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[Unroll] Add debug dumps to loop-unroll analyzer.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243471 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Zolotukhin 2015-07-28 20:07:29 +00:00
parent 0ed54d8a2f
commit c82121e77d
1 changed files with 21 additions and 2 deletions
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23
lib/Transforms/Scalar/LoopUnrollPass.cpp
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@ -543,11 +543,14 @@ analyzeLoopUnrollCost(const Loop *L, unsigned TripCount, ScalarEvolution &SE,
// unrolling. // unrolling.
unsigned RolledDynamicCost = 0; unsigned RolledDynamicCost = 0;
DEBUG(dbgs() << "Starting LoopUnroll profitability analysis...\n");
// Simulate execution of each iteration of the loop counting instructions, // Simulate execution of each iteration of the loop counting instructions,
// which would be simplified. // which would be simplified.
// Since the same load will take different values on different iterations, // Since the same load will take different values on different iterations,
// we literally have to go through all loop's iterations. // we literally have to go through all loop's iterations.
for (unsigned Iteration = 0; Iteration < TripCount; ++Iteration) { for (unsigned Iteration = 0; Iteration < TripCount; ++Iteration) {
DEBUG(dbgs() << " Analyzing iteration " << Iteration << "\n");
SimplifiedValues.clear(); SimplifiedValues.clear();
UnrolledInstAnalyzer Analyzer(Iteration, SimplifiedValues, L, SE); UnrolledInstAnalyzer Analyzer(Iteration, SimplifiedValues, L, SE);
@ -568,14 +571,24 @@ analyzeLoopUnrollCost(const Loop *L, unsigned TripCount, ScalarEvolution &SE,
// unrolled cost. // unrolled cost.
if (!Analyzer.visit(I)) if (!Analyzer.visit(I))
UnrolledCost += InstCost; UnrolledCost += InstCost;
else {
DEBUG(dbgs() << " " << I
<< " would be simplified if loop is unrolled.\n");
(void)0;
}
// Also track this instructions expected cost when executing the rolled // Also track this instructions expected cost when executing the rolled
// loop form. // loop form.
RolledDynamicCost += InstCost; RolledDynamicCost += InstCost;
// If unrolled body turns out to be too big, bail out. // If unrolled body turns out to be too big, bail out.
if (UnrolledCost > MaxUnrolledLoopSize) if (UnrolledCost > MaxUnrolledLoopSize) {
DEBUG(dbgs() << " Exceeded threshold.. exiting.\n"
<< " UnrolledCost: " << UnrolledCost
<< ", MaxUnrolledLoopSize: " << MaxUnrolledLoopSize
<< "\n");
return None; return None;
}
} }
TerminatorInst *TI = BB->getTerminator(); TerminatorInst *TI = BB->getTerminator();
@ -612,9 +625,15 @@ analyzeLoopUnrollCost(const Loop *L, unsigned TripCount, ScalarEvolution &SE,
// If we found no optimization opportunities on the first iteration, we // If we found no optimization opportunities on the first iteration, we
// won't find them on later ones too. // won't find them on later ones too.
if (UnrolledCost == RolledDynamicCost) if (UnrolledCost == RolledDynamicCost) {
DEBUG(dbgs() << " No opportunities found.. exiting.\n"
<< " UnrolledCost: " << UnrolledCost << "\n");
return None; return None;
}
} }
DEBUG(dbgs() << "Analysis finished:\n"
<< "UnrolledCost: " << UnrolledCost << ", "
<< "RolledDynamicCost: " << RolledDynamicCost << "\n");
return {{UnrolledCost, RolledDynamicCost}}; return {{UnrolledCost, RolledDynamicCost}};
} }