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Various clean-ups suggested by Chris. 

llvm-svn: 28678
This commit is contained in:
Owen Anderson 2006-06-04 00:02:23 +00:00
parent d00eacc4f9
commit eb33815f1b
1 changed files with 32 additions and 30 deletions
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62
llvm/lib/Transforms/Utils/LCSSA.cpp
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@ -31,6 +31,7 @@
#include "llvm/Pass.h" #include "llvm/Pass.h"
#include "llvm/Function.h" #include "llvm/Function.h"
#include "llvm/Instructions.h" #include "llvm/Instructions.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h" #include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Dominators.h" #include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h" #include "llvm/Analysis/LoopInfo.h"
@ -51,11 +52,11 @@ namespace {
LoopInfo *LI; // Loop information LoopInfo *LI; // Loop information
DominatorTree *DT; // Dominator Tree for the current Loop... DominatorTree *DT; // Dominator Tree for the current Loop...
DominanceFrontier *DF; // Current Dominance Frontier DominanceFrontier *DF; // Current Dominance Frontier
std::vector<BasicBlock*> *LoopBlocks;
virtual bool runOnFunction(Function &F); virtual bool runOnFunction(Function &F);
bool visitSubloop(Loop* L); bool visitSubloop(Loop* L);
void processInstruction(Instruction* Instr, void processInstruction(Instruction* Instr,
const std::vector<BasicBlock*>& LoopBlocks,
const std::vector<BasicBlock*>& exitBlocks); const std::vector<BasicBlock*>& exitBlocks);
/// This transformation requires natural loop information & requires that /// This transformation requires natural loop information & requires that
@ -71,10 +72,12 @@ namespace {
AU.addRequired<DominanceFrontier>(); AU.addRequired<DominanceFrontier>();
} }
private: private:
std::set<Instruction*> getLoopValuesUsedOutsideLoop(Loop *L, SetVector<Instruction*> getLoopValuesUsedOutsideLoop(Loop *L);
const std::vector<BasicBlock*>& LoopBlocks);
Instruction *getValueDominatingBlock(BasicBlock *BB, Instruction *getValueDominatingBlock(BasicBlock *BB,
std::map<BasicBlock*, Instruction*> PotDoms); std::map<BasicBlock*, Instruction*>& PotDoms);
bool inLoopBlocks(BasicBlock* B) { return std::binary_search(
LoopBlocks->begin(), LoopBlocks->end(), B); }
}; };
RegisterOpt<LCSSA> X("lcssa", "Loop-Closed SSA Form Pass"); RegisterOpt<LCSSA> X("lcssa", "Loop-Closed SSA Form Pass");
@ -87,6 +90,7 @@ bool LCSSA::runOnFunction(Function &F) {
LI = &getAnalysis<LoopInfo>(); LI = &getAnalysis<LoopInfo>();
DF = &getAnalysis<DominanceFrontier>(); DF = &getAnalysis<DominanceFrontier>();
DT = &getAnalysis<DominatorTree>(); DT = &getAnalysis<DominatorTree>();
LoopBlocks = new std::vector<BasicBlock*>;
for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) { for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) {
changed |= visitSubloop(*I); changed |= visitSubloop(*I);
@ -100,11 +104,11 @@ bool LCSSA::visitSubloop(Loop* L) {
visitSubloop(*I); visitSubloop(*I);
// Speed up queries by creating a sorted list of blocks // Speed up queries by creating a sorted list of blocks
std::vector<BasicBlock*> LoopBlocks(L->block_begin(), L->block_end()); LoopBlocks->clear();
std::sort(LoopBlocks.begin(), LoopBlocks.end()); LoopBlocks->insert(LoopBlocks->end(), L->block_begin(), L->block_end());
std::sort(LoopBlocks->begin(), LoopBlocks->end());
std::set<Instruction*> AffectedValues = getLoopValuesUsedOutsideLoop(L, SetVector<Instruction*> AffectedValues = getLoopValuesUsedOutsideLoop(L);
LoopBlocks);
// If no values are affected, we can save a lot of work, since we know that // If no values are affected, we can save a lot of work, since we know that
// nothing will be changed. // nothing will be changed.
@ -118,9 +122,9 @@ bool LCSSA::visitSubloop(Loop* L) {
// Iterate over all affected values for this loop and insert Phi nodes // Iterate over all affected values for this loop and insert Phi nodes
// for them in the appropriate exit blocks // for them in the appropriate exit blocks
for (std::set<Instruction*>::iterator I = AffectedValues.begin(), for (SetVector<Instruction*>::iterator I = AffectedValues.begin(),
E = AffectedValues.end(); I != E; ++I) { E = AffectedValues.end(); I != E; ++I) {
processInstruction(*I, LoopBlocks, exitBlocks); processInstruction(*I, exitBlocks);
} }
return true; // FIXME: Should be more intelligent in our return value. return true; // FIXME: Should be more intelligent in our return value.
@ -128,7 +132,6 @@ bool LCSSA::visitSubloop(Loop* L) {
/// processInstruction - /// processInstruction -
void LCSSA::processInstruction(Instruction* Instr, void LCSSA::processInstruction(Instruction* Instr,
const std::vector<BasicBlock*>& LoopBlocks,
const std::vector<BasicBlock*>& exitBlocks) const std::vector<BasicBlock*>& exitBlocks)
{ {
++NumLCSSA; // We are applying the transformation ++NumLCSSA; // We are applying the transformation
@ -155,7 +158,7 @@ void LCSSA::processInstruction(Instruction* Instr,
std::vector<PHINode*> needIncomingValues; std::vector<PHINode*> needIncomingValues;
// Calculate the IDF of these LCSSA Phi nodes, inserting new Phi's where // Calculate the IDF of these LCSSA Phi nodes, inserting new Phi's where
// necessary. Keep track of these new Phi's in Phis. // necessary. Keep track of these new Phi's in the "Phis" map.
while (!workList.empty()) { while (!workList.empty()) {
PHINode *CurPHI = workList.back(); PHINode *CurPHI = workList.back();
workList.pop_back(); workList.pop_back();
@ -171,12 +174,12 @@ void LCSSA::processInstruction(Instruction* Instr,
const DominanceFrontier::DomSetType &S = it->second; const DominanceFrontier::DomSetType &S = it->second;
for (DominanceFrontier::DomSetType::const_iterator P = S.begin(), for (DominanceFrontier::DomSetType::const_iterator P = S.begin(),
PE = S.end(); P != PE; ++P) { PE = S.end(); P != PE; ++P) {
if (Phis[*P] == 0) { Instruction *&Phi = Phis[*P];
if (Phi == 0) {
// Still doesn't have operands... // Still doesn't have operands...
PHINode *phi = new PHINode(Instr->getType(), "lcssa", (*P)->begin()); Phi = new PHINode(Instr->getType(), "lcssa", (*P)->begin());
Phis[*P] = phi;
workList.push_back(phi); workList.push_back(cast<PHINode>(Phi));
} }
} }
} }
@ -197,9 +200,9 @@ void LCSSA::processInstruction(Instruction* Instr,
for (Instruction::use_iterator UI = Instr->use_begin(), UE = Instr->use_end(); for (Instruction::use_iterator UI = Instr->use_begin(), UE = Instr->use_end();
UI != UE; ++UI) { UI != UE; ++UI) {
Instruction* use = cast<Instruction>(*UI); Instruction* use = cast<Instruction>(*UI);
// Don't need to update uses within the loop body // Don't need to update uses within the loop body, and we don't want to
if (!std::binary_search(LoopBlocks.begin(), LoopBlocks.end(), // overwrite the Phi nodes that we inserted into the exit blocks either.
use->getParent()) && if (!inLoopBlocks(use->getParent()) &&
!(std::binary_search(exitBlocks.begin(), exitBlocks.end(), !(std::binary_search(exitBlocks.begin(), exitBlocks.end(),
use->getParent()) && isa<PHINode>(use))) use->getParent()) && isa<PHINode>(use)))
Uses.push_back(use); Uses.push_back(use);
@ -213,38 +216,37 @@ void LCSSA::processInstruction(Instruction* Instr,
II != IE; ++II) { II != IE; ++II) {
if (PHINode* phi = dyn_cast<PHINode>(*II)) { if (PHINode* phi = dyn_cast<PHINode>(*II)) {
for (unsigned int i = 0; i < phi->getNumIncomingValues(); ++i) { for (unsigned int i = 0; i < phi->getNumIncomingValues(); ++i) {
Instruction* dominator = if (phi->getIncomingValue(i) == Instr) {
Instruction* dominator =
getValueDominatingBlock(phi->getIncomingBlock(i), Phis); getValueDominatingBlock(phi->getIncomingBlock(i), Phis);
if (phi->getIncomingValue(i) == Instr)
phi->setIncomingValue(i, dominator); phi->setIncomingValue(i, dominator);
}
} }
} else { } else {
(*II)->replaceUsesOfWith(Instr, Value *NewVal = getValueDominatingBlock((*II)->getParent(), Phis);
getValueDominatingBlock((*II)->getParent(), (*II)->replaceUsesOfWith(Instr, NewVal);
Phis));
} }
} }
} }
/// getLoopValuesUsedOutsideLoop - Return any values defined in the loop that /// getLoopValuesUsedOutsideLoop - Return any values defined in the loop that
/// are used by instructions outside of it. /// are used by instructions outside of it.
std::set<Instruction*> LCSSA::getLoopValuesUsedOutsideLoop(Loop *L, SetVector<Instruction*> LCSSA::getLoopValuesUsedOutsideLoop(Loop *L) {
const std::vector<BasicBlock*>& LoopBlocks) {
// FIXME: For large loops, we may be able to avoid a lot of use-scanning // FIXME: For large loops, we may be able to avoid a lot of use-scanning
// by using dominance information. In particular, if a block does not // by using dominance information. In particular, if a block does not
// dominate any of the loop exits, then none of the values defined in the // dominate any of the loop exits, then none of the values defined in the
// block could be used outside the loop. // block could be used outside the loop.
std::set<Instruction*> AffectedValues; SetVector<Instruction*> AffectedValues;
for (Loop::block_iterator BB = L->block_begin(), E = L->block_end(); for (Loop::block_iterator BB = L->block_begin(), E = L->block_end();
BB != E; ++BB) { BB != E; ++BB) {
for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E; ++I) for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E; ++I)
for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
++UI) { ++UI) {
BasicBlock *UserBB = cast<Instruction>(*UI)->getParent(); BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
if (!std::binary_search(LoopBlocks.begin(), LoopBlocks.end(), UserBB)) { if (!std::binary_search(LoopBlocks->begin(), LoopBlocks->end(), UserBB))
{
AffectedValues.insert(I); AffectedValues.insert(I);
break; break;
} }
@ -254,7 +256,7 @@ std::set<Instruction*> LCSSA::getLoopValuesUsedOutsideLoop(Loop *L,
} }
Instruction *LCSSA::getValueDominatingBlock(BasicBlock *BB, Instruction *LCSSA::getValueDominatingBlock(BasicBlock *BB,
std::map<BasicBlock*, Instruction*> PotDoms) { std::map<BasicBlock*, Instruction*>& PotDoms) {
DominatorTree::Node* bbNode = DT->getNode(BB); DominatorTree::Node* bbNode = DT->getNode(BB);
while (bbNode != 0) { while (bbNode != 0) {
std::map<BasicBlock*, Instruction*>::iterator I = std::map<BasicBlock*, Instruction*>::iterator I =