Index: llvm/trunk/lib/Target/X86/X86SelectionDAGInfo.cpp =================================================================== --- llvm/trunk/lib/Target/X86/X86SelectionDAGInfo.cpp +++ llvm/trunk/lib/Target/X86/X86SelectionDAGInfo.cpp @@ -43,24 +43,6 @@ return false; } -namespace { - -// Represents a cover of a buffer of Size bytes with Count() blocks of type AVT -// (of size UBytes() bytes), as well as how many bytes remain (BytesLeft() is -// always smaller than the block size). -struct RepMovsRepeats { - RepMovsRepeats(uint64_t Size) : Size(Size) {} - - uint64_t Count() const { return Size / UBytes(); } - uint64_t BytesLeft() const { return Size % UBytes(); } - uint64_t UBytes() const { return AVT.getSizeInBits() / 8; } - - const uint64_t Size; - MVT AVT = MVT::i8; -}; - -} // namespace - SDValue X86SelectionDAGInfo::EmitTargetCodeForMemset( SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Val, SDValue Size, unsigned Align, bool isVolatile, @@ -200,98 +182,137 @@ return Chain; } -SDValue X86SelectionDAGInfo::EmitTargetCodeForMemcpy( - SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src, - SDValue Size, unsigned Align, bool isVolatile, bool AlwaysInline, - MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const { - // This requires the copy size to be a constant, preferably - // within a subtarget-specific limit. - ConstantSDNode *ConstantSize = dyn_cast(Size); - const X86Subtarget &Subtarget = - DAG.getMachineFunction().getSubtarget(); - if (!ConstantSize) - return SDValue(); - RepMovsRepeats Repeats(ConstantSize->getZExtValue()); - if (!AlwaysInline && Repeats.Size > Subtarget.getMaxInlineSizeThreshold()) +/// Emit a single REP MOVS{B,W,D,Q} instruction. +static SDValue emitRepmovs(const X86Subtarget &Subtarget, SelectionDAG &DAG, + const SDLoc &dl, SDValue Chain, SDValue Dst, + SDValue Src, SDValue Size, MVT AVT) { + const bool Use64BitRegs = Subtarget.isTarget64BitLP64(); + const unsigned CX = Use64BitRegs ? X86::RCX : X86::ECX; + const unsigned DI = Use64BitRegs ? X86::RDI : X86::EDI; + const unsigned SI = Use64BitRegs ? X86::RSI : X86::ESI; + + SDValue InFlag; + Chain = DAG.getCopyToReg(Chain, dl, CX, Size, InFlag); + InFlag = Chain.getValue(1); + Chain = DAG.getCopyToReg(Chain, dl, DI, Dst, InFlag); + InFlag = Chain.getValue(1); + Chain = DAG.getCopyToReg(Chain, dl, SI, Src, InFlag); + InFlag = Chain.getValue(1); + + SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Glue); + SDValue Ops[] = {Chain, DAG.getValueType(AVT), InFlag}; + return DAG.getNode(X86ISD::REP_MOVS, dl, Tys, Ops); +} + +/// Emit a single REP MOVSB instruction for a particular constant size. +static SDValue emitRepmovsB(const X86Subtarget &Subtarget, SelectionDAG &DAG, + const SDLoc &dl, SDValue Chain, SDValue Dst, + SDValue Src, uint64_t Size) { + return emitRepmovs(Subtarget, DAG, dl, Chain, Dst, Src, + DAG.getIntPtrConstant(Size, dl), MVT::i8); +} + +/// Returns the best type to use with repmovs depending on alignment. +static MVT getOptimalRepmovsType(const X86Subtarget &Subtarget, + uint64_t Align) { + assert((Align != 0) && "Align is normalized"); + assert(isPowerOf2_64(Align) && "Align is a power of 2"); + switch (Align) { + case 1: + return MVT::i8; + case 2: + return MVT::i16; + case 4: + return MVT::i32; + default: + return Subtarget.is64Bit() ? MVT::i64 : MVT::i32; + } +} + +/// Returns a REP MOVS instruction, possibly with a few load/stores to implement +/// a constant size memory copy. In some cases where we know REP MOVS is +/// inefficient we return an empty SDValue so the calling code can either +/// generate a load/store sequence or call the runtime memcpy function. +static SDValue emitConstantSizeRepmov( + SelectionDAG &DAG, const X86Subtarget &Subtarget, const SDLoc &dl, + SDValue Chain, SDValue Dst, SDValue Src, uint64_t Size, EVT SizeVT, + unsigned Align, bool isVolatile, bool AlwaysInline, + MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) { + + /// TODO: Revisit next line: big copy with ERMSB on march >= haswell are very + /// efficient. + if (!AlwaysInline && Size > Subtarget.getMaxInlineSizeThreshold()) return SDValue(); - /// If not DWORD aligned, it is more efficient to call the library. However - /// if calling the library is not allowed (AlwaysInline), then soldier on as - /// the code generated here is better than the long load-store sequence we - /// would otherwise get. + /// If we have enhanced repmovs we use it. + if (Subtarget.hasERMSB()) + return emitRepmovsB(Subtarget, DAG, dl, Chain, Dst, Src, Size); + + assert(!Subtarget.hasERMSB() && "No efficient RepMovs"); + /// We assume runtime memcpy will do a better job for unaligned copies when + /// ERMS is not present. if (!AlwaysInline && (Align & 3) != 0) return SDValue(); + const MVT BlockType = getOptimalRepmovsType(Subtarget, Align); + const uint64_t BlockBytes = BlockType.getSizeInBits() / 8; + const uint64_t BlockCount = Size / BlockBytes; + const uint64_t BytesLeft = Size % BlockBytes; + SDValue RepMovs = + emitRepmovs(Subtarget, DAG, dl, Chain, Dst, Src, + DAG.getIntPtrConstant(BlockCount, dl), BlockType); + + /// RepMov can process the whole length. + if (BytesLeft == 0) + return RepMovs; + + assert(BytesLeft && "We have leftover at this point"); + + /// In case we optimize for size we use repmovsb even if it's less efficient + /// so we can save the loads/stores of the leftover. + if (DAG.getMachineFunction().getFunction().hasMinSize()) + return emitRepmovsB(Subtarget, DAG, dl, Chain, Dst, Src, Size); + + // Handle the last 1 - 7 bytes. + SmallVector Results; + Results.push_back(RepMovs); + unsigned Offset = Size - BytesLeft; + EVT DstVT = Dst.getValueType(); + EVT SrcVT = Src.getValueType(); + Results.push_back(DAG.getMemcpy( + Chain, dl, + DAG.getNode(ISD::ADD, dl, DstVT, Dst, DAG.getConstant(Offset, dl, DstVT)), + DAG.getNode(ISD::ADD, dl, SrcVT, Src, DAG.getConstant(Offset, dl, SrcVT)), + DAG.getConstant(BytesLeft, dl, SizeVT), Align, isVolatile, + /*AlwaysInline*/ true, /*isTailCall*/ false, + DstPtrInfo.getWithOffset(Offset), SrcPtrInfo.getWithOffset(Offset))); + return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Results); +} + +SDValue X86SelectionDAGInfo::EmitTargetCodeForMemcpy( + SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src, + SDValue Size, unsigned Align, bool isVolatile, bool AlwaysInline, + MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const { // If to a segment-relative address space, use the default lowering. - if (DstPtrInfo.getAddrSpace() >= 256 || - SrcPtrInfo.getAddrSpace() >= 256) + if (DstPtrInfo.getAddrSpace() >= 256 || SrcPtrInfo.getAddrSpace() >= 256) return SDValue(); - // If the base register might conflict with our physical registers, bail out. + // If the base registers conflict with our physical registers, use the default + // lowering. const MCPhysReg ClobberSet[] = {X86::RCX, X86::RSI, X86::RDI, X86::ECX, X86::ESI, X86::EDI}; if (isBaseRegConflictPossible(DAG, ClobberSet)) return SDValue(); - // If the target has enhanced REPMOVSB, then it's at least as fast to use - // REP MOVSB instead of REP MOVS{W,D,Q}, and it avoids having to handle - // BytesLeft. - if (!Subtarget.hasERMSB() && !(Align & 1)) { - if (Align & 2) - // WORD aligned - Repeats.AVT = MVT::i16; - else if (Align & 4) - // DWORD aligned - Repeats.AVT = MVT::i32; - else - // QWORD aligned - Repeats.AVT = Subtarget.is64Bit() ? MVT::i64 : MVT::i32; - - if (Repeats.BytesLeft() > 0 && - DAG.getMachineFunction().getFunction().hasMinSize()) { - // When aggressively optimizing for size, avoid generating the code to - // handle BytesLeft. - Repeats.AVT = MVT::i8; - } - } - - bool Use64BitRegs = Subtarget.isTarget64BitLP64(); - SDValue InFlag; - Chain = DAG.getCopyToReg(Chain, dl, Use64BitRegs ? X86::RCX : X86::ECX, - DAG.getIntPtrConstant(Repeats.Count(), dl), InFlag); - InFlag = Chain.getValue(1); - Chain = DAG.getCopyToReg(Chain, dl, Use64BitRegs ? X86::RDI : X86::EDI, - Dst, InFlag); - InFlag = Chain.getValue(1); - Chain = DAG.getCopyToReg(Chain, dl, Use64BitRegs ? X86::RSI : X86::ESI, - Src, InFlag); - InFlag = Chain.getValue(1); - - SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Glue); - SDValue Ops[] = { Chain, DAG.getValueType(Repeats.AVT), InFlag }; - SDValue RepMovs = DAG.getNode(X86ISD::REP_MOVS, dl, Tys, Ops); + const X86Subtarget &Subtarget = + DAG.getMachineFunction().getSubtarget(); - SmallVector Results; - Results.push_back(RepMovs); - if (Repeats.BytesLeft()) { - // Handle the last 1 - 7 bytes. - unsigned Offset = Repeats.Size - Repeats.BytesLeft(); - EVT DstVT = Dst.getValueType(); - EVT SrcVT = Src.getValueType(); - EVT SizeVT = Size.getValueType(); - Results.push_back(DAG.getMemcpy(Chain, dl, - DAG.getNode(ISD::ADD, dl, DstVT, Dst, - DAG.getConstant(Offset, dl, - DstVT)), - DAG.getNode(ISD::ADD, dl, SrcVT, Src, - DAG.getConstant(Offset, dl, - SrcVT)), - DAG.getConstant(Repeats.BytesLeft(), dl, - SizeVT), - Align, isVolatile, AlwaysInline, false, - DstPtrInfo.getWithOffset(Offset), - SrcPtrInfo.getWithOffset(Offset))); - } + /// Handle constant sizes, + if (ConstantSDNode *ConstantSize = dyn_cast(Size)) + return emitConstantSizeRepmov(DAG, Subtarget, dl, Chain, Dst, Src, + ConstantSize->getZExtValue(), + Size.getValueType(), Align, isVolatile, + AlwaysInline, DstPtrInfo, SrcPtrInfo); - return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Results); + return SDValue(); }