diff options
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/IndVarSimplify.cpp | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp index 1076e50bc2..08df9533f1 100644 --- a/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -883,6 +883,8 @@ const SCEVAddRecExpr *WidenIV::GetWideRecurrence(Instruction *NarrowUse) { /// This IV user cannot be widen. Replace this use of the original narrow IV /// with a truncation of the new wide IV to isolate and eliminate the narrow IV. static void truncateIVUse(NarrowIVDefUse DU, DominatorTree *DT) { + DEBUG(dbgs() << "INDVARS: Truncate IV " << *DU.WideDef + << " for user " << *DU.NarrowUse << "\n"); IRBuilder<> Builder(getInsertPointForUses(DU.NarrowUse, DU.NarrowDef, DT)); Value *Trunc = Builder.CreateTrunc(DU.WideDef, DU.NarrowDef->getType()); DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, Trunc); @@ -893,10 +895,27 @@ static void truncateIVUse(NarrowIVDefUse DU, DominatorTree *DT) { Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter) { // Stop traversing the def-use chain at inner-loop phis or post-loop phis. - if (isa<PHINode>(DU.NarrowUse) && - LI->getLoopFor(DU.NarrowUse->getParent()) != L) { - truncateIVUse(DU, DT); - return 0; + if (PHINode *UsePhi = dyn_cast<PHINode>(DU.NarrowUse)) { + if (LI->getLoopFor(UsePhi->getParent()) != L) { + // For LCSSA phis, sink the truncate outside the loop. + // After SimplifyCFG most loop exit targets have a single predecessor. + // Otherwise fall back to a truncate within the loop. + if (UsePhi->getNumOperands() != 1) + truncateIVUse(DU, DT); + else { + PHINode *WidePhi = + PHINode::Create(DU.WideDef->getType(), 1, UsePhi->getName() + ".wide", + UsePhi); + WidePhi->addIncoming(DU.WideDef, UsePhi->getIncomingBlock(0)); + IRBuilder<> Builder(WidePhi->getParent()->getFirstInsertionPt()); + Value *Trunc = Builder.CreateTrunc(WidePhi, DU.NarrowDef->getType()); + UsePhi->replaceAllUsesWith(Trunc); + DeadInsts.push_back(UsePhi); + DEBUG(dbgs() << "INDVARS: Widen lcssa phi " << *UsePhi + << " to " << *WidePhi << "\n"); + } + return 0; + } } // Our raison d'etre! Eliminate sign and zero extension. if (IsSigned ? isa<SExtInst>(DU.NarrowUse) : isa<ZExtInst>(DU.NarrowUse)) { |