diff options
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolutionExpander.cpp | 30 |
1 files changed, 11 insertions, 19 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp index d0b36431130..ed7386b26f8 100644 --- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp @@ -1815,11 +1815,11 @@ Value *SCEVExpander::findExistingExpansion(const SCEV *S, const Instruction *At, Loop *L) { using namespace llvm::PatternMatch; - SmallVector<BasicBlock *, 4> Latches; - L->getLoopLatches(Latches); + SmallVector<BasicBlock *, 4> ExitingBlocks; + L->getExitingBlocks(ExitingBlocks); - // Look for suitable value in simple conditions at the loop latches. - for (BasicBlock *BB : Latches) { + // Look for suitable value in simple conditions at the loop exits. + for (BasicBlock *BB : ExitingBlocks) { ICmpInst::Predicate Pred; Instruction *LHS, *RHS; BasicBlock *TrueBB, *FalseBB; @@ -1892,22 +1892,14 @@ bool SCEVExpander::isHighCostExpansionHelper( if (!ExitingBB) return true; - BranchInst *ExitingBI = dyn_cast<BranchInst>(ExitingBB->getTerminator()); - if (!ExitingBI || !ExitingBI->isConditional()) + // At the beginning of this function we already tried to find existing value + // for plain 'S'. Now try to lookup 'S + 1' since it is common pattern + // involving division. This is just a simple search heuristic. + if (!At) + At = &ExitingBB->back(); + if (!findExistingExpansion( + SE.getAddExpr(S, SE.getConstant(S->getType(), 1)), At, L)) return true; - - ICmpInst *OrigCond = dyn_cast<ICmpInst>(ExitingBI->getCondition()); - if (!OrigCond) - return true; - - const SCEV *RHS = SE.getSCEV(OrigCond->getOperand(1)); - RHS = SE.getMinusSCEV(RHS, SE.getConstant(RHS->getType(), 1)); - if (RHS != S) { - const SCEV *LHS = SE.getSCEV(OrigCond->getOperand(0)); - LHS = SE.getMinusSCEV(LHS, SE.getConstant(LHS->getType(), 1)); - if (LHS != S) - return true; - } } // HowManyLessThans uses a Max expression whenever the loop is not guarded by |
