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Minor speedups for the instcombine pass

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8894 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-10-06 17:11:01 +00:00
parent 884d6c4e10
commit 4bb7c02eba
1 changed files with 26 additions and 17 deletions
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27
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1939,17 +1939,16 @@ bool InstCombiner::runOnFunction(Function &F) {
// Check to see if we can DIE the instruction...
if (isInstructionTriviallyDead(I)) {
// Add operands to the worklist...
if (I->getNumOperands() < 4)
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
WorkList.push_back(Op);
++NumDeadInst;
BasicBlock::iterator BBI = I;
if (dceInstruction(BBI)) {
I->getParent()->getInstList().erase(I);
removeFromWorkList(I);
continue;
}
}
// Instruction isn't dead, see if we can constant propagate it...
if (Constant *C = ConstantFoldInstruction(I)) {
@ -1960,12 +1959,9 @@ bool InstCombiner::runOnFunction(Function &F) {
ReplaceInstUsesWith(*I, C);
++NumConstProp;
BasicBlock::iterator BBI = I;
if (dceInstruction(BBI)) {
removeFromWorkList(I);
I->getParent()->getInstList().erase(I);
continue;
}
}
// Now that we have an instruction, try combining it to simplify it...
if (Instruction *Result = visit(*I)) {
@ -1975,7 +1971,20 @@ bool InstCombiner::runOnFunction(Function &F) {
// Instructions can end up on the worklist more than once. Make sure
// we do not process an instruction that has been deleted.
removeFromWorkList(I);
ReplaceInstWithInst(I, Result);
// Move the name to the new instruction first...
std::string OldName = I->getName(); I->setName("");
Result->setName(I->getName());
// Insert the new instruction into the basic block...
BasicBlock *InstParent = I->getParent();
InstParent->getInstList().insert(I, Result);
// Everything uses the new instruction now...
I->replaceAllUsesWith(Result);
// Erase the old instruction.
InstParent->getInstList().erase(I);
} else {
BasicBlock::iterator II = I;