From 40827bc716e9eda3e70460207696f2ec10dd67ad Mon Sep 17 00:00:00 2001 From: Richard Osborne Date: Sat, 4 May 2013 17:17:10 +0000 Subject: [PATCH] [XCore] Simplify code that checks for an aligned base plus a constant. The code now makes use of ComputeMaskedBits, SelectionDAG::isBaseWithConstantOffset and TargetLowering::isGAPlusOffset where appropriate reducing the amount of logic needed in XCoreISelLowering. No intended functionality change. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181125 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/XCore/XCoreISelLowering.cpp | 134 ++++++++++--------------- lib/Target/XCore/XCoreISelLowering.h | 3 + 2 files changed, 56 insertions(+), 81 deletions(-) diff --git a/lib/Target/XCore/XCoreISelLowering.cpp b/lib/Target/XCore/XCoreISelLowering.cpp index 28472ea339b..357af79b6b3 100644 --- a/lib/Target/XCore/XCoreISelLowering.cpp +++ b/lib/Target/XCore/XCoreISelLowering.cpp @@ -308,55 +308,49 @@ LowerBR_JT(SDValue Op, SelectionDAG &DAG) const ScaledIndex); } -static bool -IsWordAlignedBasePlusConstantOffset(SDValue Addr, SDValue &AlignedBase, - int64_t &Offset) +SDValue XCoreTargetLowering:: +lowerLoadWordFromAlignedBasePlusOffset(DebugLoc DL, SDValue Chain, SDValue Base, + int64_t Offset, SelectionDAG &DAG) const { - if (Addr.getOpcode() != ISD::ADD) { - return false; + if ((Offset & 0x3) == 0) { + return DAG.getLoad(getPointerTy(), DL, Chain, Base, MachinePointerInfo(), + false, false, false, 0); } - ConstantSDNode *CN = 0; - if (!(CN = dyn_cast(Addr.getOperand(1)))) { - return false; - } - int64_t off = CN->getSExtValue(); - const SDValue &Base = Addr.getOperand(0); - const SDValue *Root = &Base; - if (Base.getOpcode() == ISD::ADD && - Base.getOperand(1).getOpcode() == ISD::SHL) { - ConstantSDNode *CN = dyn_cast(Base.getOperand(1) - .getOperand(1)); - if (CN && (CN->getSExtValue() >= 2)) { - Root = &Base.getOperand(0); - } - } - if (isa(*Root)) { - // All frame indicies are word aligned - AlignedBase = Base; - Offset = off; - return true; - } - if (Root->getOpcode() == XCoreISD::DPRelativeWrapper || - Root->getOpcode() == XCoreISD::CPRelativeWrapper) { - // All dp / cp relative addresses are word aligned - AlignedBase = Base; - Offset = off; - return true; - } - // Check for an aligned global variable. - if (GlobalAddressSDNode *GA = dyn_cast(*Root)) { - const GlobalValue *GV = GA->getGlobal(); - if (GA->getOffset() == 0 && GV->getAlignment() >= 4) { - AlignedBase = Base; - Offset = off; - return true; - } - } - return false; + // Lower to pair of consecutive word aligned loads plus some bit shifting. + int32_t HighOffset = RoundUpToAlignment(Offset, 4); + int32_t LowOffset = HighOffset - 4; + SDValue LowAddr = DAG.getNode(ISD::ADD, DL, MVT::i32, Base, + DAG.getConstant(LowOffset, MVT::i32)); + SDValue HighAddr = DAG.getNode(ISD::ADD, DL, MVT::i32, Base, + DAG.getConstant(HighOffset, MVT::i32)); + SDValue LowShift = DAG.getConstant((Offset - LowOffset) * 8, MVT::i32); + SDValue HighShift = DAG.getConstant((HighOffset - Offset) * 8, MVT::i32); + + SDValue Low = DAG.getLoad(getPointerTy(), DL, Chain, + LowAddr, MachinePointerInfo(), + false, false, false, 0); + SDValue High = DAG.getLoad(getPointerTy(), DL, Chain, + HighAddr, MachinePointerInfo(), + false, false, false, 0); + SDValue LowShifted = DAG.getNode(ISD::SRL, DL, MVT::i32, Low, LowShift); + SDValue HighShifted = DAG.getNode(ISD::SHL, DL, MVT::i32, High, HighShift); + SDValue Result = DAG.getNode(ISD::OR, DL, MVT::i32, LowShifted, HighShifted); + Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Low.getValue(1), + High.getValue(1)); + SDValue Ops[] = { Result, Chain }; + return DAG.getMergeValues(Ops, 2, DL); +} + +static bool isWordAligned(SDValue Value, SelectionDAG &DAG) +{ + APInt KnownZero, KnownOne; + DAG.ComputeMaskedBits(Value, KnownZero, KnownOne); + return KnownZero.countTrailingOnes() >= 2; } SDValue XCoreTargetLowering:: LowerLOAD(SDValue Op, SelectionDAG &DAG) const { + const TargetLowering &TLI = DAG.getTargetLoweringInfo(); LoadSDNode *LD = cast(Op); assert(LD->getExtensionType() == ISD::NON_EXTLOAD && "Unexpected extension type"); @@ -374,45 +368,23 @@ LowerLOAD(SDValue Op, SelectionDAG &DAG) const { SDValue BasePtr = LD->getBasePtr(); DebugLoc DL = Op.getDebugLoc(); - SDValue Base; - int64_t Offset; - if (!LD->isVolatile() && - IsWordAlignedBasePlusConstantOffset(BasePtr, Base, Offset)) { - if (Offset % 4 == 0) { - // We've managed to infer better alignment information than the load - // already has. Use an aligned load. - // - return DAG.getLoad(getPointerTy(), DL, Chain, BasePtr, - MachinePointerInfo(), - false, false, false, 0); + if (!LD->isVolatile()) { + const GlobalValue *GV; + int64_t Offset = 0; + if (DAG.isBaseWithConstantOffset(BasePtr) && + isWordAligned(BasePtr->getOperand(0), DAG)) { + SDValue NewBasePtr = BasePtr->getOperand(0); + Offset = cast(BasePtr->getOperand(1))->getSExtValue(); + return lowerLoadWordFromAlignedBasePlusOffset(DL, Chain, NewBasePtr, + Offset, DAG); + } + if (TLI.isGAPlusOffset(BasePtr.getNode(), GV, Offset) && + MinAlign(GV->getAlignment(), 4) == 4) { + SDValue NewBasePtr = DAG.getGlobalAddress(GV, DL, + BasePtr->getValueType(0)); + return lowerLoadWordFromAlignedBasePlusOffset(DL, Chain, NewBasePtr, + Offset, DAG); } - // Lower to - // ldw low, base[offset >> 2] - // ldw high, base[(offset >> 2) + 1] - // shr low_shifted, low, (offset & 0x3) * 8 - // shl high_shifted, high, 32 - (offset & 0x3) * 8 - // or result, low_shifted, high_shifted - SDValue LowOffset = DAG.getConstant(Offset & ~0x3, MVT::i32); - SDValue HighOffset = DAG.getConstant((Offset & ~0x3) + 4, MVT::i32); - SDValue LowShift = DAG.getConstant((Offset & 0x3) * 8, MVT::i32); - SDValue HighShift = DAG.getConstant(32 - (Offset & 0x3) * 8, MVT::i32); - - SDValue LowAddr = DAG.getNode(ISD::ADD, DL, MVT::i32, Base, LowOffset); - SDValue HighAddr = DAG.getNode(ISD::ADD, DL, MVT::i32, Base, HighOffset); - - SDValue Low = DAG.getLoad(getPointerTy(), DL, Chain, - LowAddr, MachinePointerInfo(), - false, false, false, 0); - SDValue High = DAG.getLoad(getPointerTy(), DL, Chain, - HighAddr, MachinePointerInfo(), - false, false, false, 0); - SDValue LowShifted = DAG.getNode(ISD::SRL, DL, MVT::i32, Low, LowShift); - SDValue HighShifted = DAG.getNode(ISD::SHL, DL, MVT::i32, High, HighShift); - SDValue Result = DAG.getNode(ISD::OR, DL, MVT::i32, LowShifted, HighShifted); - Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Low.getValue(1), - High.getValue(1)); - SDValue Ops[] = { Result, Chain }; - return DAG.getMergeValues(Ops, 2, DL); } if (LD->getAlignment() == 2) { diff --git a/lib/Target/XCore/XCoreISelLowering.h b/lib/Target/XCore/XCoreISelLowering.h index 7362b0c44ac..4ea5d9ff063 100644 --- a/lib/Target/XCore/XCoreISelLowering.h +++ b/lib/Target/XCore/XCoreISelLowering.h @@ -135,6 +135,9 @@ namespace llvm { SDValue getReturnAddressFrameIndex(SelectionDAG &DAG) const; SDValue getGlobalAddressWrapper(SDValue GA, const GlobalValue *GV, SelectionDAG &DAG) const; + SDValue lowerLoadWordFromAlignedBasePlusOffset(DebugLoc DL, SDValue Chain, + SDValue Base, int64_t Offset, + SelectionDAG &DAG) const; // Lower Operand specifics SDValue LowerLOAD(SDValue Op, SelectionDAG &DAG) const;