-//===- 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
//
// Notice that:
// * This pass has a habit of making definitions be dead. It is a good idea
-// to to run a DIE pass sometime after running this pass.
+// to run a DIE pass sometime after running this pass.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/ConstantHandling.h"
-#include "llvm/Instruction.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/Instruction.h"
#include "llvm/Pass.h"
-#include "llvm/Support/InstIterator.h"
-#include "Support/StatisticReporter.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
#include <set>
+using namespace llvm;
-static Statistic<> NumInstKilled("constprop - Number of instructions killed");
+#define DEBUG_TYPE "constprop"
+
+STATISTIC(NumInstKilled, "Number of instructions killed");
namespace {
- struct ConstantPropogation : public FunctionPass {
- bool runOnFunction(Function &F);
+ struct ConstantPropagation : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ ConstantPropagation() : FunctionPass(ID) {
+ initializeConstantPropagationPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnFunction(Function &F) override;
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.preservesCFG();
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.setPreservesCFG();
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
}
};
-
- RegisterOpt<ConstantPropogation> X("constprop","Simple constant propogation");
}
-Pass *createConstantPropogationPass() {
- return new ConstantPropogation();
-}
+char ConstantPropagation::ID = 0;
+INITIALIZE_PASS_BEGIN(ConstantPropagation, "constprop",
+ "Simple constant propagation", false, false)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_END(ConstantPropagation, "constprop",
+ "Simple constant propagation", false, false)
+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;
+ const DataLayout &DL = F.getParent()->getDataLayout();
+ TargetLibraryInfo *TLI =
+ &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
while (!WorkList.empty()) {
Instruction *I = *WorkList.begin();
WorkList.erase(WorkList.begin()); // Get an element from the worklist...
if (!I->use_empty()) // Don't muck with dead instructions...
- if (Constant *C = ConstantFoldInstruction(I)) {
+ if (Constant *C = ConstantFoldInstruction(I, &DL, TLI)) {
// Add all of the users of this instruction to the worklist, they might
- // be constant propogatable now...
- for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
- UI != UE; ++UI)
- WorkList.insert(cast<Instruction>(*UI));
-
+ // be constant propagatable now...
+ for (User *U : I->users())
+ WorkList.insert(cast<Instruction>(U));
+
// Replace all of the uses of a variable with uses of the constant.
I->replaceAllUsesWith(C);
+ // Remove the dead instruction.
+ WorkList.erase(I);
+ I->eraseFromParent();
+
// We made a change to the function...
Changed = true;
++NumInstKilled;