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[SCEVExpander] Fix a failed cast<> assertion
SCEVExpander::replaceCongruentIVs assumes the backedge value of an SCEV-analysable PHI to always be an instruction, when this is not necessarily true. For now address this by bailing out of the optimization if the backedge value of the PHI is a non-Instruction. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269213 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjoy Das
parent
5bbe5abe5e
commit
2731c7a952
@ -1794,51 +1794,55 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
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continue;
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if (BasicBlock *LatchBlock = L->getLoopLatch()) {
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Instruction *OrigInc =
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cast<Instruction>(OrigPhiRef->getIncomingValueForBlock(LatchBlock));
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Instruction *OrigInc = dyn_cast<Instruction>(
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OrigPhiRef->getIncomingValueForBlock(LatchBlock));
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Instruction *IsomorphicInc =
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cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
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dyn_cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
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// If this phi has the same width but is more canonical, replace the
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// original with it. As part of the "more canonical" determination,
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// respect a prior decision to use an IV chain.
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if (OrigPhiRef->getType() == Phi->getType() &&
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!(ChainedPhis.count(Phi) ||
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isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)) &&
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(ChainedPhis.count(Phi) ||
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isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
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std::swap(OrigPhiRef, Phi);
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std::swap(OrigInc, IsomorphicInc);
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}
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// Replacing the congruent phi is sufficient because acyclic redundancy
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// elimination, CSE/GVN, should handle the rest. However, once SCEV proves
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// that a phi is congruent, it's often the head of an IV user cycle that
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// is isomorphic with the original phi. It's worth eagerly cleaning up the
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// common case of a single IV increment so that DeleteDeadPHIs can remove
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// cycles that had postinc uses.
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const SCEV *TruncExpr = SE.getTruncateOrNoop(SE.getSCEV(OrigInc),
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IsomorphicInc->getType());
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if (OrigInc != IsomorphicInc && TruncExpr == SE.getSCEV(IsomorphicInc) &&
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SE.LI.replacementPreservesLCSSAForm(IsomorphicInc, OrigInc) &&
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hoistIVInc(OrigInc, IsomorphicInc)) {
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DEBUG_WITH_TYPE(DebugType,
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dbgs() << "INDVARS: Eliminated congruent iv.inc: "
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<< *IsomorphicInc << '\n');
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Value *NewInc = OrigInc;
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if (OrigInc->getType() != IsomorphicInc->getType()) {
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Instruction *IP = nullptr;
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if (PHINode *PN = dyn_cast<PHINode>(OrigInc))
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IP = &*PN->getParent()->getFirstInsertionPt();
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else
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IP = OrigInc->getNextNode();
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IRBuilder<> Builder(IP);
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Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
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NewInc = Builder.
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CreateTruncOrBitCast(OrigInc, IsomorphicInc->getType(), IVName);
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if (OrigInc && IsomorphicInc) {
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// If this phi has the same width but is more canonical, replace the
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// original with it. As part of the "more canonical" determination,
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// respect a prior decision to use an IV chain.
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if (OrigPhiRef->getType() == Phi->getType() &&
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!(ChainedPhis.count(Phi) ||
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isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)) &&
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(ChainedPhis.count(Phi) ||
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isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
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std::swap(OrigPhiRef, Phi);
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std::swap(OrigInc, IsomorphicInc);
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}
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// Replacing the congruent phi is sufficient because acyclic
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// redundancy elimination, CSE/GVN, should handle the
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// rest. However, once SCEV proves that a phi is congruent,
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// it's often the head of an IV user cycle that is isomorphic
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// with the original phi. It's worth eagerly cleaning up the
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// common case of a single IV increment so that DeleteDeadPHIs
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// can remove cycles that had postinc uses.
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const SCEV *TruncExpr =
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SE.getTruncateOrNoop(SE.getSCEV(OrigInc), IsomorphicInc->getType());
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if (OrigInc != IsomorphicInc &&
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TruncExpr == SE.getSCEV(IsomorphicInc) &&
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SE.LI.replacementPreservesLCSSAForm(IsomorphicInc, OrigInc) &&
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hoistIVInc(OrigInc, IsomorphicInc)) {
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DEBUG_WITH_TYPE(DebugType,
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dbgs() << "INDVARS: Eliminated congruent iv.inc: "
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<< *IsomorphicInc << '\n');
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Value *NewInc = OrigInc;
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if (OrigInc->getType() != IsomorphicInc->getType()) {
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Instruction *IP = nullptr;
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if (PHINode *PN = dyn_cast<PHINode>(OrigInc))
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IP = &*PN->getParent()->getFirstInsertionPt();
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else
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IP = OrigInc->getNextNode();
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IRBuilder<> Builder(IP);
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Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
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NewInc = Builder.CreateTruncOrBitCast(
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OrigInc, IsomorphicInc->getType(), IVName);
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}
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IsomorphicInc->replaceAllUsesWith(NewInc);
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DeadInsts.emplace_back(IsomorphicInc);
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}
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IsomorphicInc->replaceAllUsesWith(NewInc);
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DeadInsts.emplace_back(IsomorphicInc);
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}
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}
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DEBUG_WITH_TYPE(DebugType, dbgs() << "INDVARS: Eliminated congruent iv: "
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@ -39,3 +39,73 @@ loop_1:
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leave:
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ret void
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}
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; @ReplaceArg_0 and @ReplaceArg_1 used to trigger a failed cast<>
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; assertion in SCEVExpander.
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define void @ReplaceArg_0(i32 %val) {
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; CHECK-LABEL: @ReplaceArg_0(
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entry:
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br i1 undef, label %loop_0.cond, label %for.body.us
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for.body.us:
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br label %loop_0.cond
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loop_0.cond:
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br i1 true, label %loop_0.ph, label %loop_1.ph
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loop_0.ph:
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br label %loop_0
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loop_1.exit:
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br label %loop_1.ph
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loop_1.ph:
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%c.lcssa = phi i32 [ 0, %loop_0.cond ], [ %val, %loop_1.exit ]
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br label %loop_1
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loop_0:
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br i1 undef, label %loop_0, label %loop_1.exit
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loop_1:
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%d.1 = phi i32 [ %c.lcssa, %loop_1 ], [ %val, %loop_1.ph ]
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%t.1 = phi i32 [ %val, %loop_1 ], [ %c.lcssa, %loop_1.ph ]
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br i1 undef, label %leave, label %loop_1
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leave:
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ret void
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}
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define void @ReplaceArg_1(i32 %val) {
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; CHECK-LABEL: @ReplaceArg_1(
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entry:
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br i1 undef, label %loop_0.cond, label %for.body.us
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for.body.us:
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br label %loop_0.cond
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loop_0.cond:
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br i1 true, label %loop_0.ph, label %loop_1.ph
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loop_0.ph:
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br label %loop_0
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loop_1.exit:
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br label %loop_1.ph
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loop_1.ph:
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%c.lcssa = phi i32 [ 0, %loop_0.cond ], [ %val, %loop_1.exit ]
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br label %loop_1
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loop_0:
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br i1 undef, label %loop_0, label %loop_1.exit
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loop_1:
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%t.1 = phi i32 [ %val, %loop_1 ], [ %c.lcssa, %loop_1.ph ]
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%d.1 = phi i32 [ %c.lcssa, %loop_1 ], [ %val, %loop_1.ph ]
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br i1 undef, label %leave, label %loop_1
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leave:
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ret void
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}
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