going to emit the address arithmetic anyway because + // it's used by a non-address operation. + if (V.getOpcode() == ISD::SHL && isWorthFoldingSHL(V)) return true; - if (Subtarget->hasAddrLSLFast() && V.getOpcode() == ISD::ADD) { + if (V.getOpcode() == ISD::ADD) { const SDValue LHS = V.getOperand(0); const SDValue RHS = V.getOperand(1); if (LHS.getOpcode() == ISD::SHL && isWorthFoldingSHL(LHS)) @@ -1203,7 +1208,7 @@ bool AArch64DAGToDAGISel::SelectExtendedSHL(SDValue N, unsigned Size, if (ShiftVal != 0 && ShiftVal != LegalShiftVal) return false; - return isWorthFoldingAddr(N); + return isWorthFoldingAddr(N, Size); } bool AArch64DAGToDAGISel::SelectAddrModeWRO(SDValue N, unsigned Size, @@ -1231,7 +1236,7 @@ bool AArch64DAGToDAGISel::SelectAddrModeWRO(SDValue N, unsigned Size, } // Remember if it is worth folding N when it produces extended register. - bool IsExtendedRegisterWorthFolding = isWorthFoldingAddr(N); + bool IsExtendedRegisterWorthFolding = isWorthFoldingAddr(N, Size); // Try to match a shifted extend on the RHS. if (IsExtendedRegisterWorthFolding && RHS.getOpcode() == ISD::SHL && @@ -1261,7 +1266,7 @@ bool AArch64DAGToDAGISel::SelectAddrModeWRO(SDValue N, unsigned Size, Offset = narrowIfNeeded(CurDAG, LHS.getOperand(0)); SignExtend = CurDAG->getTargetConstant(Ext == AArch64_AM::SXTW, dl, MVT::i32); - if (isWorthFoldingAddr(LHS)) + if (isWorthFoldingAddr(LHS, Size)) return true; } @@ -1273,7 +1278,7 @@ bool AArch64DAGToDAGISel::SelectAddrModeWRO(SDValue N, unsigned Size, Offset = narrowIfNeeded(CurDAG, RHS.getOperand(0)); SignExtend = CurDAG->getTargetConstant(Ext == AArch64_AM::SXTW, dl, MVT::i32); - if (isWorthFoldingAddr(RHS)) + if (isWorthFoldingAddr(RHS, Size)) return true; } @@ -1343,7 +1348,7 @@ bool AArch64DAGToDAGISel::SelectAddrModeXRO(SDValue N, unsigned Size, } // Remember if it is worth folding N when it produces extended register. - bool IsExtendedRegisterWorthFolding = isWorthFoldingAddr(N); + bool IsExtendedRegisterWorthFolding = isWorthFoldingAddr(N, Size); // Try to match a shifted extend on the RHS. if (IsExtendedRegisterWorthFolding && RHS.getOpcode() == ISD::SHL && |