diff options
Diffstat (limited to 'lib/Target/Mips/MipsISelDAGToDAG.cpp')
-rw-r--r-- | lib/Target/Mips/MipsISelDAGToDAG.cpp | 53 |
1 files changed, 52 insertions, 1 deletions
diff --git a/lib/Target/Mips/MipsISelDAGToDAG.cpp b/lib/Target/Mips/MipsISelDAGToDAG.cpp index 9ba54d6bb73c..e5997af3bcc5 100644 --- a/lib/Target/Mips/MipsISelDAGToDAG.cpp +++ b/lib/Target/Mips/MipsISelDAGToDAG.cpp @@ -65,7 +65,7 @@ bool MipsDAGToDAGISel::runOnMachineFunction(MachineFunction &MF) { /// getGlobalBaseReg - Output the instructions required to put the /// GOT address into a register. SDNode *MipsDAGToDAGISel::getGlobalBaseReg() { - unsigned GlobalBaseReg = MF->getInfo<MipsFunctionInfo>()->getGlobalBaseReg(); + Register GlobalBaseReg = MF->getInfo<MipsFunctionInfo>()->getGlobalBaseReg(); return CurDAG->getRegister(GlobalBaseReg, getTargetLowering()->getPointerTy( CurDAG->getDataLayout())) .getNode(); @@ -217,6 +217,51 @@ bool MipsDAGToDAGISel::selectVSplatMaskR(SDValue N, SDValue &Imm) const { return false; } +/// Convert vector addition with vector subtraction if that allows to encode +/// constant as an immediate and thus avoid extra 'ldi' instruction. +/// add X, <-1, -1...> --> sub X, <1, 1...> +bool MipsDAGToDAGISel::selectVecAddAsVecSubIfProfitable(SDNode *Node) { + assert(Node->getOpcode() == ISD::ADD && "Should only get 'add' here."); + + EVT VT = Node->getValueType(0); + assert(VT.isVector() && "Should only be called for vectors."); + + SDValue X = Node->getOperand(0); + SDValue C = Node->getOperand(1); + + auto *BVN = dyn_cast<BuildVectorSDNode>(C); + if (!BVN) + return false; + + APInt SplatValue, SplatUndef; + unsigned SplatBitSize; + bool HasAnyUndefs; + + if (!BVN->isConstantSplat(SplatValue, SplatUndef, SplatBitSize, HasAnyUndefs, + 8, !Subtarget->isLittle())) + return false; + + auto IsInlineConstant = [](const APInt &Imm) { return Imm.isIntN(5); }; + + if (IsInlineConstant(SplatValue)) + return false; // Can already be encoded as an immediate. + + APInt NegSplatValue = 0 - SplatValue; + if (!IsInlineConstant(NegSplatValue)) + return false; // Even if we negate it it won't help. + + SDLoc DL(Node); + + SDValue NegC = CurDAG->FoldConstantArithmetic( + ISD::SUB, DL, VT, CurDAG->getConstant(0, DL, VT).getNode(), C.getNode()); + assert(NegC && "Constant-folding failed!"); + SDValue NewNode = CurDAG->getNode(ISD::SUB, DL, VT, X, NegC); + + ReplaceNode(Node, NewNode.getNode()); + SelectCode(NewNode.getNode()); + return true; +} + /// Select instructions not customized! Used for /// expanded, promoted and normal instructions void MipsDAGToDAGISel::Select(SDNode *Node) { @@ -236,6 +281,12 @@ void MipsDAGToDAGISel::Select(SDNode *Node) { switch(Opcode) { default: break; + case ISD::ADD: + if (Node->getSimpleValueType(0).isVector() && + selectVecAddAsVecSubIfProfitable(Node)) + return; + break; + // Get target GOT address. case ISD::GLOBAL_OFFSET_TABLE: ReplaceNode(Node, getGlobalBaseReg()); |