diff options
Diffstat (limited to 'contrib/llvm/lib/CodeGen/MachineSSAUpdater.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/MachineSSAUpdater.cpp | 361 |
1 files changed, 0 insertions, 361 deletions
diff --git a/contrib/llvm/lib/CodeGen/MachineSSAUpdater.cpp b/contrib/llvm/lib/CodeGen/MachineSSAUpdater.cpp deleted file mode 100644 index e8b42047b49f..000000000000 --- a/contrib/llvm/lib/CodeGen/MachineSSAUpdater.cpp +++ /dev/null @@ -1,361 +0,0 @@ -//===- MachineSSAUpdater.cpp - Unstructured SSA Update Tool ---------------===// -// -// 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 implements the MachineSSAUpdater class. It's based on SSAUpdater -// class in lib/Transforms/Utils. -// -//===----------------------------------------------------------------------===// - -#include "llvm/CodeGen/MachineSSAUpdater.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/CodeGen/MachineBasicBlock.h" -#include "llvm/CodeGen/MachineFunction.h" -#include "llvm/CodeGen/MachineInstr.h" -#include "llvm/CodeGen/MachineInstrBuilder.h" -#include "llvm/CodeGen/MachineOperand.h" -#include "llvm/CodeGen/MachineRegisterInfo.h" -#include "llvm/CodeGen/TargetInstrInfo.h" -#include "llvm/CodeGen/TargetOpcodes.h" -#include "llvm/CodeGen/TargetSubtargetInfo.h" -#include "llvm/IR/DebugLoc.h" -#include "llvm/Support/Debug.h" -#include "llvm/Support/ErrorHandling.h" -#include "llvm/Support/raw_ostream.h" -#include "llvm/Transforms/Utils/SSAUpdaterImpl.h" -#include <utility> - -using namespace llvm; - -#define DEBUG_TYPE "machine-ssaupdater" - -using AvailableValsTy = DenseMap<MachineBasicBlock *, unsigned>; - -static AvailableValsTy &getAvailableVals(void *AV) { - return *static_cast<AvailableValsTy*>(AV); -} - -MachineSSAUpdater::MachineSSAUpdater(MachineFunction &MF, - SmallVectorImpl<MachineInstr*> *NewPHI) - : InsertedPHIs(NewPHI), TII(MF.getSubtarget().getInstrInfo()), - MRI(&MF.getRegInfo()) {} - -MachineSSAUpdater::~MachineSSAUpdater() { - delete static_cast<AvailableValsTy*>(AV); -} - -/// Initialize - Reset this object to get ready for a new set of SSA -/// updates. ProtoValue is the value used to name PHI nodes. -void MachineSSAUpdater::Initialize(unsigned V) { - if (!AV) - AV = new AvailableValsTy(); - else - getAvailableVals(AV).clear(); - - VR = V; - VRC = MRI->getRegClass(VR); -} - -/// HasValueForBlock - Return true if the MachineSSAUpdater already has a value for -/// the specified block. -bool MachineSSAUpdater::HasValueForBlock(MachineBasicBlock *BB) const { - return getAvailableVals(AV).count(BB); -} - -/// AddAvailableValue - Indicate that a rewritten value is available in the -/// specified block with the specified value. -void MachineSSAUpdater::AddAvailableValue(MachineBasicBlock *BB, unsigned V) { - getAvailableVals(AV)[BB] = V; -} - -/// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is -/// live at the end of the specified block. -unsigned MachineSSAUpdater::GetValueAtEndOfBlock(MachineBasicBlock *BB) { - return GetValueAtEndOfBlockInternal(BB); -} - -static -unsigned LookForIdenticalPHI(MachineBasicBlock *BB, - SmallVectorImpl<std::pair<MachineBasicBlock *, unsigned>> &PredValues) { - if (BB->empty()) - return 0; - - MachineBasicBlock::iterator I = BB->begin(); - if (!I->isPHI()) - return 0; - - AvailableValsTy AVals; - for (unsigned i = 0, e = PredValues.size(); i != e; ++i) - AVals[PredValues[i].first] = PredValues[i].second; - while (I != BB->end() && I->isPHI()) { - bool Same = true; - for (unsigned i = 1, e = I->getNumOperands(); i != e; i += 2) { - unsigned SrcReg = I->getOperand(i).getReg(); - MachineBasicBlock *SrcBB = I->getOperand(i+1).getMBB(); - if (AVals[SrcBB] != SrcReg) { - Same = false; - break; - } - } - if (Same) - return I->getOperand(0).getReg(); - ++I; - } - return 0; -} - -/// InsertNewDef - Insert an empty PHI or IMPLICIT_DEF instruction which define -/// a value of the given register class at the start of the specified basic -/// block. It returns the virtual register defined by the instruction. -static -MachineInstrBuilder InsertNewDef(unsigned Opcode, - MachineBasicBlock *BB, MachineBasicBlock::iterator I, - const TargetRegisterClass *RC, - MachineRegisterInfo *MRI, - const TargetInstrInfo *TII) { - unsigned NewVR = MRI->createVirtualRegister(RC); - return BuildMI(*BB, I, DebugLoc(), TII->get(Opcode), NewVR); -} - -/// GetValueInMiddleOfBlock - Construct SSA form, materializing a value that -/// is live in the middle of the specified block. -/// -/// GetValueInMiddleOfBlock is the same as GetValueAtEndOfBlock except in one -/// important case: if there is a definition of the rewritten value after the -/// 'use' in BB. Consider code like this: -/// -/// X1 = ... -/// SomeBB: -/// use(X) -/// X2 = ... -/// br Cond, SomeBB, OutBB -/// -/// In this case, there are two values (X1 and X2) added to the AvailableVals -/// set by the client of the rewriter, and those values are both live out of -/// their respective blocks. However, the use of X happens in the *middle* of -/// a block. Because of this, we need to insert a new PHI node in SomeBB to -/// merge the appropriate values, and this value isn't live out of the block. -unsigned MachineSSAUpdater::GetValueInMiddleOfBlock(MachineBasicBlock *BB) { - // If there is no definition of the renamed variable in this block, just use - // GetValueAtEndOfBlock to do our work. - if (!HasValueForBlock(BB)) - return GetValueAtEndOfBlockInternal(BB); - - // If there are no predecessors, just return undef. - if (BB->pred_empty()) { - // Insert an implicit_def to represent an undef value. - MachineInstr *NewDef = InsertNewDef(TargetOpcode::IMPLICIT_DEF, - BB, BB->getFirstTerminator(), - VRC, MRI, TII); - return NewDef->getOperand(0).getReg(); - } - - // Otherwise, we have the hard case. Get the live-in values for each - // predecessor. - SmallVector<std::pair<MachineBasicBlock*, unsigned>, 8> PredValues; - unsigned SingularValue = 0; - - bool isFirstPred = true; - for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(), - E = BB->pred_end(); PI != E; ++PI) { - MachineBasicBlock *PredBB = *PI; - unsigned PredVal = GetValueAtEndOfBlockInternal(PredBB); - PredValues.push_back(std::make_pair(PredBB, PredVal)); - - // Compute SingularValue. - if (isFirstPred) { - SingularValue = PredVal; - isFirstPred = false; - } else if (PredVal != SingularValue) - SingularValue = 0; - } - - // Otherwise, if all the merged values are the same, just use it. - if (SingularValue != 0) - return SingularValue; - - // If an identical PHI is already in BB, just reuse it. - unsigned DupPHI = LookForIdenticalPHI(BB, PredValues); - if (DupPHI) - return DupPHI; - - // Otherwise, we do need a PHI: insert one now. - MachineBasicBlock::iterator Loc = BB->empty() ? BB->end() : BB->begin(); - MachineInstrBuilder InsertedPHI = InsertNewDef(TargetOpcode::PHI, BB, - Loc, VRC, MRI, TII); - - // Fill in all the predecessors of the PHI. - for (unsigned i = 0, e = PredValues.size(); i != e; ++i) - InsertedPHI.addReg(PredValues[i].second).addMBB(PredValues[i].first); - - // See if the PHI node can be merged to a single value. This can happen in - // loop cases when we get a PHI of itself and one other value. - if (unsigned ConstVal = InsertedPHI->isConstantValuePHI()) { - InsertedPHI->eraseFromParent(); - return ConstVal; - } - - // If the client wants to know about all new instructions, tell it. - if (InsertedPHIs) InsertedPHIs->push_back(InsertedPHI); - - LLVM_DEBUG(dbgs() << " Inserted PHI: " << *InsertedPHI << "\n"); - return InsertedPHI->getOperand(0).getReg(); -} - -static -MachineBasicBlock *findCorrespondingPred(const MachineInstr *MI, - MachineOperand *U) { - for (unsigned i = 1, e = MI->getNumOperands(); i != e; i += 2) { - if (&MI->getOperand(i) == U) - return MI->getOperand(i+1).getMBB(); - } - - llvm_unreachable("MachineOperand::getParent() failure?"); -} - -/// RewriteUse - Rewrite a use of the symbolic value. This handles PHI nodes, -/// which use their value in the corresponding predecessor. -void MachineSSAUpdater::RewriteUse(MachineOperand &U) { - MachineInstr *UseMI = U.getParent(); - unsigned NewVR = 0; - if (UseMI->isPHI()) { - MachineBasicBlock *SourceBB = findCorrespondingPred(UseMI, &U); - NewVR = GetValueAtEndOfBlockInternal(SourceBB); - } else { - NewVR = GetValueInMiddleOfBlock(UseMI->getParent()); - } - - U.setReg(NewVR); -} - -/// SSAUpdaterTraits<MachineSSAUpdater> - Traits for the SSAUpdaterImpl -/// template, specialized for MachineSSAUpdater. -namespace llvm { - -template<> -class SSAUpdaterTraits<MachineSSAUpdater> { -public: - using BlkT = MachineBasicBlock; - using ValT = unsigned; - using PhiT = MachineInstr; - using BlkSucc_iterator = MachineBasicBlock::succ_iterator; - - static BlkSucc_iterator BlkSucc_begin(BlkT *BB) { return BB->succ_begin(); } - static BlkSucc_iterator BlkSucc_end(BlkT *BB) { return BB->succ_end(); } - - /// Iterator for PHI operands. - class PHI_iterator { - private: - MachineInstr *PHI; - unsigned idx; - - public: - explicit PHI_iterator(MachineInstr *P) // begin iterator - : PHI(P), idx(1) {} - PHI_iterator(MachineInstr *P, bool) // end iterator - : PHI(P), idx(PHI->getNumOperands()) {} - - PHI_iterator &operator++() { idx += 2; return *this; } - bool operator==(const PHI_iterator& x) const { return idx == x.idx; } - bool operator!=(const PHI_iterator& x) const { return !operator==(x); } - - unsigned getIncomingValue() { return PHI->getOperand(idx).getReg(); } - - MachineBasicBlock *getIncomingBlock() { - return PHI->getOperand(idx+1).getMBB(); - } - }; - - static inline PHI_iterator PHI_begin(PhiT *PHI) { return PHI_iterator(PHI); } - - static inline PHI_iterator PHI_end(PhiT *PHI) { - return PHI_iterator(PHI, true); - } - - /// FindPredecessorBlocks - Put the predecessors of BB into the Preds - /// vector. - static void FindPredecessorBlocks(MachineBasicBlock *BB, - SmallVectorImpl<MachineBasicBlock*> *Preds){ - for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(), - E = BB->pred_end(); PI != E; ++PI) - Preds->push_back(*PI); - } - - /// GetUndefVal - Create an IMPLICIT_DEF instruction with a new register. - /// Add it into the specified block and return the register. - static unsigned GetUndefVal(MachineBasicBlock *BB, - MachineSSAUpdater *Updater) { - // Insert an implicit_def to represent an undef value. - MachineInstr *NewDef = InsertNewDef(TargetOpcode::IMPLICIT_DEF, - BB, BB->getFirstTerminator(), - Updater->VRC, Updater->MRI, - Updater->TII); - return NewDef->getOperand(0).getReg(); - } - - /// CreateEmptyPHI - Create a PHI instruction that defines a new register. - /// Add it into the specified block and return the register. - static unsigned CreateEmptyPHI(MachineBasicBlock *BB, unsigned NumPreds, - MachineSSAUpdater *Updater) { - MachineBasicBlock::iterator Loc = BB->empty() ? BB->end() : BB->begin(); - MachineInstr *PHI = InsertNewDef(TargetOpcode::PHI, BB, Loc, - Updater->VRC, Updater->MRI, - Updater->TII); - return PHI->getOperand(0).getReg(); - } - - /// AddPHIOperand - Add the specified value as an operand of the PHI for - /// the specified predecessor block. - static void AddPHIOperand(MachineInstr *PHI, unsigned Val, - MachineBasicBlock *Pred) { - MachineInstrBuilder(*Pred->getParent(), PHI).addReg(Val).addMBB(Pred); - } - - /// InstrIsPHI - Check if an instruction is a PHI. - static MachineInstr *InstrIsPHI(MachineInstr *I) { - if (I && I->isPHI()) - return I; - return nullptr; - } - - /// ValueIsPHI - Check if the instruction that defines the specified register - /// is a PHI instruction. - static MachineInstr *ValueIsPHI(unsigned Val, MachineSSAUpdater *Updater) { - return InstrIsPHI(Updater->MRI->getVRegDef(Val)); - } - - /// ValueIsNewPHI - Like ValueIsPHI but also check if the PHI has no source - /// operands, i.e., it was just added. - static MachineInstr *ValueIsNewPHI(unsigned Val, MachineSSAUpdater *Updater) { - MachineInstr *PHI = ValueIsPHI(Val, Updater); - if (PHI && PHI->getNumOperands() <= 1) - return PHI; - return nullptr; - } - - /// GetPHIValue - For the specified PHI instruction, return the register - /// that it defines. - static unsigned GetPHIValue(MachineInstr *PHI) { - return PHI->getOperand(0).getReg(); - } -}; - -} // end namespace llvm - -/// GetValueAtEndOfBlockInternal - Check to see if AvailableVals has an entry -/// for the specified BB and if so, return it. If not, construct SSA form by -/// first calculating the required placement of PHIs and then inserting new -/// PHIs where needed. -unsigned MachineSSAUpdater::GetValueAtEndOfBlockInternal(MachineBasicBlock *BB){ - AvailableValsTy &AvailableVals = getAvailableVals(AV); - if (unsigned V = AvailableVals[BB]) - return V; - - SSAUpdaterImpl<MachineSSAUpdater> Impl(this, &AvailableVals, InsertedPHIs); - return Impl.GetValue(BB); -} |