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https://github.com/c64scene-ar/llvm-6502.git
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529919ff31
Summary: Now that the DataLayout is a mandatory part of the module, let's start cleaning the codebase. This patch is a first attempt at doing that. This patch is not exactly NFC as for instance some places were passing a nullptr instead of the DataLayout, possibly just because there was a default value on the DataLayout argument to many functions in the API. Even though it is not purely NFC, there is no change in the validation. I turned as many pointer to DataLayout to references, this helped figuring out all the places where a nullptr could come up. I had initially a local version of this patch broken into over 30 independant, commits but some later commit were cleaning the API and touching part of the code modified in the previous commits, so it seemed cleaner without the intermediate state. Test Plan: Reviewers: echristo Subscribers: llvm-commits From: Mehdi Amini <mehdi.amini@apple.com> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231740 91177308-0d34-0410-b5e6-96231b3b80d8
99 lines
3.2 KiB
C++
99 lines
3.2 KiB
C++
//===- ConstantProp.cpp - Code to perform Simple Constant Propagation -----===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements constant propagation and merging:
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//
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// Specifically, this:
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// * Converts instructions like "add int 1, 2" into 3
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//
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// Notice that:
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// * This pass has a habit of making definitions be dead. It is a good idea
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// to run a DIE pass sometime after running this pass.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/ConstantFolding.h"
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#include "llvm/IR/Constant.h"
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#include "llvm/IR/InstIterator.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include <set>
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using namespace llvm;
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#define DEBUG_TYPE "constprop"
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STATISTIC(NumInstKilled, "Number of instructions killed");
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namespace {
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struct ConstantPropagation : public FunctionPass {
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static char ID; // Pass identification, replacement for typeid
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ConstantPropagation() : FunctionPass(ID) {
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initializeConstantPropagationPass(*PassRegistry::getPassRegistry());
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}
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bool runOnFunction(Function &F) override;
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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AU.addRequired<TargetLibraryInfoWrapperPass>();
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}
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};
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}
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char ConstantPropagation::ID = 0;
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INITIALIZE_PASS_BEGIN(ConstantPropagation, "constprop",
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"Simple constant propagation", false, false)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
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INITIALIZE_PASS_END(ConstantPropagation, "constprop",
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"Simple constant propagation", false, false)
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FunctionPass *llvm::createConstantPropagationPass() {
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return new ConstantPropagation();
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}
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bool ConstantPropagation::runOnFunction(Function &F) {
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// Initialize the worklist to all of the instructions ready to process...
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std::set<Instruction*> WorkList;
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for(inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i) {
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WorkList.insert(&*i);
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}
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bool Changed = false;
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const DataLayout &DL = F.getParent()->getDataLayout();
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TargetLibraryInfo *TLI =
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&getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
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while (!WorkList.empty()) {
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Instruction *I = *WorkList.begin();
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WorkList.erase(WorkList.begin()); // Get an element from the worklist...
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if (!I->use_empty()) // Don't muck with dead instructions...
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if (Constant *C = ConstantFoldInstruction(I, DL, TLI)) {
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// Add all of the users of this instruction to the worklist, they might
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// be constant propagatable now...
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for (User *U : I->users())
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WorkList.insert(cast<Instruction>(U));
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// Replace all of the uses of a variable with uses of the constant.
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I->replaceAllUsesWith(C);
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// Remove the dead instruction.
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WorkList.erase(I);
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I->eraseFromParent();
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// We made a change to the function...
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Changed = true;
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++NumInstKilled;
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}
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}
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return Changed;
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}
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