initial implementation of ValueNumbering interface.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3541 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueNumbering.cpp b/lib/Analysis/ValueNumbering.cpp
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--- /dev/null
+++ b/lib/Analysis/ValueNumbering.cpp
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+//===- ValueNumbering.cpp - Value #'ing Implementation ----------*- C++ -*-===//
+//
+// This file implements the non-abstract Value Numbering methods as well as a
+// default implementation for the analysis group.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/BasicValueNumbering.h"
+#include "llvm/Support/InstVisitor.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Type.h"
+#include "llvm/iMemory.h"
+#include "llvm/InstrTypes.h"
+
+// 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() {}
+
+//===----------------------------------------------------------------------===//
+// BasicValueNumbering Pass Implementation
+//===----------------------------------------------------------------------===//
+//
+// Because of the way .a files work, the implementation of the
+// BasicValueNumbering 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 {
+ // Register this pass...
+ RegisterOpt<BasicValueNumbering>
+ X("basicvn", "Basic Value Numbering (default GVN impl)");
+
+ // Declare that we implement the ValueNumbering interface
+ RegisterAnalysisGroup<ValueNumbering, BasicValueNumbering, true> Y;
+} // End of anonymous namespace
+
+namespace {
+ /// BVNImpl - Implement BasicValueNumbering 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 visitBinaryOperator(Instruction &I);
+ void visitGetElementPtrInst(GetElementPtrInst &I);
+ void visitCastInst(CastInst &I);
+ void visitShiftInst(ShiftInst &I) { visitBinaryOperator((Instruction&)I); }
+ void visitInstruction(Instruction &) {
+ // Cannot value number calls or terminator instructions...
+ }
+ };
+}
+
+// getEqualNumberNodes - Return nodes with the same value number as the
+// specified Value. This fills in the argument vector with any equal values.
+//
+void BasicValueNumbering::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 (Instruction *Other = dyn_cast<Instruction>(*UI))
+ // Check to see if this new cast is not I, but has the same operand...
+ if (Other != &I && Other->getOpcode() == I.getOpcode() &&
+ Other->getOperand(0) == Op && // Is the operand the same?
+ // Is it embeded in the same function? (This could be false if LHS
+ // is a constant or global!)
+ Other->getParent()->getParent() == F &&
+
+ // Check that the types are the same, since this code handles casts...
+ Other->getType() == I.getType()) {
+
+ // 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 embeded 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 and associative, the instruction can
+ // match if the operands are swapped!
+ //
+ if ((I1.getOperand(0) == I2->getOperand(1) &&
+ I1.getOperand(1) == I2->getOperand(0)) &&
+ (I1.getOpcode() == Instruction::Add ||
+ I1.getOpcode() == Instruction::Mul ||
+ I1.getOpcode() == Instruction::And ||
+ I1.getOpcode() == Instruction::Or ||
+ I1.getOpcode() == Instruction::Xor))
+ return true;
+
+ return false;
+}
+
+void BVNImpl::visitBinaryOperator(Instruction &I) {
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+ Function *F = I.getParent()->getParent();
+
+ 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 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);
+ Function *F = I.getParent()->getParent();
+
+ 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);
+ }
+}