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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/Function.h"
#include "llvm/Instructions.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h"
@ -51,11 +52,11 @@ namespace {
LoopInfo *LI; // Loop information
DominatorTree *DT; // Dominator Tree for the current Loop...
DominanceFrontier *DF; // Current Dominance Frontier
std::vector<BasicBlock*> *LoopBlocks;
virtual bool runOnFunction(Function &F);
bool visitSubloop(Loop* L);
void processInstruction(Instruction* Instr,
const std::vector<BasicBlock*>& LoopBlocks,
const std::vector<BasicBlock*>& exitBlocks);
/// This transformation requires natural loop information & requires that
@ -71,10 +72,12 @@ namespace {
AU.addRequired<DominanceFrontier>();
}
private:
std::set<Instruction*> getLoopValuesUsedOutsideLoop(Loop *L,
const std::vector<BasicBlock*>& LoopBlocks);
SetVector<Instruction*> getLoopValuesUsedOutsideLoop(Loop *L);
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");
@ -87,6 +90,7 @@ bool LCSSA::runOnFunction(Function &F) {
LI = &getAnalysis<LoopInfo>();
DF = &getAnalysis<DominanceFrontier>();
DT = &getAnalysis<DominatorTree>();
LoopBlocks = new std::vector<BasicBlock*>;
for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) {
changed |= visitSubloop(*I);
@ -100,11 +104,11 @@ bool LCSSA::visitSubloop(Loop* L) {
visitSubloop(*I);
// Speed up queries by creating a sorted list of blocks
std::vector<BasicBlock*> LoopBlocks(L->block_begin(), L->block_end());
std::sort(LoopBlocks.begin(), LoopBlocks.end());
LoopBlocks->clear();
LoopBlocks->insert(LoopBlocks->end(), L->block_begin(), L->block_end());
std::sort(LoopBlocks->begin(), LoopBlocks->end());
std::set<Instruction*> AffectedValues = getLoopValuesUsedOutsideLoop(L,
LoopBlocks);
SetVector<Instruction*> AffectedValues = getLoopValuesUsedOutsideLoop(L);
// If no values are affected, we can save a lot of work, since we know that
// 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
// 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) {
processInstruction(*I, LoopBlocks, exitBlocks);
processInstruction(*I, exitBlocks);
}
return true; // FIXME: Should be more intelligent in our return value.
@ -128,7 +132,6 @@ bool LCSSA::visitSubloop(Loop* L) {
/// processInstruction -
void LCSSA::processInstruction(Instruction* Instr,
const std::vector<BasicBlock*>& LoopBlocks,
const std::vector<BasicBlock*>& exitBlocks)
{
++NumLCSSA; // We are applying the transformation
@ -155,7 +158,7 @@ void LCSSA::processInstruction(Instruction* Instr,
std::vector<PHINode*> needIncomingValues;
// 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()) {
PHINode *CurPHI = workList.back();
workList.pop_back();
@ -171,12 +174,12 @@ void LCSSA::processInstruction(Instruction* Instr,
const DominanceFrontier::DomSetType &S = it->second;
for (DominanceFrontier::DomSetType::const_iterator P = S.begin(),
PE = S.end(); P != PE; ++P) {
if (Phis[*P] == 0) {
Instruction *&Phi = Phis[*P];
if (Phi == 0) {
// Still doesn't have operands...
PHINode *phi = new PHINode(Instr->getType(), "lcssa", (*P)->begin());
Phis[*P] = phi;
Phi = new PHINode(Instr->getType(), "lcssa", (*P)->begin());
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();
UI != UE; ++UI) {
Instruction* use = cast<Instruction>(*UI);
// Don't need to update uses within the loop body
if (!std::binary_search(LoopBlocks.begin(), LoopBlocks.end(),
use->getParent()) &&
// Don't need to update uses within the loop body, and we don't want to
// overwrite the Phi nodes that we inserted into the exit blocks either.
if (!inLoopBlocks(use->getParent()) &&
!(std::binary_search(exitBlocks.begin(), exitBlocks.end(),
use->getParent()) && isa<PHINode>(use)))
Uses.push_back(use);
@ -213,38 +216,37 @@ void LCSSA::processInstruction(Instruction* Instr,
II != IE; ++II) {
if (PHINode* phi = dyn_cast<PHINode>(*II)) {
for (unsigned int i = 0; i < phi->getNumIncomingValues(); ++i) {
Instruction* dominator =
if (phi->getIncomingValue(i) == Instr) {
Instruction* dominator =
getValueDominatingBlock(phi->getIncomingBlock(i), Phis);
if (phi->getIncomingValue(i) == Instr)
phi->setIncomingValue(i, dominator);
}
}
} else {
(*II)->replaceUsesOfWith(Instr,
getValueDominatingBlock((*II)->getParent(),
Phis));
Value *NewVal = getValueDominatingBlock((*II)->getParent(), Phis);
(*II)->replaceUsesOfWith(Instr, NewVal);
}
}
}
/// getLoopValuesUsedOutsideLoop - Return any values defined in the loop that
/// are used by instructions outside of it.
std::set<Instruction*> LCSSA::getLoopValuesUsedOutsideLoop(Loop *L,
const std::vector<BasicBlock*>& LoopBlocks) {
SetVector<Instruction*> LCSSA::getLoopValuesUsedOutsideLoop(Loop *L) {
// 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
// dominate any of the loop exits, then none of the values defined in the
// 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();
BB != E; ++BB) {
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;
++UI) {
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);
break;
}
@ -254,7 +256,7 @@ std::set<Instruction*> LCSSA::getLoopValuesUsedOutsideLoop(Loop *L,
}
Instruction *LCSSA::getValueDominatingBlock(BasicBlock *BB,
std::map<BasicBlock*, Instruction*> PotDoms) {
std::map<BasicBlock*, Instruction*>& PotDoms) {
DominatorTree::Node* bbNode = DT->getNode(BB);
while (bbNode != 0) {
std::map<BasicBlock*, Instruction*>::iterator I =