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refactor some code, no functionality change.

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llvm-svn: 36037
This commit is contained in:
Chris Lattner 2007-04-15 00:07:55 +00:00
parent 4543ee2ff9
commit ecd0fda993
1 changed files with 77 additions and 58 deletions
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61
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -352,6 +352,7 @@ namespace {
bool isSigned, bool Inside, Instruction &IB);
Instruction *PromoteCastOfAllocation(CastInst &CI, AllocationInst &AI);
Instruction *MatchBSwap(BinaryOperator &I);
bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
};
@ -8818,37 +8819,61 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
// ends with an unconditional branch, try to move it to the successor block.
BBI = &SI; ++BBI;
if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
if (BI->isUnconditional()) {
if (BI->isUnconditional())
if (SimplifyStoreAtEndOfBlock(SI))
return 0; // xform done!
return 0;
}
/// SimplifyStoreAtEndOfBlock - Turn things like:
/// if () { *P = v1; } else { *P = v2 }
/// into a phi node with a store in the successor.
///
bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
BasicBlock *StoreBB = SI.getParent();
// Check to see if the successor block has exactly two incoming edges. If
// so, see if the other predecessor contains a store to the same location.
// if so, insert a PHI node (if needed) and move the stores down.
BasicBlock *Dest = BI->getSuccessor(0);
BasicBlock *Dest = StoreBB->getTerminator()->getSuccessor(0);
// Determine whether Dest has exactly two predecessors and, if so, compute
// the other predecessor.
pred_iterator PI = pred_begin(Dest);
BasicBlock *Other = 0;
if (*PI != BI->getParent())
if (*PI != StoreBB)
Other = *PI;
++PI;
if (PI != pred_end(Dest)) {
if (*PI != BI->getParent())
if (PI == pred_end(Dest))
return false;
if (*PI != StoreBB) {
if (Other)
Other = 0;
else
return false;
Other = *PI;
if (++PI != pred_end(Dest))
Other = 0;
}
if (Other) { // If only one other pred...
BBI = Other->getTerminator();
if (++PI != pred_end(Dest))
return false;
BasicBlock::iterator BBI = Other->getTerminator();
BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
// Make sure this other block ends in an unconditional branch and that
// there is an instruction before the branch.
if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
BBI != Other->begin()) {
if (!OtherBr || !cast<BranchInst>(BBI)->isUnconditional() ||
BBI == Other->begin())
return false;
// See if the last instruction in other block is a store to the same location.
--BBI;
StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
// If this instruction is a store to the same location.
if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1))
return false;
// Okay, we know we can perform this transformation. Insert a PHI
// node now if we need it.
Value *MergedVal = OtherStore->getOperand(0);
@ -8871,13 +8896,7 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
EraseInstFromFunction(SI);
EraseInstFromFunction(*OtherStore);
++NumCombined;
return 0;
}
}
}
}
return 0;
return true;
}