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make PRE of loads preserve the alignment of the moved load instruction.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88865 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-11-15 19:58:31 +00:00
parent 1fb5630474
commit 4e447ebc58
1 changed files with 8 additions and 5 deletions
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13
lib/Transforms/Scalar/JumpThreading.cpp
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@ -585,6 +585,8 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) {
if (isa<Constant>(CondCmp->getOperand(1)))
SimplifyValue = CondCmp->getOperand(0);
// TODO: There are other places where load PRE would be profitable, such as
// more complex comparisons.
if (LoadInst *LI = dyn_cast<LoadInst>(SimplifyValue))
if (SimplifyPartiallyRedundantLoad(LI))
return true;
@ -752,7 +754,7 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
Value *LoadedPtr = LI->getOperand(0);
// If the loaded operand is defined in the LoadBB, it can't be available.
// FIXME: Could do PHI translation, that would be fun :)
// TODO: Could do simple PHI translation, that would be fun :)
if (Instruction *PtrOp = dyn_cast<Instruction>(LoadedPtr))
if (PtrOp->getParent() == LoadBB)
return false;
@ -761,8 +763,8 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
// the entry to its block.
BasicBlock::iterator BBIt = LI;
if (Value *AvailableVal = FindAvailableLoadedValue(LoadedPtr, LoadBB,
BBIt, 6)) {
if (Value *AvailableVal =
FindAvailableLoadedValue(LoadedPtr, LoadBB, BBIt, 6)) {
// If the value if the load is locally available within the block, just use
// it. This frequently occurs for reg2mem'd allocas.
//cerr << "LOAD ELIMINATED:\n" << *BBIt << *LI << "\n";
@ -845,7 +847,7 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
// Split them out to their own block.
UnavailablePred =
SplitBlockPredecessors(LoadBB, &PredsToSplit[0], PredsToSplit.size(),
"thread-split", this);
"thread-pre-split", this);
}
// If the value isn't available in all predecessors, then there will be
@ -854,7 +856,8 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
if (UnavailablePred) {
assert(UnavailablePred->getTerminator()->getNumSuccessors() == 1 &&
"Can't handle critical edge here!");
Value *NewVal = new LoadInst(LoadedPtr, LI->getName()+".pr",
Value *NewVal = new LoadInst(LoadedPtr, LI->getName()+".pr", false,
LI->getAlignment(),
UnavailablePred->getTerminator());
AvailablePreds.push_back(std::make_pair(UnavailablePred, NewVal));
}