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Pull in r191896 from upstream llvm trunk:

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CaptureTracking: Plug a loophole in the "too many uses" heuristic.

  The heuristic was added to avoid spending too much compile time in a
  specially crafted test case (PR17461, PR16474) with many uses on a
  select or bitcast instruction can still trigger the slow case. Add a
  check for that case.

  This only affects compile time, don't have a good way to test it.

This fixes the excessive compile time spent on a specific file of the
graphics/rawtherapee port.

Reported by:	mandree
MFC after:	3 days
This commit is contained in:
Dimitry Andric 2013-11-19 17:53:19 +00:00
parent 5313966ea6
commit 110f993aa9
1 changed files with 6 additions and 0 deletions
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6
contrib/llvm/lib/Analysis/CaptureTracking.cpp
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@ -146,8 +146,14 @@ void llvm::PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker) {
case Instruction::PHI:
case Instruction::Select:
// The original value is not captured via this if the new value isn't.
Count = 0;
for (Instruction::use_iterator UI = I->use_begin(), UE = I->use_end();
UI != UE; ++UI) {
// If there are lots of uses, conservatively say that the value
// is captured to avoid taking too much compile time.
if (Count++ >= Threshold)
return Tracker->tooManyUses();
Use *U = &UI.getUse();
if (Visited.insert(U))
if (Tracker->shouldExplore(U))