[llvm] c71890e - [LoopPeel][NFC] Exit early if there is no room for peeling
Igor Kudrin via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 26 07:45:06 PDT 2022
Author: Igor Kudrin
Date: 2022-04-26T18:43:56+04:00
New Revision: c71890e158df43d2aa4fbdbfb7adf6791d4cb66b
URL: https://github.com/llvm/llvm-project/commit/c71890e158df43d2aa4fbdbfb7adf6791d4cb66b
DIFF: https://github.com/llvm/llvm-project/commit/c71890e158df43d2aa4fbdbfb7adf6791d4cb66b.diff
LOG: [LoopPeel][NFC] Exit early if there is no room for peeling
Differential Revision: https://reviews.llvm.org/D123864
Added:
Modified:
llvm/lib/Transforms/Utils/LoopPeel.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Utils/LoopPeel.cpp b/llvm/lib/Transforms/Utils/LoopPeel.cpp
index 609e10c212e9d..23df7a0cd34b8 100644
--- a/llvm/lib/Transforms/Utils/LoopPeel.cpp
+++ b/llvm/lib/Transforms/Utils/LoopPeel.cpp
@@ -386,6 +386,10 @@ void llvm::computePeelCount(Loop *L, unsigned LoopSize,
if (!PP.AllowPeeling)
return;
+ // Check that we can peel at least one iteration.
+ if (2 * LoopSize > Threshold)
+ return;
+
unsigned AlreadyPeeled = 0;
if (auto Peeled = getOptionalIntLoopAttribute(L, PeeledCountMetaData))
AlreadyPeeled = *Peeled;
@@ -398,47 +402,45 @@ void llvm::computePeelCount(Loop *L, unsigned LoopSize,
// which every Phi is guaranteed to become an invariant, and try to peel the
// maximum number of iterations among these values, thus turning all those
// Phis into invariants.
- // First, check that we can peel at least one iteration.
- if (2 * LoopSize <= Threshold && UnrollPeelMaxCount > 0) {
- // Store the pre-calculated values here.
- SmallDenseMap<PHINode *, Optional<unsigned> > IterationsToInvariance;
- // Now go through all Phis to calculate their the number of iterations they
- // need to become invariants.
- // Start the max computation with the PP.PeelCount value set by the target
- // in TTI.getPeelingPreferences or by the flag -unroll-peel-count.
- unsigned DesiredPeelCount = TargetPeelCount;
- BasicBlock *BackEdge = L->getLoopLatch();
- assert(BackEdge && "Loop is not in simplified form?");
- for (auto BI = L->getHeader()->begin(); isa<PHINode>(&*BI); ++BI) {
- PHINode *Phi = cast<PHINode>(&*BI);
- auto ToInvariance = calculateIterationsToInvariance(
- Phi, L, BackEdge, IterationsToInvariance);
- if (ToInvariance)
- DesiredPeelCount = std::max(DesiredPeelCount, *ToInvariance);
- }
- // Pay respect to limitations implied by loop size and the max peel count.
- unsigned MaxPeelCount = UnrollPeelMaxCount;
- MaxPeelCount = std::min(MaxPeelCount, Threshold / LoopSize - 1);
-
- DesiredPeelCount = std::max(DesiredPeelCount,
- countToEliminateCompares(*L, MaxPeelCount, SE));
-
- if (DesiredPeelCount == 0)
- DesiredPeelCount = peelToTurnInvariantLoadsDerefencebale(*L, DT);
-
- if (DesiredPeelCount > 0) {
- DesiredPeelCount = std::min(DesiredPeelCount, MaxPeelCount);
- // Consider max peel count limitation.
- assert(DesiredPeelCount > 0 && "Wrong loop size estimation?");
- if (DesiredPeelCount + AlreadyPeeled <= UnrollPeelMaxCount) {
- LLVM_DEBUG(dbgs() << "Peel " << DesiredPeelCount
- << " iteration(s) to turn"
- << " some Phis into invariants.\n");
- PP.PeelCount = DesiredPeelCount;
- PP.PeelProfiledIterations = false;
- return;
- }
+ // Store the pre-calculated values here.
+ SmallDenseMap<PHINode *, Optional<unsigned>> IterationsToInvariance;
+ // Now go through all Phis to calculate their the number of iterations they
+ // need to become invariants.
+ // Start the max computation with the PP.PeelCount value set by the target
+ // in TTI.getPeelingPreferences or by the flag -unroll-peel-count.
+ unsigned DesiredPeelCount = TargetPeelCount;
+ BasicBlock *BackEdge = L->getLoopLatch();
+ assert(BackEdge && "Loop is not in simplified form?");
+ for (auto BI = L->getHeader()->begin(); isa<PHINode>(&*BI); ++BI) {
+ PHINode *Phi = cast<PHINode>(&*BI);
+ auto ToInvariance = calculateIterationsToInvariance(Phi, L, BackEdge,
+ IterationsToInvariance);
+ if (ToInvariance)
+ DesiredPeelCount = std::max(DesiredPeelCount, *ToInvariance);
+ }
+
+ // Pay respect to limitations implied by loop size and the max peel count.
+ unsigned MaxPeelCount = UnrollPeelMaxCount;
+ MaxPeelCount = std::min(MaxPeelCount, Threshold / LoopSize - 1);
+
+ DesiredPeelCount = std::max(DesiredPeelCount,
+ countToEliminateCompares(*L, MaxPeelCount, SE));
+
+ if (DesiredPeelCount == 0)
+ DesiredPeelCount = peelToTurnInvariantLoadsDerefencebale(*L, DT);
+
+ if (DesiredPeelCount > 0) {
+ DesiredPeelCount = std::min(DesiredPeelCount, MaxPeelCount);
+ // Consider max peel count limitation.
+ assert(DesiredPeelCount > 0 && "Wrong loop size estimation?");
+ if (DesiredPeelCount + AlreadyPeeled <= UnrollPeelMaxCount) {
+ LLVM_DEBUG(dbgs() << "Peel " << DesiredPeelCount
+ << " iteration(s) to turn"
+ << " some Phis into invariants.\n");
+ PP.PeelCount = DesiredPeelCount;
+ PP.PeelProfiledIterations = false;
+ return;
}
}
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