lib/Analysis/ValueNumbering.cpp - llvm - Git at Google

 //===- ValueNumbering.cpp - Value #'ing Implementation ----------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file 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"
 #include "llvm/Support/Compiler.h"
 using namespace llvm;

 char ValueNumbering::ID = 0;
 // 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 VISIBILITY_HIDDEN BasicVN
       : public ImmutablePass, public ValueNumbering {
     static char ID; // Class identification, replacement for typeinfo
     BasicVN() : ImmutablePass((intptr_t)&ID) {}

     /// 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;
   };

   char BasicVN::ID = 0;
   // Register this pass...
   RegisterPass<BasicVN>
   X("basicvn", "Basic Value Numbering (default GVN impl)");

   // Declare that we implement the ValueNumbering interface
   RegisterAnalysisGroup<ValueNumbering, true> Y(X);

   /// BVNImpl - Implement BasicVN in terms of a visitor class that
   /// handles the different types of instructions as appropriate.
   ///
   struct VISIBILITY_HIDDEN BVNImpl : public InstVisitor<BVNImpl> {
     std::vector<Value*> &RetVals;
     explicit BVNImpl(std::vector<Value*> &RV) : RetVals(RV) {}

     void visitCastInst(CastInst &I);
     void visitGetElementPtrInst(GetElementPtrInst &I);
     void visitCmpInst(CmpInst &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 opcode is the same
       if (Other->getOpcode() == Instruction::CastOps(I.getOpcode()) &&
           // Check that the destination types are the same
           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);
       }
 }

 void  BVNImpl::visitCmpInst(CmpInst &CI1) {
   Value *LHS = CI1.getOperand(0);
   for (Value::use_iterator UI = LHS->use_begin(), UE = LHS->use_end();
        UI != UE; ++UI)
     if (CmpInst *CI2 = dyn_cast<CmpInst>(*UI))
       // Check to see if this compare instruction is not CI, but same opcode,
       // same predicate, and in the same function.
       if (CI2 != &CI1 && CI2->getOpcode() == CI1.getOpcode() &&
           CI2->getPredicate() == CI1.getPredicate() &&
           CI2->getParent()->getParent() == CI1.getParent()->getParent())
         // If the operands are the same
         if ((CI2->getOperand(0) == CI1.getOperand(0) &&
             CI2->getOperand(1) == CI1.getOperand(1)) ||
             // Or the compare is commutative and the operands are reversed
             (CI1.isCommutative() &&
              CI2->getOperand(0) == CI1.getOperand(1) &&
              CI2->getOperand(1) == CI1.getOperand(0)))
           // Then the instructiosn are identical, add to list.
           RetVals.push_back(CI2);
 }


 // 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;

   // If they are CmpInst instructions, check their predicates
   if (CmpInst *CI1 = dyn_cast<CmpInst>(&const_cast<Instruction&>(I1)))
     if (CI1->getPredicate() != cast<CmpInst>(I2)->getPredicate())
       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)
	//===- ValueNumbering.cpp - Value #'ing Implementation ----------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file 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"
	#include "llvm/Support/Compiler.h"
	using namespace llvm;

	char ValueNumbering::ID = 0;
	// 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 VISIBILITY_HIDDEN BasicVN
	: public ImmutablePass, public ValueNumbering {
	static char ID; // Class identification, replacement for typeinfo
	BasicVN() : ImmutablePass((intptr_t)&ID) {}

	/// 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;
	};

	char BasicVN::ID = 0;
	// Register this pass...
	RegisterPass<BasicVN>
	X("basicvn", "Basic Value Numbering (default GVN impl)");

	// Declare that we implement the ValueNumbering interface
	RegisterAnalysisGroup<ValueNumbering, true> Y(X);

	/// BVNImpl - Implement BasicVN in terms of a visitor class that
	/// handles the different types of instructions as appropriate.
	///
	struct VISIBILITY_HIDDEN BVNImpl : public InstVisitor<BVNImpl> {
	std::vector<Value*> &RetVals;
	explicit BVNImpl(std::vector<Value*> &RV) : RetVals(RV) {}

	void visitCastInst(CastInst &I);
	void visitGetElementPtrInst(GetElementPtrInst &I);
	void visitCmpInst(CmpInst &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 opcode is the same
	if (Other->getOpcode() == Instruction::CastOps(I.getOpcode()) &&
	// Check that the destination types are the same
	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);
	}
	}

	void BVNImpl::visitCmpInst(CmpInst &CI1) {
	Value *LHS = CI1.getOperand(0);
	for (Value::use_iterator UI = LHS->use_begin(), UE = LHS->use_end();
	UI != UE; ++UI)
	if (CmpInst CI2 = dyn_cast<CmpInst>(UI))
	// Check to see if this compare instruction is not CI, but same opcode,
	// same predicate, and in the same function.
	if (CI2 != &CI1 && CI2->getOpcode() == CI1.getOpcode() &&
	CI2->getPredicate() == CI1.getPredicate() &&
	CI2->getParent()->getParent() == CI1.getParent()->getParent())
	// If the operands are the same
	if ((CI2->getOperand(0) == CI1.getOperand(0) &&
	CI2->getOperand(1) == CI1.getOperand(1)) \|\|
	// Or the compare is commutative and the operands are reversed
	(CI1.isCommutative() &&
	CI2->getOperand(0) == CI1.getOperand(1) &&
	CI2->getOperand(1) == CI1.getOperand(0)))
	// Then the instructiosn are identical, add to list.
	RetVals.push_back(CI2);
	}



	// 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;

	// If they are CmpInst instructions, check their predicates
	if (CmpInst *CI1 = dyn_cast<CmpInst>(&const_cast<Instruction&>(I1)))
	if (CI1->getPredicate() != cast<CmpInst>(I2)->getPredicate())
	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)