mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-30 21:29:28 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47111 91177308-0d34-0410-b5e6-96231b3b80d8
1253 lines
38 KiB
C++
1253 lines
38 KiB
C++
//===- GVN.cpp - Eliminate redundant values and loads ------------===//
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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. It also performs simple dead load elimination.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "gvn"
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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/IntrinsicInst.h"
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#include "llvm/Instructions.h"
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#include "llvm/Value.h"
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#include "llvm/ADT/BitVector.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/SmallPtrSet.h"
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#include "llvm/ADT/SmallVector.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/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/MemoryDependenceAnalysis.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Support/Compiler.h"
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using namespace llvm;
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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 VISIBILITY_HIDDEN Expression {
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enum ExpressionOpcode { ADD, SUB, MUL, 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, EMPTY,
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TOMBSTONE };
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ExpressionOpcode opcode;
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const Type* type;
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uint32_t firstVN;
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uint32_t secondVN;
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uint32_t thirdVN;
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SmallVector<uint32_t, 4> varargs;
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Value* function;
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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 if (function != other.function)
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return false;
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else if (firstVN != other.firstVN)
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return false;
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else if (secondVN != other.secondVN)
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return false;
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else if (thirdVN != other.thirdVN)
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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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if (opcode != other.opcode)
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return true;
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else if (opcode == EMPTY || opcode == TOMBSTONE)
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return false;
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else if (type != other.type)
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return true;
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else if (function != other.function)
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return true;
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else if (firstVN != other.firstVN)
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return true;
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else if (secondVN != other.secondVN)
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return true;
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else if (thirdVN != other.thirdVN)
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return true;
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else {
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if (varargs.size() != other.varargs.size())
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return true;
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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 true;
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return false;
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}
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}
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};
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class VISIBILITY_HIDDEN 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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AliasAnalysis* AA;
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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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public:
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ValueTable() : nextValueNumber(1) { }
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uint32_t lookup_or_add(Value* V);
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uint32_t lookup(Value* V) const;
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void add(Value* V, uint32_t num);
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void clear();
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void erase(Value* v);
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unsigned size();
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void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
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uint32_t hash_operand(Value* v);
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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 = e.firstVN + hash * 37;
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hash = e.secondVN + hash * 37;
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hash = e.thirdVN + hash * 37;
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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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hash * 37;
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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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hash = (unsigned)((uintptr_t)e.function >> 4) ^
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(unsigned)((uintptr_t)e.function >> 9) +
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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
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ValueTable::getOpcode(BinaryOperator* BO) {
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switch(BO->getOpcode()) {
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case Instruction::Add:
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return Expression::ADD;
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case Instruction::Sub:
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return Expression::SUB;
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case Instruction::Mul:
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return Expression::MUL;
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case Instruction::UDiv:
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return Expression::UDIV;
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case Instruction::SDiv:
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return Expression::SDIV;
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case Instruction::FDiv:
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return Expression::FDIV;
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case Instruction::URem:
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return Expression::UREM;
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case Instruction::SRem:
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return Expression::SREM;
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case Instruction::FRem:
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return Expression::FREM;
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case Instruction::Shl:
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return Expression::SHL;
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case Instruction::LShr:
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return Expression::LSHR;
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case Instruction::AShr:
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return Expression::ASHR;
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case Instruction::And:
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return Expression::AND;
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case Instruction::Or:
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return Expression::OR;
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case Instruction::Xor:
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return Expression::XOR;
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// THIS SHOULD NEVER HAPPEN
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default:
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assert(0 && "Binary operator with unknown opcode?");
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return Expression::ADD;
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}
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}
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Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
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if (C->getOpcode() == Instruction::ICmp) {
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switch (C->getPredicate()) {
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case ICmpInst::ICMP_EQ:
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return Expression::ICMPEQ;
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case ICmpInst::ICMP_NE:
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return Expression::ICMPNE;
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case ICmpInst::ICMP_UGT:
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return Expression::ICMPUGT;
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case ICmpInst::ICMP_UGE:
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return Expression::ICMPUGE;
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case ICmpInst::ICMP_ULT:
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return Expression::ICMPULT;
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case ICmpInst::ICMP_ULE:
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return Expression::ICMPULE;
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case ICmpInst::ICMP_SGT:
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return Expression::ICMPSGT;
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case ICmpInst::ICMP_SGE:
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return Expression::ICMPSGE;
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case ICmpInst::ICMP_SLT:
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return Expression::ICMPSLT;
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case ICmpInst::ICMP_SLE:
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return Expression::ICMPSLE;
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// THIS SHOULD NEVER HAPPEN
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default:
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assert(0 && "Comparison with unknown predicate?");
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return Expression::ICMPEQ;
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}
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} else {
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switch (C->getPredicate()) {
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case FCmpInst::FCMP_OEQ:
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return Expression::FCMPOEQ;
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case FCmpInst::FCMP_OGT:
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return Expression::FCMPOGT;
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case FCmpInst::FCMP_OGE:
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return Expression::FCMPOGE;
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case FCmpInst::FCMP_OLT:
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return Expression::FCMPOLT;
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case FCmpInst::FCMP_OLE:
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return Expression::FCMPOLE;
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case FCmpInst::FCMP_ONE:
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return Expression::FCMPONE;
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case FCmpInst::FCMP_ORD:
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return Expression::FCMPORD;
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case FCmpInst::FCMP_UNO:
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return Expression::FCMPUNO;
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case FCmpInst::FCMP_UEQ:
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return Expression::FCMPUEQ;
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case FCmpInst::FCMP_UGT:
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return Expression::FCMPUGT;
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case FCmpInst::FCMP_UGE:
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return Expression::FCMPUGE;
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case FCmpInst::FCMP_ULT:
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return Expression::FCMPULT;
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case FCmpInst::FCMP_ULE:
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return Expression::FCMPULE;
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case FCmpInst::FCMP_UNE:
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return Expression::FCMPUNE;
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// THIS SHOULD NEVER HAPPEN
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default:
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assert(0 && "Comparison with unknown predicate?");
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return Expression::FCMPOEQ;
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}
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}
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}
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Expression::ExpressionOpcode
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ValueTable::getOpcode(CastInst* C) {
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switch(C->getOpcode()) {
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case Instruction::Trunc:
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return Expression::TRUNC;
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case Instruction::ZExt:
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return Expression::ZEXT;
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case Instruction::SExt:
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return Expression::SEXT;
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case Instruction::FPToUI:
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return Expression::FPTOUI;
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case Instruction::FPToSI:
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return Expression::FPTOSI;
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case Instruction::UIToFP:
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return Expression::UITOFP;
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case Instruction::SIToFP:
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return Expression::SITOFP;
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case Instruction::FPTrunc:
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return Expression::FPTRUNC;
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case Instruction::FPExt:
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return Expression::FPEXT;
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case Instruction::PtrToInt:
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return Expression::PTRTOINT;
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case Instruction::IntToPtr:
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return Expression::INTTOPTR;
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case Instruction::BitCast:
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return Expression::BITCAST;
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// THIS SHOULD NEVER HAPPEN
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default:
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assert(0 && "Cast operator with unknown opcode?");
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return Expression::BITCAST;
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}
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}
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uint32_t ValueTable::hash_operand(Value* v) {
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if (CallInst* CI = dyn_cast<CallInst>(v))
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if (!AA->doesNotAccessMemory(CI))
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return nextValueNumber++;
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return lookup_or_add(v);
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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.firstVN = 0;
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e.secondVN = 0;
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e.thirdVN = 0;
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e.function = C->getCalledFunction();
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e.opcode = Expression::CALL;
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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(hash_operand(*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.firstVN = hash_operand(BO->getOperand(0));
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e.secondVN = hash_operand(BO->getOperand(1));
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e.thirdVN = 0;
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e.function = 0;
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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.firstVN = hash_operand(C->getOperand(0));
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e.secondVN = hash_operand(C->getOperand(1));
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e.thirdVN = 0;
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e.function = 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(CastInst* C) {
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Expression e;
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e.firstVN = hash_operand(C->getOperand(0));
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e.secondVN = 0;
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e.thirdVN = 0;
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e.function = 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.firstVN = hash_operand(S->getOperand(0));
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e.secondVN = hash_operand(S->getOperand(1));
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e.thirdVN = hash_operand(S->getOperand(2));
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e.function = 0;
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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.firstVN = hash_operand(E->getOperand(0));
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e.secondVN = hash_operand(E->getOperand(1));
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e.thirdVN = 0;
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e.function = 0;
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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.firstVN = hash_operand(I->getOperand(0));
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e.secondVN = hash_operand(I->getOperand(1));
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e.thirdVN = hash_operand(I->getOperand(2));
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e.function = 0;
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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.firstVN = hash_operand(I->getCondition());
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e.secondVN = hash_operand(I->getTrueValue());
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e.thirdVN = hash_operand(I->getFalseValue());
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e.function = 0;
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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.firstVN = hash_operand(G->getPointerOperand());
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e.secondVN = 0;
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e.thirdVN = 0;
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e.function = 0;
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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(hash_operand(*I));
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return e;
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}
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//===----------------------------------------------------------------------===//
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// ValueTable External Functions
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//===----------------------------------------------------------------------===//
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|
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/// lookup_or_add - Returns the value number for the specified value, assigning
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/// it a new number if it did not have one before.
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uint32_t ValueTable::lookup_or_add(Value* V) {
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DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
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if (VI != valueNumbering.end())
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return VI->second;
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if (CallInst* C = dyn_cast<CallInst>(V)) {
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if (AA->onlyReadsMemory(C)) { // includes doesNotAccessMemory
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Expression e = create_expression(C);
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DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
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if (EI != expressionNumbering.end()) {
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valueNumbering.insert(std::make_pair(V, EI->second));
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return EI->second;
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} else {
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expressionNumbering.insert(std::make_pair(e, nextValueNumber));
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valueNumbering.insert(std::make_pair(V, nextValueNumber));
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return nextValueNumber++;
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}
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} else {
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valueNumbering.insert(std::make_pair(V, nextValueNumber));
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return nextValueNumber++;
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}
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} else if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
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Expression e = create_expression(BO);
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DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
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if (EI != expressionNumbering.end()) {
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valueNumbering.insert(std::make_pair(V, EI->second));
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return EI->second;
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} else {
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expressionNumbering.insert(std::make_pair(e, nextValueNumber));
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valueNumbering.insert(std::make_pair(V, nextValueNumber));
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return nextValueNumber++;
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}
|
|
} else if (CmpInst* C = dyn_cast<CmpInst>(V)) {
|
|
Expression e = create_expression(C);
|
|
|
|
DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
|
|
if (EI != expressionNumbering.end()) {
|
|
valueNumbering.insert(std::make_pair(V, EI->second));
|
|
return EI->second;
|
|
} else {
|
|
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
|
|
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
|
|
|
return nextValueNumber++;
|
|
}
|
|
} else if (ShuffleVectorInst* U = dyn_cast<ShuffleVectorInst>(V)) {
|
|
Expression e = create_expression(U);
|
|
|
|
DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
|
|
if (EI != expressionNumbering.end()) {
|
|
valueNumbering.insert(std::make_pair(V, EI->second));
|
|
return EI->second;
|
|
} else {
|
|
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
|
|
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
|
|
|
return nextValueNumber++;
|
|
}
|
|
} else if (ExtractElementInst* U = dyn_cast<ExtractElementInst>(V)) {
|
|
Expression e = create_expression(U);
|
|
|
|
DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
|
|
if (EI != expressionNumbering.end()) {
|
|
valueNumbering.insert(std::make_pair(V, EI->second));
|
|
return EI->second;
|
|
} else {
|
|
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
|
|
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
|
|
|
return nextValueNumber++;
|
|
}
|
|
} else if (InsertElementInst* U = dyn_cast<InsertElementInst>(V)) {
|
|
Expression e = create_expression(U);
|
|
|
|
DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
|
|
if (EI != expressionNumbering.end()) {
|
|
valueNumbering.insert(std::make_pair(V, EI->second));
|
|
return EI->second;
|
|
} else {
|
|
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
|
|
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
|
|
|
return nextValueNumber++;
|
|
}
|
|
} else if (SelectInst* U = dyn_cast<SelectInst>(V)) {
|
|
Expression e = create_expression(U);
|
|
|
|
DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
|
|
if (EI != expressionNumbering.end()) {
|
|
valueNumbering.insert(std::make_pair(V, EI->second));
|
|
return EI->second;
|
|
} else {
|
|
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
|
|
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
|
|
|
return nextValueNumber++;
|
|
}
|
|
} else if (CastInst* U = dyn_cast<CastInst>(V)) {
|
|
Expression e = create_expression(U);
|
|
|
|
DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
|
|
if (EI != expressionNumbering.end()) {
|
|
valueNumbering.insert(std::make_pair(V, EI->second));
|
|
return EI->second;
|
|
} else {
|
|
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
|
|
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
|
|
|
return nextValueNumber++;
|
|
}
|
|
} else if (GetElementPtrInst* U = dyn_cast<GetElementPtrInst>(V)) {
|
|
Expression e = create_expression(U);
|
|
|
|
DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
|
|
if (EI != expressionNumbering.end()) {
|
|
valueNumbering.insert(std::make_pair(V, EI->second));
|
|
return EI->second;
|
|
} else {
|
|
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
|
|
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
|
|
|
return nextValueNumber++;
|
|
}
|
|
} else {
|
|
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
|
return nextValueNumber++;
|
|
}
|
|
}
|
|
|
|
/// lookup - Returns the value number of the specified value. Fails if
|
|
/// the value has not yet been numbered.
|
|
uint32_t ValueTable::lookup(Value* V) const {
|
|
DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
|
|
if (VI != valueNumbering.end())
|
|
return VI->second;
|
|
else
|
|
assert(0 && "Value not numbered?");
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// clear - Remove all entries from the ValueTable
|
|
void ValueTable::clear() {
|
|
valueNumbering.clear();
|
|
expressionNumbering.clear();
|
|
nextValueNumber = 1;
|
|
}
|
|
|
|
/// erase - Remove a value from the value numbering
|
|
void ValueTable::erase(Value* V) {
|
|
valueNumbering.erase(V);
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// ValueNumberedSet Class
|
|
//===----------------------------------------------------------------------===//
|
|
namespace {
|
|
class ValueNumberedSet {
|
|
private:
|
|
SmallPtrSet<Value*, 8> contents;
|
|
BitVector numbers;
|
|
public:
|
|
ValueNumberedSet() { numbers.resize(1); }
|
|
ValueNumberedSet(const ValueNumberedSet& other) {
|
|
numbers = other.numbers;
|
|
contents = other.contents;
|
|
}
|
|
|
|
typedef SmallPtrSet<Value*, 8>::iterator iterator;
|
|
|
|
iterator begin() { return contents.begin(); }
|
|
iterator end() { return contents.end(); }
|
|
|
|
bool insert(Value* v) { return contents.insert(v); }
|
|
void insert(iterator I, iterator E) { contents.insert(I, E); }
|
|
void erase(Value* v) { contents.erase(v); }
|
|
unsigned count(Value* v) { return contents.count(v); }
|
|
size_t size() { return contents.size(); }
|
|
|
|
void set(unsigned i) {
|
|
if (i >= numbers.size())
|
|
numbers.resize(i+1);
|
|
|
|
numbers.set(i);
|
|
}
|
|
|
|
void operator=(const ValueNumberedSet& other) {
|
|
contents = other.contents;
|
|
numbers = other.numbers;
|
|
}
|
|
|
|
void reset(unsigned i) {
|
|
if (i < numbers.size())
|
|
numbers.reset(i);
|
|
}
|
|
|
|
bool test(unsigned i) {
|
|
if (i >= numbers.size())
|
|
return false;
|
|
|
|
return numbers.test(i);
|
|
}
|
|
|
|
void clear() {
|
|
contents.clear();
|
|
numbers.clear();
|
|
}
|
|
};
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// GVN Pass
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
namespace {
|
|
|
|
class VISIBILITY_HIDDEN GVN : public FunctionPass {
|
|
bool runOnFunction(Function &F);
|
|
public:
|
|
static char ID; // Pass identification, replacement for typeid
|
|
GVN() : FunctionPass((intptr_t)&ID) { }
|
|
|
|
private:
|
|
ValueTable VN;
|
|
|
|
DenseMap<BasicBlock*, ValueNumberedSet> availableOut;
|
|
|
|
typedef DenseMap<Value*, SmallPtrSet<Instruction*, 4> > PhiMapType;
|
|
PhiMapType phiMap;
|
|
|
|
|
|
// This transformation requires dominator postdominator info
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesCFG();
|
|
AU.addRequired<DominatorTree>();
|
|
AU.addRequired<MemoryDependenceAnalysis>();
|
|
AU.addRequired<AliasAnalysis>();
|
|
AU.addPreserved<AliasAnalysis>();
|
|
AU.addPreserved<MemoryDependenceAnalysis>();
|
|
}
|
|
|
|
// Helper fuctions
|
|
// FIXME: eliminate or document these better
|
|
Value* find_leader(ValueNumberedSet& vals, uint32_t v) ;
|
|
void val_insert(ValueNumberedSet& s, Value* v);
|
|
bool processLoad(LoadInst* L,
|
|
DenseMap<Value*, LoadInst*>& lastLoad,
|
|
SmallVector<Instruction*, 4>& toErase);
|
|
bool processInstruction(Instruction* I,
|
|
ValueNumberedSet& currAvail,
|
|
DenseMap<Value*, LoadInst*>& lastSeenLoad,
|
|
SmallVector<Instruction*, 4>& toErase);
|
|
bool processNonLocalLoad(LoadInst* L,
|
|
SmallVector<Instruction*, 4>& toErase);
|
|
bool processMemCpy(MemCpyInst* M, SmallVector<Instruction*, 4>& toErase);
|
|
Value *GetValueForBlock(BasicBlock *BB, LoadInst* orig,
|
|
DenseMap<BasicBlock*, Value*> &Phis,
|
|
bool top_level = false);
|
|
void dump(DenseMap<BasicBlock*, Value*>& d);
|
|
bool iterateOnFunction(Function &F);
|
|
Value* CollapsePhi(PHINode* p);
|
|
bool isSafeReplacement(PHINode* p, Instruction* inst);
|
|
};
|
|
|
|
char GVN::ID = 0;
|
|
|
|
}
|
|
|
|
// createGVNPass - The public interface to this file...
|
|
FunctionPass *llvm::createGVNPass() { return new GVN(); }
|
|
|
|
static RegisterPass<GVN> X("gvn",
|
|
"Global Value Numbering");
|
|
|
|
STATISTIC(NumGVNInstr, "Number of instructions deleted");
|
|
STATISTIC(NumGVNLoad, "Number of loads deleted");
|
|
|
|
/// find_leader - Given a set and a value number, return the first
|
|
/// element of the set with that value number, or 0 if no such element
|
|
/// is present
|
|
Value* GVN::find_leader(ValueNumberedSet& vals, uint32_t v) {
|
|
if (!vals.test(v))
|
|
return 0;
|
|
|
|
for (ValueNumberedSet::iterator I = vals.begin(), E = vals.end();
|
|
I != E; ++I)
|
|
if (v == VN.lookup(*I))
|
|
return *I;
|
|
|
|
assert(0 && "No leader found, but present bit is set?");
|
|
return 0;
|
|
}
|
|
|
|
/// val_insert - Insert a value into a set only if there is not a value
|
|
/// with the same value number already in the set
|
|
void GVN::val_insert(ValueNumberedSet& s, Value* v) {
|
|
uint32_t num = VN.lookup(v);
|
|
if (!s.test(num))
|
|
s.insert(v);
|
|
}
|
|
|
|
void GVN::dump(DenseMap<BasicBlock*, Value*>& d) {
|
|
printf("{\n");
|
|
for (DenseMap<BasicBlock*, Value*>::iterator I = d.begin(),
|
|
E = d.end(); I != E; ++I) {
|
|
if (I->second == MemoryDependenceAnalysis::None)
|
|
printf("None\n");
|
|
else
|
|
I->second->dump();
|
|
}
|
|
printf("}\n");
|
|
}
|
|
|
|
Value* GVN::CollapsePhi(PHINode* p) {
|
|
DominatorTree &DT = getAnalysis<DominatorTree>();
|
|
Value* constVal = p->hasConstantValue();
|
|
|
|
if (constVal) {
|
|
if (Instruction* inst = dyn_cast<Instruction>(constVal)) {
|
|
if (DT.dominates(inst, p))
|
|
if (isSafeReplacement(p, inst))
|
|
return inst;
|
|
} else {
|
|
return constVal;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
bool GVN::isSafeReplacement(PHINode* p, Instruction* inst) {
|
|
if (!isa<PHINode>(inst))
|
|
return true;
|
|
|
|
for (Instruction::use_iterator UI = p->use_begin(), E = p->use_end();
|
|
UI != E; ++UI)
|
|
if (PHINode* use_phi = dyn_cast<PHINode>(UI))
|
|
if (use_phi->getParent() == inst->getParent())
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/// GetValueForBlock - Get the value to use within the specified basic block.
|
|
/// available values are in Phis.
|
|
Value *GVN::GetValueForBlock(BasicBlock *BB, LoadInst* orig,
|
|
DenseMap<BasicBlock*, Value*> &Phis,
|
|
bool top_level) {
|
|
|
|
// If we have already computed this value, return the previously computed val.
|
|
DenseMap<BasicBlock*, Value*>::iterator V = Phis.find(BB);
|
|
if (V != Phis.end() && !top_level) return V->second;
|
|
|
|
BasicBlock* singlePred = BB->getSinglePredecessor();
|
|
if (singlePred) {
|
|
Value *ret = GetValueForBlock(singlePred, orig, Phis);
|
|
Phis[BB] = ret;
|
|
return ret;
|
|
}
|
|
// Otherwise, the idom is the loop, so we need to insert a PHI node. Do so
|
|
// now, then get values to fill in the incoming values for the PHI.
|
|
PHINode *PN = new PHINode(orig->getType(), orig->getName()+".rle",
|
|
BB->begin());
|
|
PN->reserveOperandSpace(std::distance(pred_begin(BB), pred_end(BB)));
|
|
|
|
if (Phis.count(BB) == 0)
|
|
Phis.insert(std::make_pair(BB, PN));
|
|
|
|
// Fill in the incoming values for the block.
|
|
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
|
|
Value* val = GetValueForBlock(*PI, orig, Phis);
|
|
|
|
PN->addIncoming(val, *PI);
|
|
}
|
|
AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
|
|
AA.copyValue(orig, PN);
|
|
|
|
// Attempt to collapse PHI nodes that are trivially redundant
|
|
Value* v = CollapsePhi(PN);
|
|
if (v) {
|
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
|
|
MD.removeInstruction(PN);
|
|
PN->replaceAllUsesWith(v);
|
|
|
|
for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
|
|
E = Phis.end(); I != E; ++I)
|
|
if (I->second == PN)
|
|
I->second = v;
|
|
|
|
PN->eraseFromParent();
|
|
|
|
Phis[BB] = v;
|
|
|
|
return v;
|
|
}
|
|
|
|
// Cache our phi construction results
|
|
phiMap[orig->getPointerOperand()].insert(PN);
|
|
return PN;
|
|
}
|
|
|
|
/// processNonLocalLoad - Attempt to eliminate a load whose dependencies are
|
|
/// non-local by performing PHI construction.
|
|
bool GVN::processNonLocalLoad(LoadInst* L,
|
|
SmallVector<Instruction*, 4>& toErase) {
|
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
|
|
// Find the non-local dependencies of the load
|
|
DenseMap<BasicBlock*, Value*> deps;
|
|
MD.getNonLocalDependency(L, deps);
|
|
|
|
DenseMap<BasicBlock*, Value*> repl;
|
|
|
|
// Filter out useless results (non-locals, etc)
|
|
for (DenseMap<BasicBlock*, Value*>::iterator I = deps.begin(), E = deps.end();
|
|
I != E; ++I)
|
|
if (I->second == MemoryDependenceAnalysis::None) {
|
|
return false;
|
|
} else if (I->second == MemoryDependenceAnalysis::NonLocal) {
|
|
continue;
|
|
} else if (StoreInst* S = dyn_cast<StoreInst>(I->second)) {
|
|
if (S->getPointerOperand() == L->getPointerOperand())
|
|
repl[I->first] = S->getOperand(0);
|
|
else
|
|
return false;
|
|
} else if (LoadInst* LD = dyn_cast<LoadInst>(I->second)) {
|
|
if (LD->getPointerOperand() == L->getPointerOperand())
|
|
repl[I->first] = LD;
|
|
else
|
|
return false;
|
|
} else {
|
|
return false;
|
|
}
|
|
|
|
// Use cached PHI construction information from previous runs
|
|
SmallPtrSet<Instruction*, 4>& p = phiMap[L->getPointerOperand()];
|
|
for (SmallPtrSet<Instruction*, 4>::iterator I = p.begin(), E = p.end();
|
|
I != E; ++I) {
|
|
if ((*I)->getParent() == L->getParent()) {
|
|
MD.removeInstruction(L);
|
|
L->replaceAllUsesWith(*I);
|
|
toErase.push_back(L);
|
|
NumGVNLoad++;
|
|
|
|
return true;
|
|
} else {
|
|
repl.insert(std::make_pair((*I)->getParent(), *I));
|
|
}
|
|
}
|
|
|
|
// Perform PHI construction
|
|
SmallPtrSet<BasicBlock*, 4> visited;
|
|
Value* v = GetValueForBlock(L->getParent(), L, repl, true);
|
|
|
|
MD.removeInstruction(L);
|
|
L->replaceAllUsesWith(v);
|
|
toErase.push_back(L);
|
|
NumGVNLoad++;
|
|
|
|
return true;
|
|
}
|
|
|
|
/// processLoad - Attempt to eliminate a load, first by eliminating it
|
|
/// locally, and then attempting non-local elimination if that fails.
|
|
bool GVN::processLoad(LoadInst* L,
|
|
DenseMap<Value*, LoadInst*>& lastLoad,
|
|
SmallVector<Instruction*, 4>& toErase) {
|
|
if (L->isVolatile()) {
|
|
lastLoad[L->getPointerOperand()] = L;
|
|
return false;
|
|
}
|
|
|
|
Value* pointer = L->getPointerOperand();
|
|
LoadInst*& last = lastLoad[pointer];
|
|
|
|
// ... to a pointer that has been loaded from before...
|
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
bool removedNonLocal = false;
|
|
Instruction* dep = MD.getDependency(L);
|
|
if (dep == MemoryDependenceAnalysis::NonLocal &&
|
|
L->getParent() != &L->getParent()->getParent()->getEntryBlock()) {
|
|
removedNonLocal = processNonLocalLoad(L, toErase);
|
|
|
|
if (!removedNonLocal)
|
|
last = L;
|
|
|
|
return removedNonLocal;
|
|
}
|
|
|
|
|
|
bool deletedLoad = false;
|
|
|
|
// Walk up the dependency chain until we either find
|
|
// a dependency we can use, or we can't walk any further
|
|
while (dep != MemoryDependenceAnalysis::None &&
|
|
dep != MemoryDependenceAnalysis::NonLocal &&
|
|
(isa<LoadInst>(dep) || isa<StoreInst>(dep))) {
|
|
// ... that depends on a store ...
|
|
if (StoreInst* S = dyn_cast<StoreInst>(dep)) {
|
|
if (S->getPointerOperand() == pointer) {
|
|
// Remove it!
|
|
MD.removeInstruction(L);
|
|
|
|
L->replaceAllUsesWith(S->getOperand(0));
|
|
toErase.push_back(L);
|
|
deletedLoad = true;
|
|
NumGVNLoad++;
|
|
}
|
|
|
|
// Whether we removed it or not, we can't
|
|
// go any further
|
|
break;
|
|
} else if (!last) {
|
|
// If we don't depend on a store, and we haven't
|
|
// been loaded before, bail.
|
|
break;
|
|
} else if (dep == last) {
|
|
// Remove it!
|
|
MD.removeInstruction(L);
|
|
|
|
L->replaceAllUsesWith(last);
|
|
toErase.push_back(L);
|
|
deletedLoad = true;
|
|
NumGVNLoad++;
|
|
|
|
break;
|
|
} else {
|
|
dep = MD.getDependency(L, dep);
|
|
}
|
|
}
|
|
|
|
if (dep != MemoryDependenceAnalysis::None &&
|
|
dep != MemoryDependenceAnalysis::NonLocal &&
|
|
isa<AllocationInst>(dep)) {
|
|
// Check that this load is actually from the
|
|
// allocation we found
|
|
Value* v = L->getOperand(0);
|
|
while (true) {
|
|
if (BitCastInst *BC = dyn_cast<BitCastInst>(v))
|
|
v = BC->getOperand(0);
|
|
else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(v))
|
|
v = GEP->getOperand(0);
|
|
else
|
|
break;
|
|
}
|
|
if (v == dep) {
|
|
// If this load depends directly on an allocation, there isn't
|
|
// anything stored there; therefore, we can optimize this load
|
|
// to undef.
|
|
MD.removeInstruction(L);
|
|
|
|
L->replaceAllUsesWith(UndefValue::get(L->getType()));
|
|
toErase.push_back(L);
|
|
deletedLoad = true;
|
|
NumGVNLoad++;
|
|
}
|
|
}
|
|
|
|
if (!deletedLoad)
|
|
last = L;
|
|
|
|
return deletedLoad;
|
|
}
|
|
|
|
/// processMemCpy - perform simplication of memcpy's. If we have memcpy A which
|
|
/// copies X to Y, and memcpy B which copies Y to Z, then we can rewrite B to be
|
|
/// a memcpy from X to Z (or potentially a memmove, depending on circumstances).
|
|
/// This allows later passes to remove the first memcpy altogether.
|
|
bool GVN::processMemCpy(MemCpyInst* M,
|
|
SmallVector<Instruction*, 4>& toErase) {
|
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
|
|
// First, we have to check that the dependency is another memcpy
|
|
Instruction* dep = MD.getDependency(M);
|
|
if (dep == MemoryDependenceAnalysis::None ||
|
|
dep == MemoryDependenceAnalysis::NonLocal ||
|
|
!isa<MemCpyInst>(dep))
|
|
return false;
|
|
|
|
// We can only transforms memcpy's where the dest of one is the source of the
|
|
// other
|
|
MemCpyInst* MDep = cast<MemCpyInst>(dep);
|
|
if (M->getSource() != MDep->getDest())
|
|
return false;
|
|
|
|
// Second, the length of the memcpy's must be the same, or the preceeding one
|
|
// must be larger than the following one.
|
|
ConstantInt* C1 = dyn_cast<ConstantInt>(MDep->getLength());
|
|
ConstantInt* C2 = dyn_cast<ConstantInt>(M->getLength());
|
|
if (!C1 || !C2)
|
|
return false;
|
|
|
|
uint64_t CpySize = C1->getValue().getZExtValue();
|
|
uint64_t DepSize = C2->getValue().getZExtValue();
|
|
|
|
if (DepSize < CpySize)
|
|
return false;
|
|
|
|
// Finally, we have to make sure that the dest of the second does not
|
|
// alias the source of the first
|
|
AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
|
|
if (AA.alias(M->getRawDest(), CpySize, MDep->getRawSource(), DepSize) !=
|
|
AliasAnalysis::NoAlias)
|
|
return false;
|
|
else if (AA.alias(M->getRawDest(), CpySize, M->getRawSource(), CpySize) !=
|
|
AliasAnalysis::NoAlias)
|
|
return false;
|
|
else if (AA.alias(MDep->getRawDest(), DepSize, MDep->getRawSource(), DepSize)
|
|
!= AliasAnalysis::NoAlias)
|
|
return false;
|
|
|
|
// If all checks passed, then we can transform these memcpy's
|
|
bool is32bit = M->getIntrinsicID() == Intrinsic::memcpy_i32;
|
|
Function* MemMoveFun = Intrinsic::getDeclaration(
|
|
M->getParent()->getParent()->getParent(),
|
|
is32bit ? Intrinsic::memcpy_i32 :
|
|
Intrinsic::memcpy_i64);
|
|
|
|
std::vector<Value*> args;
|
|
args.push_back(M->getRawDest());
|
|
args.push_back(MDep->getRawSource());
|
|
args.push_back(M->getLength());
|
|
args.push_back(M->getAlignment());
|
|
|
|
CallInst* C = new CallInst(MemMoveFun, args.begin(), args.end(), "", M);
|
|
|
|
if (MD.getDependency(C) == MDep) {
|
|
MD.dropInstruction(M);
|
|
toErase.push_back(M);
|
|
return true;
|
|
} else {
|
|
MD.removeInstruction(C);
|
|
toErase.push_back(C);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/// processInstruction - When calculating availability, handle an instruction
|
|
/// by inserting it into the appropriate sets
|
|
bool GVN::processInstruction(Instruction* I,
|
|
ValueNumberedSet& currAvail,
|
|
DenseMap<Value*, LoadInst*>& lastSeenLoad,
|
|
SmallVector<Instruction*, 4>& toErase) {
|
|
if (LoadInst* L = dyn_cast<LoadInst>(I)) {
|
|
return processLoad(L, lastSeenLoad, toErase);
|
|
} else if (MemCpyInst* M = dyn_cast<MemCpyInst>(I)) {
|
|
return processMemCpy(M, toErase);
|
|
}
|
|
|
|
unsigned num = VN.lookup_or_add(I);
|
|
|
|
// Collapse PHI nodes
|
|
if (PHINode* p = dyn_cast<PHINode>(I)) {
|
|
Value* constVal = CollapsePhi(p);
|
|
|
|
if (constVal) {
|
|
for (PhiMapType::iterator PI = phiMap.begin(), PE = phiMap.end();
|
|
PI != PE; ++PI)
|
|
if (PI->second.count(p))
|
|
PI->second.erase(p);
|
|
|
|
p->replaceAllUsesWith(constVal);
|
|
toErase.push_back(p);
|
|
}
|
|
// Perform value-number based elimination
|
|
} else if (currAvail.test(num)) {
|
|
Value* repl = find_leader(currAvail, num);
|
|
|
|
if (CallInst* CI = dyn_cast<CallInst>(I)) {
|
|
AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
|
|
if (!AA.doesNotAccessMemory(CI)) {
|
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
if (cast<Instruction>(repl)->getParent() != CI->getParent() ||
|
|
MD.getDependency(CI) != MD.getDependency(cast<CallInst>(repl))) {
|
|
// There must be an intervening may-alias store, so nothing from
|
|
// this point on will be able to be replaced with the preceding call
|
|
currAvail.erase(repl);
|
|
currAvail.insert(I);
|
|
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Remove it!
|
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
MD.removeInstruction(I);
|
|
|
|
VN.erase(I);
|
|
I->replaceAllUsesWith(repl);
|
|
toErase.push_back(I);
|
|
return true;
|
|
} else if (!I->isTerminator()) {
|
|
currAvail.set(num);
|
|
currAvail.insert(I);
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
// GVN::runOnFunction - This is the main transformation entry point for a
|
|
// function.
|
|
//
|
|
bool GVN::runOnFunction(Function& F) {
|
|
VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
|
|
|
|
bool changed = false;
|
|
bool shouldContinue = true;
|
|
|
|
while (shouldContinue) {
|
|
shouldContinue = iterateOnFunction(F);
|
|
changed |= shouldContinue;
|
|
}
|
|
|
|
return changed;
|
|
}
|
|
|
|
|
|
// GVN::iterateOnFunction - Executes one iteration of GVN
|
|
bool GVN::iterateOnFunction(Function &F) {
|
|
// Clean out global sets from any previous functions
|
|
VN.clear();
|
|
availableOut.clear();
|
|
phiMap.clear();
|
|
|
|
bool changed_function = false;
|
|
|
|
DominatorTree &DT = getAnalysis<DominatorTree>();
|
|
|
|
SmallVector<Instruction*, 4> toErase;
|
|
|
|
// Top-down walk of the dominator tree
|
|
for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
|
|
E = df_end(DT.getRootNode()); DI != E; ++DI) {
|
|
|
|
// Get the set to update for this block
|
|
ValueNumberedSet& currAvail = availableOut[DI->getBlock()];
|
|
DenseMap<Value*, LoadInst*> lastSeenLoad;
|
|
|
|
BasicBlock* BB = DI->getBlock();
|
|
|
|
// A block inherits AVAIL_OUT from its dominator
|
|
if (DI->getIDom() != 0)
|
|
currAvail = availableOut[DI->getIDom()->getBlock()];
|
|
|
|
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
|
|
BI != BE; ) {
|
|
changed_function |= processInstruction(BI, currAvail,
|
|
lastSeenLoad, toErase);
|
|
|
|
NumGVNInstr += toErase.size();
|
|
|
|
// Avoid iterator invalidation
|
|
++BI;
|
|
|
|
for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
|
|
E = toErase.end(); I != E; ++I) {
|
|
(*I)->eraseFromParent();
|
|
}
|
|
|
|
toErase.clear();
|
|
}
|
|
}
|
|
|
|
return changed_function;
|
|
}
|