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Add experimental -enable-lsr-phielim option. 

I'm not sure we will need it in the long run, but the option is
currently useful for checking if the output of LSR is "clean".

llvm-svn: 141634
This commit is contained in:
Andrew Trick 2011-10-11 02:30:45 +00:00
parent f9201c572e
commit ecbe22bb8d
1 changed files with 22 additions and 0 deletions
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22
llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -83,6 +83,12 @@ cl::opt<bool> EnableNested(
cl::opt<bool> EnableRetry(
"enable-lsr-retry", cl::Hidden, cl::desc("Enable LSR retry"));
// Temporary flag to cleanup congruent phis after LSR phi expansion.
// It's currently disabled until we can determine whether it's truly useful or
// not. The flag should be removed after the v3.0 release.
cl::opt<bool> EnablePhiElim(
"enable-lsr-phielim", cl::Hidden, cl::desc("Enable LSR phi elimination"));
}
namespace {
@ -3816,6 +3822,14 @@ LSRInstance::LSRInstance(const TargetLowering *tli, Loop *l, Pass *P)
// Skip nested loops until we can model them better with formulae.
if (!EnableNested && !L->empty()) {
if (EnablePhiElim) {
// Remove any extra phis created by processing inner loops.
SmallVector<WeakVH, 16> DeadInsts;
SCEVExpander Rewriter(SE, "lsr");
Changed |= Rewriter.replaceCongruentIVs(L, &DT, DeadInsts);
Changed |= DeleteTriviallyDeadInstructions(DeadInsts);
}
DEBUG(dbgs() << "LSR skipping outer loop " << *L << "\n");
return;
}
@ -3861,6 +3875,14 @@ LSRInstance::LSRInstance(const TargetLowering *tli, Loop *l, Pass *P)
// Now that we've decided what we want, make it so.
ImplementSolution(Solution, P);
if (EnablePhiElim) {
// Remove any extra phis created by processing inner loops.
SmallVector<WeakVH, 16> DeadInsts;
SCEVExpander Rewriter(SE, "lsr");
Changed |= Rewriter.replaceCongruentIVs(L, &DT, DeadInsts);
Changed |= DeleteTriviallyDeadInstructions(DeadInsts);
}
}
void LSRInstance::print_factors_and_types(raw_ostream &OS) const {