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Clean up and refactor LCSSA a bunch. It should also run faster now, though
there's still a lot of work to be done on it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28506 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
parent
3fddf241d8
commit
2480737211
@ -1,4 +1,4 @@
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//===-- LCSSA.cpp - Convert loops into loop-closed SSA form ------===//
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//===-- LCSSA.cpp - Convert loops into loop-closed SSA form ---------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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@ -27,14 +27,14 @@
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Pass.h"
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#include "llvm/Function.h"
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#include "llvm/Instructions.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include <iostream>
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#include <algorithm>
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#include <set>
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#include <vector>
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@ -44,26 +44,28 @@ namespace {
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class LCSSA : public FunctionPass {
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public:
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LoopInfo *LI; // Loop information
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// LoopProcessWorklist - List of loops we need to process.
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std::vector<Loop*> LoopProcessWorklist;
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DominatorTree *DT; // Dominator Tree for the current Loop...
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DominanceFrontier *DF; // Current Dominance Frontier
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virtual bool runOnFunction(Function &F);
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bool visitLoop(Loop *L, Value *V);
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bool LCSSA::visitSubloop(Loop* L);
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/// This transformation requires natural loop information & requires that
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/// loop preheaders be inserted into the CFG...
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///
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesCFG();
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AU.addRequiredID(LoopSimplifyID);
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AU.addPreservedID(LoopSimplifyID);
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AU.addRequired<LoopInfo>();
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AU.addPreserved<LoopInfo>();
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AU.addRequired<DominatorTree>(); // Not sure if this one will actually
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// be needed.
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AU.addRequired<DominanceFrontier>();
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}
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private:
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void addSubloopsToWorklist(Loop* L);
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std::set<Value*> loopValuesUsedOutsideLoop(Loop *L);
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std::set<Instruction*> getLoopValuesUsedOutsideLoop(Loop *L,
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std::vector<BasicBlock*> LoopBlocks);
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};
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RegisterOpt<LCSSA> X("lcssa", "Loop-Closed SSA Form Pass");
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@ -74,86 +76,68 @@ FunctionPass *llvm::createLCSSAPass() { return new LCSSA(); }
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bool LCSSA::runOnFunction(Function &F) {
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bool changed = false;
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LI = &getAnalysis<LoopInfo>();
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DF = &getAnalysis<DominanceFrontier>();
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DT = &getAnalysis<DominatorTree>();
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for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) {
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addSubloopsToWorklist(*I);
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LoopProcessWorklist.push_back(*I);
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}
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for (std::vector<Loop*>::iterator I = LoopProcessWorklist.begin(),
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E = LoopProcessWorklist.end(); I != E; ++I) {
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std::set<Value*> AffectedValues = loopValuesUsedOutsideLoop(*I);
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if (!AffectedValues.empty()) {
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for (std::set<Value*>::iterator VI = AffectedValues.begin(),
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VE = AffectedValues.end(); VI != VE; ++VI)
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changed |= visitLoop(*I, *VI);
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}
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changed |= visitSubloop(*I);
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}
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return changed;
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}
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bool LCSSA::visitLoop(Loop *L, Value* V) {
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// We will be doing lots of "loop contains block" queries. Loop::contains is
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// linear time, use a set to speed this up.
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std::set<BasicBlock*> LoopBlocks;
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for (Loop::block_iterator BB = L->block_begin(), E = L->block_end();
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BB != E; ++BB)
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LoopBlocks.insert(*BB);
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bool LCSSA::visitSubloop(Loop* L) {
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for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
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visitSubloop(*I);
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// Speed up queries by creating a sorted list of blocks
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std::vector<BasicBlock*> LoopBlocks(L->block_begin(), L->block_end());
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std::sort(LoopBlocks.begin(), LoopBlocks.end());
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std::set<Instruction*> AffectedValues = getLoopValuesUsedOutsideLoop(L,
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LoopBlocks);
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std::vector<BasicBlock*> exitBlocks;
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L->getExitBlocks(exitBlocks);
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for (std::vector<BasicBlock*>::iterator BBI = exitBlocks.begin(),
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BBE = exitBlocks.end(); BBI != BBE; ++BBI) {
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PHINode *phi = new PHINode(V->getType(), "lcssa");
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(*BBI)->getInstList().insert((*BBI)->front(), phi);
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for (std::set<Instruction*>::iterator I = AffectedValues.begin(),
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E = AffectedValues.end(); I != E; ++I) {
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for (std::vector<BasicBlock*>::iterator BBI = exitBlocks.begin(),
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BBE = exitBlocks.end(); BBI != BBE; ++BBI) {
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PHINode *phi = new PHINode((*I)->getType(), "lcssa");
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(*BBI)->getInstList().insert((*BBI)->front(), phi);
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for (pred_iterator PI = pred_begin(*BBI), PE = pred_end(*BBI); PI != PE;
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++PI)
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phi->addIncoming(V, *PI);
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for (pred_iterator PI = pred_begin(*BBI), PE = pred_end(*BBI); PI != PE;
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++PI)
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phi->addIncoming(*I, *PI);
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}
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for (Value::use_iterator UI = (*I)->use_begin(), UE = (*I)->use_end();
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UI != UE; ++UI) {
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BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
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if (!std::binary_search(LoopBlocks.begin(), LoopBlocks.end(), UserBB))
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; // FIXME: This should update the SSA form.
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}
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}
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for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
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++UI) {
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BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
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if (!LoopBlocks.count(UserBB))
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; // FIXME: This should update the SSA form through the rest of the graph.
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}
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return false;
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return true; // FIXME: Should be more intelligent in our return value.
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}
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void LCSSA::addSubloopsToWorklist(Loop* L) {
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for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) {
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addSubloopsToWorklist(*I);
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LoopProcessWorklist.push_back(*I);
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}
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}
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/// getLoopValuesUsedOutsideLoop - Return any values defined in the loop that
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/// are used by instructions outside of it.
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std::set<Instruction*> LCSSA::getLoopValuesUsedOutsideLoop(Loop *L,
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std::vector<BasicBlock*> LoopBlocks) {
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/// loopValuesUsedOutsideLoop - Return true if there are any values defined in
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/// the loop that are used by instructions outside of it.
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std::set<Value*> LCSSA::loopValuesUsedOutsideLoop(Loop *L) {
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std::set<Value*> AffectedValues;
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// We will be doing lots of "loop contains block" queries. Loop::contains is
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// linear time, use a set to speed this up.
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std::set<BasicBlock*> LoopBlocks;
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for (Loop::block_iterator BB = L->block_begin(), E = L->block_end();
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BB != E; ++BB)
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LoopBlocks.insert(*BB);
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std::set<Instruction*> AffectedValues;
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for (Loop::block_iterator BB = L->block_begin(), E = L->block_end();
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BB != E; ++BB) {
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for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E; ++I)
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for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
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++UI) {
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BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
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if (!LoopBlocks.count(UserBB))
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if (!std::binary_search(LoopBlocks.begin(), LoopBlocks.end(), UserBB))
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AffectedValues.insert(I);
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}
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}
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return AffectedValues;
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}
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}
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