Make sure to update alias analysis information as we transform the function.

This fixes PR420 and Regression/Transforms/LICM/2004-09-14-AliasAnalysisInvalidate.llx

llvm-svn: 16348
This commit is contained in:
Chris Lattner 2004-09-15 01:04:07 +00:00
parent 9b9932bd94
commit a346578d92
1 changed files with 57 additions and 21 deletions

View File

@ -184,13 +184,13 @@ namespace {
///
void PromoteValuesInLoop();
/// findPromotableValuesInLoop - Check the current loop for stores to
/// FindPromotableValuesInLoop - Check the current loop for stores to
/// definite pointers, which are not loaded and stored through may aliases.
/// If these are found, create an alloca for the value, add it to the
/// PromotedValues list, and keep track of the mapping from value to
/// alloca...
///
void findPromotableValuesInLoop(
void FindPromotableValuesInLoop(
std::vector<std::pair<AllocaInst*, Value*> > &PromotedValues,
std::map<Value*, AllocaInst*> &Val2AlMap);
};
@ -546,7 +546,7 @@ void LICM::sink(Instruction &I) {
if (AI) {
std::vector<AllocaInst*> Allocas;
Allocas.push_back(AI);
PromoteMemToReg(Allocas, *DT, *DF, AA->getTargetData());
PromoteMemToReg(Allocas, *DT, *DF, AA->getTargetData(), CurAST);
}
}
}
@ -617,20 +617,47 @@ void LICM::PromoteValuesInLoop() {
std::vector<std::pair<AllocaInst*, Value*> > PromotedValues;
std::map<Value*, AllocaInst*> ValueToAllocaMap; // Map of ptr to alloca
findPromotableValuesInLoop(PromotedValues, ValueToAllocaMap);
if (ValueToAllocaMap.empty()) return; // If there are values to promote...
FindPromotableValuesInLoop(PromotedValues, ValueToAllocaMap);
if (ValueToAllocaMap.empty()) return; // If there are values to promote.
Changed = true;
NumPromoted += PromotedValues.size();
std::vector<Value*> PointerValueNumbers;
// Emit a copy from the value into the alloca'd value in the loop preheader
TerminatorInst *LoopPredInst = Preheader->getTerminator();
for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) {
// Load from the memory we are promoting...
LoadInst *LI = new LoadInst(PromotedValues[i].second,
PromotedValues[i].second->getName()+".promoted",
LoopPredInst);
// Store into the temporary alloca...
Value *Ptr = PromotedValues[i].second;
// If we are promoting a pointer value, update alias information for the
// inserted load.
Value *LoadValue = 0;
if (isa<PointerType>(cast<PointerType>(Ptr->getType())->getElementType())) {
// Locate a load or store through the pointer, and assign the same value
// to LI as we are loading or storing. Since we know that the value is
// stored in this loop, this will always succeed.
for (Value::use_iterator UI = Ptr->use_begin(), E = Ptr->use_end();
UI != E; ++UI)
if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
LoadValue = LI;
break;
} else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
if (SI->getOperand(1) == LI) {
LoadValue = SI->getOperand(0);
break;
}
}
assert(LoadValue && "No store through the pointer found!");
PointerValueNumbers.push_back(LoadValue); // Remember this for later.
}
// Load from the memory we are promoting.
LoadInst *LI = new LoadInst(Ptr, Ptr->getName()+".promoted", LoopPredInst);
if (LoadValue) CurAST->copyValue(LoadValue, LI);
// Store into the temporary alloca.
new StoreInst(LI, PromotedValues[i].first, LoopPredInst);
}
@ -669,45 +696,51 @@ void LICM::PromoteValuesInLoop() {
CurLoop->getExitBlocks(ExitBlocks);
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
if (ProcessedBlocks.insert(ExitBlocks[i]).second) {
// Copy all of the allocas into their memory locations...
// Copy all of the allocas into their memory locations.
BasicBlock::iterator BI = ExitBlocks[i]->begin();
while (isa<PHINode>(*BI))
++BI; // Skip over all of the phi nodes in the block...
++BI; // Skip over all of the phi nodes in the block.
Instruction *InsertPos = BI;
unsigned PVN = 0;
for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) {
// Load from the alloca...
// Load from the alloca.
LoadInst *LI = new LoadInst(PromotedValues[i].first, "", InsertPos);
// Store into the memory we promoted...
// If this is a pointer type, update alias info appropriately.
if (isa<PointerType>(LI->getType()))
CurAST->copyValue(PointerValueNumbers[PVN++], LI);
// Store into the memory we promoted.
new StoreInst(LI, PromotedValues[i].second, InsertPos);
}
}
// Now that we have done the deed, use the mem2reg functionality to promote
// all of the new allocas we just created into real SSA registers...
// all of the new allocas we just created into real SSA registers.
//
std::vector<AllocaInst*> PromotedAllocas;
PromotedAllocas.reserve(PromotedValues.size());
for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i)
PromotedAllocas.push_back(PromotedValues[i].first);
PromoteMemToReg(PromotedAllocas, *DT, *DF, AA->getTargetData());
PromoteMemToReg(PromotedAllocas, *DT, *DF, AA->getTargetData(), CurAST);
}
/// findPromotableValuesInLoop - Check the current loop for stores to definite
/// FindPromotableValuesInLoop - Check the current loop for stores to definite
/// pointers, which are not loaded and stored through may aliases. If these are
/// found, create an alloca for the value, add it to the PromotedValues list,
/// and keep track of the mapping from value to alloca...
/// and keep track of the mapping from value to alloca.
///
void LICM::findPromotableValuesInLoop(
void LICM::FindPromotableValuesInLoop(
std::vector<std::pair<AllocaInst*, Value*> > &PromotedValues,
std::map<Value*, AllocaInst*> &ValueToAllocaMap) {
Instruction *FnStart = CurLoop->getHeader()->getParent()->begin()->begin();
// Loop over all of the alias sets in the tracker object...
// Loop over all of the alias sets in the tracker object.
for (AliasSetTracker::iterator I = CurAST->begin(), E = CurAST->end();
I != E; ++I) {
AliasSet &AS = *I;
// We can promote this alias set if it has a store, if it is a "Must" alias
// set, if the pointer is loop invariant, if if we are not eliminating any
// set, if the pointer is loop invariant, and if we are not eliminating any
// volatile loads or stores.
if (!AS.isForwardingAliasSet() && AS.isMod() && AS.isMustAlias() &&
!AS.isVolatile() && CurLoop->isLoopInvariant(AS.begin()->first)) {
@ -729,6 +762,9 @@ void LICM::findPromotableValuesInLoop(
const Type *Ty = cast<PointerType>(V->getType())->getElementType();
AllocaInst *AI = new AllocaInst(Ty, 0, V->getName()+".tmp", FnStart);
PromotedValues.push_back(std::make_pair(AI, V));
// Update the AST and alias analysis.
CurAST->copyValue(V, AI);
for (AliasSet::iterator I = AS.begin(), E = AS.end(); I != E; ++I)
ValueToAllocaMap.insert(std::make_pair(I->first, AI));