Index: lib/Transforms/Scalar/LICM.cpp =================================================================== --- lib/Transforms/Scalar/LICM.cpp +++ lib/Transforms/Scalar/LICM.cpp @@ -31,6 +31,7 @@ //===----------------------------------------------------------------------===// #include "llvm/Transforms/Scalar/LICM.h" +#include "llvm/ADT/SetOperations.h" #include "llvm/ADT/Statistic.h" #include "llvm/Analysis/AliasAnalysis.h" #include "llvm/Analysis/AliasSetTracker.h" @@ -41,6 +42,7 @@ #include "llvm/Analysis/GuardUtils.h" #include "llvm/Analysis/Loads.h" #include "llvm/Analysis/LoopInfo.h" +#include "llvm/Analysis/LoopIterator.h" #include "llvm/Analysis/LoopPass.h" #include "llvm/Analysis/MemoryBuiltins.h" #include "llvm/Analysis/MemorySSA.h" @@ -75,6 +77,8 @@ #define DEBUG_TYPE "licm" +STATISTIC(NumCreatedBlocks, "Number of blocks created"); +STATISTIC(NumClonedBranches, "Number of branches cloned"); STATISTIC(NumSunk, "Number of instructions sunk out of loop"); STATISTIC(NumHoisted, "Number of instructions hoisted out of loop"); STATISTIC(NumMovedLoads, "Number of load insts hoisted or sunk"); @@ -103,7 +107,7 @@ const LoopSafetyInfo *SafetyInfo, TargetTransformInfo *TTI, bool &FreeInLoop); static void hoist(Instruction &I, const DominatorTree *DT, const Loop *CurLoop, - ICFLoopSafetyInfo *SafetyInfo, + BasicBlock *Dest, ICFLoopSafetyInfo *SafetyInfo, OptimizationRemarkEmitter *ORE); static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT, const Loop *CurLoop, ICFLoopSafetyInfo *SafetyInfo, @@ -437,6 +441,225 @@ return Changed; } +// This is a helper class for hoistRegion to make it able to hoist control flow +// in order to be able to hoist phis. The way this works is that we initially +// start hoisting to the loop preheader, and when we see a loop invariant branch +// we make note of this. When we then come to hoist an instruction that's +// conditional on such a branch we duplicate the branch and the relevant control +// flow, then hoist the instruction into the block corresponding to its original +// block in the duplicated control flow. +class ControlFlowHoister { +private: + // Information about the loop we are hoisting from + LoopInfo *LI; + DominatorTree *DT; + Loop *CurLoop; + + // A map of blocks in the loop to the block their instructions will be hoisted + // to. + DenseMap HoistDestinationMap; + + // The branches that we can hoist, mapped to the block that marks a + // convergence point of their control flow. + DenseMap HoistableBranches; + +public: + ControlFlowHoister(LoopInfo *LI, DominatorTree *DT, Loop *CurLoop) + : LI(LI), DT(DT), CurLoop(CurLoop) {} + + void registerPossiblyHoistableBranch(BranchInst *BI) { + // We can only hoist conditional branches with loop invariant operands. + if (!BI->isConditional() || !CurLoop->hasLoopInvariantOperands(BI)) + return; + + // The branch destinations need to be in the loop, and we don't gain + // anything by duplicating conditional branches with duplicate successors, + // as it's essentially the same as an unconditional branch. + BasicBlock *TrueDest = BI->getSuccessor(0); + BasicBlock *FalseDest = BI->getSuccessor(1); + if (!CurLoop->contains(TrueDest) || !CurLoop->contains(FalseDest) || + TrueDest == FalseDest) + return; + + // We can hoist BI if one branch destination is the successor of the other, + // or both have common successor which we check by seeing if the + // intersection of their successors is non-empty. + // TODO: This could be expanded to allowing branches where both ends + // eventually converge to a single block. + SmallPtrSet TrueDestSucc, FalseDestSucc; + TrueDestSucc.insert(succ_begin(TrueDest), succ_end(TrueDest)); + FalseDestSucc.insert(succ_begin(FalseDest), succ_end(FalseDest)); + BasicBlock *CommonSucc = nullptr; + if (TrueDestSucc.count(FalseDest)) { + CommonSucc = FalseDest; + } else if (FalseDestSucc.count(TrueDest)) { + CommonSucc = TrueDest; + } else { + set_intersect(TrueDestSucc, FalseDestSucc); + // If there's one common successor use that. + if (TrueDestSucc.size() == 1) + CommonSucc = *TrueDestSucc.begin(); + // If there's more than one pick whichever appears first in the block list + // (we can't use the value returned by TrueDestSucc.begin() as it's + // unpredicatable which element gets returned). + else if (!TrueDestSucc.empty()) { + Function *F = TrueDest->getParent(); + auto IsSucc = [&](BasicBlock &BB) { return TrueDestSucc.count(&BB); }; + auto It = std::find_if(F->begin(), F->end(), IsSucc); + assert(It != F->end() && "Could not find successor in function"); + CommonSucc = &*It; + } + } + // The common successor has to be dominated by the branch, as otherwise + // there will be some other path to the successor that will not be + // controlled by this branch so any phi we hoist would be controlled by the + // wrong condition. This also takes care of avoiding hoisting of loop back + // edges. + // TODO: In some cases this could be relaxed if the successor is dominated + // by another block that's been hoisted and we can guarantee that the + // control flow has been replicated exactly. + if (CommonSucc && DT->dominates(BI, CommonSucc)) + HoistableBranches[BI] = CommonSucc; + } + + bool canHoistPHI(PHINode *PN) { + // The phi must have loop invariant operands. + if (!CurLoop->hasLoopInvariantOperands(PN)) + return false; + // We can hoist phis if the block they are in is the target of hoistable + // branches which cover all of the predecessors of the block. + SmallPtrSet PredecessorBlocks; + BasicBlock *BB = PN->getParent(); + for (BasicBlock *PredBB : predecessors(BB)) + PredecessorBlocks.insert(PredBB); + // If we have less predecessor blocks than predecessors then the phi will + // have more than one incoming value for the same block which we can't + // handle. + // TODO: This could be handled be erasing some of the duplicate incoming + // values. + if (PredecessorBlocks.size() != pred_size(BB)) + return false; + for (auto &Pair : HoistableBranches) { + if (Pair.second == BB) { + // Which blocks are predecessors via this branch depends on if the + // branch is triangle-like or diamond-like. + if (Pair.first->getSuccessor(0) == BB) { + PredecessorBlocks.erase(Pair.first->getParent()); + PredecessorBlocks.erase(Pair.first->getSuccessor(1)); + } else if (Pair.first->getSuccessor(1) == BB) { + PredecessorBlocks.erase(Pair.first->getParent()); + PredecessorBlocks.erase(Pair.first->getSuccessor(0)); + } else { + PredecessorBlocks.erase(Pair.first->getSuccessor(0)); + PredecessorBlocks.erase(Pair.first->getSuccessor(1)); + } + } + } + // PredecessorBlocks will now be empty if for every predecessor of BB we + // found a hoistable branch source. + return PredecessorBlocks.empty(); + } + + BasicBlock *getOrCreateHoistedBlock(BasicBlock *BB) { + // If BB has already been hoisted, return that + if (HoistDestinationMap.count(BB)) + return HoistDestinationMap[BB]; + + // Check if this block is conditional based on a pending branch + auto HasBBAsSuccessor = + [&](DenseMap::value_type &Pair) { + return BB != Pair.second && (Pair.first->getSuccessor(0) == BB || + Pair.first->getSuccessor(1) == BB); + }; + auto It = std::find_if(HoistableBranches.begin(), HoistableBranches.end(), + HasBBAsSuccessor); + + // If not involved in a pending branch, hoist to preheader + BasicBlock *InitialPreheader = CurLoop->getLoopPreheader(); + if (It == HoistableBranches.end()) { + LLVM_DEBUG(dbgs() << "LICM using " << InitialPreheader->getName() + << " as hoist destination for " << BB->getName() + << "\n"); + HoistDestinationMap[BB] = InitialPreheader; + return InitialPreheader; + } + BranchInst *BI = It->first; + assert(std::find_if(++It, HoistableBranches.end(), HasBBAsSuccessor) == + HoistableBranches.end() && + "BB is expected to be the target of at most one branch"); + + LLVMContext &C = BB->getContext(); + BasicBlock *TrueDest = BI->getSuccessor(0); + BasicBlock *FalseDest = BI->getSuccessor(1); + BasicBlock *CommonSucc = HoistableBranches[BI]; + BasicBlock *HoistTarget = getOrCreateHoistedBlock(BI->getParent()); + + // Create hoisted versions of blocks that currently don't have them + auto CreateHoistedBlock = [&](BasicBlock *Orig) { + if (HoistDestinationMap.count(Orig)) + return HoistDestinationMap[Orig]; + BasicBlock *New = + BasicBlock::Create(C, Orig->getName() + ".licm", Orig->getParent()); + HoistDestinationMap[Orig] = New; + DT->addNewBlock(New, HoistTarget); + if (CurLoop->getParentLoop()) + CurLoop->getParentLoop()->addBasicBlockToLoop(New, *LI); + ++NumCreatedBlocks; + LLVM_DEBUG(dbgs() << "LICM created " << New->getName() + << " as hoist destination for " << Orig->getName() + << "\n"); + return New; + }; + BasicBlock *HoistTrueDest = CreateHoistedBlock(TrueDest); + BasicBlock *HoistFalseDest = CreateHoistedBlock(FalseDest); + BasicBlock *HoistCommonSucc = CreateHoistedBlock(CommonSucc); + + // Link up these blocks with branches. + if (!HoistCommonSucc->getTerminator()) { + // The new common successor we've generated will branch to whatever that + // hoist target branched to. + BasicBlock *TargetSucc = HoistTarget->getSingleSuccessor(); + assert(TargetSucc && "Expected hoist target to have a single successor"); + HoistCommonSucc->moveBefore(TargetSucc); + BranchInst::Create(TargetSucc, HoistCommonSucc); + } + if (!HoistTrueDest->getTerminator()) { + HoistTrueDest->moveBefore(HoistCommonSucc); + BranchInst::Create(HoistCommonSucc, HoistTrueDest); + } + if (!HoistFalseDest->getTerminator()) { + HoistFalseDest->moveBefore(HoistCommonSucc); + BranchInst::Create(HoistCommonSucc, HoistFalseDest); + } + + // If BI is being cloned to what was originally the preheader then + // HoistCommonSucc will now be the new preheader. + if (HoistTarget == InitialPreheader) { + // Phis in the loop header now need to use the new preheader. + InitialPreheader->replaceSuccessorsPhiUsesWith(HoistCommonSucc); + // The new preheader dominates the loop header. + DomTreeNode *PreheaderNode = DT->getNode(HoistCommonSucc); + DomTreeNode *HeaderNode = DT->getNode(CurLoop->getHeader()); + DT->changeImmediateDominator(HeaderNode, PreheaderNode); + // The preheader hoist destination is now the new preheader, with the + // exception of the hoist destination of this branch. + for (auto &Pair : HoistDestinationMap) + if (Pair.second == InitialPreheader && Pair.first != BI->getParent()) + Pair.second = HoistCommonSucc; + } + + // Now finally clone BI. + ReplaceInstWithInst( + HoistTarget->getTerminator(), + BranchInst::Create(HoistTrueDest, HoistFalseDest, BI->getCondition())); + ++NumClonedBranches; + + assert(CurLoop->getLoopPreheader() && + "Hoisting blocks should not have destroyed preheader"); + return HoistDestinationMap[BB]; + } +}; + /// Walk the specified region of the CFG (defined by all blocks dominated by /// the specified block, and that are in the current loop) in depth first /// order w.r.t the DominatorTree. This allows us to visit definitions before @@ -451,13 +674,23 @@ CurLoop != nullptr && CurAST != nullptr && SafetyInfo != nullptr && "Unexpected input to hoistRegion"); - // We want to visit parents before children. We will enque all the parents - // before their children in the worklist and process the worklist in order. - SmallVector Worklist = collectChildrenInLoop(N, CurLoop); + ControlFlowHoister CFH(LI, DT, CurLoop); + + // Keep track of instructions that have been hoisted, as they may need to be + // re-hoisted if they end up not dominating all of their uses. + SmallVector HoistedInstructions; + // Record what the original preheader is, as we'll need it later if we need to + // re-hoist instructions. + BasicBlock *OriginalPreheader = CurLoop->getLoopPreheader(); + + // For PHI hoisting to work we need to hoist blocks before their successors. + // We can do this by iterating through the blocks in the loop in reverse + // post-order. + LoopBlocksRPO Worklist(CurLoop); + Worklist.perform(LI); bool Changed = false; - for (DomTreeNode *DTN : Worklist) { - BasicBlock *BB = DTN->getBlock(); + for (BasicBlock *BB : Worklist) { // Only need to process the contents of this block if it is not part of a // subloop (which would already have been processed). if (inSubLoop(BB, CurLoop, LI)) @@ -483,13 +716,16 @@ // Try hoisting the instruction out to the preheader. We can only do // this if all of the operands of the instruction are loop invariant and // if it is safe to hoist the instruction. - // + // TODO: It may be safe to hoist if we are hoisting to a conditional block + // and we have accurately duplicated the control flow from the loop header + // to that block. if (CurLoop->hasLoopInvariantOperands(&I) && canSinkOrHoistInst(I, AA, DT, CurLoop, CurAST, true, ORE) && isSafeToExecuteUnconditionally( I, DT, CurLoop, SafetyInfo, ORE, CurLoop->getLoopPreheader()->getTerminator())) { - hoist(I, DT, CurLoop, SafetyInfo, ORE); + hoist(I, DT, CurLoop, CFH.getOrCreateHoistedBlock(BB), SafetyInfo, ORE); + HoistedInstructions.push_back(&I); Changed = true; continue; } @@ -514,7 +750,9 @@ I.replaceAllUsesWith(Product); eraseInstruction(I, *SafetyInfo, CurAST); - hoist(*ReciprocalDivisor, DT, CurLoop, SafetyInfo, ORE); + hoist(*ReciprocalDivisor, DT, CurLoop, CFH.getOrCreateHoistedBlock(BB), + SafetyInfo, ORE); + HoistedInstructions.push_back(ReciprocalDivisor); Changed = true; continue; } @@ -526,13 +764,58 @@ CurLoop->hasLoopInvariantOperands(&I) && SafetyInfo->isGuaranteedToExecute(I, DT, CurLoop) && SafetyInfo->doesNotWriteMemoryBefore(I, CurLoop)) { - hoist(I, DT, CurLoop, SafetyInfo, ORE); + hoist(I, DT, CurLoop, CFH.getOrCreateHoistedBlock(BB), SafetyInfo, ORE); + HoistedInstructions.push_back(&I); Changed = true; continue; } + + if (PHINode *PN = dyn_cast(&I)) { + if (CFH.canHoistPHI(PN)) { + // Redirect incoming blocks first to ensure that we create hoisted + // versions of those blocks before we hoist the phi. + for (unsigned int i = 0; i < PN->getNumIncomingValues(); ++i) + PN->setIncomingBlock( + i, CFH.getOrCreateHoistedBlock(PN->getIncomingBlock(i))); + hoist(*PN, DT, CurLoop, CFH.getOrCreateHoistedBlock(BB), SafetyInfo, + ORE); + assert(DT->dominates(PN, BB) && "Conditional PHIs not expected"); + Changed = true; + continue; + } + } + + // Remember possibly hoistable branches so we can actually hoist them + // later if needed. + if (BranchInst *BI = dyn_cast(&I)) + CFH.registerPossiblyHoistableBranch(BI); } } + // If we hoisted instructions to a conditional block they may not dominate + // their uses that weren't hoisted (such as phis where some operands are not + // loop invariant). If so make them unconditional by moving them to the end of + // the original preheader, which is guaranteed to dominate everything in the + // loop. We iterate through the instructions in reverse order which ensures + // that when we rehoist an instruction we rehoist its operands. + Instruction *HoistPoint = OriginalPreheader->getTerminator(); + for (Instruction *I : reverse(HoistedInstructions)) { + if (!llvm::all_of(I->uses(), [&](Use &U) { return DT->dominates(I, U); })) { + LLVM_DEBUG(dbgs() << "LICM rehoisting to " << OriginalPreheader->getName() + << ": " << *I << "\n"); + moveInstructionBefore(*I, *HoistPoint, *SafetyInfo); + HoistPoint = I; + Changed = true; + } + } + + // Now that we've finished hoisting make sure that LI and DT are still valid. +#ifndef NDEBUG + assert(DT->verify(DominatorTree::VerificationLevel::Fast) && + "Dominator tree verification failed"); + LI->verify(*DT); +#endif + return Changed; } @@ -1100,9 +1383,9 @@ /// is safe to hoist, this instruction is called to do the dirty work. /// static void hoist(Instruction &I, const DominatorTree *DT, const Loop *CurLoop, - ICFLoopSafetyInfo *SafetyInfo, OptimizationRemarkEmitter *ORE) { - auto *Preheader = CurLoop->getLoopPreheader(); - LLVM_DEBUG(dbgs() << "LICM hoisting to " << Preheader->getName() << ": " << I + BasicBlock *Dest, ICFLoopSafetyInfo *SafetyInfo, + OptimizationRemarkEmitter *ORE) { + LLVM_DEBUG(dbgs() << "LICM hoisting to " << Dest->getName() << ": " << I << "\n"); ORE->emit([&]() { return OptimizationRemark(DEBUG_TYPE, "Hoisted", &I) << "hoisting " @@ -1120,8 +1403,12 @@ !SafetyInfo->isGuaranteedToExecute(I, DT, CurLoop)) I.dropUnknownNonDebugMetadata(); - // Move the new node to the Preheader, before its terminator. - moveInstructionBefore(I, *Preheader->getTerminator(), *SafetyInfo); + if (isa(I)) + // Move the new node to the end of the phi list in the destination block. + moveInstructionBefore(I, *Dest->getFirstNonPHI(), *SafetyInfo); + else + // Move the new node to the destination block, before its terminator. + moveInstructionBefore(I, *Dest->getTerminator(), *SafetyInfo); // Do not retain debug locations when we are moving instructions to different // basic blocks, because we want to avoid jumpy line tables. Calls, however, Index: test/Transforms/LICM/hoist-phi.ll =================================================================== --- /dev/null +++ test/Transforms/LICM/hoist-phi.ll @@ -0,0 +1,1164 @@ +; RUN: opt -S -licm < %s | FileCheck %s +; RUN: opt -passes='require,loop(licm)' -S < %s | FileCheck %s + +; CHECK-LABEL: @triangle_phi +define void @triangle_phi(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK: %cmp1 = icmp sgt i32 %x, 0 +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: %add = add i32 %x, 1 +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: phi i32 [ %add, %[[IF_LICM]] ], [ %x, %entry ] +; CHECK: store i32 %phi, i32* %p +; CHECK: %cmp2 = icmp ne i32 %phi, 0 +; CHECK: br label %loop + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %then + +if: + %add = add i32 %x, 1 + br label %then + +then: + %phi = phi i32 [ %add, %if ], [ %x, %loop ] + store i32 %phi, i32* %p + %cmp2 = icmp ne i32 %phi, 0 + br i1 %cmp2, label %loop, label %end + +end: + ret void +} + +; CHECK-LABEL: @diamond_phi +define void @diamond_phi(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK: %cmp1 = icmp sgt i32 %x, 0 +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[ELSE_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: %add = add i32 %x, 1 +; CHECK: br label %[[THEN_LICM:.*]] + +; CHECK: [[ELSE_LICM]]: +; CHECK: %sub = sub i32 %x, 1 +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]] +; CHECK: %phi = phi i32 [ %add, %[[IF_LICM]] ], [ %sub, %[[ELSE_LICM]] ] +; CHECK: store i32 %phi, i32* %p +; CHECK: %cmp2 = icmp ne i32 %phi, 0 +; CHECK: br label %loop + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %else + +if: + %add = add i32 %x, 1 + br label %then + +else: + %sub = sub i32 %x, 1 + br label %then + +then: + %phi = phi i32 [ %add, %if ], [ %sub, %else ] + store i32 %phi, i32* %p + %cmp2 = icmp ne i32 %phi, 0 + br i1 %cmp2, label %loop, label %end + +end: + ret void +} + +; TODO: This is currently too complicated for us to be able to hoist the phi. +; CHECK-LABEL: @three_way_phi +define void @three_way_phi(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp sgt i32 %x, 0 +; CHECK-DAG: %add = add i32 %x, 1 +; CHECK-DAG: %cmp2 = icmp sgt i32 %add, 0 +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[ELSE_LICM:.*]] + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM:.*]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %sub = sub i32 %x, 1 +; CHECK: br label %loop + +entry: + br label %loop + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %then + +if: + %add = add i32 %x, 1 + %cmp2 = icmp sgt i32 %add, 0 + br i1 %cmp2, label %if.if, label %then + +if.if: + %sub = sub i32 %x, 1 + br label %then + +then: + %phi = phi i32 [ 0, %loop ], [ %add, %if ], [ %sub, %if.if ] + store i32 %phi, i32* %p + %cmp3 = icmp ne i32 %phi, 0 + br i1 %cmp3, label %loop, label %end + +end: + ret void +} + +; TODO: This is currently too complicated for us to be able to hoist the phi. +; CHECK-LABEL: @tree_phi +define void @tree_phi(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp sgt i32 %x, 0 +; CHECK-DAG: %add = add i32 %x, 1 +; CHECK-DAG: %cmp2 = icmp sgt i32 %add, 0 +; CHECK-DAG: %sub = sub i32 %x, 1 +; CHECK: br label %loop + +entry: + br label %loop + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %else + +if: + %add = add i32 %x, 1 + %cmp2 = icmp sgt i32 %add, 0 + br i1 %cmp2, label %if.if, label %if.else + +if.if: + br label %then + +if.else: + br label %then + +else: + %sub = sub i32 %x, 1 + br label %then + +then: + %phi = phi i32 [ %add, %if.if ], [ 0, %if.else ], [ %sub, %else ] + store i32 %phi, i32* %p + %cmp3 = icmp ne i32 %phi, 0 + br i1 %cmp3, label %loop, label %end + +end: + ret void +} + +; TODO: We can hoist the first phi, but not the second. +; CHECK-LABEL: @phi_phi +define void @phi_phi(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp sgt i32 %x, 0 +; CHECK-DAG: %add = add i32 %x, 1 +; CHECK-DAG: %cmp2 = icmp sgt i32 %add, 0 +; CHECK-DAG: %sub = sub i32 %x, 1 +; CHECK: br i1 %cmp2, label %[[IF_IF_LICM:.*]], label %[[IF_ELSE_LICM:.*]] + +; CHECK: [[IF_IF_LICM]]: +; CHECK: br label %[[IF_THEN_LICM:.*]] + +; CHECK: [[IF_ELSE_LICM]]: +; CHECK: br label %[[IF_THEN_LICM]] + +; CHECK: [[IF_THEN_LICM]]: +; CHECK: %phi1 = phi i32 [ %add, %[[IF_IF_LICM]] ], [ 0, %[[IF_ELSE_LICM]] ] +; CHECK: br label %loop + +entry: + br label %loop + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %else + +if: + %add = add i32 %x, 1 + %cmp2 = icmp sgt i32 %add, 0 + br i1 %cmp2, label %if.if, label %if.else + +if.if: + br label %if.then + +if.else: + br label %if.then + +if.then: + %phi1 = phi i32 [ %add, %if.if ], [ 0, %if.else ] + br label %then + +else: + %sub = sub i32 %x, 1 + br label %then + +then: + %phi2 = phi i32 [ %phi1, %if.then ], [ %sub, %else ] + store i32 %phi2, i32* %p + %cmp3 = icmp ne i32 %phi2, 0 + br i1 %cmp3, label %loop, label %end + +end: + ret void +} + +; Check that we correctly duplicate empty control flow. +; CHECK-LABEL: @empty_triangle_phi +define i8 @empty_triangle_phi(i32 %x, i32 %y) { +; CHECK-LABEL: entry: +; CHECK: %cmp1 = icmp eq i32 %x, 0 +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i8 [ 0, %[[IF_LICM]] ], [ 1, %entry ] +; CHECK: %cmp2 = icmp eq i32 %y, 0 +; CHECK: br label %loop + +loop: + %cmp1 = icmp eq i32 %x, 0 + br i1 %cmp1, label %if, label %then + +if: + br label %then + +then: + %phi = phi i8 [ 0, %if ], [ 1, %loop ] + %cmp2 = icmp eq i32 %y, 0 + br i1 %cmp2, label %end, label %loop + +end: + ret i8 %phi +} + +; CHECK-LABEL: @empty_diamond_phi +define i8 @empty_diamond_phi(i32 %x, i32 %y) { +; CHECK-LABEL: entry: +; CHECK: %cmp1 = icmp eq i32 %x, 0 +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[ELSE_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM:.*]] + +; CHECK: [[ELSE_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i8 [ 0, %[[IF_LICM]] ], [ 1, %[[ELSE_LICM]] ] +; CHECK: %cmp2 = icmp eq i32 %y, 0 +; CHECK: br label %loop + +loop: + %cmp1 = icmp eq i32 %x, 0 + br i1 %cmp1, label %if, label %else + +if: + br label %then + +else: + br label %then + +then: + %phi = phi i8 [ 0, %if ], [ 1, %else ] + %cmp2 = icmp eq i32 %y, 0 + br i1 %cmp2, label %end, label %loop + +end: + ret i8 %phi +} + +; Check that we correctly handle the case that the first thing we try to hoist is a phi. +; CHECK-LABEL: @empty_triangle_phi_first +define i8 @empty_triangle_phi_first(i32 %x, i1 %cond) { +; CHECK-LABEL: entry: +; CHECK: br i1 %cond, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i8 [ 0, %[[IF_LICM]] ], [ 1, %entry ] +; CHECK: %cmp = icmp eq i32 %x, 0 +; CHECK: br label %loop + +loop: + br i1 %cond, label %if, label %then + +if: + br label %then + +then: + %phi = phi i8 [ 0, %if ], [ 1, %loop ] + %cmp = icmp eq i32 %x, 0 + br i1 %cmp, label %end, label %loop + +end: + ret i8 %phi +} + +; CHECK-LABEL: @empty_diamond_phi +define i8 @empty_diamond_phi_first(i32 %x, i1 %cond) { +; CHECK-LABEL: entry: +; CHECK: br i1 %cond, label %[[IF_LICM:.*]], label %[[ELSE_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM:.*]] + +; CHECK: [[ELSE_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i8 [ 0, %[[IF_LICM]] ], [ 1, %[[ELSE_LICM]] ] +; CHECK: %cmp = icmp eq i32 %x, 0 +; CHECK: br label %loop + +loop: + br i1 %cond, label %if, label %else + +if: + br label %then + +else: + br label %then + +then: + %phi = phi i8 [ 0, %if ], [ 1, %else ] + %cmp = icmp eq i32 %x, 0 + br i1 %cmp, label %end, label %loop + +end: + ret i8 %phi +} + +; CHECK-LABEL: @empty_triangle_phi_first +define i8 @empty_triangle_phi_first_empty_loop_head(i32 %x, i1 %cond) { +; CHECK-LABEL: entry: +; CHECK: br i1 %cond, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i8 [ 0, %[[IF_LICM]] ], [ 1, %entry ] +; CHECK: %cmp = icmp eq i32 %x, 0 +; CHECK: br label %loop + +loop: + br label %test + +test: + br i1 %cond, label %if, label %then + +if: + br label %then + +then: + %phi = phi i8 [ 0, %if ], [ 1, %test ] + %cmp = icmp eq i32 %x, 0 + br i1 %cmp, label %end, label %loop + +end: + ret i8 %phi +} + +; CHECK-LABEL: @empty_diamond_phi_first_empty_loop_head +define i8 @empty_diamond_phi_first_empty_loop_head(i32 %x, i1 %cond) { +; CHECK-LABEL: entry: +; CHECK: br i1 %cond, label %[[IF_LICM:.*]], label %[[ELSE_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM:.*]] + +; CHECK: [[ELSE_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i8 [ 0, %[[IF_LICM]] ], [ 1, %[[ELSE_LICM]] ] +; CHECK: %cmp = icmp eq i32 %x, 0 +; CHECK: br label %loop + +loop: + br label %test + +test: + br i1 %cond, label %if, label %else + +if: + br label %then + +else: + br label %then + +then: + %phi = phi i8 [ 0, %if ], [ 1, %else ] + %cmp = icmp eq i32 %x, 0 + br i1 %cmp, label %end, label %loop + +end: + ret i8 %phi +} + +; The phi is on one branch of a diamond while simultaneously at the end of a +; triangle. Check that we duplicate the triangle and not the diamond. +; CHECK-LABEL: @triangle_diamond +define void @triangle_diamond(i32* %ptr, i32 %x, i32 %y) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp ne i32 %x, 0 +; CHECK-DAG: %cmp2 = icmp ne i32 %y, 0 +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i32 [ 0, %[[IF_LICM]] ], [ 127, %entry ] + +loop: + %cmp1 = icmp ne i32 %x, 0 + br i1 %cmp1, label %if, label %then + +if: + %cmp2 = icmp ne i32 %y, 0 + br i1 %cmp2, label %if.then, label %then + +then: + %phi = phi i32 [ 0, %if ], [ 127, %loop ] + store i32 %phi, i32* %ptr + br label %end + +if.then: + br label %end + +end: + br label %loop +} + +; As the previous, but the end of the diamond is the head of the loop. +; CHECK-LABEL: @triangle_diamond_backedge +define void @triangle_diamond_backedge(i32* %ptr, i32 %x, i32 %y) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp ne i32 %x, 0 +; CHECK-DAG: %cmp2 = icmp ne i32 %y, 0 +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i32 [ 0, %[[IF_LICM]] ], [ 127, %entry ] + +loop: + %cmp1 = icmp ne i32 %x, 0 + br i1 %cmp1, label %if, label %then + +if: + %cmp2 = icmp ne i32 %y, 0 + br i1 %cmp2, label %backedge, label %then + +then: + %phi = phi i32 [ 0, %if ], [ 127, %loop ] + store i32 %phi, i32* %ptr + br label %loop + +backedge: + br label %loop +} + +; TODO: The inner diamonds can be hoisted, but not currently the outer diamond +; CHECK-LABEL: @diamonds_inside_diamond +define void @diamonds_inside_diamond(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp sgt i32 %x, 0 +; CHECK-DAG: %cmp3 = icmp slt i32 %x, -10 +; CHECK: br i1 %cmp3, label %[[ELSE_IF_LICM:.*]], label %[[ELSE_ELSE_LICM:.*]] +entry: + br label %loop + +; CHECK: [[ELSE_IF_LICM]]: +; CHECK: br label %[[ELSE_THEN_LICM:.*]] + +; CHECK: [[ELSE_ELSE_LICM]]: +; CHECK: br label %[[ELSE_THEN_LICM]] + +; CHECK: [[ELSE_THEN_LICM]]: +; CHECK: %phi2 = phi i32 [ 2, %[[ELSE_IF_LICM]] ], [ 3, %[[ELSE_ELSE_LICM]] ] +; CHECK: %cmp2 = icmp sgt i32 %x, 10 +; CHECK: br i1 %cmp2, label %[[IF_IF_LICM:.*]], label %[[IF_ELSE_LICM:.*]] + +; CHECK: [[IF_IF_LICM]]: +; CHECK: br label %[[IF_THEN_LICM:.*]] + +; CHECK: [[IF_ELSE_LICM]]: +; CHECK: br label %[[IF_THEN_LICM]] + +; CHECK: [[IF_THEN_LICM]]: +; CHECK: %phi1 = phi i32 [ 0, %[[IF_IF_LICM]] ], [ 1, %[[IF_ELSE_LICM]] ] +; CHECK: br label %loop + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %else + +if: + %cmp2 = icmp sgt i32 %x, 10 + br i1 %cmp2, label %if.if, label %if.else + +if.if: + br label %if.then + +if.else: + br label %if.then + +if.then: + %phi1 = phi i32 [ 0, %if.if ], [ 1, %if.else ] + br label %then + +else: + %cmp3 = icmp slt i32 %x, -10 + br i1 %cmp3, label %else.if, label %else.else + +else.if: + br label %else.then + +else.else: + br label %else.then + +else.then: + %phi2 = phi i32 [ 2, %else.if ], [ 3, %else.else ] + br label %then + +then: + %phi3 = phi i32 [ %phi1, %if.then ], [ %phi2, %else.then ] + store i32 %phi3, i32* %p + %cmp4 = icmp ne i32 %phi3, 0 + br i1 %cmp4, label %loop, label %end + +end: + ret void +} + +; We can hoist blocks that contain an edge that exits the loop by ignoring that +; edge in the hoisted block. +; CHECK-LABEL: @triangle_phi_loopexit +define void @triangle_phi_loopexit(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK-DAG: %add = add i32 %x, 1 +; CHECK-DAG: %cmp1 = icmp sgt i32 %x, 0 +; CHECK-DAG: %cmp2 = icmp sgt i32 10, %add +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi = phi i32 [ %add, %[[IF_LICM]] ], [ %x, %entry ] + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %then + +if: + %add = add i32 %x, 1 + %cmp2 = icmp sgt i32 10, %add + br i1 %cmp2, label %then, label %end + +then: + %phi = phi i32 [ %add, %if ], [ %x, %loop ] + store i32 %phi, i32* %p + %cmp3 = icmp ne i32 %phi, 0 + br i1 %cmp3, label %loop, label %end + +end: + ret void +} + +; CHECK-LABEL: @diamond_phi_oneloopexit +define void @diamond_phi_oneloopexit(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK-DAG: %add = add i32 %x, 1 +; CHECK-DAG: %cmp1 = icmp sgt i32 %x, 0 +; CHECK-DAG: %cmp2 = icmp sgt i32 10, %add +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM:.*]] + +; CHECK: [[ELSE_LICM]]: +; CHECK: %sub = sub i32 %x, 1 +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]] +; CHECK: %phi = phi i32 [ %add, %[[IF_LICM]] ], [ %sub, %[[ELSE_LICM]] ] +; CHECK: %cmp3 = icmp ne i32 %phi, 0 +; CHECK: br label %loop + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %else + +if: + %add = add i32 %x, 1 + %cmp2 = icmp sgt i32 10, %add + br i1 %cmp2, label %then, label %end + +else: + %sub = sub i32 %x, 1 + br label %then + +then: + %phi = phi i32 [ %add, %if ], [ %sub, %else ] + store i32 %phi, i32* %p + %cmp3 = icmp ne i32 %phi, 0 + br i1 %cmp3, label %loop, label %end + +end: + ret void +} + +; CHECK-LABEL: @diamond_phi_twoloopexit +define void @diamond_phi_twoloopexit(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK-DAG: %sub = sub i32 %x, 1 +; CHECK-DAG: %add = add i32 %x, 1 +; CHECK-DAG: %cmp1 = icmp sgt i32 %x, 0 +; CHECK-DAG: %cmp2 = icmp sgt i32 10, %add +; CHECK-DAG: %cmp3 = icmp sgt i32 10, %sub +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM:.*]] + +; CHECK: [[ELSE_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]] +; CHECK: %phi = phi i32 [ %add, %[[IF_LICM]] ], [ %sub, %[[ELSE_LICM]] ] +; CHECK: %cmp4 = icmp ne i32 %phi, 0 +; CHECK: br label %loop + +loop: + %cmp1 = icmp sgt i32 %x, 0 + br i1 %cmp1, label %if, label %else + +if: + %add = add i32 %x, 1 + %cmp2 = icmp sgt i32 10, %add + br i1 %cmp2, label %then, label %end + +else: + %sub = sub i32 %x, 1 + %cmp3 = icmp sgt i32 10, %sub + br i1 %cmp3, label %then, label %end + +then: + %phi = phi i32 [ %add, %if ], [ %sub, %else ] + store i32 %phi, i32* %p + %cmp4 = icmp ne i32 %phi, 0 + br i1 %cmp4, label %loop, label %end + +end: + ret void +} + +; The store cannot be hoisted, so add and shr cannot be hoisted into a +; conditional block. +; CHECK-LABEL: @conditional_use +define void @conditional_use(i32 %x, i32* %p) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cond = icmp ugt i32 %x, 0 +; CHECK-DAG: %add = add i32 %x, 5 +; CHECK-DAG: %shr = ashr i32 %add, 1 +; CHECK: br label %loop +entry: + br label %loop + +loop: + %cond = icmp ugt i32 %x, 0 + br i1 %cond, label %if, label %else + +; CHECK-LABEL: if: +; CHECK: store i32 %shr, i32* %p, align 4 +if: + %add = add i32 %x, 5 + %shr = ashr i32 %add, 1 + store i32 %shr, i32* %p, align 4 + br label %then + +else: + br label %then + +then: + br label %loop +} + +; A diamond with two triangles on the left and one on the right. This test is +; to check that we have a unique loop preheader when we hoist the store (and so +; don't fail an assertion). +; CHECK-LABEL: @triangles_in_diamond +define void @triangles_in_diamond(i32* %ptr) { +; CHECK-LABEL: entry: +; CHECK: store i32 0, i32* %ptr, align 4 +; CHECK: br label %loop +entry: + br label %loop + +loop: + br i1 undef, label %left_triangle_1, label %right_triangle + +left_triangle_1: + br i1 undef, label %left_triangle_1_if, label %left_triangle_2 + +left_triangle_1_if: + br label %left_triangle_2 + +left_triangle_2: + br i1 undef, label %left_triangle_2_if, label %left_triangle_2_then + +left_triangle_2_if: + br label %left_triangle_2_then + +left_triangle_2_then: + br label %loop.end + +right_triangle: + br i1 undef, label %right_triangle.if, label %right_triangle.then + +right_triangle.if: + br label %right_triangle.then + +right_triangle.then: + br label %loop.end + +loop.end: + store i32 0, i32* %ptr, align 4 + br label %loop +} + +; %cmp dominates its used after being hoisted, but not after %brmerge is rehoisted +; CHECK-LABEL: @rehoist +define void @rehoist(i8* %this, i32 %x) { +; CHECK-LABEL: entry: +; CHECK-DAG: %sub = add nsw i32 %x, -1 +; CHECK-DAG: %fptr = bitcast i8* %this to void (i8*)* +; CHECK-DAG: %cmp = icmp eq i32 0, %sub +; CHECK-DAG: %brmerge = or i1 %cmp, true +entry: + %sub = add nsw i32 %x, -1 + br label %loop + +loop: + br i1 undef, label %if1, label %else1 + +if1: + %fptr = bitcast i8* %this to void (i8*)* + call void %fptr(i8* %this) + br label %then1 + +else1: + br label %then1 + +then1: + %cmp = icmp eq i32 0, %sub + br i1 %cmp, label %end, label %else2 + +else2: + %brmerge = or i1 %cmp, true + br i1 %brmerge, label %if3, label %end + +if3: + br label %end + +end: + br label %loop +} + +; A test case that uses empty blocks in a way that can cause control flow +; hoisting to get confused. +; CHECK-LABEL: @empty_blocks_multiple_conditional_branches +define void @empty_blocks_multiple_conditional_branches(float %arg, float* %ptr) { +; CHECK-LABEL: entry +; CHECK-DAG: %div1 = fmul float %arg, 4.000000e+00 +; CHECK-DAG: %div2 = fmul float %arg, 2.000000e+00 +entry: + br label %loop + +; The exact path to the phi isn't checked here, because it depends on whether +; cond2 or cond3 is hoisted first +; CHECK: %phi = phi float [ 0.000000e+00, %{{.*}} ], [ %div1, %{{.*}} ] +; CHECK: br label %loop + +loop: + br i1 undef, label %backedge2, label %cond1 + +cond1: + br i1 undef, label %cond1.if, label %cond1.else + +cond1.else: + br label %cond3 + +cond1.if: + br label %cond1.if.next + +cond1.if.next: + br label %cond2 + +cond2: + %div1 = fmul float %arg, 4.000000e+00 + br i1 undef, label %cond2.if, label %cond2.then + +cond2.if: + br label %cond2.then + +cond2.then: + %phi = phi float [ 0.000000e+00, %cond2 ], [ %div1, %cond2.if ] + store float %phi, float* %ptr + br label %backedge2 + +cond3: + br i1 undef, label %cond3.then, label %cond3.if + +cond3.if: + %div2 = fmul float %arg, 2.000000e+00 + store float %div2, float* %ptr + br label %cond3.then + +cond3.then: + br label %loop + +backedge2: + br label %loop +} + +; We can't do much here, so mainly just check that we don't crash. +; CHECK-LABEL: @many_path_phi +define void @many_path_phi(i32* %ptr1, i32* %ptr2) { +; CHECK-LABEL: entry: +; CHECK-DAG: %gep3 = getelementptr inbounds i32, i32* %ptr2, i32 2 +; CHECK-DAG: %gep2 = getelementptr inbounds i32, i32* %ptr2, i32 2 +; CHECK: br label %loop +entry: + br label %loop + +loop: + %phi1 = phi i32 [ 0, %entry ], [ %phi2, %end ] + %cmp1 = icmp ugt i32 %phi1, 3 + br i1 %cmp1, label %cond2, label %cond1 + +cond1: + br i1 undef, label %end, label %cond1.else + +cond1.else: + %gep2 = getelementptr inbounds i32, i32* %ptr2, i32 2 + %val2 = load i32, i32* %gep2, align 4 + %cmp2 = icmp eq i32 %val2, 13 + br i1 %cmp2, label %cond1.end, label %end + +cond1.end: + br label %end + +cond2: + br i1 undef, label %end, label %cond2.else + +cond2.else: + %gep3 = getelementptr inbounds i32, i32* %ptr2, i32 2 + %val3 = load i32, i32* %gep3, align 4 + %cmp3 = icmp eq i32 %val3, 13 + br i1 %cmp3, label %cond2.end, label %end + +cond2.end: + br label %end + +end: + %phi2 = phi i32 [ 1, %cond1 ], [ 2, %cond1.else ], [ 3, %cond1.end ], [ 4, %cond2 ], [ 5, %cond2.else ], [ 6, %cond2.end ] + br label %loop +} + +; Check that we correctly handle the hoisting of %gep when theres a critical +; edge that branches to the preheader. +; CHECK-LABEL: @crit_edge +define void @crit_edge(i32* %ptr, i32 %idx, i1 %cond1, i1 %cond2) { +; CHECK-LABEL: entry: +; CHECK: %gep = getelementptr inbounds i32, i32* %ptr, i32 %idx +; CHECK: br label %preheader +entry: + br label %preheader + +preheader: + br label %loop + +loop: + br i1 %cond1, label %then, label %if + +if: + %gep = getelementptr inbounds i32, i32* %ptr, i32 %idx + %val = load i32, i32* %gep + br label %then + +then: + %phi = phi i32 [ %val, %if ], [ 0, %loop ] + store i32 %phi, i32* %ptr + br i1 %cond2, label %loop, label %crit_edge + +crit_edge: + br label %preheader +} + +; Check that the conditional sub is correctly hoisted from the inner loop to the +; preheader of the outer loop. +; CHECK-LABEL: @hoist_from_innermost_loop +define void @hoist_from_innermost_loop(i32 %nx, i32* %ptr) { +; CHECK-LABEL: entry: +; CHECK-DAG: %sub = sub nsw i32 0, %nx +; CHECK: br label %outer_loop +entry: + br label %outer_loop + +outer_loop: + br label %middle_loop + +middle_loop: + br label %inner_loop + +inner_loop: + br i1 undef, label %inner_loop_end, label %if + +if: + %sub = sub nsw i32 0, %nx + store i32 %sub, i32* %ptr, align 4 + br label %inner_loop_end + +inner_loop_end: + br i1 undef, label %inner_loop, label %middle_loop_end + +middle_loop_end: + br i1 undef, label %middle_loop, label %outer_loop_end + +outer_loop_end: + br label %outer_loop +} + +; We have a diamond starting from %if, but %if.if is also reachable from %loop, +; so %gep should not be conditionally hoisted. +; CHECK-LABEL: @diamond_with_extra_in_edge +define void @diamond_with_extra_in_edge(i32* %ptr1, i32* %ptr2, i32 %arg) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp2 = icmp ne i32 0, %arg +; CHECK-DAG: %gep = getelementptr i32, i32* %ptr1, i32 4 +; CHECK: br label %loop +entry: + br label %loop + +loop: + %phi1 = phi i32 [ 0, %entry ], [ %phi2, %then ] + %cmp1 = icmp ugt i32 16, %phi1 + br i1 %cmp1, label %if, label %if.if + +if: + %cmp2 = icmp ne i32 0, %arg + br i1 %cmp2, label %if.if, label %if.else + +if.if: + %gep = getelementptr i32, i32* %ptr1, i32 4 + %val = load i32, i32* %gep, align 4 + br label %then + +if.else: + br label %then + +then: + %phi2 = phi i32 [ %val, %if.if ], [ %phi1, %if.else ] + store i32 %phi2, i32* %ptr2, align 4 + br label %loop +} + +; %loop/%if/%then form a triangle, but %loop/%if/%then/%end also form a diamond. +; The triangle should be picked for conditional hoisting. +; CHECK-LABEL: @both_triangle_and_diamond +define void @both_triangle_and_diamond(i32* %ptr1, i32* %ptr2, i32 %arg) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp ne i32 0, %arg +; CHECK-DAG: %gep = getelementptr i32, i32* %ptr1, i32 4 +; CHECK: br i1 %cmp1, label %[[IF_LICM:.*]], label %[[THEN_LICM:.*]] +entry: + br label %loop + +; CHECK: [[IF_LICM]]: +; CHECK: br label %[[THEN_LICM]] + +; CHECK: [[THEN_LICM]]: +; CHECK: %phi2 = phi i32 [ 0, %[[IF_LICM]] ], [ 1, %entry ] +; CHECK: br label %loop + +loop: + %phi1 = phi i32 [ 0, %entry ], [ %phi3, %end ] + %cmp1 = icmp ne i32 0, %arg + br i1 %cmp1, label %if, label %then + +if: + %gep = getelementptr i32, i32* %ptr1, i32 4 + %val = load i32, i32* %gep, align 4 + %cmp2 = icmp ugt i32 16, %phi1 + br i1 %cmp2, label %end, label %then + +then: + %phi2 = phi i32 [ 0, %if ], [ 1, %loop ] + br label %end + +end: + %phi3 = phi i32 [ %phi2, %then ], [ %val, %if ] + store i32 %phi3, i32* %ptr2, align 4 + br label %loop +} + +; We shouldn't duplicate the branch at the end of %loop and should instead hoist +; %val to %entry. +; CHECK-LABEL: @same_destination_branch +define i32 @same_destination_branch(i32 %arg1, i32 %arg2) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp ne i32 %arg2, 0 +; CHECK-DAG: %val = add i32 %arg1, 1 +; CHECK: br label %loop +entry: + br label %loop + +loop: + %phi = phi i32 [ 0, %entry ], [ %add, %then ] + %add = add i32 %phi, 1 + %cmp1 = icmp ne i32 %arg2, 0 + br i1 %cmp1, label %if, label %if + +if: + %val = add i32 %arg1, 1 + br label %then + +then: + %cmp2 = icmp ne i32 %val, %phi + br i1 %cmp2, label %loop, label %end + +end: + ret i32 %val +} + +; Diamond-like control flow but the left/right blocks actually have the same +; destinations. +; TODO: We could potentially hoist all of phi2-4, but currently only hoist phi2. +; CHECK-LABEL: @diamond_like_same_destinations +define i32 @diamond_like_same_destinations(i32 %arg1, i32 %arg2) { +; CHECK-LABEL: entry: +; CHECK-DAG: %cmp1 = icmp ne i32 %arg1, 0 +; CHECK-DAG: %cmp2 = icmp ugt i32 %arg2, 1 +; CHECK-DAG: %cmp3 = icmp ugt i32 %arg2, 2 +; CHECK: br i1 %cmp1, label %[[LEFT1_LICM:.*]], label %[[RIGHT1_LICM:.*]] +entry: + br label %loop + +; CHECK: [[LEFT1_LICM]]: +; CHECK: br label %[[LEFT2_LICM:.*]] + +; CHECK: [[RIGHT1_LICM]]: +; CHECK: br label %[[LEFT2_LICM]] + +; CHECK: [[LEFT2_LICM]]: +; CHECK: %phi2 = phi i32 [ 0, %[[LEFT1_LICM]] ], [ 1, %[[RIGHT1_LICM]] ] +; CHECK: br label %loop + +loop: + %phi1 = phi i32 [ 0, %entry ], [ %add, %loopend ] + %add = add i32 %phi1, 1 + %cmp1 = icmp ne i32 %arg1, 0 + br i1 %cmp1, label %left1, label %right1 + +left1: + %cmp2 = icmp ugt i32 %arg2, 1 + br i1 %cmp2, label %left2, label %right2 + +right1: + %cmp3 = icmp ugt i32 %arg2, 2 + br i1 %cmp3, label %left2, label %right2 + +left2: + %phi2 = phi i32 [ 0, %left1 ], [ 1, %right1 ] + br label %loopend + +right2: + %phi3 = phi i32 [ 2, %left1 ], [ 3, %right1 ] + br label %loopend + +loopend: + %phi4 = phi i32 [ %phi2, %left2 ], [ %phi3, %right2 ] + %cmp4 = icmp ne i32 %phi1, 32 + br i1 %cmp4, label %loop, label %end + +end: + ret i32 %phi4 +} + +; A phi with multiple incoming values for the same block due to a branch with +; two destinations that are actually the same. We can't hoist this. +; TODO: This could be hoisted by erasing one of the incoming values. +; CHECK-LABEL: @phi_multiple_values_same_block +define i32 @phi_multiple_values_same_block(i32 %arg) { +; CHECK-LABEL: entry: +; CHECK: %cmp = icmp sgt i32 %arg, 4 +; CHECK-NOT: phi +; CHECK: br label %loop +entry: + br label %loop + +loop: + %cmp = icmp sgt i32 %arg, 4 + br i1 %cmp, label %if, label %then + +if: + br i1 undef, label %then, label %then + +then: + %phi = phi i32 [ %arg, %loop ], [ 1, %if ], [ 1, %if ] + br i1 undef, label %exit, label %loop + +exit: + ret i32 %phi +} Index: test/Transforms/LoopVectorize/invariant-store-vectorization.ll =================================================================== --- test/Transforms/LoopVectorize/invariant-store-vectorization.ll +++ test/Transforms/LoopVectorize/invariant-store-vectorization.ll @@ -266,19 +266,26 @@ ; variant/invariant values being stored to invariant address. ; test checks that the last element of the phi is extracted and scalar stored ; into the uniform address within the loop. -; Since the condition and the phi is loop invariant, they are LICM'ed after +; Since the condition and the phi is loop invariant, they are LICM'ed before ; vectorization. ; CHECK-LABEL: inv_val_store_to_inv_address_conditional_inv ; CHECK-NEXT: entry: +; CHECK-NEXT: [[B1:%.*]] = bitcast i32* [[B:%.*]] to i8* +; CHECK-NEXT: [[A4:%.*]] = bitcast i32* [[A:%.*]] to i8* ; CHECK-NEXT: [[NTRUNC:%.*]] = trunc i64 [[N:%.*]] to i32 ; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[NTRUNC]], [[K:%.*]] +; CHECK-NEXT: br i1 [[CMP]], label %[[COND_STORE_LICM:.*]], label %[[COND_STORE_K_LICM:.*]] +; CHECK: [[COND_STORE_LICM]]: +; CHECK-NEXT: br label %[[LATCH_LICM:.*]] +; CHECK: [[COND_STORE_K_LICM]]: +; CHECK-NEXT: br label %[[LATCH_LICM]] +; CHECK: [[LATCH_LICM]]: +; CHECK-NEXT: [[STOREVAL:%.*]] = phi i32 [ [[NTRUNC]], %[[COND_STORE_LICM]] ], [ [[K]], %[[COND_STORE_K_LICM]] ] ; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i64 [[N]], 1 ; CHECK-NEXT: [[SMAX:%.*]] = select i1 [[TMP0]], i64 [[N]], i64 1 ; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[SMAX]], 4 ; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_MEMCHECK:%.*]] ; CHECK: vector.memcheck: -; CHECK-NEXT: [[A4:%.*]] = bitcast i32* [[A:%.*]] to i8* -; CHECK-NEXT: [[B1:%.*]] = bitcast i32* [[B:%.*]] to i8* ; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i64 [[N]], 1 ; CHECK-NEXT: [[SMAX2:%.*]] = select i1 [[TMP1]], i64 [[N]], i64 1 ; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i32, i32* [[B]], i64 [[SMAX2]] @@ -291,17 +298,13 @@ ; CHECK-NEXT: [[N_VEC:%.*]] = and i64 [[SMAX]], 9223372036854775804 ; CHECK-NEXT: [[BROADCAST_SPLATINSERT5:%.*]] = insertelement <4 x i32> undef, i32 [[NTRUNC]], i32 0 ; CHECK-NEXT: [[BROADCAST_SPLAT6:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT5]], <4 x i32> undef, <4 x i32> zeroinitializer -; CHECK-NEXT: [[TMP2:%.*]] = insertelement <4 x i1> undef, i1 [[CMP]], i32 3 -; CHECK-NEXT: [[TMP3:%.*]] = insertelement <4 x i32> undef, i32 [[K]], i32 3 -; CHECK-NEXT: [[PREDPHI:%.*]] = select <4 x i1> [[TMP2]], <4 x i32> [[BROADCAST_SPLAT6]], <4 x i32> [[TMP3]] -; CHECK-NEXT: [[TMP5:%.*]] = extractelement <4 x i32> [[PREDPHI]], i32 3 ; CHECK-NEXT: br label [[VECTOR_BODY:%.*]] ; CHECK: vector.body: ; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ] ; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds i32, i32* [[B]], i64 [[INDEX]] ; CHECK-NEXT: [[TMP7:%.*]] = bitcast i32* [[TMP6]] to <4 x i32>* ; CHECK-NEXT: store <4 x i32> [[BROADCAST_SPLAT6]], <4 x i32>* [[TMP7]], align 4 -; CHECK-NEXT: store i32 [[TMP5]], i32* [[A]], align 4 +; CHECK-NEXT: store i32 [[STOREVAL]], i32* [[A]], align 4 ; CHECK-NEXT: [[INDEX_NEXT]] = add i64 [[INDEX]], 4 ; CHECK-NEXT: [[TMP8:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]] ; CHECK-NEXT: br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]] @@ -321,7 +324,6 @@ ; CHECK: cond_store_k: ; CHECK-NEXT: br label [[LATCH]] ; CHECK: latch: -; CHECK-NEXT: [[STOREVAL:%.*]] = phi i32 [ [[NTRUNC]], [[COND_STORE]] ], [ [[K]], [[COND_STORE_K]] ] ; CHECK-NEXT: store i32 [[STOREVAL]], i32* [[A]], align 4 ; CHECK-NEXT: [[I_NEXT]] = add nuw nsw i64 [[I]], 1 ; CHECK-NEXT: [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]