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Diffstat (limited to 'contrib/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp')
| -rw-r--r-- | contrib/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp b/contrib/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp new file mode 100644 index 0000000..c7ebb5d --- /dev/null +++ b/contrib/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp @@ -0,0 +1,293 @@ +//===-- SystemZSelectionDAGInfo.cpp - SystemZ SelectionDAG Info -----------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the SystemZSelectionDAGInfo class. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "systemz-selectiondag-info" +#include "SystemZTargetMachine.h" +#include "llvm/CodeGen/SelectionDAG.h" + +using namespace llvm; + +SystemZSelectionDAGInfo:: +SystemZSelectionDAGInfo(const SystemZTargetMachine &TM) + : TargetSelectionDAGInfo(TM) { +} + +SystemZSelectionDAGInfo::~SystemZSelectionDAGInfo() { +} + +// Decide whether it is best to use a loop or straight-line code for +// a block operation of Size bytes with source address Src and destination +// address Dest. Sequence is the opcode to use for straight-line code +// (such as MVC) and Loop is the opcode to use for loops (such as MVC_LOOP). +// Return the chain for the completed operation. +static SDValue emitMemMem(SelectionDAG &DAG, SDLoc DL, unsigned Sequence, + unsigned Loop, SDValue Chain, SDValue Dst, + SDValue Src, uint64_t Size) { + EVT PtrVT = Src.getValueType(); + // The heuristic we use is to prefer loops for anything that would + // require 7 or more MVCs. With these kinds of sizes there isn't + // much to choose between straight-line code and looping code, + // since the time will be dominated by the MVCs themselves. + // However, the loop has 4 or 5 instructions (depending on whether + // the base addresses can be proved equal), so there doesn't seem + // much point using a loop for 5 * 256 bytes or fewer. Anything in + // the range (5 * 256, 6 * 256) will need another instruction after + // the loop, so it doesn't seem worth using a loop then either. + // The next value up, 6 * 256, can be implemented in the same + // number of straight-line MVCs as 6 * 256 - 1. + if (Size > 6 * 256) + return DAG.getNode(Loop, DL, MVT::Other, Chain, Dst, Src, + DAG.getConstant(Size, PtrVT), + DAG.getConstant(Size / 256, PtrVT)); + return DAG.getNode(Sequence, DL, MVT::Other, Chain, Dst, Src, + DAG.getConstant(Size, PtrVT)); +} + +SDValue SystemZSelectionDAGInfo:: +EmitTargetCodeForMemcpy(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Dst, SDValue Src, SDValue Size, unsigned Align, + bool IsVolatile, bool AlwaysInline, + MachinePointerInfo DstPtrInfo, + MachinePointerInfo SrcPtrInfo) const { + if (IsVolatile) + return SDValue(); + + if (ConstantSDNode *CSize = dyn_cast<ConstantSDNode>(Size)) + return emitMemMem(DAG, DL, SystemZISD::MVC, SystemZISD::MVC_LOOP, + Chain, Dst, Src, CSize->getZExtValue()); + return SDValue(); +} + +// Handle a memset of 1, 2, 4 or 8 bytes with the operands given by +// Chain, Dst, ByteVal and Size. These cases are expected to use +// MVI, MVHHI, MVHI and MVGHI respectively. +static SDValue memsetStore(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Dst, uint64_t ByteVal, uint64_t Size, + unsigned Align, + MachinePointerInfo DstPtrInfo) { + uint64_t StoreVal = ByteVal; + for (unsigned I = 1; I < Size; ++I) + StoreVal |= ByteVal << (I * 8); + return DAG.getStore(Chain, DL, + DAG.getConstant(StoreVal, MVT::getIntegerVT(Size * 8)), + Dst, DstPtrInfo, false, false, Align); +} + +SDValue SystemZSelectionDAGInfo:: +EmitTargetCodeForMemset(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Dst, SDValue Byte, SDValue Size, + unsigned Align, bool IsVolatile, + MachinePointerInfo DstPtrInfo) const { + EVT PtrVT = Dst.getValueType(); + + if (IsVolatile) + return SDValue(); + + if (ConstantSDNode *CSize = dyn_cast<ConstantSDNode>(Size)) { + uint64_t Bytes = CSize->getZExtValue(); + if (Bytes == 0) + return SDValue(); + if (ConstantSDNode *CByte = dyn_cast<ConstantSDNode>(Byte)) { + // Handle cases that can be done using at most two of + // MVI, MVHI, MVHHI and MVGHI. The latter two can only be + // used if ByteVal is all zeros or all ones; in other casees, + // we can move at most 2 halfwords. + uint64_t ByteVal = CByte->getZExtValue(); + if (ByteVal == 0 || ByteVal == 255 ? + Bytes <= 16 && CountPopulation_64(Bytes) <= 2 : + Bytes <= 4) { + unsigned Size1 = Bytes == 16 ? 8 : 1 << findLastSet(Bytes); + unsigned Size2 = Bytes - Size1; + SDValue Chain1 = memsetStore(DAG, DL, Chain, Dst, ByteVal, Size1, + Align, DstPtrInfo); + if (Size2 == 0) + return Chain1; + Dst = DAG.getNode(ISD::ADD, DL, PtrVT, Dst, + DAG.getConstant(Size1, PtrVT)); + DstPtrInfo = DstPtrInfo.getWithOffset(Size1); + SDValue Chain2 = memsetStore(DAG, DL, Chain, Dst, ByteVal, Size2, + std::min(Align, Size1), DstPtrInfo); + return DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Chain1, Chain2); + } + } else { + // Handle one and two bytes using STC. + if (Bytes <= 2) { + SDValue Chain1 = DAG.getStore(Chain, DL, Byte, Dst, DstPtrInfo, + false, false, Align); + if (Bytes == 1) + return Chain1; + SDValue Dst2 = DAG.getNode(ISD::ADD, DL, PtrVT, Dst, + DAG.getConstant(1, PtrVT)); + SDValue Chain2 = DAG.getStore(Chain, DL, Byte, Dst2, + DstPtrInfo.getWithOffset(1), + false, false, 1); + return DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Chain1, Chain2); + } + } + assert(Bytes >= 2 && "Should have dealt with 0- and 1-byte cases already"); + + // Handle the special case of a memset of 0, which can use XC. + ConstantSDNode *CByte = dyn_cast<ConstantSDNode>(Byte); + if (CByte && CByte->getZExtValue() == 0) + return emitMemMem(DAG, DL, SystemZISD::XC, SystemZISD::XC_LOOP, + Chain, Dst, Dst, Bytes); + + // Copy the byte to the first location and then use MVC to copy + // it to the rest. + Chain = DAG.getStore(Chain, DL, Byte, Dst, DstPtrInfo, + false, false, Align); + SDValue DstPlus1 = DAG.getNode(ISD::ADD, DL, PtrVT, Dst, + DAG.getConstant(1, PtrVT)); + return emitMemMem(DAG, DL, SystemZISD::MVC, SystemZISD::MVC_LOOP, + Chain, DstPlus1, Dst, Bytes - 1); + } + return SDValue(); +} + +// Use CLC to compare [Src1, Src1 + Size) with [Src2, Src2 + Size), +// deciding whether to use a loop or straight-line code. +static SDValue emitCLC(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Src1, SDValue Src2, uint64_t Size) { + SDVTList VTs = DAG.getVTList(MVT::Other, MVT::Glue); + EVT PtrVT = Src1.getValueType(); + // A two-CLC sequence is a clear win over a loop, not least because it + // needs only one branch. A three-CLC sequence needs the same number + // of branches as a loop (i.e. 2), but is shorter. That brings us to + // lengths greater than 768 bytes. It seems relatively likely that + // a difference will be found within the first 768 bytes, so we just + // optimize for the smallest number of branch instructions, in order + // to avoid polluting the prediction buffer too much. A loop only ever + // needs 2 branches, whereas a straight-line sequence would need 3 or more. + if (Size > 3 * 256) + return DAG.getNode(SystemZISD::CLC_LOOP, DL, VTs, Chain, Src1, Src2, + DAG.getConstant(Size, PtrVT), + DAG.getConstant(Size / 256, PtrVT)); + return DAG.getNode(SystemZISD::CLC, DL, VTs, Chain, Src1, Src2, + DAG.getConstant(Size, PtrVT)); +} + +// Convert the current CC value into an integer that is 0 if CC == 0, +// less than zero if CC == 1 and greater than zero if CC >= 2. +// The sequence starts with IPM, which puts CC into bits 29 and 28 +// of an integer and clears bits 30 and 31. +static SDValue addIPMSequence(SDLoc DL, SDValue Glue, SelectionDAG &DAG) { + SDValue IPM = DAG.getNode(SystemZISD::IPM, DL, MVT::i32, Glue); + SDValue SRL = DAG.getNode(ISD::SRL, DL, MVT::i32, IPM, + DAG.getConstant(SystemZ::IPM_CC, MVT::i32)); + SDValue ROTL = DAG.getNode(ISD::ROTL, DL, MVT::i32, SRL, + DAG.getConstant(31, MVT::i32)); + return ROTL; +} + +std::pair<SDValue, SDValue> SystemZSelectionDAGInfo:: +EmitTargetCodeForMemcmp(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Src1, SDValue Src2, SDValue Size, + MachinePointerInfo Op1PtrInfo, + MachinePointerInfo Op2PtrInfo) const { + if (ConstantSDNode *CSize = dyn_cast<ConstantSDNode>(Size)) { + uint64_t Bytes = CSize->getZExtValue(); + assert(Bytes > 0 && "Caller should have handled 0-size case"); + Chain = emitCLC(DAG, DL, Chain, Src1, Src2, Bytes); + SDValue Glue = Chain.getValue(1); + return std::make_pair(addIPMSequence(DL, Glue, DAG), Chain); + } + return std::make_pair(SDValue(), SDValue()); +} + +std::pair<SDValue, SDValue> SystemZSelectionDAGInfo:: +EmitTargetCodeForMemchr(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Src, SDValue Char, SDValue Length, + MachinePointerInfo SrcPtrInfo) const { + // Use SRST to find the character. End is its address on success. + EVT PtrVT = Src.getValueType(); + SDVTList VTs = DAG.getVTList(PtrVT, MVT::Other, MVT::Glue); + Length = DAG.getZExtOrTrunc(Length, DL, PtrVT); + Char = DAG.getZExtOrTrunc(Char, DL, MVT::i32); + Char = DAG.getNode(ISD::AND, DL, MVT::i32, Char, + DAG.getConstant(255, MVT::i32)); + SDValue Limit = DAG.getNode(ISD::ADD, DL, PtrVT, Src, Length); + SDValue End = DAG.getNode(SystemZISD::SEARCH_STRING, DL, VTs, Chain, + Limit, Src, Char); + Chain = End.getValue(1); + SDValue Glue = End.getValue(2); + + // Now select between End and null, depending on whether the character + // was found. + SmallVector<SDValue, 5> Ops; + Ops.push_back(End); + Ops.push_back(DAG.getConstant(0, PtrVT)); + Ops.push_back(DAG.getConstant(SystemZ::CCMASK_SRST, MVT::i32)); + Ops.push_back(DAG.getConstant(SystemZ::CCMASK_SRST_FOUND, MVT::i32)); + Ops.push_back(Glue); + VTs = DAG.getVTList(PtrVT, MVT::Glue); + End = DAG.getNode(SystemZISD::SELECT_CCMASK, DL, VTs, &Ops[0], Ops.size()); + return std::make_pair(End, Chain); +} + +std::pair<SDValue, SDValue> SystemZSelectionDAGInfo:: +EmitTargetCodeForStrcpy(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Dest, SDValue Src, + MachinePointerInfo DestPtrInfo, + MachinePointerInfo SrcPtrInfo, bool isStpcpy) const { + SDVTList VTs = DAG.getVTList(Dest.getValueType(), MVT::Other); + SDValue EndDest = DAG.getNode(SystemZISD::STPCPY, DL, VTs, Chain, Dest, Src, + DAG.getConstant(0, MVT::i32)); + return std::make_pair(isStpcpy ? EndDest : Dest, EndDest.getValue(1)); +} + +std::pair<SDValue, SDValue> SystemZSelectionDAGInfo:: +EmitTargetCodeForStrcmp(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Src1, SDValue Src2, + MachinePointerInfo Op1PtrInfo, + MachinePointerInfo Op2PtrInfo) const { + SDVTList VTs = DAG.getVTList(Src1.getValueType(), MVT::Other, MVT::Glue); + SDValue Unused = DAG.getNode(SystemZISD::STRCMP, DL, VTs, Chain, Src1, Src2, + DAG.getConstant(0, MVT::i32)); + Chain = Unused.getValue(1); + SDValue Glue = Chain.getValue(2); + return std::make_pair(addIPMSequence(DL, Glue, DAG), Chain); +} + +// Search from Src for a null character, stopping once Src reaches Limit. +// Return a pair of values, the first being the number of nonnull characters +// and the second being the out chain. +// +// This can be used for strlen by setting Limit to 0. +static std::pair<SDValue, SDValue> getBoundedStrlen(SelectionDAG &DAG, SDLoc DL, + SDValue Chain, SDValue Src, + SDValue Limit) { + EVT PtrVT = Src.getValueType(); + SDVTList VTs = DAG.getVTList(PtrVT, MVT::Other, MVT::Glue); + SDValue End = DAG.getNode(SystemZISD::SEARCH_STRING, DL, VTs, Chain, + Limit, Src, DAG.getConstant(0, MVT::i32)); + Chain = End.getValue(1); + SDValue Len = DAG.getNode(ISD::SUB, DL, PtrVT, End, Src); + return std::make_pair(Len, Chain); +} + +std::pair<SDValue, SDValue> SystemZSelectionDAGInfo:: +EmitTargetCodeForStrlen(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Src, MachinePointerInfo SrcPtrInfo) const { + EVT PtrVT = Src.getValueType(); + return getBoundedStrlen(DAG, DL, Chain, Src, DAG.getConstant(0, PtrVT)); +} + +std::pair<SDValue, SDValue> SystemZSelectionDAGInfo:: +EmitTargetCodeForStrnlen(SelectionDAG &DAG, SDLoc DL, SDValue Chain, + SDValue Src, SDValue MaxLength, + MachinePointerInfo SrcPtrInfo) const { + EVT PtrVT = Src.getValueType(); + MaxLength = DAG.getZExtOrTrunc(MaxLength, DL, PtrVT); + SDValue Limit = DAG.getNode(ISD::ADD, DL, PtrVT, Src, MaxLength); + return getBoundedStrlen(DAG, DL, Chain, Src, Limit); +} |
