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Don't allow dead instructions to stop sinking early.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10386 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-12-10 20:43:29 +00:00
parent 88369d214f
commit df45bd3803
1 changed files with 9 additions and 10 deletions
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19
lib/Transforms/Scalar/LICM.cpp
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@ -366,7 +366,12 @@ void LICM::sink(Instruction &I) {
DEBUG(std::cerr << "LICM sinking instruction: " << I);
const std::vector<BasicBlock*> &ExitBlocks = CurLoop->getExitBlocks();
std::vector<Value*> Operands(I.op_begin(), I.op_end());
if (isa<LoadInst>(I)) ++NumMovedLoads;
++NumSunk;
Changed = true;
// The case where there is only a single exit node of this loop is common
// enough that we handle it as a special (more efficient) case. It is more
// efficient to handle because there are no PHI nodes that need to be placed.
@ -386,7 +391,6 @@ void LICM::sink(Instruction &I) {
} else if (ExitBlocks.size() == 0) {
// The instruction is actually dead if there ARE NO exit blocks.
I.getParent()->getInstList().erase(&I);
return; // Don't count this as a sunk instruction, don't check operands.
} else {
// Otherwise, if we have multiple exits, use the PromoteMem2Reg function to
// do all of the hard work of inserting PHI nodes as necessary. We convert
@ -469,17 +473,12 @@ void LICM::sink(Instruction &I) {
PromoteMemToReg(Allocas, *DT, *DF, AA->getTargetData());
}
if (isa<LoadInst>(I)) ++NumMovedLoads;
++NumSunk;
Changed = true;
// Since we just sunk an instruction, check to see if any other instructions
// used by this instruction are now sinkable. If so, sink them too.
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
if (Instruction *OpI = dyn_cast<Instruction>(I.getOperand(i)))
for (unsigned i = 0, e = Operands.size(); i != e; ++i)
if (Instruction *OpI = dyn_cast<Instruction>(Operands[i]))
if (CurLoop->contains(OpI->getParent()) && canSinkOrHoistInst(*OpI) &&
isNotUsedInLoop(*OpI) &&
isSafeToExecuteUnconditionally(*OpI))
isNotUsedInLoop(*OpI) && isSafeToExecuteUnconditionally(*OpI))
sink(*OpI);
}