diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp | 44 |
1 files changed, 39 insertions, 5 deletions
diff --git a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp index 8e81541c233..85db6e5e110 100644 --- a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp +++ b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp @@ -446,6 +446,15 @@ struct LoopStructure { BasicBlock *LatchExit; unsigned LatchBrExitIdx; + // The loop represented by this instance of LoopStructure is semantically + // equivalent to: + // + // intN_ty inc = IndVarIncreasing ? 1 : -1; + // pred_ty predicate = IndVarIncreasing ? ICMP_SLT : ICMP_SGT; + // + // for (intN_ty iv = IndVarStart; predicate(iv, LoopExitAt); iv = IndVarNext) + // ... body ... + Value *IndVarNext; Value *IndVarStart; Value *LoopExitAt; @@ -789,6 +798,10 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP return None; } + const SCEV *StartNext = IndVarNext->getStart(); + const SCEV *Addend = SE.getNegativeSCEV(IndVarNext->getStepRecurrence(SE)); + const SCEV *IndVarStart = SE.getAddExpr(StartNext, Addend); + ConstantInt *One = ConstantInt::get(IndVarTy, 1); // TODO: generalize the predicates here to also match their unsigned variants. if (IsIncreasing) { @@ -809,10 +822,22 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP return None; } + if (!SE.isLoopEntryGuardedByCond( + &L, CmpInst::ICMP_SLT, IndVarStart, + SE.getAddExpr(RightSCEV, SE.getOne(RightSCEV->getType())))) { + FailureReason = "Induction variable start not bounded by upper limit"; + return None; + } + IRBuilder<> B(Preheader->getTerminator()); RightValue = B.CreateAdd(RightValue, One); + } else { + if (!SE.isLoopEntryGuardedByCond(&L, CmpInst::ICMP_SLT, IndVarStart, + RightSCEV)) { + FailureReason = "Induction variable start not bounded by upper limit"; + return None; + } } - } else { bool FoundExpectedPred = (Pred == ICmpInst::ICMP_SGT && LatchBrExitIdx == 1) || @@ -831,15 +856,24 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP return None; } + if (!SE.isLoopEntryGuardedByCond( + &L, CmpInst::ICMP_SGT, IndVarStart, + SE.getMinusSCEV(RightSCEV, SE.getOne(RightSCEV->getType())))) { + FailureReason = "Induction variable start not bounded by lower limit"; + return None; + } + IRBuilder<> B(Preheader->getTerminator()); RightValue = B.CreateSub(RightValue, One); + } else { + if (!SE.isLoopEntryGuardedByCond(&L, CmpInst::ICMP_SGT, IndVarStart, + RightSCEV)) { + FailureReason = "Induction variable start not bounded by lower limit"; + return None; + } } } - const SCEV *StartNext = IndVarNext->getStart(); - const SCEV *Addend = SE.getNegativeSCEV(IndVarNext->getStepRecurrence(SE)); - const SCEV *IndVarStart = SE.getAddExpr(StartNext, Addend); - BasicBlock *LatchExit = LatchBr->getSuccessor(LatchBrExitIdx); assert(SE.getLoopDisposition(LatchCount, &L) == |
