mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-09-07 01:54:50 +00:00
832f61117d
of instcombine that is currently in the middle of the loop pass pipeline. This commit only checks in the pass; it will hopefully be enabled by default later. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122719 91177308-0d34-0410-b5e6-96231b3b80d8
113 lines
3.5 KiB
C++
113 lines
3.5 KiB
C++
//===- LoopInstSimplify.cpp - Loop Instruction Simplification Pass --------===//
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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 pass performs lightweight instruction simplification on loop bodies.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "loop-instsimplify"
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/ADT/Statistic.h"
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using namespace llvm;
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STATISTIC(NumSimplified, "Number of redundant instructions simplified");
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namespace {
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class LoopInstSimplify : public LoopPass {
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public:
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static char ID; // Pass ID, replacement for typeid
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LoopInstSimplify() : LoopPass(ID) {
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initializeLoopInstSimplifyPass(*PassRegistry::getPassRegistry());
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}
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bool runOnLoop(Loop*, LPPassManager&);
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virtual void getAnalysisUsage(AnalysisUsage& AU) const {
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AU.setPreservesCFG();
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AU.addRequired<DominatorTree>();
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AU.addPreserved<DominatorTree>();
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AU.addRequired<LoopInfo>();
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AU.addPreserved<LoopInfo>();
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AU.addPreservedID(LCSSAID);
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}
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};
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}
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char LoopInstSimplify::ID = 0;
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INITIALIZE_PASS_BEGIN(LoopInstSimplify, "loop-instsimplify",
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"Simplify instructions in loops", false, false)
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INITIALIZE_PASS_DEPENDENCY(DominatorTree)
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INITIALIZE_PASS_DEPENDENCY(LoopInfo)
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INITIALIZE_PASS_DEPENDENCY(LCSSA)
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INITIALIZE_PASS_END(LoopInstSimplify, "loop-instsimplify",
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"Simplify instructions in loops", false, false)
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Pass* llvm::createLoopInstSimplifyPass() {
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return new LoopInstSimplify();
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}
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bool LoopInstSimplify::runOnLoop(Loop* L, LPPassManager& LPM) {
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DominatorTree* DT = &getAnalysis<DominatorTree>();
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const LoopInfo* LI = &getAnalysis<LoopInfo>();
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const TargetData* TD = getAnalysisIfAvailable<TargetData>();
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bool Changed = false;
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bool LocalChanged;
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do {
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LocalChanged = false;
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SmallPtrSet<BasicBlock*, 32> Visited;
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SmallVector<BasicBlock*, 32> VisitStack;
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VisitStack.push_back(L->getHeader());
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while (!VisitStack.empty()) {
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BasicBlock* BB = VisitStack.back();
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VisitStack.pop_back();
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if (Visited.count(BB))
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continue;
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Visited.insert(BB);
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for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
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Instruction* I = BI++;
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// Don't bother simplifying unused instructions.
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if (!I->use_empty()) {
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if (Value* V = SimplifyInstruction(I, TD, DT)) {
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I->replaceAllUsesWith(V);
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LocalChanged = true;
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++NumSimplified;
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}
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}
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LocalChanged |= RecursivelyDeleteTriviallyDeadInstructions(I);
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}
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Changed |= LocalChanged;
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DomTreeNode* Node = DT->getNode(BB);
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const std::vector<DomTreeNode*>& Children = Node->getChildren();
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for (unsigned i = 0; i < Children.size(); ++i) {
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// Only visit children that are in the same loop.
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BasicBlock* ChildBB = Children[i]->getBlock();
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if (!Visited.count(ChildBB) && LI->getLoopFor(ChildBB) == L)
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VisitStack.push_back(ChildBB);
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}
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}
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} while (LocalChanged);
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// Nothing that SimplifyInstruction() does should invalidate LCSSA form.
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assert(L->isLCSSAForm(*DT));
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return Changed;
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}
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