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llvm-mirror/lib/Analysis/ValueNumbering.cpp
Reid Spencer 560366562b For PR780:
1. Fix the macros in IncludeFile.h to put everything in the llvm namespace
2. Replace the previous explicit mechanism in all the .h and .cpp files
   with the macros in IncludeFile.h
This gets us a consistent mechanism throughout LLVM for ensuring linkage.
Next step is to make sure its used in enough places.

llvm-svn: 28715
2006-06-07 22:00:26 +00:00

244 lines
9.2 KiB
C++

//===- ValueNumbering.cpp - Value #'ing Implementation ----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the non-abstract Value Numbering methods as well as a
// default implementation for the analysis group.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/ValueNumbering.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/BasicBlock.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Type.h"
using namespace llvm;
// Register the ValueNumbering interface, providing a nice name to refer to.
static RegisterAnalysisGroup<ValueNumbering> X("Value Numbering");
/// ValueNumbering destructor: DO NOT move this to the header file for
/// ValueNumbering or else clients of the ValueNumbering class may not depend on
/// the ValueNumbering.o file in the current .a file, causing alias analysis
/// support to not be included in the tool correctly!
///
ValueNumbering::~ValueNumbering() {}
//===----------------------------------------------------------------------===//
// Basic ValueNumbering Pass Implementation
//===----------------------------------------------------------------------===//
//
// Because of the way .a files work, the implementation of the BasicVN class
// MUST be in the ValueNumbering file itself, or else we run the risk of
// ValueNumbering being used, but the default implementation not being linked
// into the tool that uses it. As such, we register and implement the class
// here.
//
namespace {
/// BasicVN - This class is the default implementation of the ValueNumbering
/// interface. It walks the SSA def-use chains to trivially identify
/// lexically identical expressions. This does not require any ahead of time
/// analysis, so it is a very fast default implementation.
///
struct BasicVN : public ImmutablePass, public ValueNumbering {
/// getEqualNumberNodes - Return nodes with the same value number as the
/// specified Value. This fills in the argument vector with any equal
/// values.
///
/// This is where our implementation is.
///
virtual void getEqualNumberNodes(Value *V1,
std::vector<Value*> &RetVals) const;
};
// Register this pass...
RegisterOpt<BasicVN>
X("basicvn", "Basic Value Numbering (default GVN impl)");
// Declare that we implement the ValueNumbering interface
RegisterAnalysisGroup<ValueNumbering, BasicVN, true> Y;
/// BVNImpl - Implement BasicVN in terms of a visitor class that
/// handles the different types of instructions as appropriate.
///
struct BVNImpl : public InstVisitor<BVNImpl> {
std::vector<Value*> &RetVals;
BVNImpl(std::vector<Value*> &RV) : RetVals(RV) {}
void visitCastInst(CastInst &I);
void visitGetElementPtrInst(GetElementPtrInst &I);
void handleBinaryInst(Instruction &I);
void visitBinaryOperator(Instruction &I) { handleBinaryInst(I); }
void visitShiftInst(Instruction &I) { handleBinaryInst(I); }
void visitExtractElementInst(Instruction &I) { handleBinaryInst(I); }
void handleTernaryInst(Instruction &I);
void visitSelectInst(Instruction &I) { handleTernaryInst(I); }
void visitInsertElementInst(Instruction &I) { handleTernaryInst(I); }
void visitShuffleVectorInst(Instruction &I) { handleTernaryInst(I); }
void visitInstruction(Instruction &) {
// Cannot value number calls or terminator instructions.
}
};
}
ImmutablePass *llvm::createBasicVNPass() { return new BasicVN(); }
// getEqualNumberNodes - Return nodes with the same value number as the
// specified Value. This fills in the argument vector with any equal values.
//
void BasicVN::getEqualNumberNodes(Value *V, std::vector<Value*> &RetVals) const{
assert(V->getType() != Type::VoidTy &&
"Can only value number non-void values!");
// We can only handle the case where I is an instruction!
if (Instruction *I = dyn_cast<Instruction>(V))
BVNImpl(RetVals).visit(I);
}
void BVNImpl::visitCastInst(CastInst &CI) {
Instruction &I = (Instruction&)CI;
Value *Op = I.getOperand(0);
Function *F = I.getParent()->getParent();
for (Value::use_iterator UI = Op->use_begin(), UE = Op->use_end();
UI != UE; ++UI)
if (CastInst *Other = dyn_cast<CastInst>(*UI))
// Check that the types are the same, since this code handles casts...
if (Other->getType() == I.getType() &&
// Is it embedded in the same function? (This could be false if LHS
// is a constant or global!)
Other->getParent()->getParent() == F &&
// Check to see if this new cast is not I.
Other != &I) {
// These instructions are identical. Add to list...
RetVals.push_back(Other);
}
}
// isIdenticalBinaryInst - Return true if the two binary instructions are
// identical.
//
static inline bool isIdenticalBinaryInst(const Instruction &I1,
const Instruction *I2) {
// Is it embedded in the same function? (This could be false if LHS
// is a constant or global!)
if (I1.getOpcode() != I2->getOpcode() ||
I1.getParent()->getParent() != I2->getParent()->getParent())
return false;
// They are identical if both operands are the same!
if (I1.getOperand(0) == I2->getOperand(0) &&
I1.getOperand(1) == I2->getOperand(1))
return true;
// If the instruction is commutative, the instruction can match if the
// operands are swapped!
//
if ((I1.getOperand(0) == I2->getOperand(1) &&
I1.getOperand(1) == I2->getOperand(0)) &&
I1.isCommutative())
return true;
return false;
}
// isIdenticalTernaryInst - Return true if the two ternary instructions are
// identical.
//
static inline bool isIdenticalTernaryInst(const Instruction &I1,
const Instruction *I2) {
// Is it embedded in the same function? (This could be false if LHS
// is a constant or global!)
if (I1.getParent()->getParent() != I2->getParent()->getParent())
return false;
// They are identical if all operands are the same!
return I1.getOperand(0) == I2->getOperand(0) &&
I1.getOperand(1) == I2->getOperand(1) &&
I1.getOperand(2) == I2->getOperand(2);
}
void BVNImpl::handleBinaryInst(Instruction &I) {
Value *LHS = I.getOperand(0);
for (Value::use_iterator UI = LHS->use_begin(), UE = LHS->use_end();
UI != UE; ++UI)
if (Instruction *Other = dyn_cast<Instruction>(*UI))
// Check to see if this new binary operator is not I, but same operand...
if (Other != &I && isIdenticalBinaryInst(I, Other)) {
// These instructions are identical. Handle the situation.
RetVals.push_back(Other);
}
}
// IdenticalComplexInst - Return true if the two instructions are the same, by
// using a brute force comparison. This is useful for instructions with an
// arbitrary number of arguments.
//
static inline bool IdenticalComplexInst(const Instruction *I1,
const Instruction *I2) {
assert(I1->getOpcode() == I2->getOpcode());
// Equal if they are in the same function...
return I1->getParent()->getParent() == I2->getParent()->getParent() &&
// And return the same type...
I1->getType() == I2->getType() &&
// And have the same number of operands...
I1->getNumOperands() == I2->getNumOperands() &&
// And all of the operands are equal.
std::equal(I1->op_begin(), I1->op_end(), I2->op_begin());
}
void BVNImpl::visitGetElementPtrInst(GetElementPtrInst &I) {
Value *Op = I.getOperand(0);
// Try to pick a local operand if possible instead of a constant or a global
// that might have a lot of uses.
for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
if (isa<Instruction>(I.getOperand(i)) || isa<Argument>(I.getOperand(i))) {
Op = I.getOperand(i);
break;
}
for (Value::use_iterator UI = Op->use_begin(), UE = Op->use_end();
UI != UE; ++UI)
if (GetElementPtrInst *Other = dyn_cast<GetElementPtrInst>(*UI))
// Check to see if this new getelementptr is not I, but same operand...
if (Other != &I && IdenticalComplexInst(&I, Other)) {
// These instructions are identical. Handle the situation.
RetVals.push_back(Other);
}
}
void BVNImpl::handleTernaryInst(Instruction &I) {
Value *Op0 = I.getOperand(0);
Instruction *OtherInst;
for (Value::use_iterator UI = Op0->use_begin(), UE = Op0->use_end();
UI != UE; ++UI)
if ((OtherInst = dyn_cast<Instruction>(*UI)) &&
OtherInst->getOpcode() == I.getOpcode()) {
// Check to see if this new select is not I, but has the same operands.
if (OtherInst != &I && isIdenticalTernaryInst(I, OtherInst)) {
// These instructions are identical. Handle the situation.
RetVals.push_back(OtherInst);
}
}
}
// Ensure that users of ValueNumbering.h will link with this file
DEFINING_FILE_FOR(BasicValueNumbering)