diff options
Diffstat (limited to 'lib/Transforms/Utils/LoopUnrollRuntime.cpp')
-rw-r--r-- | lib/Transforms/Utils/LoopUnrollRuntime.cpp | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/lib/Transforms/Utils/LoopUnrollRuntime.cpp index 381d8fc..d1774df 100644 --- a/lib/Transforms/Utils/LoopUnrollRuntime.cpp +++ b/lib/Transforms/Utils/LoopUnrollRuntime.cpp @@ -278,7 +278,8 @@ static void CloneLoopBlocks(Loop *L, Value *NewIter, const bool UnrollProlog, /// ... /// End: /// -bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI, +bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, + bool AllowExpensiveTripCount, LoopInfo *LI, LPPassManager *LPM) { // for now, only unroll loops that contain a single exit if (!L->getExitingBlock()) @@ -312,15 +313,20 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI, if (isa<SCEVCouldNotCompute>(TripCountSC)) return false; + BasicBlock *Header = L->getHeader(); + const DataLayout &DL = Header->getModule()->getDataLayout(); + SCEVExpander Expander(*SE, DL, "loop-unroll"); + if (!AllowExpensiveTripCount && Expander.isHighCostExpansion(TripCountSC, L)) + return false; + // We only handle cases when the unroll factor is a power of 2. // Count is the loop unroll factor, the number of extra copies added + 1. if (!isPowerOf2_32(Count)) return false; // This constraint lets us deal with an overflowing trip count easily; see the - // comment on ModVal below. This check is equivalent to `Log2(Count) < - // BEWidth`. - if (static_cast<uint64_t>(Count) > (1ULL << BEWidth)) + // comment on ModVal below. + if (Log2_32(Count) > BEWidth) return false; // If this loop is nested, then the loop unroller changes the code in @@ -333,18 +339,15 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI, auto *DT = DTWP ? &DTWP->getDomTree() : nullptr; BasicBlock *PH = L->getLoopPreheader(); - BasicBlock *Header = L->getHeader(); BasicBlock *Latch = L->getLoopLatch(); // It helps to splits the original preheader twice, one for the end of the // prolog code and one for a new loop preheader BasicBlock *PEnd = SplitEdge(PH, Header, DT, LI); BasicBlock *NewPH = SplitBlock(PEnd, PEnd->getTerminator(), DT, LI); BranchInst *PreHeaderBR = cast<BranchInst>(PH->getTerminator()); - const DataLayout &DL = Header->getModule()->getDataLayout(); // Compute the number of extra iterations required, which is: // extra iterations = run-time trip count % (loop unroll factor + 1) - SCEVExpander Expander(*SE, DL, "loop-unroll"); Value *TripCount = Expander.expandCodeFor(TripCountSC, TripCountSC->getType(), PreHeaderBR); Value *BECount = Expander.expandCodeFor(BECountSC, BECountSC->getType(), |