mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-11-15 20:06:46 +00:00
844731a7f1
several things that were neither in an anonymous namespace nor static but not intended to be global. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51017 91177308-0d34-0410-b5e6-96231b3b80d8
91 lines
2.8 KiB
C++
91 lines
2.8 KiB
C++
//===- ConstantProp.cpp - Code to perform Simple Constant Propagation -----===//
|
|
//
|
|
// 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.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "constprop"
|
|
#include "llvm/Transforms/Scalar.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 "llvm/ADT/Statistic.h"
|
|
#include <set>
|
|
using namespace llvm;
|
|
|
|
STATISTIC(NumInstKilled, "Number of instructions killed");
|
|
|
|
namespace {
|
|
struct VISIBILITY_HIDDEN ConstantPropagation : public FunctionPass {
|
|
static char ID; // Pass identification, replacement for typeid
|
|
ConstantPropagation() : FunctionPass((intptr_t)&ID) {}
|
|
|
|
bool runOnFunction(Function &F);
|
|
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesCFG();
|
|
}
|
|
};
|
|
}
|
|
|
|
char ConstantPropagation::ID = 0;
|
|
static RegisterPass<ConstantPropagation>
|
|
X("constprop", "Simple constant propagation");
|
|
|
|
FunctionPass *llvm::createConstantPropagationPass() {
|
|
return new ConstantPropagation();
|
|
}
|
|
|
|
|
|
bool ConstantPropagation::runOnFunction(Function &F) {
|
|
// Initialize the worklist to all of the instructions ready to process...
|
|
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()) {
|
|
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)) {
|
|
// Add all of the users of this instruction to the worklist, they might
|
|
// 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;
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|