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PPCInstrInfo.cpp
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PPCInstrInfo.cpp
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//===-- PPCInstrInfo.cpp - PowerPC Instruction Information ----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains the PowerPC implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "PPCInstrInfo.h"
#include "MCTargetDesc/PPCPredicates.h"
#include "PPC.h"
#include "PPCHazardRecognizers.h"
#include "PPCInstrBuilder.h"
#include "PPCMachineFunctionInfo.h"
#include "PPCTargetMachine.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/MachineCombinerPattern.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/CodeGen/RegisterClassInfo.h"
#include "llvm/CodeGen/RegisterPressure.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "ppc-instr-info"
#define GET_INSTRMAP_INFO
#define GET_INSTRINFO_CTOR_DTOR
#include "PPCGenInstrInfo.inc"
STATISTIC(NumStoreSPILLVSRRCAsVec,
"Number of spillvsrrc spilled to stack as vec");
STATISTIC(NumStoreSPILLVSRRCAsGpr,
"Number of spillvsrrc spilled to stack as gpr");
STATISTIC(NumGPRtoVSRSpill, "Number of gpr spills to spillvsrrc");
STATISTIC(CmpIselsConverted,
"Number of ISELs that depend on comparison of constants converted");
STATISTIC(MissedConvertibleImmediateInstrs,
"Number of compare-immediate instructions fed by constants");
STATISTIC(NumRcRotatesConvertedToRcAnd,
"Number of record-form rotates converted to record-form andi");
static cl::
opt<bool> DisableCTRLoopAnal("disable-ppc-ctrloop-analysis", cl::Hidden,
cl::desc("Disable analysis for CTR loops"));
static cl::opt<bool> DisableCmpOpt("disable-ppc-cmp-opt",
cl::desc("Disable compare instruction optimization"), cl::Hidden);
static cl::opt<bool> VSXSelfCopyCrash("crash-on-ppc-vsx-self-copy",
cl::desc("Causes the backend to crash instead of generating a nop VSX copy"),
cl::Hidden);
static cl::opt<bool>
UseOldLatencyCalc("ppc-old-latency-calc", cl::Hidden,
cl::desc("Use the old (incorrect) instruction latency calculation"));
static cl::opt<float>
FMARPFactor("ppc-fma-rp-factor", cl::Hidden, cl::init(1.5),
cl::desc("register pressure factor for the transformations."));
static cl::opt<bool> EnableFMARegPressureReduction(
"ppc-fma-rp-reduction", cl::Hidden, cl::init(true),
cl::desc("enable register pressure reduce in machine combiner pass."));
// Pin the vtable to this file.
void PPCInstrInfo::anchor() {}
PPCInstrInfo::PPCInstrInfo(PPCSubtarget &STI)
: PPCGenInstrInfo(PPC::ADJCALLSTACKDOWN, PPC::ADJCALLSTACKUP,
/* CatchRetOpcode */ -1,
STI.isPPC64() ? PPC::BLR8 : PPC::BLR),
Subtarget(STI), RI(STI.getTargetMachine()) {}
/// CreateTargetHazardRecognizer - Return the hazard recognizer to use for
/// this target when scheduling the DAG.
ScheduleHazardRecognizer *
PPCInstrInfo::CreateTargetHazardRecognizer(const TargetSubtargetInfo *STI,
const ScheduleDAG *DAG) const {
unsigned Directive =
static_cast<const PPCSubtarget *>(STI)->getCPUDirective();
if (Directive == PPC::DIR_440 || Directive == PPC::DIR_A2 ||
Directive == PPC::DIR_E500mc || Directive == PPC::DIR_E5500) {
const InstrItineraryData *II =
static_cast<const PPCSubtarget *>(STI)->getInstrItineraryData();
return new ScoreboardHazardRecognizer(II, DAG);
}
return TargetInstrInfo::CreateTargetHazardRecognizer(STI, DAG);
}
/// CreateTargetPostRAHazardRecognizer - Return the postRA hazard recognizer
/// to use for this target when scheduling the DAG.
ScheduleHazardRecognizer *
PPCInstrInfo::CreateTargetPostRAHazardRecognizer(const InstrItineraryData *II,
const ScheduleDAG *DAG) const {
unsigned Directive =
DAG->MF.getSubtarget<PPCSubtarget>().getCPUDirective();
// FIXME: Leaving this as-is until we have POWER9 scheduling info
if (Directive == PPC::DIR_PWR7 || Directive == PPC::DIR_PWR8)
return new PPCDispatchGroupSBHazardRecognizer(II, DAG);
// Most subtargets use a PPC970 recognizer.
if (Directive != PPC::DIR_440 && Directive != PPC::DIR_A2 &&
Directive != PPC::DIR_E500mc && Directive != PPC::DIR_E5500) {
assert(DAG->TII && "No InstrInfo?");
return new PPCHazardRecognizer970(*DAG);
}
return new ScoreboardHazardRecognizer(II, DAG);
}
unsigned PPCInstrInfo::getInstrLatency(const InstrItineraryData *ItinData,
const MachineInstr &MI,
unsigned *PredCost) const {
if (!ItinData || UseOldLatencyCalc)
return PPCGenInstrInfo::getInstrLatency(ItinData, MI, PredCost);
// The default implementation of getInstrLatency calls getStageLatency, but
// getStageLatency does not do the right thing for us. While we have
// itinerary, most cores are fully pipelined, and so the itineraries only
// express the first part of the pipeline, not every stage. Instead, we need
// to use the listed output operand cycle number (using operand 0 here, which
// is an output).
unsigned Latency = 1;
unsigned DefClass = MI.getDesc().getSchedClass();
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI.getOperand(i);
if (!MO.isReg() || !MO.isDef() || MO.isImplicit())
continue;
int Cycle = ItinData->getOperandCycle(DefClass, i);
if (Cycle < 0)
continue;
Latency = std::max(Latency, (unsigned) Cycle);
}
return Latency;
}
int PPCInstrInfo::getOperandLatency(const InstrItineraryData *ItinData,
const MachineInstr &DefMI, unsigned DefIdx,
const MachineInstr &UseMI,
unsigned UseIdx) const {
int Latency = PPCGenInstrInfo::getOperandLatency(ItinData, DefMI, DefIdx,
UseMI, UseIdx);
if (!DefMI.getParent())
return Latency;
const MachineOperand &DefMO = DefMI.getOperand(DefIdx);
Register Reg = DefMO.getReg();
bool IsRegCR;
if (Register::isVirtualRegister(Reg)) {
const MachineRegisterInfo *MRI =
&DefMI.getParent()->getParent()->getRegInfo();
IsRegCR = MRI->getRegClass(Reg)->hasSuperClassEq(&PPC::CRRCRegClass) ||
MRI->getRegClass(Reg)->hasSuperClassEq(&PPC::CRBITRCRegClass);
} else {
IsRegCR = PPC::CRRCRegClass.contains(Reg) ||
PPC::CRBITRCRegClass.contains(Reg);
}
if (UseMI.isBranch() && IsRegCR) {
if (Latency < 0)
Latency = getInstrLatency(ItinData, DefMI);
// On some cores, there is an additional delay between writing to a condition
// register, and using it from a branch.
unsigned Directive = Subtarget.getCPUDirective();
switch (Directive) {
default: break;
case PPC::DIR_7400:
case PPC::DIR_750:
case PPC::DIR_970:
case PPC::DIR_E5500:
case PPC::DIR_PWR4:
case PPC::DIR_PWR5:
case PPC::DIR_PWR5X:
case PPC::DIR_PWR6:
case PPC::DIR_PWR6X:
case PPC::DIR_PWR7:
case PPC::DIR_PWR8:
// FIXME: Is this needed for POWER9?
Latency += 2;
break;
}
}
return Latency;
}
/// This is an architecture-specific helper function of reassociateOps.
/// Set special operand attributes for new instructions after reassociation.
void PPCInstrInfo::setSpecialOperandAttr(MachineInstr &OldMI1,
MachineInstr &OldMI2,
MachineInstr &NewMI1,
MachineInstr &NewMI2) const {
// Propagate FP flags from the original instructions.
// But clear poison-generating flags because those may not be valid now.
uint16_t IntersectedFlags = OldMI1.getFlags() & OldMI2.getFlags();
NewMI1.setFlags(IntersectedFlags);
NewMI1.clearFlag(MachineInstr::MIFlag::NoSWrap);
NewMI1.clearFlag(MachineInstr::MIFlag::NoUWrap);
NewMI1.clearFlag(MachineInstr::MIFlag::IsExact);
NewMI2.setFlags(IntersectedFlags);
NewMI2.clearFlag(MachineInstr::MIFlag::NoSWrap);
NewMI2.clearFlag(MachineInstr::MIFlag::NoUWrap);
NewMI2.clearFlag(MachineInstr::MIFlag::IsExact);
}
void PPCInstrInfo::setSpecialOperandAttr(MachineInstr &MI,
uint16_t Flags) const {
MI.setFlags(Flags);
MI.clearFlag(MachineInstr::MIFlag::NoSWrap);
MI.clearFlag(MachineInstr::MIFlag::NoUWrap);
MI.clearFlag(MachineInstr::MIFlag::IsExact);
}
// This function does not list all associative and commutative operations, but
// only those worth feeding through the machine combiner in an attempt to
// reduce the critical path. Mostly, this means floating-point operations,
// because they have high latencies(>=5) (compared to other operations, such as
// and/or, which are also associative and commutative, but have low latencies).
bool PPCInstrInfo::isAssociativeAndCommutative(const MachineInstr &Inst) const {
switch (Inst.getOpcode()) {
// Floating point:
// FP Add:
case PPC::FADD:
case PPC::FADDS:
// FP Multiply:
case PPC::FMUL:
case PPC::FMULS:
// Altivec Add:
case PPC::VADDFP:
// VSX Add:
case PPC::XSADDDP:
case PPC::XVADDDP:
case PPC::XVADDSP:
case PPC::XSADDSP:
// VSX Multiply:
case PPC::XSMULDP:
case PPC::XVMULDP:
case PPC::XVMULSP:
case PPC::XSMULSP:
return Inst.getFlag(MachineInstr::MIFlag::FmReassoc) &&
Inst.getFlag(MachineInstr::MIFlag::FmNsz);
// Fixed point:
// Multiply:
case PPC::MULHD:
case PPC::MULLD:
case PPC::MULHW:
case PPC::MULLW:
return true;
default:
return false;
}
}
#define InfoArrayIdxFMAInst 0
#define InfoArrayIdxFAddInst 1
#define InfoArrayIdxFMULInst 2
#define InfoArrayIdxAddOpIdx 3
#define InfoArrayIdxMULOpIdx 4
#define InfoArrayIdxFSubInst 5
// Array keeps info for FMA instructions:
// Index 0(InfoArrayIdxFMAInst): FMA instruction;
// Index 1(InfoArrayIdxFAddInst): ADD instruction associated with FMA;
// Index 2(InfoArrayIdxFMULInst): MUL instruction associated with FMA;
// Index 3(InfoArrayIdxAddOpIdx): ADD operand index in FMA operands;
// Index 4(InfoArrayIdxMULOpIdx): first MUL operand index in FMA operands;
// second MUL operand index is plus 1;
// Index 5(InfoArrayIdxFSubInst): SUB instruction associated with FMA.
static const uint16_t FMAOpIdxInfo[][6] = {
// FIXME: Add more FMA instructions like XSNMADDADP and so on.
{PPC::XSMADDADP, PPC::XSADDDP, PPC::XSMULDP, 1, 2, PPC::XSSUBDP},
{PPC::XSMADDASP, PPC::XSADDSP, PPC::XSMULSP, 1, 2, PPC::XSSUBSP},
{PPC::XVMADDADP, PPC::XVADDDP, PPC::XVMULDP, 1, 2, PPC::XVSUBDP},
{PPC::XVMADDASP, PPC::XVADDSP, PPC::XVMULSP, 1, 2, PPC::XVSUBSP},
{PPC::FMADD, PPC::FADD, PPC::FMUL, 3, 1, PPC::FSUB},
{PPC::FMADDS, PPC::FADDS, PPC::FMULS, 3, 1, PPC::FSUBS}};
// Check if an opcode is a FMA instruction. If it is, return the index in array
// FMAOpIdxInfo. Otherwise, return -1.
int16_t PPCInstrInfo::getFMAOpIdxInfo(unsigned Opcode) const {
for (unsigned I = 0; I < std::size(FMAOpIdxInfo); I++)
if (FMAOpIdxInfo[I][InfoArrayIdxFMAInst] == Opcode)
return I;
return -1;
}
// On PowerPC target, we have two kinds of patterns related to FMA:
// 1: Improve ILP.
// Try to reassociate FMA chains like below:
//
// Pattern 1:
// A = FADD X, Y (Leaf)
// B = FMA A, M21, M22 (Prev)
// C = FMA B, M31, M32 (Root)
// -->
// A = FMA X, M21, M22
// B = FMA Y, M31, M32
// C = FADD A, B
//
// Pattern 2:
// A = FMA X, M11, M12 (Leaf)
// B = FMA A, M21, M22 (Prev)
// C = FMA B, M31, M32 (Root)
// -->
// A = FMUL M11, M12
// B = FMA X, M21, M22
// D = FMA A, M31, M32
// C = FADD B, D
//
// breaking the dependency between A and B, allowing FMA to be executed in
// parallel (or back-to-back in a pipeline) instead of depending on each other.
//
// 2: Reduce register pressure.
// Try to reassociate FMA with FSUB and a constant like below:
// C is a floating point const.
//
// Pattern 1:
// A = FSUB X, Y (Leaf)
// D = FMA B, C, A (Root)
// -->
// A = FMA B, Y, -C
// D = FMA A, X, C
//
// Pattern 2:
// A = FSUB X, Y (Leaf)
// D = FMA B, A, C (Root)
// -->
// A = FMA B, Y, -C
// D = FMA A, X, C
//
// Before the transformation, A must be assigned with different hardware
// register with D. After the transformation, A and D must be assigned with
// same hardware register due to TIE attribute of FMA instructions.
//
bool PPCInstrInfo::getFMAPatterns(
MachineInstr &Root, SmallVectorImpl<MachineCombinerPattern> &Patterns,
bool DoRegPressureReduce) const {
MachineBasicBlock *MBB = Root.getParent();
const MachineRegisterInfo *MRI = &MBB->getParent()->getRegInfo();
const TargetRegisterInfo *TRI = &getRegisterInfo();
auto IsAllOpsVirtualReg = [](const MachineInstr &Instr) {
for (const auto &MO : Instr.explicit_operands())
if (!(MO.isReg() && Register::isVirtualRegister(MO.getReg())))
return false;
return true;
};
auto IsReassociableAddOrSub = [&](const MachineInstr &Instr,
unsigned OpType) {
if (Instr.getOpcode() !=
FMAOpIdxInfo[getFMAOpIdxInfo(Root.getOpcode())][OpType])
return false;
// Instruction can be reassociated.
// fast math flags may prohibit reassociation.
if (!(Instr.getFlag(MachineInstr::MIFlag::FmReassoc) &&
Instr.getFlag(MachineInstr::MIFlag::FmNsz)))
return false;
// Instruction operands are virtual registers for reassociation.
if (!IsAllOpsVirtualReg(Instr))
return false;
// For register pressure reassociation, the FSub must have only one use as
// we want to delete the sub to save its def.
if (OpType == InfoArrayIdxFSubInst &&
!MRI->hasOneNonDBGUse(Instr.getOperand(0).getReg()))
return false;
return true;
};
auto IsReassociableFMA = [&](const MachineInstr &Instr, int16_t &AddOpIdx,
int16_t &MulOpIdx, bool IsLeaf) {
int16_t Idx = getFMAOpIdxInfo(Instr.getOpcode());
if (Idx < 0)
return false;
// Instruction can be reassociated.
// fast math flags may prohibit reassociation.
if (!(Instr.getFlag(MachineInstr::MIFlag::FmReassoc) &&
Instr.getFlag(MachineInstr::MIFlag::FmNsz)))
return false;
// Instruction operands are virtual registers for reassociation.
if (!IsAllOpsVirtualReg(Instr))
return false;
MulOpIdx = FMAOpIdxInfo[Idx][InfoArrayIdxMULOpIdx];
if (IsLeaf)
return true;
AddOpIdx = FMAOpIdxInfo[Idx][InfoArrayIdxAddOpIdx];
const MachineOperand &OpAdd = Instr.getOperand(AddOpIdx);
MachineInstr *MIAdd = MRI->getUniqueVRegDef(OpAdd.getReg());
// If 'add' operand's def is not in current block, don't do ILP related opt.
if (!MIAdd || MIAdd->getParent() != MBB)
return false;
// If this is not Leaf FMA Instr, its 'add' operand should only have one use
// as this fma will be changed later.
return IsLeaf ? true : MRI->hasOneNonDBGUse(OpAdd.getReg());
};
int16_t AddOpIdx = -1;
int16_t MulOpIdx = -1;
bool IsUsedOnceL = false;
bool IsUsedOnceR = false;
MachineInstr *MULInstrL = nullptr;
MachineInstr *MULInstrR = nullptr;
auto IsRPReductionCandidate = [&]() {
// Currently, we only support float and double.
// FIXME: add support for other types.
unsigned Opcode = Root.getOpcode();
if (Opcode != PPC::XSMADDASP && Opcode != PPC::XSMADDADP)
return false;
// Root must be a valid FMA like instruction.
// Treat it as leaf as we don't care its add operand.
if (IsReassociableFMA(Root, AddOpIdx, MulOpIdx, true)) {
assert((MulOpIdx >= 0) && "mul operand index not right!");
Register MULRegL = TRI->lookThruSingleUseCopyChain(
Root.getOperand(MulOpIdx).getReg(), MRI);
Register MULRegR = TRI->lookThruSingleUseCopyChain(
Root.getOperand(MulOpIdx + 1).getReg(), MRI);
if (!MULRegL && !MULRegR)
return false;
if (MULRegL && !MULRegR) {
MULRegR =
TRI->lookThruCopyLike(Root.getOperand(MulOpIdx + 1).getReg(), MRI);
IsUsedOnceL = true;
} else if (!MULRegL && MULRegR) {
MULRegL =
TRI->lookThruCopyLike(Root.getOperand(MulOpIdx).getReg(), MRI);
IsUsedOnceR = true;
} else {
IsUsedOnceL = true;
IsUsedOnceR = true;
}
if (!Register::isVirtualRegister(MULRegL) ||
!Register::isVirtualRegister(MULRegR))
return false;
MULInstrL = MRI->getVRegDef(MULRegL);
MULInstrR = MRI->getVRegDef(MULRegR);
return true;
}
return false;
};
// Register pressure fma reassociation patterns.
if (DoRegPressureReduce && IsRPReductionCandidate()) {
assert((MULInstrL && MULInstrR) && "wrong register preduction candidate!");
// Register pressure pattern 1
if (isLoadFromConstantPool(MULInstrL) && IsUsedOnceR &&
IsReassociableAddOrSub(*MULInstrR, InfoArrayIdxFSubInst)) {
LLVM_DEBUG(dbgs() << "add pattern REASSOC_XY_BCA\n");
Patterns.push_back(MachineCombinerPattern::REASSOC_XY_BCA);
return true;
}
// Register pressure pattern 2
if ((isLoadFromConstantPool(MULInstrR) && IsUsedOnceL &&
IsReassociableAddOrSub(*MULInstrL, InfoArrayIdxFSubInst))) {
LLVM_DEBUG(dbgs() << "add pattern REASSOC_XY_BAC\n");
Patterns.push_back(MachineCombinerPattern::REASSOC_XY_BAC);
return true;
}
}
// ILP fma reassociation patterns.
// Root must be a valid FMA like instruction.
AddOpIdx = -1;
if (!IsReassociableFMA(Root, AddOpIdx, MulOpIdx, false))
return false;
assert((AddOpIdx >= 0) && "add operand index not right!");
Register RegB = Root.getOperand(AddOpIdx).getReg();
MachineInstr *Prev = MRI->getUniqueVRegDef(RegB);
// Prev must be a valid FMA like instruction.
AddOpIdx = -1;
if (!IsReassociableFMA(*Prev, AddOpIdx, MulOpIdx, false))
return false;
assert((AddOpIdx >= 0) && "add operand index not right!");
Register RegA = Prev->getOperand(AddOpIdx).getReg();
MachineInstr *Leaf = MRI->getUniqueVRegDef(RegA);
AddOpIdx = -1;
if (IsReassociableFMA(*Leaf, AddOpIdx, MulOpIdx, true)) {
Patterns.push_back(MachineCombinerPattern::REASSOC_XMM_AMM_BMM);
LLVM_DEBUG(dbgs() << "add pattern REASSOC_XMM_AMM_BMM\n");
return true;
}
if (IsReassociableAddOrSub(*Leaf, InfoArrayIdxFAddInst)) {
Patterns.push_back(MachineCombinerPattern::REASSOC_XY_AMM_BMM);
LLVM_DEBUG(dbgs() << "add pattern REASSOC_XY_AMM_BMM\n");
return true;
}
return false;
}
void PPCInstrInfo::finalizeInsInstrs(
MachineInstr &Root, MachineCombinerPattern &P,
SmallVectorImpl<MachineInstr *> &InsInstrs) const {
assert(!InsInstrs.empty() && "Instructions set to be inserted is empty!");
MachineFunction *MF = Root.getMF();
MachineRegisterInfo *MRI = &MF->getRegInfo();
const TargetRegisterInfo *TRI = &getRegisterInfo();
MachineConstantPool *MCP = MF->getConstantPool();
int16_t Idx = getFMAOpIdxInfo(Root.getOpcode());
if (Idx < 0)
return;
uint16_t FirstMulOpIdx = FMAOpIdxInfo[Idx][InfoArrayIdxMULOpIdx];
// For now we only need to fix up placeholder for register pressure reduce
// patterns.
Register ConstReg = 0;
switch (P) {
case MachineCombinerPattern::REASSOC_XY_BCA:
ConstReg =
TRI->lookThruCopyLike(Root.getOperand(FirstMulOpIdx).getReg(), MRI);
break;
case MachineCombinerPattern::REASSOC_XY_BAC:
ConstReg =
TRI->lookThruCopyLike(Root.getOperand(FirstMulOpIdx + 1).getReg(), MRI);
break;
default:
// Not register pressure reduce patterns.
return;
}
MachineInstr *ConstDefInstr = MRI->getVRegDef(ConstReg);
// Get const value from const pool.
const Constant *C = getConstantFromConstantPool(ConstDefInstr);
assert(isa<llvm::ConstantFP>(C) && "not a valid constant!");
// Get negative fp const.
APFloat F1((dyn_cast<ConstantFP>(C))->getValueAPF());
F1.changeSign();
Constant *NegC = ConstantFP::get(dyn_cast<ConstantFP>(C)->getContext(), F1);
Align Alignment = MF->getDataLayout().getPrefTypeAlign(C->getType());
// Put negative fp const into constant pool.
unsigned ConstPoolIdx = MCP->getConstantPoolIndex(NegC, Alignment);
MachineOperand *Placeholder = nullptr;
// Record the placeholder PPC::ZERO8 we add in reassociateFMA.
for (auto *Inst : InsInstrs) {
for (MachineOperand &Operand : Inst->explicit_operands()) {
assert(Operand.isReg() && "Invalid instruction in InsInstrs!");
if (Operand.getReg() == PPC::ZERO8) {
Placeholder = &Operand;
break;
}
}
}
assert(Placeholder && "Placeholder does not exist!");
// Generate instructions to load the const fp from constant pool.
// We only support PPC64 and medium code model.
Register LoadNewConst =
generateLoadForNewConst(ConstPoolIdx, &Root, C->getType(), InsInstrs);
// Fill the placeholder with the new load from constant pool.
Placeholder->setReg(LoadNewConst);
}
bool PPCInstrInfo::shouldReduceRegisterPressure(
MachineBasicBlock *MBB, RegisterClassInfo *RegClassInfo) const {
if (!EnableFMARegPressureReduction)
return false;
// Currently, we only enable register pressure reducing in machine combiner
// for: 1: PPC64; 2: Code Model is Medium; 3: Power9 which also has vector
// support.
//
// So we need following instructions to access a TOC entry:
//
// %6:g8rc_and_g8rc_nox0 = ADDIStocHA8 $x2, %const.0
// %7:vssrc = DFLOADf32 target-flags(ppc-toc-lo) %const.0,
// killed %6:g8rc_and_g8rc_nox0, implicit $x2 :: (load 4 from constant-pool)
//
// FIXME: add more supported targets, like Small and Large code model, PPC32,
// AIX.
if (!(Subtarget.isPPC64() && Subtarget.hasP9Vector() &&
Subtarget.getTargetMachine().getCodeModel() == CodeModel::Medium))
return false;
const TargetRegisterInfo *TRI = &getRegisterInfo();
MachineFunction *MF = MBB->getParent();
MachineRegisterInfo *MRI = &MF->getRegInfo();
auto GetMBBPressure = [&](MachineBasicBlock *MBB) -> std::vector<unsigned> {
RegionPressure Pressure;
RegPressureTracker RPTracker(Pressure);
// Initialize the register pressure tracker.
RPTracker.init(MBB->getParent(), RegClassInfo, nullptr, MBB, MBB->end(),
/*TrackLaneMasks*/ false, /*TrackUntiedDefs=*/true);
for (MachineBasicBlock::iterator MII = MBB->instr_end(),
MIE = MBB->instr_begin();
MII != MIE; --MII) {
MachineInstr &MI = *std::prev(MII);
if (MI.isDebugValue() || MI.isDebugLabel())
continue;
RegisterOperands RegOpers;
RegOpers.collect(MI, *TRI, *MRI, false, false);
RPTracker.recedeSkipDebugValues();
assert(&*RPTracker.getPos() == &MI && "RPTracker sync error!");
RPTracker.recede(RegOpers);
}
// Close the RPTracker to finalize live ins.
RPTracker.closeRegion();
return RPTracker.getPressure().MaxSetPressure;
};
// For now we only care about float and double type fma.
unsigned VSSRCLimit = TRI->getRegPressureSetLimit(
*MBB->getParent(), PPC::RegisterPressureSets::VSSRC);
// Only reduce register pressure when pressure is high.
return GetMBBPressure(MBB)[PPC::RegisterPressureSets::VSSRC] >
(float)VSSRCLimit * FMARPFactor;
}
bool PPCInstrInfo::isLoadFromConstantPool(MachineInstr *I) const {
// I has only one memory operand which is load from constant pool.
if (!I->hasOneMemOperand())
return false;
MachineMemOperand *Op = I->memoperands()[0];
return Op->isLoad() && Op->getPseudoValue() &&
Op->getPseudoValue()->kind() == PseudoSourceValue::ConstantPool;
}
Register PPCInstrInfo::generateLoadForNewConst(
unsigned Idx, MachineInstr *MI, Type *Ty,
SmallVectorImpl<MachineInstr *> &InsInstrs) const {
// Now we only support PPC64, Medium code model and P9 with vector.
// We have immutable pattern to access const pool. See function
// shouldReduceRegisterPressure.
assert((Subtarget.isPPC64() && Subtarget.hasP9Vector() &&
Subtarget.getTargetMachine().getCodeModel() == CodeModel::Medium) &&
"Target not supported!\n");
MachineFunction *MF = MI->getMF();
MachineRegisterInfo *MRI = &MF->getRegInfo();
// Generate ADDIStocHA8
Register VReg1 = MRI->createVirtualRegister(&PPC::G8RC_and_G8RC_NOX0RegClass);
MachineInstrBuilder TOCOffset =
BuildMI(*MF, MI->getDebugLoc(), get(PPC::ADDIStocHA8), VReg1)
.addReg(PPC::X2)
.addConstantPoolIndex(Idx);
assert((Ty->isFloatTy() || Ty->isDoubleTy()) &&
"Only float and double are supported!");
unsigned LoadOpcode;
// Should be float type or double type.
if (Ty->isFloatTy())
LoadOpcode = PPC::DFLOADf32;
else
LoadOpcode = PPC::DFLOADf64;
const TargetRegisterClass *RC = MRI->getRegClass(MI->getOperand(0).getReg());
Register VReg2 = MRI->createVirtualRegister(RC);
MachineMemOperand *MMO = MF->getMachineMemOperand(
MachinePointerInfo::getConstantPool(*MF), MachineMemOperand::MOLoad,
Ty->getScalarSizeInBits() / 8, MF->getDataLayout().getPrefTypeAlign(Ty));
// Generate Load from constant pool.
MachineInstrBuilder Load =
BuildMI(*MF, MI->getDebugLoc(), get(LoadOpcode), VReg2)
.addConstantPoolIndex(Idx)
.addReg(VReg1, getKillRegState(true))
.addMemOperand(MMO);
Load->getOperand(1).setTargetFlags(PPCII::MO_TOC_LO);
// Insert the toc load instructions into InsInstrs.
InsInstrs.insert(InsInstrs.begin(), Load);
InsInstrs.insert(InsInstrs.begin(), TOCOffset);
return VReg2;
}
// This function returns the const value in constant pool if the \p I is a load
// from constant pool.
const Constant *
PPCInstrInfo::getConstantFromConstantPool(MachineInstr *I) const {
MachineFunction *MF = I->getMF();
MachineRegisterInfo *MRI = &MF->getRegInfo();
MachineConstantPool *MCP = MF->getConstantPool();
assert(I->mayLoad() && "Should be a load instruction.\n");
for (auto MO : I->uses()) {
if (!MO.isReg())
continue;
Register Reg = MO.getReg();
if (Reg == 0 || !Register::isVirtualRegister(Reg))
continue;
// Find the toc address.
MachineInstr *DefMI = MRI->getVRegDef(Reg);
for (auto MO2 : DefMI->uses())
if (MO2.isCPI())
return (MCP->getConstants())[MO2.getIndex()].Val.ConstVal;
}
return nullptr;
}
bool PPCInstrInfo::getMachineCombinerPatterns(
MachineInstr &Root, SmallVectorImpl<MachineCombinerPattern> &Patterns,
bool DoRegPressureReduce) const {
// Using the machine combiner in this way is potentially expensive, so
// restrict to when aggressive optimizations are desired.
if (Subtarget.getTargetMachine().getOptLevel() != CodeGenOpt::Aggressive)
return false;
if (getFMAPatterns(Root, Patterns, DoRegPressureReduce))
return true;
return TargetInstrInfo::getMachineCombinerPatterns(Root, Patterns,
DoRegPressureReduce);
}
void PPCInstrInfo::genAlternativeCodeSequence(
MachineInstr &Root, MachineCombinerPattern Pattern,
SmallVectorImpl<MachineInstr *> &InsInstrs,
SmallVectorImpl<MachineInstr *> &DelInstrs,
DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const {
switch (Pattern) {
case MachineCombinerPattern::REASSOC_XY_AMM_BMM:
case MachineCombinerPattern::REASSOC_XMM_AMM_BMM:
case MachineCombinerPattern::REASSOC_XY_BCA:
case MachineCombinerPattern::REASSOC_XY_BAC:
reassociateFMA(Root, Pattern, InsInstrs, DelInstrs, InstrIdxForVirtReg);
break;
default:
// Reassociate default patterns.
TargetInstrInfo::genAlternativeCodeSequence(Root, Pattern, InsInstrs,
DelInstrs, InstrIdxForVirtReg);
break;
}
}
void PPCInstrInfo::reassociateFMA(
MachineInstr &Root, MachineCombinerPattern Pattern,
SmallVectorImpl<MachineInstr *> &InsInstrs,
SmallVectorImpl<MachineInstr *> &DelInstrs,
DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const {
MachineFunction *MF = Root.getMF();
MachineRegisterInfo &MRI = MF->getRegInfo();
const TargetRegisterInfo *TRI = &getRegisterInfo();
MachineOperand &OpC = Root.getOperand(0);
Register RegC = OpC.getReg();
const TargetRegisterClass *RC = MRI.getRegClass(RegC);
MRI.constrainRegClass(RegC, RC);
unsigned FmaOp = Root.getOpcode();
int16_t Idx = getFMAOpIdxInfo(FmaOp);
assert(Idx >= 0 && "Root must be a FMA instruction");
bool IsILPReassociate =
(Pattern == MachineCombinerPattern::REASSOC_XY_AMM_BMM) ||
(Pattern == MachineCombinerPattern::REASSOC_XMM_AMM_BMM);
uint16_t AddOpIdx = FMAOpIdxInfo[Idx][InfoArrayIdxAddOpIdx];
uint16_t FirstMulOpIdx = FMAOpIdxInfo[Idx][InfoArrayIdxMULOpIdx];
MachineInstr *Prev = nullptr;
MachineInstr *Leaf = nullptr;
switch (Pattern) {
default:
llvm_unreachable("not recognized pattern!");
case MachineCombinerPattern::REASSOC_XY_AMM_BMM:
case MachineCombinerPattern::REASSOC_XMM_AMM_BMM:
Prev = MRI.getUniqueVRegDef(Root.getOperand(AddOpIdx).getReg());
Leaf = MRI.getUniqueVRegDef(Prev->getOperand(AddOpIdx).getReg());
break;
case MachineCombinerPattern::REASSOC_XY_BAC: {
Register MULReg =
TRI->lookThruCopyLike(Root.getOperand(FirstMulOpIdx).getReg(), &MRI);
Leaf = MRI.getVRegDef(MULReg);
break;
}
case MachineCombinerPattern::REASSOC_XY_BCA: {
Register MULReg = TRI->lookThruCopyLike(
Root.getOperand(FirstMulOpIdx + 1).getReg(), &MRI);
Leaf = MRI.getVRegDef(MULReg);
break;
}
}
uint16_t IntersectedFlags = 0;
if (IsILPReassociate)
IntersectedFlags = Root.getFlags() & Prev->getFlags() & Leaf->getFlags();
else
IntersectedFlags = Root.getFlags() & Leaf->getFlags();
auto GetOperandInfo = [&](const MachineOperand &Operand, Register &Reg,
bool &KillFlag) {
Reg = Operand.getReg();
MRI.constrainRegClass(Reg, RC);
KillFlag = Operand.isKill();
};
auto GetFMAInstrInfo = [&](const MachineInstr &Instr, Register &MulOp1,
Register &MulOp2, Register &AddOp,
bool &MulOp1KillFlag, bool &MulOp2KillFlag,
bool &AddOpKillFlag) {
GetOperandInfo(Instr.getOperand(FirstMulOpIdx), MulOp1, MulOp1KillFlag);
GetOperandInfo(Instr.getOperand(FirstMulOpIdx + 1), MulOp2, MulOp2KillFlag);
GetOperandInfo(Instr.getOperand(AddOpIdx), AddOp, AddOpKillFlag);
};
Register RegM11, RegM12, RegX, RegY, RegM21, RegM22, RegM31, RegM32, RegA11,
RegA21, RegB;
bool KillX = false, KillY = false, KillM11 = false, KillM12 = false,
KillM21 = false, KillM22 = false, KillM31 = false, KillM32 = false,
KillA11 = false, KillA21 = false, KillB = false;
GetFMAInstrInfo(Root, RegM31, RegM32, RegB, KillM31, KillM32, KillB);
if (IsILPReassociate)
GetFMAInstrInfo(*Prev, RegM21, RegM22, RegA21, KillM21, KillM22, KillA21);
if (Pattern == MachineCombinerPattern::REASSOC_XMM_AMM_BMM) {
GetFMAInstrInfo(*Leaf, RegM11, RegM12, RegA11, KillM11, KillM12, KillA11);
GetOperandInfo(Leaf->getOperand(AddOpIdx), RegX, KillX);
} else if (Pattern == MachineCombinerPattern::REASSOC_XY_AMM_BMM) {
GetOperandInfo(Leaf->getOperand(1), RegX, KillX);
GetOperandInfo(Leaf->getOperand(2), RegY, KillY);
} else {
// Get FSUB instruction info.
GetOperandInfo(Leaf->getOperand(1), RegX, KillX);
GetOperandInfo(Leaf->getOperand(2), RegY, KillY);
}
// Create new virtual registers for the new results instead of
// recycling legacy ones because the MachineCombiner's computation of the
// critical path requires a new register definition rather than an existing
// one.
// For register pressure reassociation, we only need create one virtual
// register for the new fma.
Register NewVRA = MRI.createVirtualRegister(RC);
InstrIdxForVirtReg.insert(std::make_pair(NewVRA, 0));
Register NewVRB = 0;
if (IsILPReassociate) {
NewVRB = MRI.createVirtualRegister(RC);
InstrIdxForVirtReg.insert(std::make_pair(NewVRB, 1));
}
Register NewVRD = 0;
if (Pattern == MachineCombinerPattern::REASSOC_XMM_AMM_BMM) {
NewVRD = MRI.createVirtualRegister(RC);
InstrIdxForVirtReg.insert(std::make_pair(NewVRD, 2));
}
auto AdjustOperandOrder = [&](MachineInstr *MI, Register RegAdd, bool KillAdd,
Register RegMul1, bool KillRegMul1,
Register RegMul2, bool KillRegMul2) {
MI->getOperand(AddOpIdx).setReg(RegAdd);
MI->getOperand(AddOpIdx).setIsKill(KillAdd);
MI->getOperand(FirstMulOpIdx).setReg(RegMul1);
MI->getOperand(FirstMulOpIdx).setIsKill(KillRegMul1);
MI->getOperand(FirstMulOpIdx + 1).setReg(RegMul2);
MI->getOperand(FirstMulOpIdx + 1).setIsKill(KillRegMul2);
};
MachineInstrBuilder NewARegPressure, NewCRegPressure;
switch (Pattern) {
default:
llvm_unreachable("not recognized pattern!");
case MachineCombinerPattern::REASSOC_XY_AMM_BMM: {
// Create new instructions for insertion.
MachineInstrBuilder MINewB =
BuildMI(*MF, Prev->getDebugLoc(), get(FmaOp), NewVRB)
.addReg(RegX, getKillRegState(KillX))
.addReg(RegM21, getKillRegState(KillM21))
.addReg(RegM22, getKillRegState(KillM22));
MachineInstrBuilder MINewA =
BuildMI(*MF, Root.getDebugLoc(), get(FmaOp), NewVRA)
.addReg(RegY, getKillRegState(KillY))
.addReg(RegM31, getKillRegState(KillM31))
.addReg(RegM32, getKillRegState(KillM32));
// If AddOpIdx is not 1, adjust the order.
if (AddOpIdx != 1) {
AdjustOperandOrder(MINewB, RegX, KillX, RegM21, KillM21, RegM22, KillM22);
AdjustOperandOrder(MINewA, RegY, KillY, RegM31, KillM31, RegM32, KillM32);
}
MachineInstrBuilder MINewC =
BuildMI(*MF, Root.getDebugLoc(),
get(FMAOpIdxInfo[Idx][InfoArrayIdxFAddInst]), RegC)
.addReg(NewVRB, getKillRegState(true))
.addReg(NewVRA, getKillRegState(true));
// Update flags for newly created instructions.
setSpecialOperandAttr(*MINewA, IntersectedFlags);
setSpecialOperandAttr(*MINewB, IntersectedFlags);
setSpecialOperandAttr(*MINewC, IntersectedFlags);
// Record new instructions for insertion.
InsInstrs.push_back(MINewA);
InsInstrs.push_back(MINewB);
InsInstrs.push_back(MINewC);
break;
}
case MachineCombinerPattern::REASSOC_XMM_AMM_BMM: {
assert(NewVRD && "new FMA register not created!");
// Create new instructions for insertion.
MachineInstrBuilder MINewA =
BuildMI(*MF, Leaf->getDebugLoc(),
get(FMAOpIdxInfo[Idx][InfoArrayIdxFMULInst]), NewVRA)
.addReg(RegM11, getKillRegState(KillM11))
.addReg(RegM12, getKillRegState(KillM12));
MachineInstrBuilder MINewB =
BuildMI(*MF, Prev->getDebugLoc(), get(FmaOp), NewVRB)
.addReg(RegX, getKillRegState(KillX))
.addReg(RegM21, getKillRegState(KillM21))
.addReg(RegM22, getKillRegState(KillM22));
MachineInstrBuilder MINewD =
BuildMI(*MF, Root.getDebugLoc(), get(FmaOp), NewVRD)
.addReg(NewVRA, getKillRegState(true))
.addReg(RegM31, getKillRegState(KillM31))
.addReg(RegM32, getKillRegState(KillM32));
// If AddOpIdx is not 1, adjust the order.
if (AddOpIdx != 1) {
AdjustOperandOrder(MINewB, RegX, KillX, RegM21, KillM21, RegM22, KillM22);
AdjustOperandOrder(MINewD, NewVRA, true, RegM31, KillM31, RegM32,
KillM32);
}
MachineInstrBuilder MINewC =
BuildMI(*MF, Root.getDebugLoc(),
get(FMAOpIdxInfo[Idx][InfoArrayIdxFAddInst]), RegC)
.addReg(NewVRB, getKillRegState(true))
.addReg(NewVRD, getKillRegState(true));
// Update flags for newly created instructions.
setSpecialOperandAttr(*MINewA, IntersectedFlags);
setSpecialOperandAttr(*MINewB, IntersectedFlags);
setSpecialOperandAttr(*MINewD, IntersectedFlags);
setSpecialOperandAttr(*MINewC, IntersectedFlags);
// Record new instructions for insertion.
InsInstrs.push_back(MINewA);
InsInstrs.push_back(MINewB);
InsInstrs.push_back(MINewD);