-//===- ConstantProp.cpp - Code to perform Simple Constant Propogation -----===//
+//===- ConstantProp.cpp - Code to perform Simple Constant Propagation -----===//
//
-// This file implements constant propogation and merging:
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements constant propagation and merging:
//
// Specifically, this:
// * Converts instructions like "add int 1, 2" into 3
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "constprop"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/ConstantHandling.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Constant.h"
#include "llvm/Instruction.h"
#include "llvm/Pass.h"
+#include "llvm/Support/Compiler.h"
#include "llvm/Support/InstIterator.h"
-#include "Support/Statistic.h"
+#include "llvm/ADT/Statistic.h"
#include <set>
+using namespace llvm;
+
+STATISTIC(NumInstKilled, "Number of instructions killed");
namespace {
- Statistic<> NumInstKilled("constprop", "Number of instructions killed");
+ struct VISIBILITY_HIDDEN ConstantPropagation : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ ConstantPropagation() : FunctionPass((intptr_t)&ID) {}
- struct ConstantPropogation : public FunctionPass {
bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.preservesCFG();
+ AU.setPreservesCFG();
}
};
-
- RegisterOpt<ConstantPropogation> X("constprop","Simple constant propogation");
}
-Pass *createConstantPropogationPass() {
- return new ConstantPropogation();
+char ConstantPropagation::ID = 0;
+static RegisterPass<ConstantPropagation>
+X("constprop", "Simple constant propagation");
+
+FunctionPass *llvm::createConstantPropagationPass() {
+ return new ConstantPropagation();
}
-bool ConstantPropogation::runOnFunction(Function &F) {
+bool ConstantPropagation::runOnFunction(Function &F) {
// Initialize the worklist to all of the instructions ready to process...
- std::set<Instruction*> WorkList(inst_begin(F), inst_end(F));
+ std::set<Instruction*> WorkList;
+ for(inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i) {
+ WorkList.insert(&*i);
+ }
bool Changed = false;
while (!WorkList.empty()) {
if (!I->use_empty()) // Don't muck with dead instructions...
if (Constant *C = ConstantFoldInstruction(I)) {
// Add all of the users of this instruction to the worklist, they might
- // be constant propogatable now...
+ // be constant propagatable now...
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
UI != UE; ++UI)
WorkList.insert(cast<Instruction>(*UI));
-
+
// Replace all of the uses of a variable with uses of the constant.
I->replaceAllUsesWith(C);
+ // Remove the dead instruction.
+ WorkList.erase(I);
+ I->getParent()->getInstList().erase(I);
+
// We made a change to the function...
Changed = true;
++NumInstKilled;