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Add a straight-forward implementation of SCCVN for aggressively eliminating scalar redundancies.
llvm-svn: 85179
This commit is contained in:
Owen Anderson
parent
a883c2ebb7
commit
a8d6745830
721
lib/Transforms/Scalar/SCCVN.cpp
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721
lib/Transforms/Scalar/SCCVN.cpp
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@ -0,0 +1,721 @@
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//===- SCCVN.cpp - Eliminate redundant values -----------------------------===//
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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 global value numbering to eliminate fully redundant
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// instructions. This is based on the paper "SCC-based Value Numbering"
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// by Cooper, et al.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "sccvn"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/BasicBlock.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Operator.h"
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#include "llvm/Value.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/SparseBitVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Transforms/Utils/SSAUpdater.h"
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#include <cstdio>
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using namespace llvm;
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STATISTIC(NumSCCVNInstr, "Number of instructions deleted by SCCVN");
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STATISTIC(NumSCCVNPhi, "Number of phis deleted by SCCVN");
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//===----------------------------------------------------------------------===//
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// ValueTable Class
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//===----------------------------------------------------------------------===//
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/// This class holds the mapping between values and value numbers. It is used
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/// as an efficient mechanism to determine the expression-wise equivalence of
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/// two values.
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namespace {
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struct Expression {
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enum ExpressionOpcode { ADD, FADD, SUB, FSUB, MUL, FMUL,
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UDIV, SDIV, FDIV, UREM, SREM,
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FREM, SHL, LSHR, ASHR, AND, OR, XOR, ICMPEQ,
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ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE,
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ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ,
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FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE,
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FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE,
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FCMPULT, FCMPULE, FCMPUNE, EXTRACT, INSERT,
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SHUFFLE, SELECT, TRUNC, ZEXT, SEXT, FPTOUI,
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FPTOSI, UITOFP, SITOFP, FPTRUNC, FPEXT,
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PTRTOINT, INTTOPTR, BITCAST, GEP, CALL, CONSTANT,
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INSERTVALUE, EXTRACTVALUE, EMPTY, TOMBSTONE };
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ExpressionOpcode opcode;
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const Type* type;
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SmallVector<uint32_t, 4> varargs;
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Expression() { }
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Expression(ExpressionOpcode o) : opcode(o) { }
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bool operator==(const Expression &other) const {
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if (opcode != other.opcode)
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return false;
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else if (opcode == EMPTY || opcode == TOMBSTONE)
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return true;
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else if (type != other.type)
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return false;
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else {
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if (varargs.size() != other.varargs.size())
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return false;
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for (size_t i = 0; i < varargs.size(); ++i)
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if (varargs[i] != other.varargs[i])
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return false;
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return true;
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}
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}
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bool operator!=(const Expression &other) const {
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return !(*this == other);
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}
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};
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class ValueTable {
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private:
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DenseMap<Value*, uint32_t> valueNumbering;
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DenseMap<Expression, uint32_t> expressionNumbering;
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DenseMap<Value*, uint32_t> constantsNumbering;
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uint32_t nextValueNumber;
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Expression::ExpressionOpcode getOpcode(BinaryOperator* BO);
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Expression::ExpressionOpcode getOpcode(CmpInst* C);
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Expression::ExpressionOpcode getOpcode(CastInst* C);
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Expression create_expression(BinaryOperator* BO);
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Expression create_expression(CmpInst* C);
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Expression create_expression(ShuffleVectorInst* V);
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Expression create_expression(ExtractElementInst* C);
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Expression create_expression(InsertElementInst* V);
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Expression create_expression(SelectInst* V);
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Expression create_expression(CastInst* C);
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Expression create_expression(GetElementPtrInst* G);
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Expression create_expression(CallInst* C);
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Expression create_expression(Constant* C);
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Expression create_expression(ExtractValueInst* C);
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Expression create_expression(InsertValueInst* C);
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public:
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ValueTable() : nextValueNumber(1) { }
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uint32_t computeNumber(Value *V);
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uint32_t lookup(Value *V);
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void add(Value *V, uint32_t num);
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void clear();
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void clearExpressions();
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void erase(Value *v);
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unsigned size();
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void verifyRemoved(const Value *) const;
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};
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}
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namespace llvm {
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template <> struct DenseMapInfo<Expression> {
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static inline Expression getEmptyKey() {
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return Expression(Expression::EMPTY);
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}
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static inline Expression getTombstoneKey() {
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return Expression(Expression::TOMBSTONE);
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}
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static unsigned getHashValue(const Expression e) {
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unsigned hash = e.opcode;
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hash = ((unsigned)((uintptr_t)e.type >> 4) ^
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(unsigned)((uintptr_t)e.type >> 9));
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for (SmallVector<uint32_t, 4>::const_iterator I = e.varargs.begin(),
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E = e.varargs.end(); I != E; ++I)
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hash = *I + hash * 37;
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return hash;
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}
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static bool isEqual(const Expression &LHS, const Expression &RHS) {
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return LHS == RHS;
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}
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static bool isPod() { return true; }
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};
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}
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//===----------------------------------------------------------------------===//
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// ValueTable Internal Functions
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//===----------------------------------------------------------------------===//
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Expression::ExpressionOpcode ValueTable::getOpcode(BinaryOperator* BO) {
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switch(BO->getOpcode()) {
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default: // THIS SHOULD NEVER HAPPEN
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llvm_unreachable("Binary operator with unknown opcode?");
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case Instruction::Add: return Expression::ADD;
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case Instruction::FAdd: return Expression::FADD;
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case Instruction::Sub: return Expression::SUB;
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case Instruction::FSub: return Expression::FSUB;
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case Instruction::Mul: return Expression::MUL;
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case Instruction::FMul: return Expression::FMUL;
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case Instruction::UDiv: return Expression::UDIV;
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case Instruction::SDiv: return Expression::SDIV;
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case Instruction::FDiv: return Expression::FDIV;
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case Instruction::URem: return Expression::UREM;
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case Instruction::SRem: return Expression::SREM;
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case Instruction::FRem: return Expression::FREM;
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case Instruction::Shl: return Expression::SHL;
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case Instruction::LShr: return Expression::LSHR;
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case Instruction::AShr: return Expression::ASHR;
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case Instruction::And: return Expression::AND;
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case Instruction::Or: return Expression::OR;
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case Instruction::Xor: return Expression::XOR;
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}
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}
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Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
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if (isa<ICmpInst>(C)) {
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switch (C->getPredicate()) {
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default: // THIS SHOULD NEVER HAPPEN
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llvm_unreachable("Comparison with unknown predicate?");
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case ICmpInst::ICMP_EQ: return Expression::ICMPEQ;
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case ICmpInst::ICMP_NE: return Expression::ICMPNE;
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case ICmpInst::ICMP_UGT: return Expression::ICMPUGT;
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case ICmpInst::ICMP_UGE: return Expression::ICMPUGE;
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case ICmpInst::ICMP_ULT: return Expression::ICMPULT;
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case ICmpInst::ICMP_ULE: return Expression::ICMPULE;
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case ICmpInst::ICMP_SGT: return Expression::ICMPSGT;
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case ICmpInst::ICMP_SGE: return Expression::ICMPSGE;
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case ICmpInst::ICMP_SLT: return Expression::ICMPSLT;
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case ICmpInst::ICMP_SLE: return Expression::ICMPSLE;
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}
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} else {
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switch (C->getPredicate()) {
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default: // THIS SHOULD NEVER HAPPEN
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llvm_unreachable("Comparison with unknown predicate?");
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case FCmpInst::FCMP_OEQ: return Expression::FCMPOEQ;
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case FCmpInst::FCMP_OGT: return Expression::FCMPOGT;
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case FCmpInst::FCMP_OGE: return Expression::FCMPOGE;
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case FCmpInst::FCMP_OLT: return Expression::FCMPOLT;
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case FCmpInst::FCMP_OLE: return Expression::FCMPOLE;
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case FCmpInst::FCMP_ONE: return Expression::FCMPONE;
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case FCmpInst::FCMP_ORD: return Expression::FCMPORD;
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case FCmpInst::FCMP_UNO: return Expression::FCMPUNO;
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case FCmpInst::FCMP_UEQ: return Expression::FCMPUEQ;
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case FCmpInst::FCMP_UGT: return Expression::FCMPUGT;
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case FCmpInst::FCMP_UGE: return Expression::FCMPUGE;
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case FCmpInst::FCMP_ULT: return Expression::FCMPULT;
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case FCmpInst::FCMP_ULE: return Expression::FCMPULE;
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case FCmpInst::FCMP_UNE: return Expression::FCMPUNE;
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}
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}
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}
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Expression::ExpressionOpcode ValueTable::getOpcode(CastInst* C) {
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switch(C->getOpcode()) {
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default: // THIS SHOULD NEVER HAPPEN
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llvm_unreachable("Cast operator with unknown opcode?");
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case Instruction::Trunc: return Expression::TRUNC;
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case Instruction::ZExt: return Expression::ZEXT;
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case Instruction::SExt: return Expression::SEXT;
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case Instruction::FPToUI: return Expression::FPTOUI;
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case Instruction::FPToSI: return Expression::FPTOSI;
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case Instruction::UIToFP: return Expression::UITOFP;
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case Instruction::SIToFP: return Expression::SITOFP;
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case Instruction::FPTrunc: return Expression::FPTRUNC;
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case Instruction::FPExt: return Expression::FPEXT;
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case Instruction::PtrToInt: return Expression::PTRTOINT;
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case Instruction::IntToPtr: return Expression::INTTOPTR;
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case Instruction::BitCast: return Expression::BITCAST;
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}
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}
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Expression ValueTable::create_expression(CallInst* C) {
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Expression e;
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e.type = C->getType();
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e.opcode = Expression::CALL;
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e.varargs.push_back(lookup(C->getCalledFunction()));
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for (CallInst::op_iterator I = C->op_begin()+1, E = C->op_end();
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I != E; ++I)
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e.varargs.push_back(lookup(*I));
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return e;
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}
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Expression ValueTable::create_expression(BinaryOperator* BO) {
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Expression e;
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e.varargs.push_back(lookup(BO->getOperand(0)));
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e.varargs.push_back(lookup(BO->getOperand(1)));
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e.type = BO->getType();
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e.opcode = getOpcode(BO);
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return e;
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}
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Expression ValueTable::create_expression(CmpInst* C) {
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Expression e;
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e.varargs.push_back(lookup(C->getOperand(0)));
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e.varargs.push_back(lookup(C->getOperand(1)));
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e.type = C->getType();
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e.opcode = getOpcode(C);
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return e;
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}
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Expression ValueTable::create_expression(CastInst* C) {
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Expression e;
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e.varargs.push_back(lookup(C->getOperand(0)));
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e.type = C->getType();
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e.opcode = getOpcode(C);
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return e;
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}
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Expression ValueTable::create_expression(ShuffleVectorInst* S) {
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Expression e;
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e.varargs.push_back(lookup(S->getOperand(0)));
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e.varargs.push_back(lookup(S->getOperand(1)));
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e.varargs.push_back(lookup(S->getOperand(2)));
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e.type = S->getType();
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e.opcode = Expression::SHUFFLE;
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return e;
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}
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Expression ValueTable::create_expression(ExtractElementInst* E) {
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Expression e;
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e.varargs.push_back(lookup(E->getOperand(0)));
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e.varargs.push_back(lookup(E->getOperand(1)));
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e.type = E->getType();
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e.opcode = Expression::EXTRACT;
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return e;
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}
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Expression ValueTable::create_expression(InsertElementInst* I) {
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Expression e;
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e.varargs.push_back(lookup(I->getOperand(0)));
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e.varargs.push_back(lookup(I->getOperand(1)));
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e.varargs.push_back(lookup(I->getOperand(2)));
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e.type = I->getType();
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e.opcode = Expression::INSERT;
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return e;
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}
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Expression ValueTable::create_expression(SelectInst* I) {
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Expression e;
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e.varargs.push_back(lookup(I->getCondition()));
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e.varargs.push_back(lookup(I->getTrueValue()));
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e.varargs.push_back(lookup(I->getFalseValue()));
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e.type = I->getType();
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e.opcode = Expression::SELECT;
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return e;
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}
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Expression ValueTable::create_expression(GetElementPtrInst* G) {
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Expression e;
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e.varargs.push_back(lookup(G->getPointerOperand()));
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e.type = G->getType();
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e.opcode = Expression::GEP;
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for (GetElementPtrInst::op_iterator I = G->idx_begin(), E = G->idx_end();
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I != E; ++I)
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e.varargs.push_back(lookup(*I));
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return e;
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}
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Expression ValueTable::create_expression(ExtractValueInst* E) {
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Expression e;
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e.varargs.push_back(lookup(E->getAggregateOperand()));
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for (ExtractValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
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II != IE; ++II)
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e.varargs.push_back(*II);
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e.type = E->getType();
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e.opcode = Expression::EXTRACTVALUE;
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return e;
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}
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||||||
|
Expression ValueTable::create_expression(InsertValueInst* E) {
|
||||||
|
Expression e;
|
||||||
|
|
||||||
|
e.varargs.push_back(lookup(E->getAggregateOperand()));
|
||||||
|
e.varargs.push_back(lookup(E->getInsertedValueOperand()));
|
||||||
|
for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
|
||||||
|
II != IE; ++II)
|
||||||
|
e.varargs.push_back(*II);
|
||||||
|
e.type = E->getType();
|
||||||
|
e.opcode = Expression::INSERTVALUE;
|
||||||
|
|
||||||
|
return e;
|
||||||
|
}
|
||||||
|
|
||||||
|
//===----------------------------------------------------------------------===//
|
||||||
|
// ValueTable External Functions
|
||||||
|
//===----------------------------------------------------------------------===//
|
||||||
|
|
||||||
|
/// add - Insert a value into the table with a specified value number.
|
||||||
|
void ValueTable::add(Value *V, uint32_t num) {
|
||||||
|
valueNumbering[V] = num;
|
||||||
|
}
|
||||||
|
|
||||||
|
/// computeNumber - Returns the value number for the specified value, assigning
|
||||||
|
/// it a new number if it did not have one before.
|
||||||
|
uint32_t ValueTable::computeNumber(Value *V) {
|
||||||
|
if (uint32_t v = valueNumbering[V])
|
||||||
|
return v;
|
||||||
|
else if (uint32_t v= constantsNumbering[V])
|
||||||
|
return v;
|
||||||
|
|
||||||
|
if (!isa<Instruction>(V)) {
|
||||||
|
constantsNumbering[V] = nextValueNumber;
|
||||||
|
return nextValueNumber++;
|
||||||
|
}
|
||||||
|
|
||||||
|
Instruction* I = cast<Instruction>(V);
|
||||||
|
Expression exp;
|
||||||
|
switch (I->getOpcode()) {
|
||||||
|
case Instruction::Add:
|
||||||
|
case Instruction::FAdd:
|
||||||
|
case Instruction::Sub:
|
||||||
|
case Instruction::FSub:
|
||||||
|
case Instruction::Mul:
|
||||||
|
case Instruction::FMul:
|
||||||
|
case Instruction::UDiv:
|
||||||
|
case Instruction::SDiv:
|
||||||
|
case Instruction::FDiv:
|
||||||
|
case Instruction::URem:
|
||||||
|
case Instruction::SRem:
|
||||||
|
case Instruction::FRem:
|
||||||
|
case Instruction::Shl:
|
||||||
|
case Instruction::LShr:
|
||||||
|
case Instruction::AShr:
|
||||||
|
case Instruction::And:
|
||||||
|
case Instruction::Or :
|
||||||
|
case Instruction::Xor:
|
||||||
|
exp = create_expression(cast<BinaryOperator>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::ICmp:
|
||||||
|
case Instruction::FCmp:
|
||||||
|
exp = create_expression(cast<CmpInst>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::Trunc:
|
||||||
|
case Instruction::ZExt:
|
||||||
|
case Instruction::SExt:
|
||||||
|
case Instruction::FPToUI:
|
||||||
|
case Instruction::FPToSI:
|
||||||
|
case Instruction::UIToFP:
|
||||||
|
case Instruction::SIToFP:
|
||||||
|
case Instruction::FPTrunc:
|
||||||
|
case Instruction::FPExt:
|
||||||
|
case Instruction::PtrToInt:
|
||||||
|
case Instruction::IntToPtr:
|
||||||
|
case Instruction::BitCast:
|
||||||
|
exp = create_expression(cast<CastInst>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::Select:
|
||||||
|
exp = create_expression(cast<SelectInst>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::ExtractElement:
|
||||||
|
exp = create_expression(cast<ExtractElementInst>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::InsertElement:
|
||||||
|
exp = create_expression(cast<InsertElementInst>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::ShuffleVector:
|
||||||
|
exp = create_expression(cast<ShuffleVectorInst>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::ExtractValue:
|
||||||
|
exp = create_expression(cast<ExtractValueInst>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::InsertValue:
|
||||||
|
exp = create_expression(cast<InsertValueInst>(I));
|
||||||
|
break;
|
||||||
|
case Instruction::GetElementPtr:
|
||||||
|
exp = create_expression(cast<GetElementPtrInst>(I));
|
||||||
|
break;
|
||||||
|
default:
|
||||||
|
valueNumbering[V] = nextValueNumber;
|
||||||
|
return nextValueNumber++;
|
||||||
|
}
|
||||||
|
|
||||||
|
uint32_t& e = expressionNumbering[exp];
|
||||||
|
if (!e) e = nextValueNumber++;
|
||||||
|
valueNumbering[V] = e;
|
||||||
|
|
||||||
|
return e;
|
||||||
|
}
|
||||||
|
|
||||||
|
/// lookup - Returns the value number of the specified value. Returns 0 if
|
||||||
|
/// the value has not yet been numbered.
|
||||||
|
uint32_t ValueTable::lookup(Value *V) {
|
||||||
|
if (!isa<Instruction>(V)) {
|
||||||
|
if (!constantsNumbering.count(V))
|
||||||
|
constantsNumbering[V] = nextValueNumber++;
|
||||||
|
return constantsNumbering[V];
|
||||||
|
}
|
||||||
|
|
||||||
|
return valueNumbering[V];
|
||||||
|
}
|
||||||
|
|
||||||
|
/// clear - Remove all entries from the ValueTable
|
||||||
|
void ValueTable::clear() {
|
||||||
|
valueNumbering.clear();
|
||||||
|
expressionNumbering.clear();
|
||||||
|
constantsNumbering.clear();
|
||||||
|
nextValueNumber = 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
void ValueTable::clearExpressions() {
|
||||||
|
expressionNumbering.clear();
|
||||||
|
constantsNumbering.clear();
|
||||||
|
nextValueNumber = 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
/// erase - Remove a value from the value numbering
|
||||||
|
void ValueTable::erase(Value *V) {
|
||||||
|
valueNumbering.erase(V);
|
||||||
|
}
|
||||||
|
|
||||||
|
/// verifyRemoved - Verify that the value is removed from all internal data
|
||||||
|
/// structures.
|
||||||
|
void ValueTable::verifyRemoved(const Value *V) const {
|
||||||
|
for (DenseMap<Value*, uint32_t>::iterator
|
||||||
|
I = valueNumbering.begin(), E = valueNumbering.end(); I != E; ++I) {
|
||||||
|
assert(I->first != V && "Inst still occurs in value numbering map!");
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
//===----------------------------------------------------------------------===//
|
||||||
|
// SCCVN Pass
|
||||||
|
//===----------------------------------------------------------------------===//
|
||||||
|
|
||||||
|
namespace {
|
||||||
|
|
||||||
|
struct ValueNumberScope {
|
||||||
|
ValueNumberScope* parent;
|
||||||
|
DenseMap<uint32_t, Value*> table;
|
||||||
|
SparseBitVector<128> availIn;
|
||||||
|
SparseBitVector<128> availOut;
|
||||||
|
|
||||||
|
ValueNumberScope(ValueNumberScope* p) : parent(p) { }
|
||||||
|
};
|
||||||
|
|
||||||
|
class SCCVN : public FunctionPass {
|
||||||
|
bool runOnFunction(Function &F);
|
||||||
|
public:
|
||||||
|
static char ID; // Pass identification, replacement for typeid
|
||||||
|
SCCVN() : FunctionPass(&ID) { }
|
||||||
|
|
||||||
|
private:
|
||||||
|
ValueTable VT;
|
||||||
|
DenseMap<BasicBlock*, ValueNumberScope*> BBMap;
|
||||||
|
|
||||||
|
// This transformation requires dominator postdominator info
|
||||||
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
||||||
|
AU.addRequired<DominatorTree>();
|
||||||
|
|
||||||
|
AU.addPreserved<DominatorTree>();
|
||||||
|
AU.setPreservesCFG();
|
||||||
|
}
|
||||||
|
};
|
||||||
|
|
||||||
|
char SCCVN::ID = 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
// createSCCVNPass - The public interface to this file...
|
||||||
|
FunctionPass *llvm::createSCCVNPass() { return new SCCVN(); }
|
||||||
|
|
||||||
|
static RegisterPass<SCCVN> X("sccvn",
|
||||||
|
"SCC Value Numbering");
|
||||||
|
|
||||||
|
static Value *lookupNumber(ValueNumberScope *Locals, uint32_t num) {
|
||||||
|
while (Locals) {
|
||||||
|
DenseMap<uint32_t, Value*>::iterator I = Locals->table.find(num);
|
||||||
|
if (I != Locals->table.end())
|
||||||
|
return I->second;
|
||||||
|
Locals = Locals->parent;
|
||||||
|
}
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
bool SCCVN::runOnFunction(Function& F) {
|
||||||
|
// Implement the RPO version of the SCCVN algorithm. Conceptually,
|
||||||
|
// we optimisitically assume that all instructions with the same opcode have
|
||||||
|
// the same VN. Then we deepen our comparison by one level, to all
|
||||||
|
// instructions whose operands have the same opcodes get the same VN. We
|
||||||
|
// iterate this process until the partitioning stops changing, at which
|
||||||
|
// point we have computed a full numbering.
|
||||||
|
ReversePostOrderTraversal<Function*> RPOT(&F);
|
||||||
|
bool done = false;
|
||||||
|
while (!done) {
|
||||||
|
done = true;
|
||||||
|
VT.clearExpressions();
|
||||||
|
for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
|
||||||
|
E = RPOT.end(); I != E; ++I) {
|
||||||
|
BasicBlock* BB = *I;
|
||||||
|
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
|
||||||
|
BI != BE; ++BI) {
|
||||||
|
uint32_t origVN = VT.lookup(BI);
|
||||||
|
uint32_t newVN = VT.computeNumber(BI);
|
||||||
|
if (origVN != newVN)
|
||||||
|
done = false;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
// Now, do a dominator walk, eliminating simple, dominated redundancies as we
|
||||||
|
// go. Also, build the ValueNumberScope structure that will be used for
|
||||||
|
// computing full availability.
|
||||||
|
DominatorTree& DT = getAnalysis<DominatorTree>();
|
||||||
|
bool changed = false;
|
||||||
|
for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
|
||||||
|
DE = df_end(DT.getRootNode()); DI != DE; ++DI) {
|
||||||
|
BasicBlock* BB = DI->getBlock();
|
||||||
|
if (DI->getIDom())
|
||||||
|
BBMap[BB] = new ValueNumberScope(BBMap[DI->getIDom()->getBlock()]);
|
||||||
|
else
|
||||||
|
BBMap[BB] = new ValueNumberScope(0);
|
||||||
|
|
||||||
|
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
|
||||||
|
uint32_t num = VT.lookup(I);
|
||||||
|
Value* repl = lookupNumber(BBMap[BB], num);
|
||||||
|
|
||||||
|
if (repl) {
|
||||||
|
if (isa<PHINode>(I))
|
||||||
|
++NumSCCVNPhi;
|
||||||
|
else
|
||||||
|
++NumSCCVNInstr;
|
||||||
|
I->replaceAllUsesWith(repl);
|
||||||
|
Instruction* OldInst = I;
|
||||||
|
++I;
|
||||||
|
BBMap[BB]->table[num] = repl;
|
||||||
|
OldInst->eraseFromParent();
|
||||||
|
changed = true;
|
||||||
|
} else {
|
||||||
|
BBMap[BB]->table[num] = I;
|
||||||
|
BBMap[BB]->availOut.set(num);
|
||||||
|
|
||||||
|
++I;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
// FIXME: This code is commented out for now, because it can lead to the
|
||||||
|
// insertion of a lot of redundant PHIs being inserted by SSAUpdater.
|
||||||
|
#if 0
|
||||||
|
// Perform a forward data-flow to compute availability at all points on
|
||||||
|
// the CFG.
|
||||||
|
do {
|
||||||
|
changed = false;
|
||||||
|
for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
|
||||||
|
E = RPOT.end(); I != E; ++I) {
|
||||||
|
BasicBlock* BB = *I;
|
||||||
|
ValueNumberScope *VNS = BBMap[BB];
|
||||||
|
|
||||||
|
SparseBitVector<128> preds;
|
||||||
|
bool first = true;
|
||||||
|
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
|
||||||
|
PI != PE; ++PI) {
|
||||||
|
if (first) {
|
||||||
|
preds = BBMap[*PI]->availOut;
|
||||||
|
first = false;
|
||||||
|
} else {
|
||||||
|
preds &= BBMap[*PI]->availOut;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
changed |= (VNS->availIn |= preds);
|
||||||
|
changed |= (VNS->availOut |= preds);
|
||||||
|
}
|
||||||
|
} while (changed);
|
||||||
|
|
||||||
|
// Use full availability information to perform non-dominated replacements.
|
||||||
|
SSAUpdater SSU;
|
||||||
|
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) {
|
||||||
|
if (!BBMap.count(FI)) continue;
|
||||||
|
for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
|
||||||
|
BI != BE; ) {
|
||||||
|
uint32_t num = VT.lookup(BI);
|
||||||
|
if (!BBMap[FI]->availIn.test(num)) {
|
||||||
|
++BI;
|
||||||
|
continue;
|
||||||
|
}
|
||||||
|
|
||||||
|
SSU.Initialize(BI);
|
||||||
|
|
||||||
|
SmallPtrSet<BasicBlock*, 8> visited;
|
||||||
|
SmallVector<BasicBlock*, 8> stack;
|
||||||
|
visited.insert(FI);
|
||||||
|
for (pred_iterator PI = pred_begin(FI), PE = pred_end(FI);
|
||||||
|
PI != PE; ++PI)
|
||||||
|
if (!visited.count(*PI))
|
||||||
|
stack.push_back(*PI);
|
||||||
|
|
||||||
|
while (!stack.empty()) {
|
||||||
|
BasicBlock* CurrBB = stack.back();
|
||||||
|
stack.pop_back();
|
||||||
|
visited.insert(CurrBB);
|
||||||
|
|
||||||
|
ValueNumberScope* S = BBMap[CurrBB];
|
||||||
|
if (S->table.count(num)) {
|
||||||
|
SSU.AddAvailableValue(CurrBB, S->table[num]);
|
||||||
|
} else {
|
||||||
|
for (pred_iterator PI = pred_begin(CurrBB), PE = pred_end(CurrBB);
|
||||||
|
PI != PE; ++PI)
|
||||||
|
if (!visited.count(*PI))
|
||||||
|
stack.push_back(*PI);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
Value* repl = SSU.GetValueInMiddleOfBlock(FI);
|
||||||
|
BI->replaceAllUsesWith(repl);
|
||||||
|
Instruction* CurInst = BI;
|
||||||
|
++BI;
|
||||||
|
BBMap[FI]->table[num] = repl;
|
||||||
|
if (isa<PHINode>(CurInst))
|
||||||
|
++NumSCCVNPhi;
|
||||||
|
else
|
||||||
|
++NumSCCVNInstr;
|
||||||
|
|
||||||
|
CurInst->eraseFromParent();
|
||||||
|
}
|
||||||
|
}
|
||||||
|
#endif
|
||||||
|
|
||||||
|
VT.clear();
|
||||||
|
for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
|
||||||
|
I = BBMap.begin(), E = BBMap.end(); I != E; ++I)
|
||||||
|
delete I->second;
|
||||||
|
BBMap.clear();
|
||||||
|
|
||||||
|
return changed;
|
||||||
|
}
|
||||||
Loading…
Reference in New Issue
Block a user