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Diffstat (limited to 'llvm/lib/Target/Hexagon/HexagonTfrCleanup.cpp')
| -rw-r--r-- | llvm/lib/Target/Hexagon/HexagonTfrCleanup.cpp | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/llvm/lib/Target/Hexagon/HexagonTfrCleanup.cpp b/llvm/lib/Target/Hexagon/HexagonTfrCleanup.cpp new file mode 100644 index 0000000..a4b359a --- /dev/null +++ b/llvm/lib/Target/Hexagon/HexagonTfrCleanup.cpp @@ -0,0 +1,324 @@ +//===------- HexagonTfrCleanup.cpp - Hexagon Transfer Cleanup Pass -------===// +// +// 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 pass is to address a situation that appears after register allocaion +// evey now and then, namely a register copy from a source that was defined +// as an immediate value in the same block (usually just before the copy). +// +// Here is an example of actual code emitted that shows this problem: +// +// .LBB0_5: +// { +// r5 = zxtb(r8) +// r6 = or(r6, ##12345) +// } +// { +// r3 = xor(r1, r2) +// r1 = #0 <-- r1 set to #0 +// } +// { +// r7 = r1 <-- r7 set to r1 +// r0 = zxtb(r3) +// } + +#define DEBUG_TYPE "tfr-cleanup" +#include "HexagonTargetMachine.h" + +#include "llvm/CodeGen/LiveInterval.h" +#include "llvm/CodeGen/LiveIntervals.h" +#include "llvm/CodeGen/MachineFunction.h" +#include "llvm/CodeGen/MachineInstrBuilder.h" +#include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/Passes.h" +#include "llvm/CodeGen/TargetInstrInfo.h" +#include "llvm/CodeGen/TargetRegisterInfo.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetMachine.h" + +using namespace llvm; + +namespace llvm { +FunctionPass *createHexagonTfrCleanup(); +void initializeHexagonTfrCleanupPass(PassRegistry &); +} // namespace llvm + +namespace { +class HexagonTfrCleanup : public MachineFunctionPass { +public: + static char ID; + HexagonTfrCleanup() : MachineFunctionPass(ID), HII(0), TRI(0) { + PassRegistry &R = *PassRegistry::getPassRegistry(); + initializeHexagonTfrCleanupPass(R); + } + StringRef getPassName() const override { return "Hexagon TFR Cleanup"; } + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.setPreservesAll(); + MachineFunctionPass::getAnalysisUsage(AU); + } + bool runOnMachineFunction(MachineFunction &MF) override; + +private: + const HexagonInstrInfo *HII; + const TargetRegisterInfo *TRI; + + typedef DenseMap<unsigned, uint64_t> ImmediateMap; + + bool isIntReg(unsigned Reg, bool &Is32); + void setReg(unsigned R32, uint32_t V32, ImmediateMap &IMap); + bool getReg(unsigned Reg, uint64_t &Val, ImmediateMap &IMap); + bool updateImmMap(MachineInstr *MI, ImmediateMap &IMap); + bool rewriteIfImm(MachineInstr *MI, ImmediateMap &IMap, SlotIndexes *Indexes); + bool eraseIfRedundant(MachineInstr *MI, SlotIndexes *Indexes); +}; +} // namespace + +char HexagonTfrCleanup::ID = 0; + +namespace llvm { +char &HexagonTfrCleanupID = HexagonTfrCleanup::ID; +} + +bool HexagonTfrCleanup::isIntReg(unsigned Reg, bool &Is32) { + Is32 = Hexagon::IntRegsRegClass.contains(Reg); + return Is32 || Hexagon::DoubleRegsRegClass.contains(Reg); +} + +// Assign given value V32 to the specified the register R32 in the map. Only +// 32-bit registers are valid arguments. +void HexagonTfrCleanup::setReg(unsigned R32, uint32_t V32, ImmediateMap &IMap) { + ImmediateMap::iterator F = IMap.find(R32); + if (F == IMap.end()) + IMap.insert(std::make_pair(R32, V32)); + else + F->second = V32; +} + +// Retrieve a value of the provided register Reg and store it into Val. +// Return "true" if a value was found, "false" otherwise. +bool HexagonTfrCleanup::getReg(unsigned Reg, uint64_t &Val, + ImmediateMap &IMap) { + bool Is32; + if (!isIntReg(Reg, Is32)) + return false; + + if (Is32) { + ImmediateMap::iterator F = IMap.find(Reg); + if (F == IMap.end()) + return false; + Val = F->second; + return true; + } + + // For 64-bit registers, compose the value from the values of its + // subregisters. + unsigned SubL = TRI->getSubReg(Reg, Hexagon::isub_lo); + unsigned SubH = TRI->getSubReg(Reg, Hexagon::isub_hi); + ImmediateMap::iterator FL = IMap.find(SubL), FH = IMap.find(SubH); + if (FL == IMap.end() || FH == IMap.end()) + return false; + Val = (FH->second << 32) | FL->second; + return true; +} + +// Process an instruction and record the relevant information in the imme- +// diate map. +bool HexagonTfrCleanup::updateImmMap(MachineInstr *MI, ImmediateMap &IMap) { + using namespace Hexagon; + + if (MI->isCall()) { + IMap.clear(); + return true; + } + + // If this is an instruction that loads a constant into a register, + // record this information in IMap. + unsigned Opc = MI->getOpcode(); + if (Opc == A2_tfrsi || Opc == A2_tfrpi) { + unsigned DefR = MI->getOperand(0).getReg(); + bool Is32; + if (!isIntReg(DefR, Is32)) + return false; + if (!MI->getOperand(1).isImm()) { + if (!Is32) { + IMap.erase(TRI->getSubReg(DefR, isub_lo)); + IMap.erase(TRI->getSubReg(DefR, isub_hi)); + } else { + IMap.erase(DefR); + } + return false; + } + uint64_t Val = MI->getOperand(1).getImm(); + // If it's a 64-bit register, break it up into subregisters. + if (!Is32) { + uint32_t VH = (Val >> 32), VL = (Val & 0xFFFFFFFFU); + setReg(TRI->getSubReg(DefR, isub_lo), VL, IMap); + setReg(TRI->getSubReg(DefR, isub_hi), VH, IMap); + } else { + setReg(DefR, Val, IMap); + } + return true; + } + + // Not a A2_tfr[sp]i. Invalidate all modified registers in IMap. + for (MachineInstr::mop_iterator Mo = MI->operands_begin(), + E = MI->operands_end(); + Mo != E; ++Mo) { + if (Mo->isRegMask()) { + IMap.clear(); + return true; + } + if (!Mo->isReg() || !Mo->isDef()) + continue; + unsigned R = Mo->getReg(); + for (MCRegAliasIterator AR(R, TRI, true); AR.isValid(); ++AR) { + ImmediateMap::iterator F = IMap.find(*AR); + if (F != IMap.end()) + IMap.erase(F); + } + } + return true; +} + +// Rewrite the instruction as A2_tfrsi/A2_tfrpi, it is a copy of a source that +// has a known constant value. +bool HexagonTfrCleanup::rewriteIfImm(MachineInstr *MI, ImmediateMap &IMap, + SlotIndexes *Indexes) { + using namespace Hexagon; + unsigned Opc = MI->getOpcode(); + switch (Opc) { + case A2_tfr: + case A2_tfrp: + case COPY: + break; + default: + return false; + } + + unsigned DstR = MI->getOperand(0).getReg(); + unsigned SrcR = MI->getOperand(1).getReg(); + bool Tmp, Is32; + if (!isIntReg(DstR, Is32) || !isIntReg(SrcR, Tmp)) + return false; + assert(Tmp == Is32 && "Register size mismatch"); + uint64_t Val; + bool Found = getReg(SrcR, Val, IMap); + if (!Found) + return false; + + MachineBasicBlock &B = *MI->getParent(); + DebugLoc DL = MI->getDebugLoc(); + int64_t SVal = Is32 ? int32_t(Val) : Val; + auto &HST = B.getParent()->getSubtarget<HexagonSubtarget>(); + MachineInstr *NewMI; + if (Is32) + NewMI = BuildMI(B, MI, DL, HII->get(A2_tfrsi), DstR).addImm(SVal); + else if (isInt<8>(SVal)) + NewMI = BuildMI(B, MI, DL, HII->get(A2_tfrpi), DstR).addImm(SVal); + else if (isInt<8>(SVal >> 32) && isInt<8>(int32_t(Val & 0xFFFFFFFFLL))) + NewMI = BuildMI(B, MI, DL, HII->get(A2_combineii), DstR) + .addImm(int32_t(SVal >> 32)) + .addImm(int32_t(Val & 0xFFFFFFFFLL)); + else if (HST.isTinyCore()) + // Disable generating CONST64 since it requires load resource. + return false; + else + NewMI = BuildMI(B, MI, DL, HII->get(CONST64), DstR).addImm(Val); + + // Replace the MI to reuse the same slot index + if (Indexes) + Indexes->replaceMachineInstrInMaps(*MI, *NewMI); + MI->eraseFromParent(); + return true; +} + +// Remove the instruction if it is a self-assignment. +bool HexagonTfrCleanup::eraseIfRedundant(MachineInstr *MI, + SlotIndexes *Indexes) { + unsigned Opc = MI->getOpcode(); + unsigned DefR, SrcR; + bool IsUndef = false; + switch (Opc) { + case Hexagon::A2_tfr: + // Rd = Rd + DefR = MI->getOperand(0).getReg(); + SrcR = MI->getOperand(1).getReg(); + IsUndef = MI->getOperand(1).isUndef(); + break; + case Hexagon::A2_tfrt: + case Hexagon::A2_tfrf: + // if ([!]Pu) Rd = Rd + DefR = MI->getOperand(0).getReg(); + SrcR = MI->getOperand(2).getReg(); + IsUndef = MI->getOperand(2).isUndef(); + break; + default: + return false; + } + if (DefR != SrcR) + return false; + if (IsUndef) { + MachineBasicBlock &B = *MI->getParent(); + DebugLoc DL = MI->getDebugLoc(); + auto DefI = BuildMI(B, MI, DL, HII->get(TargetOpcode::IMPLICIT_DEF), DefR); + for (auto &Op : MI->operands()) + if (Op.isReg() && Op.isDef() && Op.isImplicit()) + DefI->addOperand(Op); + } + + if (Indexes) + Indexes->removeMachineInstrFromMaps(*MI); + MI->eraseFromParent(); + return true; +} + +bool HexagonTfrCleanup::runOnMachineFunction(MachineFunction &MF) { + bool Changed = false; + // Map: 32-bit register -> immediate value. + // 64-bit registers are stored through their subregisters. + ImmediateMap IMap; + SlotIndexes *Indexes = this->getAnalysisIfAvailable<SlotIndexes>(); + + auto &HST = MF.getSubtarget<HexagonSubtarget>(); + HII = HST.getInstrInfo(); + TRI = HST.getRegisterInfo(); + + for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) { + MachineBasicBlock &B = *I; + MachineBasicBlock::iterator J, F, NextJ; + IMap.clear(); + bool Inserted = false, Erased = false; + for (J = B.begin(), F = B.end(); J != F; J = NextJ) { + NextJ = std::next(J); + MachineInstr *MI = &*J; + bool E = eraseIfRedundant(MI, Indexes); + Erased |= E; + if (E) + continue; + Inserted |= rewriteIfImm(MI, IMap, Indexes); + MachineBasicBlock::iterator NewJ = std::prev(NextJ); + updateImmMap(&*NewJ, IMap); + } + bool BlockC = Inserted | Erased; + Changed |= BlockC; + if (BlockC && Indexes) + Indexes->repairIndexesInRange(&B, B.begin(), B.end()); + } + + return Changed; +} + +//===----------------------------------------------------------------------===// +// Public Constructor Functions +//===----------------------------------------------------------------------===// +INITIALIZE_PASS(HexagonTfrCleanup, "tfr-cleanup", "Hexagon TFR Cleanup", false, + false) + +FunctionPass *llvm::createHexagonTfrCleanup() { + return new HexagonTfrCleanup(); +} |