//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
}
bool doFinalization() {
+ // Free the values stored in the map
+ for (std::map<Loop *, AliasSetTracker *>::iterator
+ I = LoopToAliasMap.begin(), E = LoopToAliasMap.end(); I != E; ++I)
+ delete I->second;
+
LoopToAliasMap.clear();
return false;
}
LoopPass *llvm::createLICMPass() { return new LICM(); }
-/// Hoist expressions out of the specified loop...
+/// Hoist expressions out of the specified loop. Note, alias info for inner
+/// loop is not preserved so it is not a good idea to run LICM multiple
+/// times on one loop.
///
bool LICM::runOnLoop(Loop *L, LPPassManager &LPM) {
Changed = false;
//
// Traverse the body of the loop in depth first order on the dominator tree so
// that we are guaranteed to see definitions before we see uses. This allows
- // us to sink instructions in one pass, without iteration. AFter sinking
+ // us to sink instructions in one pass, without iteration. After sinking
// instructions, we perform another pass to hoist them out of the loop.
//
SinkRegion(DT->getNode(L->getHeader()));
// Don't hoist loads which have may-aliased stores in loop.
unsigned Size = 0;
if (LI->getType()->isSized())
- Size = AA->getTargetData().getTypeSize(LI->getType());
+ Size = AA->getTargetData().getTypeStoreSize(LI->getType());
return !pointerInvalidatedByLoop(LI->getOperand(0), Size);
} else if (CallInst *CI = dyn_cast<CallInst>(&I)) {
// Handle obvious cases efficiently.
- if (Function *Callee = CI->getCalledFunction()) {
- AliasAnalysis::ModRefBehavior Behavior =AA->getModRefBehavior(Callee, CI);
- if (Behavior == AliasAnalysis::DoesNotAccessMemory)
- return true;
- else if (Behavior == AliasAnalysis::OnlyReadsMemory) {
- // If this call only reads from memory and there are no writes to memory
- // in the loop, we can hoist or sink the call as appropriate.
- bool FoundMod = false;
- for (AliasSetTracker::iterator I = CurAST->begin(), E = CurAST->end();
- I != E; ++I) {
- AliasSet &AS = *I;
- if (!AS.isForwardingAliasSet() && AS.isMod()) {
- FoundMod = true;
- break;
- }
+ AliasAnalysis::ModRefBehavior Behavior = AA->getModRefBehavior(CI);
+ if (Behavior == AliasAnalysis::DoesNotAccessMemory)
+ return true;
+ else if (Behavior == AliasAnalysis::OnlyReadsMemory) {
+ // If this call only reads from memory and there are no writes to memory
+ // in the loop, we can hoist or sink the call as appropriate.
+ bool FoundMod = false;
+ for (AliasSetTracker::iterator I = CurAST->begin(), E = CurAST->end();
+ I != E; ++I) {
+ AliasSet &AS = *I;
+ if (!AS.isForwardingAliasSet() && AS.isMod()) {
+ FoundMod = true;
+ break;
}
- if (!FoundMod) return true;
}
+ if (!FoundMod) return true;
}
// FIXME: This should use mod/ref information to see if we can hoist or sink
void LICM::sink(Instruction &I) {
DOUT << "LICM sinking instruction: " << I;
- std::vector<BasicBlock*> ExitBlocks;
+ SmallVector<BasicBlock*, 8> ExitBlocks;
CurLoop->getExitBlocks(ExitBlocks);
if (isa<LoadInst>(I)) ++NumMovedLoads;
while (isa<PHINode>(InsertPt)) ++InsertPt;
ExitBlocks[0]->getInstList().insert(InsertPt, &I);
}
- } else if (ExitBlocks.size() == 0) {
+ } else if (ExitBlocks.empty()) {
// The instruction is actually dead if there ARE NO exit blocks.
CurAST->deleteValue(&I);
if (!I.use_empty()) // If I has users in unreachable blocks, eliminate.
return true;
// Get the exit blocks for the current loop.
- std::vector<BasicBlock*> ExitBlocks;
+ SmallVector<BasicBlock*, 8> ExitBlocks;
CurLoop->getExitBlocks(ExitBlocks);
// For each exit block, get the DT node and walk up the DT until the
//
std::set<BasicBlock*> ProcessedBlocks;
- std::vector<BasicBlock*> ExitBlocks;
+ SmallVector<BasicBlock*, 8> ExitBlocks;
CurLoop->getExitBlocks(ExitBlocks);
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
if (ProcessedBlocks.insert(ExitBlocks[i]).second) {
}
/// 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.
-///
+/// pointers, which are not loaded and stored through may aliases and are safe
+/// for promotion. 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 LICM::FindPromotableValuesInLoop(
std::vector<std::pair<AllocaInst*, Value*> > &PromotedValues,
std::map<Value*, AllocaInst*> &ValueToAllocaMap) {
Instruction *FnStart = CurLoop->getHeader()->getParent()->begin()->begin();
+ SmallVector<Instruction *, 4> LoopExits;
+ SmallVector<BasicBlock *, 4> Blocks;
+ CurLoop->getExitingBlocks(Blocks);
+ for (SmallVector<BasicBlock *, 4>::iterator BI = Blocks.begin(),
+ BE = Blocks.end(); BI != BE; ++BI) {
+ BasicBlock *BB = *BI;
+ LoopExits.push_back(BB->getTerminator());
+ }
+
// Loop over all of the alias sets in the tracker object.
for (AliasSetTracker::iterator I = CurAST->begin(), E = CurAST->end();
I != E; ++I) {
// volatile loads or stores.
if (!AS.isForwardingAliasSet() && AS.isMod() && AS.isMustAlias() &&
!AS.isVolatile() && CurLoop->isLoopInvariant(AS.begin()->first)) {
- assert(AS.begin() != AS.end() &&
+ assert(!AS.empty() &&
"Must alias set should have at least one pointer element in it!");
Value *V = AS.begin()->first;
break;
}
+ // If one use of value V inside the loop is safe then it is OK to promote
+ // this value. On the otherside if there is not any unsafe use inside the
+ // loop then also it is OK to promote this value. Otherwise it is
+ // unsafe to promote this value.
+ if (PointerOk) {
+ bool oneSafeUse = false;
+ bool oneUnsafeUse = false;
+ for(Value::use_iterator UI = V->use_begin(), UE = V->use_end();
+ UI != UE; ++UI) {
+ Instruction *Use = dyn_cast<Instruction>(*UI);
+ if (!Use || !CurLoop->contains(Use->getParent()))
+ continue;
+ for (SmallVector<Instruction *, 4>::iterator
+ ExitI = LoopExits.begin(), ExitE = LoopExits.end();
+ ExitI != ExitE; ++ExitI) {
+ Instruction *Ex = *ExitI;
+ if (!isa<PHINode>(Use) && DT->dominates(Use, Ex)) {
+ oneSafeUse = true;
+ break;
+ }
+ else
+ oneUnsafeUse = true;
+ }
+
+ if (oneSafeUse)
+ break;
+ }
+
+ if (oneSafeUse)
+ PointerOk = true;
+ else if (!oneUnsafeUse)
+ PointerOk = true;
+ else
+ PointerOk = false;
+ }
+
if (PointerOk) {
const Type *Ty = cast<PointerType>(V->getType())->getElementType();
AllocaInst *AI = new AllocaInst(Ty, 0, V->getName()+".tmp", FnStart);
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