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[IndVars] Factor out some common code into a utility function 

As requested in review of D69009

llvm-svn: 375191
This commit is contained in:
Philip Reames 2019-10-17 23:49:46 +00:00
parent 3266eac714
commit 8eaa5b9aba
1 changed files with 13 additions and 16 deletions
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29
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -2717,10 +2717,19 @@ bool IndVarSimplify::optimizeLoopExits(Loop *L, SCEVExpander &Rewriter) {
if (isa<SCEVCouldNotCompute>(MaxExitCount))
return false;
auto FoldExit = [&](BasicBlock *ExitingBB, bool IsTaken) {
BranchInst *BI = cast<BranchInst>(ExitingBB->getTerminator());
bool ExitIfTrue = !L->contains(*succ_begin(ExitingBB));
auto *OldCond = BI->getCondition();
auto *NewCond = ConstantInt::get(OldCond->getType(),
IsTaken ? ExitIfTrue : !ExitIfTrue);
BI->setCondition(NewCond);
if (OldCond->use_empty())
DeadInsts.push_back(OldCond);
};
bool Changed = false;
for (BasicBlock *ExitingBB : ExitingBlocks) {
BranchInst *BI = cast<BranchInst>(ExitingBB->getTerminator());
const SCEV *ExitCount = SE->getExitCount(L, ExitingBB);
assert(!isa<SCEVCouldNotCompute>(ExitCount) && "checked above");
@ -2730,13 +2739,7 @@ bool IndVarSimplify::optimizeLoopExits(Loop *L, SCEVExpander &Rewriter) {
// TODO: Given we know the backedge can't be taken, we should go ahead
// and break it. Or at least, kill all the header phis and simplify.
if (ExitCount->isZero()) {
bool ExitIfTrue = !L->contains(*succ_begin(ExitingBB));
auto *OldCond = BI->getCondition();
auto *NewCond = ExitIfTrue ? ConstantInt::getTrue(OldCond->getType()) :
ConstantInt::getFalse(OldCond->getType());
BI->setCondition(NewCond);
if (OldCond->use_empty())
DeadInsts.push_back(OldCond);
FoldExit(ExitingBB, true);
Changed = true;
continue;
}
@ -2758,13 +2761,7 @@ bool IndVarSimplify::optimizeLoopExits(Loop *L, SCEVExpander &Rewriter) {
// one?
if (SE->isLoopEntryGuardedByCond(L, CmpInst::ICMP_ULT,
MaxExitCount, ExitCount)) {
bool ExitIfTrue = !L->contains(*succ_begin(ExitingBB));
auto *OldCond = BI->getCondition();
auto *NewCond = ExitIfTrue ? ConstantInt::getFalse(OldCond->getType()) :
ConstantInt::getTrue(OldCond->getType());
BI->setCondition(NewCond);
if (OldCond->use_empty())
DeadInsts.push_back(OldCond);
FoldExit(ExitingBB, false);
Changed = true;
continue;
}