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https://github.com/c64scene-ar/llvm-6502.git
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0814bd85dd
EarlyCSE is giving up on the current instruction immediately when it recognizes that the current instruction makes a previous store trivially dead. There's no reason to do this. Once the previous store has been deleted, it's perfectly legal to remember the value of the current store (for value forwarding) and the fact the store occurred (it could be dead too!). Reviewed by: Hal Differential Revision: http://reviews.llvm.org/D6301 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222241 91177308-0d34-0410-b5e6-96231b3b80d8
645 lines
24 KiB
C++
645 lines
24 KiB
C++
//===- EarlyCSE.cpp - Simple and fast CSE pass ----------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass performs a simple dominator tree walk that eliminates trivially
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// redundant instructions.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/ADT/Hashing.h"
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#include "llvm/ADT/ScopedHashTable.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/AssumptionTracker.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/RecyclingAllocator.h"
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#include "llvm/Target/TargetLibraryInfo.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include <deque>
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using namespace llvm;
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using namespace llvm::PatternMatch;
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#define DEBUG_TYPE "early-cse"
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STATISTIC(NumSimplify, "Number of instructions simplified or DCE'd");
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STATISTIC(NumCSE, "Number of instructions CSE'd");
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STATISTIC(NumCSELoad, "Number of load instructions CSE'd");
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STATISTIC(NumCSECall, "Number of call instructions CSE'd");
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STATISTIC(NumDSE, "Number of trivial dead stores removed");
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static unsigned getHash(const void *V) {
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return DenseMapInfo<const void*>::getHashValue(V);
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}
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//===----------------------------------------------------------------------===//
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// SimpleValue
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//===----------------------------------------------------------------------===//
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namespace {
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/// SimpleValue - Instances of this struct represent available values in the
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/// scoped hash table.
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struct SimpleValue {
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Instruction *Inst;
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SimpleValue(Instruction *I) : Inst(I) {
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assert((isSentinel() || canHandle(I)) && "Inst can't be handled!");
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}
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bool isSentinel() const {
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return Inst == DenseMapInfo<Instruction*>::getEmptyKey() ||
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Inst == DenseMapInfo<Instruction*>::getTombstoneKey();
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}
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static bool canHandle(Instruction *Inst) {
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// This can only handle non-void readnone functions.
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if (CallInst *CI = dyn_cast<CallInst>(Inst))
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return CI->doesNotAccessMemory() && !CI->getType()->isVoidTy();
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return isa<CastInst>(Inst) || isa<BinaryOperator>(Inst) ||
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isa<GetElementPtrInst>(Inst) || isa<CmpInst>(Inst) ||
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isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
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isa<InsertElementInst>(Inst) || isa<ShuffleVectorInst>(Inst) ||
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isa<ExtractValueInst>(Inst) || isa<InsertValueInst>(Inst);
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}
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};
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}
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namespace llvm {
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template<> struct DenseMapInfo<SimpleValue> {
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static inline SimpleValue getEmptyKey() {
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return DenseMapInfo<Instruction*>::getEmptyKey();
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}
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static inline SimpleValue getTombstoneKey() {
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return DenseMapInfo<Instruction*>::getTombstoneKey();
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}
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static unsigned getHashValue(SimpleValue Val);
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static bool isEqual(SimpleValue LHS, SimpleValue RHS);
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};
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}
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unsigned DenseMapInfo<SimpleValue>::getHashValue(SimpleValue Val) {
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Instruction *Inst = Val.Inst;
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// Hash in all of the operands as pointers.
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if (BinaryOperator* BinOp = dyn_cast<BinaryOperator>(Inst)) {
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Value *LHS = BinOp->getOperand(0);
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Value *RHS = BinOp->getOperand(1);
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if (BinOp->isCommutative() && BinOp->getOperand(0) > BinOp->getOperand(1))
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std::swap(LHS, RHS);
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if (isa<OverflowingBinaryOperator>(BinOp)) {
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// Hash the overflow behavior
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unsigned Overflow =
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BinOp->hasNoSignedWrap() * OverflowingBinaryOperator::NoSignedWrap |
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BinOp->hasNoUnsignedWrap() * OverflowingBinaryOperator::NoUnsignedWrap;
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return hash_combine(BinOp->getOpcode(), Overflow, LHS, RHS);
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}
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return hash_combine(BinOp->getOpcode(), LHS, RHS);
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}
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if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
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Value *LHS = CI->getOperand(0);
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Value *RHS = CI->getOperand(1);
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CmpInst::Predicate Pred = CI->getPredicate();
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if (Inst->getOperand(0) > Inst->getOperand(1)) {
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std::swap(LHS, RHS);
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Pred = CI->getSwappedPredicate();
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}
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return hash_combine(Inst->getOpcode(), Pred, LHS, RHS);
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}
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if (CastInst *CI = dyn_cast<CastInst>(Inst))
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return hash_combine(CI->getOpcode(), CI->getType(), CI->getOperand(0));
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if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(Inst))
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return hash_combine(EVI->getOpcode(), EVI->getOperand(0),
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hash_combine_range(EVI->idx_begin(), EVI->idx_end()));
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if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(Inst))
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return hash_combine(IVI->getOpcode(), IVI->getOperand(0),
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IVI->getOperand(1),
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hash_combine_range(IVI->idx_begin(), IVI->idx_end()));
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assert((isa<CallInst>(Inst) || isa<BinaryOperator>(Inst) ||
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isa<GetElementPtrInst>(Inst) || isa<SelectInst>(Inst) ||
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isa<ExtractElementInst>(Inst) || isa<InsertElementInst>(Inst) ||
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isa<ShuffleVectorInst>(Inst)) && "Invalid/unknown instruction");
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// Mix in the opcode.
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return hash_combine(Inst->getOpcode(),
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hash_combine_range(Inst->value_op_begin(),
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Inst->value_op_end()));
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}
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bool DenseMapInfo<SimpleValue>::isEqual(SimpleValue LHS, SimpleValue RHS) {
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Instruction *LHSI = LHS.Inst, *RHSI = RHS.Inst;
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if (LHS.isSentinel() || RHS.isSentinel())
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return LHSI == RHSI;
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if (LHSI->getOpcode() != RHSI->getOpcode()) return false;
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if (LHSI->isIdenticalTo(RHSI)) return true;
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// If we're not strictly identical, we still might be a commutable instruction
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if (BinaryOperator *LHSBinOp = dyn_cast<BinaryOperator>(LHSI)) {
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if (!LHSBinOp->isCommutative())
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return false;
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assert(isa<BinaryOperator>(RHSI)
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&& "same opcode, but different instruction type?");
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BinaryOperator *RHSBinOp = cast<BinaryOperator>(RHSI);
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// Check overflow attributes
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if (isa<OverflowingBinaryOperator>(LHSBinOp)) {
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assert(isa<OverflowingBinaryOperator>(RHSBinOp)
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&& "same opcode, but different operator type?");
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if (LHSBinOp->hasNoUnsignedWrap() != RHSBinOp->hasNoUnsignedWrap() ||
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LHSBinOp->hasNoSignedWrap() != RHSBinOp->hasNoSignedWrap())
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return false;
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}
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// Commuted equality
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return LHSBinOp->getOperand(0) == RHSBinOp->getOperand(1) &&
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LHSBinOp->getOperand(1) == RHSBinOp->getOperand(0);
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}
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if (CmpInst *LHSCmp = dyn_cast<CmpInst>(LHSI)) {
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assert(isa<CmpInst>(RHSI)
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&& "same opcode, but different instruction type?");
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CmpInst *RHSCmp = cast<CmpInst>(RHSI);
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// Commuted equality
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return LHSCmp->getOperand(0) == RHSCmp->getOperand(1) &&
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LHSCmp->getOperand(1) == RHSCmp->getOperand(0) &&
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LHSCmp->getSwappedPredicate() == RHSCmp->getPredicate();
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}
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return false;
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}
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//===----------------------------------------------------------------------===//
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// CallValue
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//===----------------------------------------------------------------------===//
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namespace {
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/// CallValue - Instances of this struct represent available call values in
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/// the scoped hash table.
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struct CallValue {
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Instruction *Inst;
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CallValue(Instruction *I) : Inst(I) {
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assert((isSentinel() || canHandle(I)) && "Inst can't be handled!");
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}
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bool isSentinel() const {
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return Inst == DenseMapInfo<Instruction*>::getEmptyKey() ||
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Inst == DenseMapInfo<Instruction*>::getTombstoneKey();
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}
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static bool canHandle(Instruction *Inst) {
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// Don't value number anything that returns void.
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if (Inst->getType()->isVoidTy())
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return false;
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CallInst *CI = dyn_cast<CallInst>(Inst);
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if (!CI || !CI->onlyReadsMemory())
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return false;
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return true;
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}
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};
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}
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namespace llvm {
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template<> struct DenseMapInfo<CallValue> {
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static inline CallValue getEmptyKey() {
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return DenseMapInfo<Instruction*>::getEmptyKey();
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}
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static inline CallValue getTombstoneKey() {
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return DenseMapInfo<Instruction*>::getTombstoneKey();
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}
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static unsigned getHashValue(CallValue Val);
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static bool isEqual(CallValue LHS, CallValue RHS);
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};
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}
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unsigned DenseMapInfo<CallValue>::getHashValue(CallValue Val) {
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Instruction *Inst = Val.Inst;
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// Hash in all of the operands as pointers.
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unsigned Res = 0;
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for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i) {
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assert(!Inst->getOperand(i)->getType()->isMetadataTy() &&
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"Cannot value number calls with metadata operands");
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Res ^= getHash(Inst->getOperand(i)) << (i & 0xF);
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}
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// Mix in the opcode.
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return (Res << 1) ^ Inst->getOpcode();
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}
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bool DenseMapInfo<CallValue>::isEqual(CallValue LHS, CallValue RHS) {
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Instruction *LHSI = LHS.Inst, *RHSI = RHS.Inst;
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if (LHS.isSentinel() || RHS.isSentinel())
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return LHSI == RHSI;
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return LHSI->isIdenticalTo(RHSI);
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}
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//===----------------------------------------------------------------------===//
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// EarlyCSE pass.
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//===----------------------------------------------------------------------===//
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namespace {
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/// EarlyCSE - This pass does a simple depth-first walk over the dominator
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/// tree, eliminating trivially redundant instructions and using instsimplify
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/// to canonicalize things as it goes. It is intended to be fast and catch
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/// obvious cases so that instcombine and other passes are more effective. It
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/// is expected that a later pass of GVN will catch the interesting/hard
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/// cases.
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class EarlyCSE : public FunctionPass {
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public:
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const DataLayout *DL;
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const TargetLibraryInfo *TLI;
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DominatorTree *DT;
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AssumptionTracker *AT;
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typedef RecyclingAllocator<BumpPtrAllocator,
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ScopedHashTableVal<SimpleValue, Value*> > AllocatorTy;
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typedef ScopedHashTable<SimpleValue, Value*, DenseMapInfo<SimpleValue>,
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AllocatorTy> ScopedHTType;
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/// AvailableValues - This scoped hash table contains the current values of
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/// all of our simple scalar expressions. As we walk down the domtree, we
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/// look to see if instructions are in this: if so, we replace them with what
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/// we find, otherwise we insert them so that dominated values can succeed in
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/// their lookup.
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ScopedHTType *AvailableValues;
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/// AvailableLoads - This scoped hash table contains the current values
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/// of loads. This allows us to get efficient access to dominating loads when
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/// we have a fully redundant load. In addition to the most recent load, we
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/// keep track of a generation count of the read, which is compared against
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/// the current generation count. The current generation count is
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/// incremented after every possibly writing memory operation, which ensures
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/// that we only CSE loads with other loads that have no intervening store.
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typedef RecyclingAllocator<BumpPtrAllocator,
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ScopedHashTableVal<Value*, std::pair<Value*, unsigned> > > LoadMapAllocator;
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typedef ScopedHashTable<Value*, std::pair<Value*, unsigned>,
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DenseMapInfo<Value*>, LoadMapAllocator> LoadHTType;
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LoadHTType *AvailableLoads;
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/// AvailableCalls - This scoped hash table contains the current values
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/// of read-only call values. It uses the same generation count as loads.
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typedef ScopedHashTable<CallValue, std::pair<Value*, unsigned> > CallHTType;
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CallHTType *AvailableCalls;
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/// CurrentGeneration - This is the current generation of the memory value.
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unsigned CurrentGeneration;
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static char ID;
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explicit EarlyCSE() : FunctionPass(ID) {
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initializeEarlyCSEPass(*PassRegistry::getPassRegistry());
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}
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bool runOnFunction(Function &F) override;
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private:
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// NodeScope - almost a POD, but needs to call the constructors for the
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// scoped hash tables so that a new scope gets pushed on. These are RAII so
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// that the scope gets popped when the NodeScope is destroyed.
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class NodeScope {
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public:
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NodeScope(ScopedHTType *availableValues,
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LoadHTType *availableLoads,
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CallHTType *availableCalls) :
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Scope(*availableValues),
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LoadScope(*availableLoads),
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CallScope(*availableCalls) {}
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private:
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NodeScope(const NodeScope&) LLVM_DELETED_FUNCTION;
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void operator=(const NodeScope&) LLVM_DELETED_FUNCTION;
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ScopedHTType::ScopeTy Scope;
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LoadHTType::ScopeTy LoadScope;
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CallHTType::ScopeTy CallScope;
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};
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// StackNode - contains all the needed information to create a stack for
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// doing a depth first tranversal of the tree. This includes scopes for
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// values, loads, and calls as well as the generation. There is a child
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// iterator so that the children do not need to be store spearately.
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class StackNode {
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public:
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StackNode(ScopedHTType *availableValues,
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LoadHTType *availableLoads,
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CallHTType *availableCalls,
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unsigned cg, DomTreeNode *n,
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DomTreeNode::iterator child, DomTreeNode::iterator end) :
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CurrentGeneration(cg), ChildGeneration(cg), Node(n),
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ChildIter(child), EndIter(end),
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Scopes(availableValues, availableLoads, availableCalls),
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Processed(false) {}
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// Accessors.
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unsigned currentGeneration() { return CurrentGeneration; }
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unsigned childGeneration() { return ChildGeneration; }
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void childGeneration(unsigned generation) { ChildGeneration = generation; }
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DomTreeNode *node() { return Node; }
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DomTreeNode::iterator childIter() { return ChildIter; }
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DomTreeNode *nextChild() {
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DomTreeNode *child = *ChildIter;
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++ChildIter;
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return child;
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}
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DomTreeNode::iterator end() { return EndIter; }
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bool isProcessed() { return Processed; }
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void process() { Processed = true; }
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private:
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StackNode(const StackNode&) LLVM_DELETED_FUNCTION;
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void operator=(const StackNode&) LLVM_DELETED_FUNCTION;
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// Members.
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unsigned CurrentGeneration;
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unsigned ChildGeneration;
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DomTreeNode *Node;
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DomTreeNode::iterator ChildIter;
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DomTreeNode::iterator EndIter;
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NodeScope Scopes;
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bool Processed;
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};
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bool processNode(DomTreeNode *Node);
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// This transformation requires dominator postdominator info
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addRequired<AssumptionTracker>();
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AU.addRequired<DominatorTreeWrapperPass>();
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AU.addRequired<TargetLibraryInfo>();
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AU.setPreservesCFG();
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}
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};
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}
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char EarlyCSE::ID = 0;
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// createEarlyCSEPass - The public interface to this file.
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FunctionPass *llvm::createEarlyCSEPass() {
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return new EarlyCSE();
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}
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INITIALIZE_PASS_BEGIN(EarlyCSE, "early-cse", "Early CSE", false, false)
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INITIALIZE_PASS_DEPENDENCY(AssumptionTracker)
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INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
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INITIALIZE_PASS_END(EarlyCSE, "early-cse", "Early CSE", false, false)
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bool EarlyCSE::processNode(DomTreeNode *Node) {
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BasicBlock *BB = Node->getBlock();
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// If this block has a single predecessor, then the predecessor is the parent
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// of the domtree node and all of the live out memory values are still current
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// in this block. If this block has multiple predecessors, then they could
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// have invalidated the live-out memory values of our parent value. For now,
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// just be conservative and invalidate memory if this block has multiple
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// predecessors.
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if (!BB->getSinglePredecessor())
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++CurrentGeneration;
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/// LastStore - Keep track of the last non-volatile store that we saw... for
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/// as long as there in no instruction that reads memory. If we see a store
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/// to the same location, we delete the dead store. This zaps trivial dead
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/// stores which can occur in bitfield code among other things.
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StoreInst *LastStore = nullptr;
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bool Changed = false;
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// See if any instructions in the block can be eliminated. If so, do it. If
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// not, add them to AvailableValues.
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
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Instruction *Inst = I++;
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// Dead instructions should just be removed.
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if (isInstructionTriviallyDead(Inst, TLI)) {
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DEBUG(dbgs() << "EarlyCSE DCE: " << *Inst << '\n');
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Inst->eraseFromParent();
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Changed = true;
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++NumSimplify;
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continue;
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}
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// Skip assume intrinsics, they don't really have side effects (although
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// they're marked as such to ensure preservation of control dependencies),
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// and this pass will not disturb any of the assumption's control
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// dependencies.
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if (match(Inst, m_Intrinsic<Intrinsic::assume>())) {
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DEBUG(dbgs() << "EarlyCSE skipping assumption: " << *Inst << '\n');
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continue;
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}
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// If the instruction can be simplified (e.g. X+0 = X) then replace it with
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// its simpler value.
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if (Value *V = SimplifyInstruction(Inst, DL, TLI, DT, AT)) {
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DEBUG(dbgs() << "EarlyCSE Simplify: " << *Inst << " to: " << *V << '\n');
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Inst->replaceAllUsesWith(V);
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Inst->eraseFromParent();
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Changed = true;
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++NumSimplify;
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continue;
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}
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// If this is a simple instruction that we can value number, process it.
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if (SimpleValue::canHandle(Inst)) {
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// See if the instruction has an available value. If so, use it.
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if (Value *V = AvailableValues->lookup(Inst)) {
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DEBUG(dbgs() << "EarlyCSE CSE: " << *Inst << " to: " << *V << '\n');
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Inst->replaceAllUsesWith(V);
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Inst->eraseFromParent();
|
|
Changed = true;
|
|
++NumCSE;
|
|
continue;
|
|
}
|
|
|
|
// Otherwise, just remember that this value is available.
|
|
AvailableValues->insert(Inst, Inst);
|
|
continue;
|
|
}
|
|
|
|
// If this is a non-volatile load, process it.
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
|
|
// Ignore volatile loads.
|
|
if (!LI->isSimple()) {
|
|
LastStore = nullptr;
|
|
continue;
|
|
}
|
|
|
|
// If we have an available version of this load, and if it is the right
|
|
// generation, replace this instruction.
|
|
std::pair<Value*, unsigned> InVal =
|
|
AvailableLoads->lookup(Inst->getOperand(0));
|
|
if (InVal.first != nullptr && InVal.second == CurrentGeneration) {
|
|
DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst << " to: "
|
|
<< *InVal.first << '\n');
|
|
if (!Inst->use_empty()) Inst->replaceAllUsesWith(InVal.first);
|
|
Inst->eraseFromParent();
|
|
Changed = true;
|
|
++NumCSELoad;
|
|
continue;
|
|
}
|
|
|
|
// Otherwise, remember that we have this instruction.
|
|
AvailableLoads->insert(Inst->getOperand(0),
|
|
std::pair<Value*, unsigned>(Inst, CurrentGeneration));
|
|
LastStore = nullptr;
|
|
continue;
|
|
}
|
|
|
|
// If this instruction may read from memory, forget LastStore.
|
|
if (Inst->mayReadFromMemory())
|
|
LastStore = nullptr;
|
|
|
|
// If this is a read-only call, process it.
|
|
if (CallValue::canHandle(Inst)) {
|
|
// If we have an available version of this call, and if it is the right
|
|
// generation, replace this instruction.
|
|
std::pair<Value*, unsigned> InVal = AvailableCalls->lookup(Inst);
|
|
if (InVal.first != nullptr && InVal.second == CurrentGeneration) {
|
|
DEBUG(dbgs() << "EarlyCSE CSE CALL: " << *Inst << " to: "
|
|
<< *InVal.first << '\n');
|
|
if (!Inst->use_empty()) Inst->replaceAllUsesWith(InVal.first);
|
|
Inst->eraseFromParent();
|
|
Changed = true;
|
|
++NumCSECall;
|
|
continue;
|
|
}
|
|
|
|
// Otherwise, remember that we have this instruction.
|
|
AvailableCalls->insert(Inst,
|
|
std::pair<Value*, unsigned>(Inst, CurrentGeneration));
|
|
continue;
|
|
}
|
|
|
|
// Okay, this isn't something we can CSE at all. Check to see if it is
|
|
// something that could modify memory. If so, our available memory values
|
|
// cannot be used so bump the generation count.
|
|
if (Inst->mayWriteToMemory()) {
|
|
++CurrentGeneration;
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
|
|
// We do a trivial form of DSE if there are two stores to the same
|
|
// location with no intervening loads. Delete the earlier store.
|
|
if (LastStore &&
|
|
LastStore->getPointerOperand() == SI->getPointerOperand()) {
|
|
DEBUG(dbgs() << "EarlyCSE DEAD STORE: " << *LastStore << " due to: "
|
|
<< *Inst << '\n');
|
|
LastStore->eraseFromParent();
|
|
Changed = true;
|
|
++NumDSE;
|
|
LastStore = nullptr;
|
|
// fallthrough - we can exploit information about this store
|
|
}
|
|
|
|
// Okay, we just invalidated anything we knew about loaded values. Try
|
|
// to salvage *something* by remembering that the stored value is a live
|
|
// version of the pointer. It is safe to forward from volatile stores
|
|
// to non-volatile loads, so we don't have to check for volatility of
|
|
// the store.
|
|
AvailableLoads->insert(SI->getPointerOperand(),
|
|
std::pair<Value*, unsigned>(SI->getValueOperand(), CurrentGeneration));
|
|
|
|
// Remember that this was the last store we saw for DSE.
|
|
if (SI->isSimple())
|
|
LastStore = SI;
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
|
|
bool EarlyCSE::runOnFunction(Function &F) {
|
|
if (skipOptnoneFunction(F))
|
|
return false;
|
|
|
|
// Note, deque is being used here because there is significant performance gains
|
|
// over vector when the container becomes very large due to the specific access
|
|
// patterns. For more information see the mailing list discussion on this:
|
|
// http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120116/135228.html
|
|
std::deque<StackNode *> nodesToProcess;
|
|
|
|
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
|
|
DL = DLP ? &DLP->getDataLayout() : nullptr;
|
|
TLI = &getAnalysis<TargetLibraryInfo>();
|
|
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
|
|
AT = &getAnalysis<AssumptionTracker>();
|
|
|
|
// Tables that the pass uses when walking the domtree.
|
|
ScopedHTType AVTable;
|
|
AvailableValues = &AVTable;
|
|
LoadHTType LoadTable;
|
|
AvailableLoads = &LoadTable;
|
|
CallHTType CallTable;
|
|
AvailableCalls = &CallTable;
|
|
|
|
CurrentGeneration = 0;
|
|
bool Changed = false;
|
|
|
|
// Process the root node.
|
|
nodesToProcess.push_back(
|
|
new StackNode(AvailableValues, AvailableLoads, AvailableCalls,
|
|
CurrentGeneration, DT->getRootNode(),
|
|
DT->getRootNode()->begin(),
|
|
DT->getRootNode()->end()));
|
|
|
|
// Save the current generation.
|
|
unsigned LiveOutGeneration = CurrentGeneration;
|
|
|
|
// Process the stack.
|
|
while (!nodesToProcess.empty()) {
|
|
// Grab the first item off the stack. Set the current generation, remove
|
|
// the node from the stack, and process it.
|
|
StackNode *NodeToProcess = nodesToProcess.back();
|
|
|
|
// Initialize class members.
|
|
CurrentGeneration = NodeToProcess->currentGeneration();
|
|
|
|
// Check if the node needs to be processed.
|
|
if (!NodeToProcess->isProcessed()) {
|
|
// Process the node.
|
|
Changed |= processNode(NodeToProcess->node());
|
|
NodeToProcess->childGeneration(CurrentGeneration);
|
|
NodeToProcess->process();
|
|
} else if (NodeToProcess->childIter() != NodeToProcess->end()) {
|
|
// Push the next child onto the stack.
|
|
DomTreeNode *child = NodeToProcess->nextChild();
|
|
nodesToProcess.push_back(
|
|
new StackNode(AvailableValues,
|
|
AvailableLoads,
|
|
AvailableCalls,
|
|
NodeToProcess->childGeneration(), child,
|
|
child->begin(), child->end()));
|
|
} else {
|
|
// It has been processed, and there are no more children to process,
|
|
// so delete it and pop it off the stack.
|
|
delete NodeToProcess;
|
|
nodesToProcess.pop_back();
|
|
}
|
|
} // while (!nodes...)
|
|
|
|
// Reset the current generation.
|
|
CurrentGeneration = LiveOutGeneration;
|
|
|
|
return Changed;
|
|
}
|