void initializeLoopDistributeLegacyPass(PassRegistry&);
void initializeLoopExtractorPass(PassRegistry&);
void initializeLoopGuardWideningLegacyPassPass(PassRegistry&);
+void initializeLoopFuseLegacyPass(PassRegistry&);
void initializeLoopIdiomRecognizeLegacyPassPass(PassRegistry&);
void initializeLoopInfoWrapperPassPass(PassRegistry&);
void initializeLoopInstSimplifyLegacyPassPass(PassRegistry&);
//
FunctionPass *createLoopDistributePass();
+//===----------------------------------------------------------------------===//
+//
+// LoopFuse - Fuse loops.
+//
+FunctionPass *createLoopFusePass();
+
//===----------------------------------------------------------------------===//
//
// LoopLoadElimination - Perform loop-aware load elimination.
--- /dev/null
+//===- LoopFuse.h - Loop Fusion Pass ----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements the Loop Fusion pass.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_SCALAR_LOOPFUSE_H
+#define LLVM_TRANSFORMS_SCALAR_LOOPFUSE_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class Function;
+
+class LoopFusePass : public PassInfoMixin<LoopFusePass> {
+public:
+ PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_SCALAR_LOOPFUSE_H
#include "llvm/Transforms/Scalar/LoopDataPrefetch.h"
#include "llvm/Transforms/Scalar/LoopDeletion.h"
#include "llvm/Transforms/Scalar/LoopDistribute.h"
+#include "llvm/Transforms/Scalar/LoopFuse.h"
#include "llvm/Transforms/Scalar/LoopIdiomRecognize.h"
#include "llvm/Transforms/Scalar/LoopInstSimplify.h"
#include "llvm/Transforms/Scalar/LoopLoadElimination.h"
FUNCTION_PASS("lcssa", LCSSAPass())
FUNCTION_PASS("loop-data-prefetch", LoopDataPrefetchPass())
FUNCTION_PASS("loop-load-elim", LoopLoadEliminationPass())
+FUNCTION_PASS("loop-fuse", LoopFusePass())
FUNCTION_PASS("loop-distribute", LoopDistributePass())
FUNCTION_PASS("loop-vectorize", LoopVectorizePass())
FUNCTION_PASS("pgo-memop-opt", PGOMemOPSizeOpt())
LoopDeletion.cpp
LoopDataPrefetch.cpp
LoopDistribute.cpp
+ LoopFuse.cpp
LoopIdiomRecognize.cpp
LoopInstSimplify.cpp
LoopInterchange.cpp
--- /dev/null
+//===- LoopFuse.cpp - Loop Fusion Pass ------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements the loop fusion pass.
+/// The implementation is largely based on the following document:
+///
+/// Code Transformations to Augment the Scope of Loop Fusion in a
+/// Production Compiler
+/// Christopher Mark Barton
+/// MSc Thesis
+/// https://webdocs.cs.ualberta.ca/~amaral/thesis/ChristopherBartonMSc.pdf
+///
+/// The general approach taken is to collect sets of control flow equivalent
+/// loops and test whether they can be fused. The necessary conditions for
+/// fusion are:
+/// 1. The loops must be adjacent (there cannot be any statements between
+/// the two loops).
+/// 2. The loops must be conforming (they must execute the same number of
+/// iterations).
+/// 3. The loops must be control flow equivalent (if one loop executes, the
+/// other is guaranteed to execute).
+/// 4. There cannot be any negative distance dependencies between the loops.
+/// If all of these conditions are satisfied, it is safe to fuse the loops.
+///
+/// This implementation creates FusionCandidates that represent the loop and the
+/// necessary information needed by fusion. It then operates on the fusion
+/// candidates, first confirming that the candidate is eligible for fusion. The
+/// candidates are then collected into control flow equivalent sets, sorted in
+/// dominance order. Each set of control flow equivalent candidates is then
+/// traversed, attempting to fuse pairs of candidates in the set. If all
+/// requirements for fusion are met, the two candidates are fused, creating a
+/// new (fused) candidate which is then added back into the set to consider for
+/// additional fusion.
+///
+/// This implementation currently does not make any modifications to remove
+/// conditions for fusion. Code transformations to make loops conform to each of
+/// the conditions for fusion are discussed in more detail in the document
+/// above. These can be added to the current implementation in the future.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/LoopFuse.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/DependenceAnalysis.h"
+#include "llvm/Analysis/DomTreeUpdater.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
+#include "llvm/Analysis/PostDominators.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Verifier.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "loop-fusion"
+
+STATISTIC(FuseCounter, "Count number of loop fusions performed");
+STATISTIC(NumFusionCandidates, "Number of candidates for loop fusion");
+STATISTIC(InvalidPreheader, "Loop has invalid preheader");
+STATISTIC(InvalidHeader, "Loop has invalid header");
+STATISTIC(InvalidExitingBlock, "Loop has invalid exiting blocks");
+STATISTIC(InvalidExitBlock, "Loop has invalid exit block");
+STATISTIC(InvalidLatch, "Loop has invalid latch");
+STATISTIC(InvalidLoop, "Loop is invalid");
+STATISTIC(AddressTakenBB, "Basic block has address taken");
+STATISTIC(MayThrowException, "Loop may throw an exception");
+STATISTIC(ContainsVolatileAccess, "Loop contains a volatile access");
+STATISTIC(NotSimplifiedForm, "Loop is not in simplified form");
+STATISTIC(InvalidDependencies, "Dependencies prevent fusion");
+STATISTIC(InvalidTripCount,
+ "Loop does not have invariant backedge taken count");
+STATISTIC(UncomputableTripCount, "SCEV cannot compute trip count of loop");
+STATISTIC(NonEqualTripCount, "Candidate trip counts are not the same");
+STATISTIC(NonAdjacent, "Candidates are not adjacent");
+STATISTIC(NonEmptyPreheader, "Candidate has a non-empty preheader");
+
+enum FusionDependenceAnalysisChoice {
+ FUSION_DEPENDENCE_ANALYSIS_SCEV,
+ FUSION_DEPENDENCE_ANALYSIS_DA,
+ FUSION_DEPENDENCE_ANALYSIS_ALL,
+};
+
+static cl::opt<FusionDependenceAnalysisChoice> FusionDependenceAnalysis(
+ "loop-fusion-dependence-analysis",
+ cl::desc("Which dependence analysis should loop fusion use?"),
+ cl::values(clEnumValN(FUSION_DEPENDENCE_ANALYSIS_SCEV, "scev",
+ "Use the scalar evolution interface"),
+ clEnumValN(FUSION_DEPENDENCE_ANALYSIS_DA, "da",
+ "Use the dependence analysis interface"),
+ clEnumValN(FUSION_DEPENDENCE_ANALYSIS_ALL, "all",
+ "Use all available analyses")),
+ cl::Hidden, cl::init(FUSION_DEPENDENCE_ANALYSIS_ALL), cl::ZeroOrMore);
+
+#ifndef NDEBUG
+static cl::opt<bool>
+ VerboseFusionDebugging("loop-fusion-verbose-debug",
+ cl::desc("Enable verbose debugging for Loop Fusion"),
+ cl::Hidden, cl::init(false), cl::ZeroOrMore);
+#endif
+
+/// This class is used to represent a candidate for loop fusion. When it is
+/// constructed, it checks the conditions for loop fusion to ensure that it
+/// represents a valid candidate. It caches several parts of a loop that are
+/// used throughout loop fusion (e.g., loop preheader, loop header, etc) instead
+/// of continually querying the underlying Loop to retrieve these values. It is
+/// assumed these will not change throughout loop fusion.
+///
+/// The invalidate method should be used to indicate that the FusionCandidate is
+/// no longer a valid candidate for fusion. Similarly, the isValid() method can
+/// be used to ensure that the FusionCandidate is still valid for fusion.
+struct FusionCandidate {
+ /// Cache of parts of the loop used throughout loop fusion. These should not
+ /// need to change throughout the analysis and transformation.
+ /// These parts are cached to avoid repeatedly looking up in the Loop class.
+
+ /// Preheader of the loop this candidate represents
+ BasicBlock *Preheader;
+ /// Header of the loop this candidate represents
+ BasicBlock *Header;
+ /// Blocks in the loop that exit the loop
+ BasicBlock *ExitingBlock;
+ /// The successor block of this loop (where the exiting blocks go to)
+ BasicBlock *ExitBlock;
+ /// Latch of the loop
+ BasicBlock *Latch;
+ /// The loop that this fusion candidate represents
+ Loop *L;
+ /// Vector of instructions in this loop that read from memory
+ SmallVector<Instruction *, 16> MemReads;
+ /// Vector of instructions in this loop that write to memory
+ SmallVector<Instruction *, 16> MemWrites;
+ /// Are all of the members of this fusion candidate still valid
+ bool Valid;
+
+ /// Dominator and PostDominator trees are needed for the
+ /// FusionCandidateCompare function, required by FusionCandidateSet to
+ /// determine where the FusionCandidate should be inserted into the set. These
+ /// are used to establish ordering of the FusionCandidates based on dominance.
+ const DominatorTree *DT;
+ const PostDominatorTree *PDT;
+
+ FusionCandidate(Loop *L, const DominatorTree *DT,
+ const PostDominatorTree *PDT)
+ : Preheader(L->getLoopPreheader()), Header(L->getHeader()),
+ ExitingBlock(L->getExitingBlock()), ExitBlock(L->getExitBlock()),
+ Latch(L->getLoopLatch()), L(L), Valid(true), DT(DT), PDT(PDT) {
+
+ // Walk over all blocks in the loop and check for conditions that may
+ // prevent fusion. For each block, walk over all instructions and collect
+ // the memory reads and writes If any instructions that prevent fusion are
+ // found, invalidate this object and return.
+ for (BasicBlock *BB : L->blocks()) {
+ if (BB->hasAddressTaken()) {
+ AddressTakenBB++;
+ invalidate();
+ return;
+ }
+
+ for (Instruction &I : *BB) {
+ if (I.mayThrow()) {
+ MayThrowException++;
+ invalidate();
+ return;
+ }
+ if (StoreInst *SI = dyn_cast<StoreInst>(&I)) {
+ if (SI->isVolatile()) {
+ ContainsVolatileAccess++;
+ invalidate();
+ return;
+ }
+ }
+ if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
+ if (LI->isVolatile()) {
+ ContainsVolatileAccess++;
+ invalidate();
+ return;
+ }
+ }
+ if (I.mayWriteToMemory())
+ MemWrites.push_back(&I);
+ if (I.mayReadFromMemory())
+ MemReads.push_back(&I);
+ }
+ }
+ }
+
+ /// Check if all members of the class are valid.
+ bool isValid() const {
+ return Preheader && Header && ExitingBlock && ExitBlock && Latch && L &&
+ !L->isInvalid() && Valid;
+ }
+
+ /// Verify that all members are in sync with the Loop object.
+ void verify() const {
+ assert(isValid() && "Candidate is not valid!!");
+ assert(!L->isInvalid() && "Loop is invalid!");
+ assert(Preheader == L->getLoopPreheader() && "Preheader is out of sync");
+ assert(Header == L->getHeader() && "Header is out of sync");
+ assert(ExitingBlock == L->getExitingBlock() &&
+ "Exiting Blocks is out of sync");
+ assert(ExitBlock == L->getExitBlock() && "Exit block is out of sync");
+ assert(Latch == L->getLoopLatch() && "Latch is out of sync");
+ }
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+ LLVM_DUMP_METHOD void dump() const {
+ dbgs() << "\tPreheader: " << (Preheader ? Preheader->getName() : "nullptr")
+ << "\n"
+ << "\tHeader: " << (Header ? Header->getName() : "nullptr") << "\n"
+ << "\tExitingBB: "
+ << (ExitingBlock ? ExitingBlock->getName() : "nullptr") << "\n"
+ << "\tExitBB: " << (ExitBlock ? ExitBlock->getName() : "nullptr")
+ << "\n"
+ << "\tLatch: " << (Latch ? Latch->getName() : "nullptr") << "\n";
+ }
+#endif
+
+private:
+ // This is only used internally for now, to clear the MemWrites and MemReads
+ // list and setting Valid to false. I can't envision other uses of this right
+ // now, since once FusionCandidates are put into the FusionCandidateSet they
+ // are immutable. Thus, any time we need to change/update a FusionCandidate,
+ // we must create a new one and insert it into the FusionCandidateSet to
+ // ensure the FusionCandidateSet remains ordered correctly.
+ void invalidate() {
+ MemWrites.clear();
+ MemReads.clear();
+ Valid = false;
+ }
+};
+
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
+ const FusionCandidate &FC) {
+ if (FC.isValid())
+ OS << FC.Preheader->getName();
+ else
+ OS << "<Invalid>";
+
+ return OS;
+}
+
+struct FusionCandidateCompare {
+ /// Comparison functor to sort two Control Flow Equivalent fusion candidates
+ /// into dominance order.
+ /// If LHS dominates RHS and RHS post-dominates LHS, return true;
+ /// IF RHS dominates LHS and LHS post-dominates RHS, return false;
+ bool operator()(const FusionCandidate &LHS,
+ const FusionCandidate &RHS) const {
+ const DominatorTree *DT = LHS.DT;
+
+ // Do not save PDT to local variable as it is only used in asserts and thus
+ // will trigger an unused variable warning if building without asserts.
+ assert(DT && LHS.PDT && "Expecting valid dominator tree");
+
+ if (DT->dominates(LHS.Preheader, RHS.Preheader)) {
+ // Verify RHS Postdominates LHS
+ assert(LHS.PDT->dominates(RHS.Preheader, LHS.Preheader));
+ return true;
+ }
+
+ if (DT->dominates(RHS.Preheader, LHS.Preheader)) {
+ // RHS dominates LHS
+ // Verify LHS post-dominates RHS
+ assert(LHS.PDT->dominates(LHS.Preheader, RHS.Preheader));
+ return false;
+ }
+ // If LHS does not dominate RHS and RHS does not dominate LHS then there is
+ // no dominance relationship between the two FusionCandidates. Thus, they
+ // should not be in the same set together.
+ llvm_unreachable(
+ "No dominance relationship between these fusion candidates!");
+ }
+};
+
+namespace {
+using LoopVector = SmallVector<Loop *, 4>;
+
+// Set of Control Flow Equivalent (CFE) Fusion Candidates, sorted in dominance
+// order. Thus, if FC0 comes *before* FC1 in a FusionCandidateSet, then FC0
+// dominates FC1 and FC1 post-dominates FC0.
+// std::set was chosen because we want a sorted data structure with stable
+// iterators. A subsequent patch to loop fusion will enable fusing non-ajdacent
+// loops by moving intervening code around. When this intervening code contains
+// loops, those loops will be moved also. The corresponding FusionCandidates
+// will also need to be moved accordingly. As this is done, having stable
+// iterators will simplify the logic. Similarly, having an efficient insert that
+// keeps the FusionCandidateSet sorted will also simplify the implementation.
+using FusionCandidateSet = std::set<FusionCandidate, FusionCandidateCompare>;
+using FusionCandidateCollection = SmallVector<FusionCandidateSet, 4>;
+} // namespace
+
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
+ const FusionCandidateSet &CandSet) {
+ for (auto IT : CandSet)
+ OS << IT << "\n";
+
+ return OS;
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+static void
+printFusionCandidates(const FusionCandidateCollection &FusionCandidates) {
+ LLVM_DEBUG(dbgs() << "Fusion Candidates: \n");
+ for (const auto &CandidateSet : FusionCandidates) {
+ LLVM_DEBUG({
+ dbgs() << "*** Fusion Candidate Set ***\n";
+ dbgs() << CandidateSet;
+ dbgs() << "****************************\n";
+ });
+ }
+}
+#endif
+
+/// Collect all loops in function at the same nest level, starting at the
+/// outermost level.
+///
+/// This data structure collects all loops at the same nest level for a
+/// given function (specified by the LoopInfo object). It starts at the
+/// outermost level.
+struct LoopDepthTree {
+ using LoopsOnLevelTy = SmallVector<LoopVector, 4>;
+ using iterator = LoopsOnLevelTy::iterator;
+ using const_iterator = LoopsOnLevelTy::const_iterator;
+
+ LoopDepthTree(LoopInfo &LI) : Depth(1) {
+ if (!LI.empty())
+ LoopsOnLevel.emplace_back(LoopVector(LI.rbegin(), LI.rend()));
+ }
+
+ /// Test whether a given loop has been removed from the function, and thus is
+ /// no longer valid.
+ bool isRemovedLoop(const Loop *L) const { return RemovedLoops.count(L); }
+
+ /// Record that a given loop has been removed from the function and is no
+ /// longer valid.
+ void removeLoop(const Loop *L) { RemovedLoops.insert(L); }
+
+ /// Descend the tree to the next (inner) nesting level
+ void descend() {
+ LoopsOnLevelTy LoopsOnNextLevel;
+
+ for (const LoopVector &LV : *this)
+ for (Loop *L : LV)
+ if (!isRemovedLoop(L) && L->begin() != L->end())
+ LoopsOnNextLevel.emplace_back(LoopVector(L->begin(), L->end()));
+
+ LoopsOnLevel = LoopsOnNextLevel;
+ RemovedLoops.clear();
+ Depth++;
+ }
+
+ bool empty() const { return size() == 0; }
+ size_t size() const { return LoopsOnLevel.size() - RemovedLoops.size(); }
+ unsigned getDepth() const { return Depth; }
+
+ iterator begin() { return LoopsOnLevel.begin(); }
+ iterator end() { return LoopsOnLevel.end(); }
+ const_iterator begin() const { return LoopsOnLevel.begin(); }
+ const_iterator end() const { return LoopsOnLevel.end(); }
+
+private:
+ /// Set of loops that have been removed from the function and are no longer
+ /// valid.
+ SmallPtrSet<const Loop *, 8> RemovedLoops;
+
+ /// Depth of the current level, starting at 1 (outermost loops).
+ unsigned Depth;
+
+ /// Vector of loops at the current depth level that have the same parent loop
+ LoopsOnLevelTy LoopsOnLevel;
+};
+
+#ifndef NDEBUG
+static void printLoopVector(const LoopVector &LV) {
+ dbgs() << "****************************\n";
+ for (auto L : LV)
+ printLoop(*L, dbgs());
+ dbgs() << "****************************\n";
+}
+#endif
+
+static void reportLoopFusion(const FusionCandidate &FC0,
+ const FusionCandidate &FC1,
+ OptimizationRemarkEmitter &ORE) {
+ using namespace ore;
+ ORE.emit(
+ OptimizationRemark(DEBUG_TYPE, "LoopFusion", FC0.Preheader->getParent())
+ << "Fused " << NV("Cand1", StringRef(FC0.Preheader->getName()))
+ << " with " << NV("Cand2", StringRef(FC1.Preheader->getName())));
+}
+
+struct LoopFuser {
+private:
+ // Sets of control flow equivalent fusion candidates for a given nest level.
+ FusionCandidateCollection FusionCandidates;
+
+ LoopDepthTree LDT;
+ DomTreeUpdater DTU;
+
+ LoopInfo &LI;
+ DominatorTree &DT;
+ DependenceInfo &DI;
+ ScalarEvolution &SE;
+ PostDominatorTree &PDT;
+ OptimizationRemarkEmitter &ORE;
+
+public:
+ LoopFuser(LoopInfo &LI, DominatorTree &DT, DependenceInfo &DI,
+ ScalarEvolution &SE, PostDominatorTree &PDT,
+ OptimizationRemarkEmitter &ORE, const DataLayout &DL)
+ : LDT(LI), DTU(DT, PDT, DomTreeUpdater::UpdateStrategy::Lazy), LI(LI),
+ DT(DT), DI(DI), SE(SE), PDT(PDT), ORE(ORE) {}
+
+ /// This is the main entry point for loop fusion. It will traverse the
+ /// specified function and collect candidate loops to fuse, starting at the
+ /// outermost nesting level and working inwards.
+ bool fuseLoops(Function &F) {
+#ifndef NDEBUG
+ if (VerboseFusionDebugging) {
+ LI.print(dbgs());
+ }
+#endif
+
+ LLVM_DEBUG(dbgs() << "Performing Loop Fusion on function " << F.getName()
+ << "\n");
+ bool Changed = false;
+
+ while (!LDT.empty()) {
+ LLVM_DEBUG(dbgs() << "Got " << LDT.size() << " loop sets for depth "
+ << LDT.getDepth() << "\n";);
+
+ for (const LoopVector &LV : LDT) {
+ assert(LV.size() > 0 && "Empty loop set was build!");
+
+ // Skip singleton loop sets as they do not offer fusion opportunities on
+ // this level.
+ if (LV.size() == 1)
+ continue;
+#ifndef NDEBUG
+ if (VerboseFusionDebugging) {
+ LLVM_DEBUG({
+ dbgs() << " Visit loop set (#" << LV.size() << "):\n";
+ printLoopVector(LV);
+ });
+ }
+#endif
+
+ collectFusionCandidates(LV);
+ Changed |= fuseCandidates();
+ }
+
+ // Finished analyzing candidates at this level.
+ // Descend to the next level and clear all of the candidates currently
+ // collected. Note that it will not be possible to fuse any of the
+ // existing candidates with new candidates because the new candidates will
+ // be at a different nest level and thus not be control flow equivalent
+ // with all of the candidates collected so far.
+ LLVM_DEBUG(dbgs() << "Descend one level!\n");
+ LDT.descend();
+ FusionCandidates.clear();
+ }
+
+ if (Changed)
+ LLVM_DEBUG(dbgs() << "Function after Loop Fusion: \n"; F.dump(););
+
+#ifndef NDEBUG
+ assert(DT.verify());
+ assert(PDT.verify());
+ LI.verify(DT);
+ SE.verify();
+#endif
+
+ LLVM_DEBUG(dbgs() << "Loop Fusion complete\n");
+ return Changed;
+ }
+
+private:
+ /// Determine if two fusion candidates are control flow equivalent.
+ ///
+ /// Two fusion candidates are control flow equivalent if when one executes,
+ /// the other is guaranteed to execute. This is determined using dominators
+ /// and post-dominators: if A dominates B and B post-dominates A then A and B
+ /// are control-flow equivalent.
+ bool isControlFlowEquivalent(const FusionCandidate &FC0,
+ const FusionCandidate &FC1) const {
+ assert(FC0.Preheader && FC1.Preheader && "Expecting valid preheaders");
+
+ if (DT.dominates(FC0.Preheader, FC1.Preheader))
+ return PDT.dominates(FC1.Preheader, FC0.Preheader);
+
+ if (DT.dominates(FC1.Preheader, FC0.Preheader))
+ return PDT.dominates(FC0.Preheader, FC1.Preheader);
+
+ return false;
+ }
+
+ /// Determine if a fusion candidate (representing a loop) is eligible for
+ /// fusion. Note that this only checks whether a single loop can be fused - it
+ /// does not check whether it is *legal* to fuse two loops together.
+ bool eligibleForFusion(const FusionCandidate &FC) const {
+ if (!FC.isValid()) {
+ LLVM_DEBUG(dbgs() << "FC " << FC << " has invalid CFG requirements!\n");
+ if (!FC.Preheader)
+ InvalidPreheader++;
+ if (!FC.Header)
+ InvalidHeader++;
+ if (!FC.ExitingBlock)
+ InvalidExitingBlock++;
+ if (!FC.ExitBlock)
+ InvalidExitBlock++;
+ if (!FC.Latch)
+ InvalidLatch++;
+ if (FC.L->isInvalid())
+ InvalidLoop++;
+
+ return false;
+ }
+
+ // Require ScalarEvolution to be able to determine a trip count.
+ if (!SE.hasLoopInvariantBackedgeTakenCount(FC.L)) {
+ LLVM_DEBUG(dbgs() << "Loop " << FC.L->getName()
+ << " trip count not computable!\n");
+ InvalidTripCount++;
+ return false;
+ }
+
+ if (!FC.L->isLoopSimplifyForm()) {
+ LLVM_DEBUG(dbgs() << "Loop " << FC.L->getName()
+ << " is not in simplified form!\n");
+ NotSimplifiedForm++;
+ return false;
+ }
+
+ return true;
+ }
+
+ /// Iterate over all loops in the given loop set and identify the loops that
+ /// are eligible for fusion. Place all eligible fusion candidates into Control
+ /// Flow Equivalent sets, sorted by dominance.
+ void collectFusionCandidates(const LoopVector &LV) {
+ for (Loop *L : LV) {
+ FusionCandidate CurrCand(L, &DT, &PDT);
+ if (!eligibleForFusion(CurrCand))
+ continue;
+
+ // Go through each list in FusionCandidates and determine if L is control
+ // flow equivalent with the first loop in that list. If it is, append LV.
+ // If not, go to the next list.
+ // If no suitable list is found, start another list and add it to
+ // FusionCandidates.
+ bool FoundSet = false;
+
+ for (auto &CurrCandSet : FusionCandidates) {
+ if (isControlFlowEquivalent(*CurrCandSet.begin(), CurrCand)) {
+ CurrCandSet.insert(CurrCand);
+ FoundSet = true;
+#ifndef NDEBUG
+ if (VerboseFusionDebugging)
+ LLVM_DEBUG(dbgs() << "Adding " << CurrCand
+ << " to existing candidate set\n");
+#endif
+ break;
+ }
+ }
+ if (!FoundSet) {
+ // No set was found. Create a new set and add to FusionCandidates
+#ifndef NDEBUG
+ if (VerboseFusionDebugging)
+ LLVM_DEBUG(dbgs() << "Adding " << CurrCand << " to new set\n");
+#endif
+ FusionCandidateSet NewCandSet;
+ NewCandSet.insert(CurrCand);
+ FusionCandidates.push_back(NewCandSet);
+ }
+ NumFusionCandidates++;
+ }
+ }
+
+ /// Determine if it is beneficial to fuse two loops.
+ ///
+ /// For now, this method simply returns true because we want to fuse as much
+ /// as possible (primarily to test the pass). This method will evolve, over
+ /// time, to add heuristics for profitability of fusion.
+ bool isBeneficialFusion(const FusionCandidate &FC0,
+ const FusionCandidate &FC1) {
+ return true;
+ }
+
+ /// Determine if two fusion candidates have the same trip count (i.e., they
+ /// execute the same number of iterations).
+ ///
+ /// Note that for now this method simply returns a boolean value because there
+ /// are no mechanisms in loop fusion to handle different trip counts. In the
+ /// future, this behaviour can be extended to adjust one of the loops to make
+ /// the trip counts equal (e.g., loop peeling). When this is added, this
+ /// interface may need to change to return more information than just a
+ /// boolean value.
+ bool identicalTripCounts(const FusionCandidate &FC0,
+ const FusionCandidate &FC1) const {
+ const SCEV *TripCount0 = SE.getBackedgeTakenCount(FC0.L);
+ if (isa<SCEVCouldNotCompute>(TripCount0)) {
+ UncomputableTripCount++;
+ LLVM_DEBUG(dbgs() << "Trip count of first loop could not be computed!");
+ return false;
+ }
+
+ const SCEV *TripCount1 = SE.getBackedgeTakenCount(FC1.L);
+ if (isa<SCEVCouldNotCompute>(TripCount1)) {
+ UncomputableTripCount++;
+ LLVM_DEBUG(dbgs() << "Trip count of second loop could not be computed!");
+ return false;
+ }
+ LLVM_DEBUG(dbgs() << "\tTrip counts: " << *TripCount0 << " & "
+ << *TripCount1 << " are "
+ << (TripCount0 == TripCount1 ? "identical" : "different")
+ << "\n");
+
+ return (TripCount0 == TripCount1);
+ }
+
+ /// Walk each set of control flow equivalent fusion candidates and attempt to
+ /// fuse them. This does a single linear traversal of all candidates in the
+ /// set. The conditions for legal fusion are checked at this point. If a pair
+ /// of fusion candidates passes all legality checks, they are fused together
+ /// and a new fusion candidate is created and added to the FusionCandidateSet.
+ /// The original fusion candidates are then removed, as they are no longer
+ /// valid.
+ bool fuseCandidates() {
+ bool Fused = false;
+ LLVM_DEBUG(printFusionCandidates(FusionCandidates));
+ for (auto &CandidateSet : FusionCandidates) {
+ if (CandidateSet.size() < 2)
+ continue;
+
+ LLVM_DEBUG(dbgs() << "Attempting fusion on Candidate Set:\n"
+ << CandidateSet << "\n");
+
+ for (auto FC0 = CandidateSet.begin(); FC0 != CandidateSet.end(); ++FC0) {
+ assert(!LDT.isRemovedLoop(FC0->L) &&
+ "Should not have removed loops in CandidateSet!");
+ auto FC1 = FC0;
+ for (++FC1; FC1 != CandidateSet.end(); ++FC1) {
+ assert(!LDT.isRemovedLoop(FC1->L) &&
+ "Should not have removed loops in CandidateSet!");
+
+ LLVM_DEBUG(dbgs() << "Attempting to fuse candidate \n"; FC0->dump();
+ dbgs() << " with\n"; FC1->dump(); dbgs() << "\n");
+
+ FC0->verify();
+ FC1->verify();
+
+ if (!identicalTripCounts(*FC0, *FC1)) {
+ LLVM_DEBUG(dbgs() << "Fusion candidates do not have identical trip "
+ "counts. Not fusing.\n");
+ NonEqualTripCount++;
+ continue;
+ }
+
+ if (!isAdjacent(*FC0, *FC1)) {
+ LLVM_DEBUG(dbgs()
+ << "Fusion candidates are not adjacent. Not fusing.\n");
+ NonAdjacent++;
+ continue;
+ }
+
+ // For now we skip fusing if the second candidate has any instructions
+ // in the preheader. This is done because we currently do not have the
+ // safety checks to determine if it is save to move the preheader of
+ // the second candidate past the body of the first candidate. Once
+ // these checks are added, this condition can be removed.
+ if (!isEmptyPreheader(*FC1)) {
+ LLVM_DEBUG(dbgs() << "Fusion candidate does not have empty "
+ "preheader. Not fusing.\n");
+ NonEmptyPreheader++;
+ continue;
+ }
+
+ if (!dependencesAllowFusion(*FC0, *FC1)) {
+ LLVM_DEBUG(dbgs() << "Memory dependencies do not allow fusion!\n");
+ continue;
+ }
+
+ bool BeneficialToFuse = isBeneficialFusion(*FC0, *FC1);
+ LLVM_DEBUG(dbgs()
+ << "\tFusion appears to be "
+ << (BeneficialToFuse ? "" : "un") << "profitable!\n");
+ if (!BeneficialToFuse)
+ continue;
+
+ // All analysis has completed and has determined that fusion is legal
+ // and profitable. At this point, start transforming the code and
+ // perform fusion.
+
+ LLVM_DEBUG(dbgs() << "\tFusion is performed: " << *FC0 << " and "
+ << *FC1 << "\n");
+
+ // Report fusion to the Optimization Remarks.
+ // Note this needs to be done *before* performFusion because
+ // performFusion will change the original loops, making it not
+ // possible to identify them after fusion is complete.
+ reportLoopFusion(*FC0, *FC1, ORE);
+
+ FusionCandidate FusedCand(performFusion(*FC0, *FC1), &DT, &PDT);
+ FusedCand.verify();
+ assert(eligibleForFusion(FusedCand) &&
+ "Fused candidate should be eligible for fusion!");
+
+ // Notify the loop-depth-tree that these loops are not valid objects
+ // anymore.
+ LDT.removeLoop(FC1->L);
+
+ CandidateSet.erase(FC0);
+ CandidateSet.erase(FC1);
+
+ auto InsertPos = CandidateSet.insert(FusedCand);
+
+ assert(InsertPos.second &&
+ "Unable to insert TargetCandidate in CandidateSet!");
+
+ // Reset FC0 and FC1 the new (fused) candidate. Subsequent iterations
+ // of the FC1 loop will attempt to fuse the new (fused) loop with the
+ // remaining candidates in the current candidate set.
+ FC0 = FC1 = InsertPos.first;
+
+ LLVM_DEBUG(dbgs() << "Candidate Set (after fusion): " << CandidateSet
+ << "\n");
+
+ Fused = true;
+ }
+ }
+ }
+ return Fused;
+ }
+
+ /// Rewrite all additive recurrences in a SCEV to use a new loop.
+ class AddRecLoopReplacer : public SCEVRewriteVisitor<AddRecLoopReplacer> {
+ public:
+ AddRecLoopReplacer(ScalarEvolution &SE, const Loop &OldL, const Loop &NewL,
+ bool UseMax = true)
+ : SCEVRewriteVisitor(SE), Valid(true), UseMax(UseMax), OldL(OldL),
+ NewL(NewL) {}
+
+ const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
+ const Loop *ExprL = Expr->getLoop();
+ SmallVector<const SCEV *, 2> Operands;
+ if (ExprL == &OldL) {
+ Operands.append(Expr->op_begin(), Expr->op_end());
+ return SE.getAddRecExpr(Operands, &NewL, Expr->getNoWrapFlags());
+ }
+
+ if (OldL.contains(ExprL)) {
+ bool Pos = SE.isKnownPositive(Expr->getStepRecurrence(SE));
+ if (!UseMax || !Pos || !Expr->isAffine()) {
+ Valid = false;
+ return Expr;
+ }
+ return visit(Expr->getStart());
+ }
+
+ for (const SCEV *Op : Expr->operands())
+ Operands.push_back(visit(Op));
+ return SE.getAddRecExpr(Operands, ExprL, Expr->getNoWrapFlags());
+ }
+
+ bool wasValidSCEV() const { return Valid; }
+
+ private:
+ bool Valid, UseMax;
+ const Loop &OldL, &NewL;
+ };
+
+ /// Return false if the access functions of \p I0 and \p I1 could cause
+ /// a negative dependence.
+ bool accessDiffIsPositive(const Loop &L0, const Loop &L1, Instruction &I0,
+ Instruction &I1, bool EqualIsInvalid) {
+ Value *Ptr0 = getLoadStorePointerOperand(&I0);
+ Value *Ptr1 = getLoadStorePointerOperand(&I1);
+ if (!Ptr0 || !Ptr1)
+ return false;
+
+ const SCEV *SCEVPtr0 = SE.getSCEVAtScope(Ptr0, &L0);
+ const SCEV *SCEVPtr1 = SE.getSCEVAtScope(Ptr1, &L1);
+#ifndef NDEBUG
+ if (VerboseFusionDebugging)
+ LLVM_DEBUG(dbgs() << " Access function check: " << *SCEVPtr0 << " vs "
+ << *SCEVPtr1 << "\n");
+#endif
+ AddRecLoopReplacer Rewriter(SE, L0, L1);
+ SCEVPtr0 = Rewriter.visit(SCEVPtr0);
+#ifndef NDEBUG
+ if (VerboseFusionDebugging)
+ LLVM_DEBUG(dbgs() << " Access function after rewrite: " << *SCEVPtr0
+ << " [Valid: " << Rewriter.wasValidSCEV() << "]\n");
+#endif
+ if (!Rewriter.wasValidSCEV())
+ return false;
+
+ // TODO: isKnownPredicate doesnt work well when one SCEV is loop carried (by
+ // L0) and the other is not. We could check if it is monotone and test
+ // the beginning and end value instead.
+
+ BasicBlock *L0Header = L0.getHeader();
+ auto HasNonLinearDominanceRelation = [&](const SCEV *S) {
+ const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S);
+ if (!AddRec)
+ return false;
+ return !DT.dominates(L0Header, AddRec->getLoop()->getHeader()) &&
+ !DT.dominates(AddRec->getLoop()->getHeader(), L0Header);
+ };
+ if (SCEVExprContains(SCEVPtr1, HasNonLinearDominanceRelation))
+ return false;
+
+ ICmpInst::Predicate Pred =
+ EqualIsInvalid ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_SGE;
+ bool IsAlwaysGE = SE.isKnownPredicate(Pred, SCEVPtr0, SCEVPtr1);
+#ifndef NDEBUG
+ if (VerboseFusionDebugging)
+ LLVM_DEBUG(dbgs() << " Relation: " << *SCEVPtr0
+ << (IsAlwaysGE ? " >= " : " may < ") << *SCEVPtr1
+ << "\n");
+#endif
+ return IsAlwaysGE;
+ }
+
+ /// Return true if the dependences between @p I0 (in @p L0) and @p I1 (in
+ /// @p L1) allow loop fusion of @p L0 and @p L1. The dependence analyses
+ /// specified by @p DepChoice are used to determine this.
+ bool dependencesAllowFusion(const FusionCandidate &FC0,
+ const FusionCandidate &FC1, Instruction &I0,
+ Instruction &I1, bool AnyDep,
+ FusionDependenceAnalysisChoice DepChoice) {
+#ifndef NDEBUG
+ if (VerboseFusionDebugging) {
+ LLVM_DEBUG(dbgs() << "Check dep: " << I0 << " vs " << I1 << " : "
+ << DepChoice << "\n");
+ }
+#endif
+ switch (DepChoice) {
+ case FUSION_DEPENDENCE_ANALYSIS_SCEV:
+ return accessDiffIsPositive(*FC0.L, *FC1.L, I0, I1, AnyDep);
+ case FUSION_DEPENDENCE_ANALYSIS_DA: {
+ auto DepResult = DI.depends(&I0, &I1, true);
+ if (!DepResult)
+ return true;
+#ifndef NDEBUG
+ if (VerboseFusionDebugging) {
+ LLVM_DEBUG(dbgs() << "DA res: "; DepResult->dump(dbgs());
+ dbgs() << " [#l: " << DepResult->getLevels() << "][Ordered: "
+ << (DepResult->isOrdered() ? "true" : "false")
+ << "]\n");
+ LLVM_DEBUG(dbgs() << "DepResult Levels: " << DepResult->getLevels()
+ << "\n");
+ }
+#endif
+
+ if (DepResult->getNextPredecessor() || DepResult->getNextSuccessor())
+ LLVM_DEBUG(
+ dbgs() << "TODO: Implement pred/succ dependence handling!\n");
+
+ // TODO: Can we actually use the dependence info analysis here?
+ return false;
+ }
+
+ case FUSION_DEPENDENCE_ANALYSIS_ALL:
+ return dependencesAllowFusion(FC0, FC1, I0, I1, AnyDep,
+ FUSION_DEPENDENCE_ANALYSIS_SCEV) ||
+ dependencesAllowFusion(FC0, FC1, I0, I1, AnyDep,
+ FUSION_DEPENDENCE_ANALYSIS_DA);
+ }
+
+ llvm_unreachable("Unknown fusion dependence analysis choice!");
+ }
+
+ /// Perform a dependence check and return if @p FC0 and @p FC1 can be fused.
+ bool dependencesAllowFusion(const FusionCandidate &FC0,
+ const FusionCandidate &FC1) {
+ LLVM_DEBUG(dbgs() << "Check if " << FC0 << " can be fused with " << FC1
+ << "\n");
+ assert(FC0.L->getLoopDepth() == FC1.L->getLoopDepth());
+ assert(DT.dominates(FC0.Preheader, FC1.Preheader));
+
+ for (Instruction *WriteL0 : FC0.MemWrites) {
+ for (Instruction *WriteL1 : FC1.MemWrites)
+ if (!dependencesAllowFusion(FC0, FC1, *WriteL0, *WriteL1,
+ /* AnyDep */ false,
+ FusionDependenceAnalysis)) {
+ InvalidDependencies++;
+ return false;
+ }
+ for (Instruction *ReadL1 : FC1.MemReads)
+ if (!dependencesAllowFusion(FC0, FC1, *WriteL0, *ReadL1,
+ /* AnyDep */ false,
+ FusionDependenceAnalysis)) {
+ InvalidDependencies++;
+ return false;
+ }
+ }
+
+ for (Instruction *WriteL1 : FC1.MemWrites) {
+ for (Instruction *WriteL0 : FC0.MemWrites)
+ if (!dependencesAllowFusion(FC0, FC1, *WriteL0, *WriteL1,
+ /* AnyDep */ false,
+ FusionDependenceAnalysis)) {
+ InvalidDependencies++;
+ return false;
+ }
+ for (Instruction *ReadL0 : FC0.MemReads)
+ if (!dependencesAllowFusion(FC0, FC1, *ReadL0, *WriteL1,
+ /* AnyDep */ false,
+ FusionDependenceAnalysis)) {
+ InvalidDependencies++;
+ return false;
+ }
+ }
+
+ // Walk through all uses in FC1. For each use, find the reaching def. If the
+ // def is located in FC0 then it is is not safe to fuse.
+ for (BasicBlock *BB : FC1.L->blocks())
+ for (Instruction &I : *BB)
+ for (auto &Op : I.operands())
+ if (Instruction *Def = dyn_cast<Instruction>(Op))
+ if (FC0.L->contains(Def->getParent())) {
+ InvalidDependencies++;
+ return false;
+ }
+
+ return true;
+ }
+
+ /// Determine if the exit block of \p FC0 is the preheader of \p FC1. In this
+ /// case, there is no code in between the two fusion candidates, thus making
+ /// them adjacent.
+ bool isAdjacent(const FusionCandidate &FC0,
+ const FusionCandidate &FC1) const {
+ return FC0.ExitBlock == FC1.Preheader;
+ }
+
+ bool isEmptyPreheader(const FusionCandidate &FC) const {
+ return FC.Preheader->size() == 1;
+ }
+
+ /// Fuse two fusion candidates, creating a new fused loop.
+ ///
+ /// This method contains the mechanics of fusing two loops, represented by \p
+ /// FC0 and \p FC1. It is assumed that \p FC0 dominates \p FC1 and \p FC1
+ /// postdominates \p FC0 (making them control flow equivalent). It also
+ /// assumes that the other conditions for fusion have been met: adjacent,
+ /// identical trip counts, and no negative distance dependencies exist that
+ /// would prevent fusion. Thus, there is no checking for these conditions in
+ /// this method.
+ ///
+ /// Fusion is performed by rewiring the CFG to update successor blocks of the
+ /// components of tho loop. Specifically, the following changes are done:
+ ///
+ /// 1. The preheader of \p FC1 is removed as it is no longer necessary
+ /// (because it is currently only a single statement block).
+ /// 2. The latch of \p FC0 is modified to jump to the header of \p FC1.
+ /// 3. The latch of \p FC1 i modified to jump to the header of \p FC0.
+ /// 4. All blocks from \p FC1 are removed from FC1 and added to FC0.
+ ///
+ /// All of these modifications are done with dominator tree updates, thus
+ /// keeping the dominator (and post dominator) information up-to-date.
+ ///
+ /// This can be improved in the future by actually merging blocks during
+ /// fusion. For example, the preheader of \p FC1 can be merged with the
+ /// preheader of \p FC0. This would allow loops with more than a single
+ /// statement in the preheader to be fused. Similarly, the latch blocks of the
+ /// two loops could also be fused into a single block. This will require
+ /// analysis to prove it is safe to move the contents of the block past
+ /// existing code, which currently has not been implemented.
+ Loop *performFusion(const FusionCandidate &FC0, const FusionCandidate &FC1) {
+ assert(FC0.isValid() && FC1.isValid() &&
+ "Expecting valid fusion candidates");
+
+ LLVM_DEBUG(dbgs() << "Fusion Candidate 0: \n"; FC0.dump();
+ dbgs() << "Fusion Candidate 1: \n"; FC1.dump(););
+
+ assert(FC1.Preheader == FC0.ExitBlock);
+ assert(FC1.Preheader->size() == 1 &&
+ FC1.Preheader->getSingleSuccessor() == FC1.Header);
+
+ // Remember the phi nodes originally in the header of FC0 in order to rewire
+ // them later. However, this is only necessary if the new loop carried
+ // values might not dominate the exiting branch. While we do not generally
+ // test if this is the case but simply insert intermediate phi nodes, we
+ // need to make sure these intermediate phi nodes have different
+ // predecessors. To this end, we filter the special case where the exiting
+ // block is the latch block of the first loop. Nothing needs to be done
+ // anyway as all loop carried values dominate the latch and thereby also the
+ // exiting branch.
+ SmallVector<PHINode *, 8> OriginalFC0PHIs;
+ if (FC0.ExitingBlock != FC0.Latch)
+ for (PHINode &PHI : FC0.Header->phis())
+ OriginalFC0PHIs.push_back(&PHI);
+
+ // Replace incoming blocks for header PHIs first.
+ FC1.Preheader->replaceSuccessorsPhiUsesWith(FC0.Preheader);
+ FC0.Latch->replaceSuccessorsPhiUsesWith(FC1.Latch);
+
+ // Then modify the control flow and update DT and PDT.
+ SmallVector<DominatorTree::UpdateType, 8> TreeUpdates;
+
+ // The old exiting block of the first loop (FC0) has to jump to the header
+ // of the second as we need to execute the code in the second header block
+ // regardless of the trip count. That is, if the trip count is 0, so the
+ // back edge is never taken, we still have to execute both loop headers,
+ // especially (but not only!) if the second is a do-while style loop.
+ // However, doing so might invalidate the phi nodes of the first loop as
+ // the new values do only need to dominate their latch and not the exiting
+ // predicate. To remedy this potential problem we always introduce phi
+ // nodes in the header of the second loop later that select the loop carried
+ // value, if the second header was reached through an old latch of the
+ // first, or undef otherwise. This is sound as exiting the first implies the
+ // second will exit too, __without__ taking the back-edge. [Their
+ // trip-counts are equal after all.
+ // KB: Would this sequence be simpler to just just make FC0.ExitingBlock go
+ // to FC1.Header? I think this is basically what the three sequences are
+ // trying to accomplish; however, doing this directly in the CFG may mean
+ // the DT/PDT becomes invalid
+ FC0.ExitingBlock->getTerminator()->replaceUsesOfWith(FC1.Preheader,
+ FC1.Header);
+ TreeUpdates.emplace_back(DominatorTree::UpdateType(
+ DominatorTree::Delete, FC0.ExitingBlock, FC1.Preheader));
+ TreeUpdates.emplace_back(DominatorTree::UpdateType(
+ DominatorTree::Insert, FC0.ExitingBlock, FC1.Header));
+
+ // The pre-header of L1 is not necessary anymore.
+ assert(pred_begin(FC1.Preheader) == pred_end(FC1.Preheader));
+ FC1.Preheader->getTerminator()->eraseFromParent();
+ new UnreachableInst(FC1.Preheader->getContext(), FC1.Preheader);
+ TreeUpdates.emplace_back(DominatorTree::UpdateType(
+ DominatorTree::Delete, FC1.Preheader, FC1.Header));
+
+ // Moves the phi nodes from the second to the first loops header block.
+ while (PHINode *PHI = dyn_cast<PHINode>(&FC1.Header->front())) {
+ if (SE.isSCEVable(PHI->getType()))
+ SE.forgetValue(PHI);
+ if (PHI->hasNUsesOrMore(1))
+ PHI->moveBefore(&*FC0.Header->getFirstInsertionPt());
+ else
+ PHI->eraseFromParent();
+ }
+
+ // Introduce new phi nodes in the second loop header to ensure
+ // exiting the first and jumping to the header of the second does not break
+ // the SSA property of the phis originally in the first loop. See also the
+ // comment above.
+ Instruction *L1HeaderIP = &FC1.Header->front();
+ for (PHINode *LCPHI : OriginalFC0PHIs) {
+ int L1LatchBBIdx = LCPHI->getBasicBlockIndex(FC1.Latch);
+ assert(L1LatchBBIdx >= 0 &&
+ "Expected loop carried value to be rewired at this point!");
+
+ Value *LCV = LCPHI->getIncomingValue(L1LatchBBIdx);
+
+ PHINode *L1HeaderPHI = PHINode::Create(
+ LCV->getType(), 2, LCPHI->getName() + ".afterFC0", L1HeaderIP);
+ L1HeaderPHI->addIncoming(LCV, FC0.Latch);
+ L1HeaderPHI->addIncoming(UndefValue::get(LCV->getType()),
+ FC0.ExitingBlock);
+
+ LCPHI->setIncomingValue(L1LatchBBIdx, L1HeaderPHI);
+ }
+
+ // Replace latch terminator destinations.
+ FC0.Latch->getTerminator()->replaceUsesOfWith(FC0.Header, FC1.Header);
+ FC1.Latch->getTerminator()->replaceUsesOfWith(FC1.Header, FC0.Header);
+
+ // If FC0.Latch and FC0.ExitingBlock are the same then we have already
+ // performed the updates above.
+ if (FC0.Latch != FC0.ExitingBlock)
+ TreeUpdates.emplace_back(DominatorTree::UpdateType(
+ DominatorTree::Insert, FC0.Latch, FC1.Header));
+
+ TreeUpdates.emplace_back(DominatorTree::UpdateType(DominatorTree::Delete,
+ FC0.Latch, FC0.Header));
+ TreeUpdates.emplace_back(DominatorTree::UpdateType(DominatorTree::Insert,
+ FC1.Latch, FC0.Header));
+ TreeUpdates.emplace_back(DominatorTree::UpdateType(DominatorTree::Delete,
+ FC1.Latch, FC1.Header));
+
+ // Update DT/PDT
+ DTU.applyUpdates(TreeUpdates);
+
+ LI.removeBlock(FC1.Preheader);
+ DTU.deleteBB(FC1.Preheader);
+ DTU.flush();
+
+ // Is there a way to keep SE up-to-date so we don't need to forget the loops
+ // and rebuild the information in subsequent passes of fusion?
+ SE.forgetLoop(FC1.L);
+ SE.forgetLoop(FC0.L);
+
+ // Merge the loops.
+ SmallVector<BasicBlock *, 8> Blocks(FC1.L->block_begin(),
+ FC1.L->block_end());
+ for (BasicBlock *BB : Blocks) {
+ FC0.L->addBlockEntry(BB);
+ FC1.L->removeBlockFromLoop(BB);
+ if (LI.getLoopFor(BB) != FC1.L)
+ continue;
+ LI.changeLoopFor(BB, FC0.L);
+ }
+ while (!FC1.L->empty()) {
+ const auto &ChildLoopIt = FC1.L->begin();
+ Loop *ChildLoop = *ChildLoopIt;
+ FC1.L->removeChildLoop(ChildLoopIt);
+ FC0.L->addChildLoop(ChildLoop);
+ }
+
+ // Delete the now empty loop L1.
+ LI.erase(FC1.L);
+
+#ifndef NDEBUG
+ assert(!verifyFunction(*FC0.Header->getParent(), &errs()));
+ assert(DT.verify(DominatorTree::VerificationLevel::Fast));
+ assert(PDT.verify());
+ LI.verify(DT);
+ SE.verify();
+#endif
+
+ FuseCounter++;
+
+ LLVM_DEBUG(dbgs() << "Fusion done:\n");
+
+ return FC0.L;
+ }
+};
+
+struct LoopFuseLegacy : public FunctionPass {
+
+ static char ID;
+
+ LoopFuseLegacy() : FunctionPass(ID) {
+ initializeLoopFuseLegacyPass(*PassRegistry::getPassRegistry());
+ }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequiredID(LoopSimplifyID);
+ AU.addRequired<ScalarEvolutionWrapperPass>();
+ AU.addRequired<LoopInfoWrapperPass>();
+ AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addRequired<PostDominatorTreeWrapperPass>();
+ AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
+ AU.addRequired<DependenceAnalysisWrapperPass>();
+
+ AU.addPreserved<ScalarEvolutionWrapperPass>();
+ AU.addPreserved<LoopInfoWrapperPass>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
+ AU.addPreserved<PostDominatorTreeWrapperPass>();
+ }
+
+ bool runOnFunction(Function &F) override {
+ if (skipFunction(F))
+ return false;
+ auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+ auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ auto &DI = getAnalysis<DependenceAnalysisWrapperPass>().getDI();
+ auto &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
+ auto &PDT = getAnalysis<PostDominatorTreeWrapperPass>().getPostDomTree();
+ auto &ORE = getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
+
+ const DataLayout &DL = F.getParent()->getDataLayout();
+ LoopFuser LF(LI, DT, DI, SE, PDT, ORE, DL);
+ return LF.fuseLoops(F);
+ }
+};
+
+PreservedAnalyses LoopFusePass::run(Function &F, FunctionAnalysisManager &AM) {
+ auto &LI = AM.getResult<LoopAnalysis>(F);
+ auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
+ auto &DI = AM.getResult<DependenceAnalysis>(F);
+ auto &SE = AM.getResult<ScalarEvolutionAnalysis>(F);
+ auto &PDT = AM.getResult<PostDominatorTreeAnalysis>(F);
+ auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
+
+ const DataLayout &DL = F.getParent()->getDataLayout();
+ LoopFuser LF(LI, DT, DI, SE, PDT, ORE, DL);
+ bool Changed = LF.fuseLoops(F);
+ if (!Changed)
+ return PreservedAnalyses::all();
+
+ PreservedAnalyses PA;
+ PA.preserve<DominatorTreeAnalysis>();
+ PA.preserve<PostDominatorTreeAnalysis>();
+ PA.preserve<ScalarEvolutionAnalysis>();
+ PA.preserve<LoopAnalysis>();
+ return PA;
+}
+
+char LoopFuseLegacy::ID = 0;
+
+INITIALIZE_PASS_BEGIN(LoopFuseLegacy, "loop-fusion", "Loop Fusion", false,
+ false)
+INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(DependenceAnalysisWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)
+INITIALIZE_PASS_END(LoopFuseLegacy, "loop-fusion", "Loop Fusion", false, false)
+
+FunctionPass *llvm::createLoopFusePass() { return new LoopFuseLegacy(); }
initializeJumpThreadingPass(Registry);
initializeLegacyLICMPassPass(Registry);
initializeLegacyLoopSinkPassPass(Registry);
+ initializeLoopFuseLegacyPass(Registry);
initializeLoopDataPrefetchLegacyPassPass(Registry);
initializeLoopDeletionLegacyPassPass(Registry);
initializeLoopAccessLegacyAnalysisPass(Registry);
--- /dev/null
+; RUN: opt -S -loop-fusion -debug-only=loop-fusion -disable-output < %s 2>&1 | FileCheck %s
+; REQUIRES: asserts
+
+@B = common global [1024 x i32] zeroinitializer, align 16
+
+; CHECK that the two candidates for fusion are placed into separate candidate
+; sets because they are not control flow equivalent.
+
+; CHECK: Performing Loop Fusion on function non_cfe
+; CHECK: Fusion Candidates:
+; CHECK: *** Fusion Candidate Set ***
+; CHECK: bb
+; CHECK: ****************************
+; CHECK: *** Fusion Candidate Set ***
+; CHECK: bb20.preheader
+; CHECK: ****************************
+; CHECK: Loop Fusion complete
+define void @non_cfe(i32* noalias %arg) {
+bb:
+ br label %bb5
+
+bb5: ; preds = %bb14, %bb
+ %indvars.iv2 = phi i64 [ %indvars.iv.next3, %bb14 ], [ 0, %bb ]
+ %.01 = phi i32 [ 0, %bb ], [ %tmp15, %bb14 ]
+ %exitcond4 = icmp ne i64 %indvars.iv2, 100
+ br i1 %exitcond4, label %bb7, label %bb16
+
+bb7: ; preds = %bb5
+ %tmp = add nsw i32 %.01, -3
+ %tmp8 = add nuw nsw i64 %indvars.iv2, 3
+ %tmp9 = trunc i64 %tmp8 to i32
+ %tmp10 = mul nsw i32 %tmp, %tmp9
+ %tmp11 = trunc i64 %indvars.iv2 to i32
+ %tmp12 = srem i32 %tmp10, %tmp11
+ %tmp13 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv2
+ store i32 %tmp12, i32* %tmp13, align 4
+ br label %bb14
+
+bb14: ; preds = %bb7
+ %indvars.iv.next3 = add nuw nsw i64 %indvars.iv2, 1
+ %tmp15 = add nuw nsw i32 %.01, 1
+ br label %bb5
+
+bb16: ; preds = %bb5
+ %tmp17 = load i32, i32* %arg, align 4
+ %tmp18 = icmp slt i32 %tmp17, 0
+ br i1 %tmp18, label %bb20, label %bb33
+
+bb20: ; preds = %bb30, %bb16
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb30 ], [ 0, %bb16 ]
+ %.0 = phi i32 [ 0, %bb16 ], [ %tmp31, %bb30 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb22, label %bb33
+
+bb22: ; preds = %bb20
+ %tmp23 = add nsw i32 %.0, -3
+ %tmp24 = add nuw nsw i64 %indvars.iv, 3
+ %tmp25 = trunc i64 %tmp24 to i32
+ %tmp26 = mul nsw i32 %tmp23, %tmp25
+ %tmp27 = trunc i64 %indvars.iv to i32
+ %tmp28 = srem i32 %tmp26, %tmp27
+ %tmp29 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
+ store i32 %tmp28, i32* %tmp29, align 4
+ br label %bb30
+
+bb30: ; preds = %bb22
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ %tmp31 = add nuw nsw i32 %.0, 1
+ br label %bb20
+
+bb33: ; preds = %bb20, %bb16
+ ret void
+}
+
+; Check that fusion detects the two canddates are not adjacent (the exit block
+; of the first candidate is not the preheader of the second candidate).
+
+; CHECK: Performing Loop Fusion on function non_adjacent
+; CHECK: Fusion Candidates:
+; CHECK: *** Fusion Candidate Set ***
+; CHECK-NEXT: [[LOOP1PREHEADER:bb[0-9]*]]
+; CHECK-NEXT: [[LOOP2PREHEADER:bb[0-9]*]]
+; CHECK-NEXT: ****************************
+; CHECK: Attempting fusion on Candidate Set:
+; CHECK-NEXT: [[LOOP1PREHEADER]]
+; CHECK-NEXT: [[LOOP2PREHEADER]]
+; CHECK: Fusion candidates are not adjacent. Not fusing.
+; CHECK: Loop Fusion complete
+define void @non_adjacent(i32* noalias %arg) {
+bb:
+ br label %bb3
+
+bb3: ; preds = %bb11, %bb
+ %.01 = phi i64 [ 0, %bb ], [ %tmp12, %bb11 ]
+ %exitcond2 = icmp ne i64 %.01, 100
+ br i1 %exitcond2, label %bb5, label %bb4
+
+bb4: ; preds = %bb3
+ br label %bb13
+
+bb5: ; preds = %bb3
+ %tmp = add nsw i64 %.01, -3
+ %tmp6 = add nuw nsw i64 %.01, 3
+ %tmp7 = mul nsw i64 %tmp, %tmp6
+ %tmp8 = srem i64 %tmp7, %.01
+ %tmp9 = trunc i64 %tmp8 to i32
+ %tmp10 = getelementptr inbounds i32, i32* %arg, i64 %.01
+ store i32 %tmp9, i32* %tmp10, align 4
+ br label %bb11
+
+bb11: ; preds = %bb5
+ %tmp12 = add nuw nsw i64 %.01, 1
+ br label %bb3
+
+bb13: ; preds = %bb4
+ br label %bb14
+
+bb14: ; preds = %bb23, %bb13
+ %.0 = phi i64 [ 0, %bb13 ], [ %tmp24, %bb23 ]
+ %exitcond = icmp ne i64 %.0, 100
+ br i1 %exitcond, label %bb16, label %bb15
+
+bb15: ; preds = %bb14
+ br label %bb25
+
+bb16: ; preds = %bb14
+ %tmp17 = add nsw i64 %.0, -3
+ %tmp18 = add nuw nsw i64 %.0, 3
+ %tmp19 = mul nsw i64 %tmp17, %tmp18
+ %tmp20 = srem i64 %tmp19, %.0
+ %tmp21 = trunc i64 %tmp20 to i32
+ %tmp22 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %.0
+ store i32 %tmp21, i32* %tmp22, align 4
+ br label %bb23
+
+bb23: ; preds = %bb16
+ %tmp24 = add nuw nsw i64 %.0, 1
+ br label %bb14
+
+bb25: ; preds = %bb15
+ ret void
+}
+
+; Check that the different bounds are detected and prevent fusion.
+
+; CHECK: Performing Loop Fusion on function different_bounds
+; CHECK: Fusion Candidates:
+; CHECK: *** Fusion Candidate Set ***
+; CHECK-NEXT: [[LOOP1PREHEADER:bb[0-9]*]]
+; CHECK-NEXT: [[LOOP2PREHEADER:bb[0-9]*]]
+; CHECK-NEXT: ****************************
+; CHECK: Attempting fusion on Candidate Set:
+; CHECK-NEXT: [[LOOP1PREHEADER]]
+; CHECK-NEXT: [[LOOP2PREHEADER]]
+; CHECK: Fusion candidates do not have identical trip counts. Not fusing.
+; CHECK: Loop Fusion complete
+define void @different_bounds(i32* noalias %arg) {
+bb:
+ br label %bb3
+
+bb3: ; preds = %bb11, %bb
+ %.01 = phi i64 [ 0, %bb ], [ %tmp12, %bb11 ]
+ %exitcond2 = icmp ne i64 %.01, 100
+ br i1 %exitcond2, label %bb5, label %bb4
+
+bb4: ; preds = %bb3
+ br label %bb13
+
+bb5: ; preds = %bb3
+ %tmp = add nsw i64 %.01, -3
+ %tmp6 = add nuw nsw i64 %.01, 3
+ %tmp7 = mul nsw i64 %tmp, %tmp6
+ %tmp8 = srem i64 %tmp7, %.01
+ %tmp9 = trunc i64 %tmp8 to i32
+ %tmp10 = getelementptr inbounds i32, i32* %arg, i64 %.01
+ store i32 %tmp9, i32* %tmp10, align 4
+ br label %bb11
+
+bb11: ; preds = %bb5
+ %tmp12 = add nuw nsw i64 %.01, 1
+ br label %bb3
+
+bb13: ; preds = %bb4
+ br label %bb14
+
+bb14: ; preds = %bb23, %bb13
+ %.0 = phi i64 [ 0, %bb13 ], [ %tmp24, %bb23 ]
+ %exitcond = icmp ne i64 %.0, 200
+ br i1 %exitcond, label %bb16, label %bb15
+
+bb15: ; preds = %bb14
+ br label %bb25
+
+bb16: ; preds = %bb14
+ %tmp17 = add nsw i64 %.0, -3
+ %tmp18 = add nuw nsw i64 %.0, 3
+ %tmp19 = mul nsw i64 %tmp17, %tmp18
+ %tmp20 = srem i64 %tmp19, %.0
+ %tmp21 = trunc i64 %tmp20 to i32
+ %tmp22 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %.0
+ store i32 %tmp21, i32* %tmp22, align 4
+ br label %bb23
+
+bb23: ; preds = %bb16
+ %tmp24 = add nuw nsw i64 %.0, 1
+ br label %bb14
+
+bb25: ; preds = %bb15
+ ret void
+}
+
+; Check that the negative dependence between the two candidates is identified
+; and prevents fusion.
+
+; CHECK: Performing Loop Fusion on function negative_dependence
+; CHECK: Fusion Candidates:
+; CHECK: *** Fusion Candidate Set ***
+; CHECK-NEXT: [[LOOP1PREHEADER:bb[0-9]*]]
+; CHECK-NEXT: [[LOOP2PREHEADER:bb[0-9]*]]
+; CHECK-NEXT: ****************************
+; CHECK: Attempting fusion on Candidate Set:
+; CHECK-NEXT: [[LOOP1PREHEADER]]
+; CHECK-NEXT: [[LOOP2PREHEADER]]
+; CHECK: Memory dependencies do not allow fusion!
+; CHECK: Loop Fusion complete
+define void @negative_dependence(i32* noalias %arg) {
+bb:
+ br label %bb5
+
+bb5: ; preds = %bb9, %bb
+ %indvars.iv2 = phi i64 [ %indvars.iv.next3, %bb9 ], [ 0, %bb ]
+ %exitcond4 = icmp ne i64 %indvars.iv2, 100
+ br i1 %exitcond4, label %bb7, label %bb11
+
+bb7: ; preds = %bb5
+ %tmp = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv2
+ %tmp8 = trunc i64 %indvars.iv2 to i32
+ store i32 %tmp8, i32* %tmp, align 4
+ br label %bb9
+
+bb9: ; preds = %bb7
+ %indvars.iv.next3 = add nuw nsw i64 %indvars.iv2, 1
+ br label %bb5
+
+bb11: ; preds = %bb18, %bb5
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb18 ], [ 0, %bb5 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb13, label %bb19
+
+bb13: ; preds = %bb11
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ %tmp14 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv.next
+ %tmp15 = load i32, i32* %tmp14, align 4
+ %tmp16 = shl nsw i32 %tmp15, 1
+ %tmp17 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
+ store i32 %tmp16, i32* %tmp17, align 4
+ br label %bb18
+
+bb18: ; preds = %bb13
+ br label %bb11
+
+bb19: ; preds = %bb11
+ ret void
+}
+
+; Check for values defined in Loop 0 and used in Loop 1.
+; It is not safe to fuse in this case, because the second loop has
+; a use of %.01.lcssa which is defined in the body of loop 0. The
+; first loop must execute completely in order to compute the correct
+; value of %.01.lcssa to be used in the second loop.
+
+; CHECK: Performing Loop Fusion on function sumTest
+; CHECK: Fusion Candidates:
+; CHECK: *** Fusion Candidate Set ***
+; CHECK-NEXT: [[LOOP1PREHEADER:bb[0-9]*]]
+; CHECK-NEXT: [[LOOP2PREHEADER:bb[0-9]*]]
+; CHECK-NEXT: ****************************
+; CHECK: Attempting fusion on Candidate Set:
+; CHECK-NEXT: [[LOOP1PREHEADER]]
+; CHECK-NEXT: [[LOOP2PREHEADER]]
+; CHECK: Memory dependencies do not allow fusion!
+; CHECK: Loop Fusion complete
+define i32 @sumTest(i32* noalias %arg) {
+bb:
+ br label %bb6
+
+bb6: ; preds = %bb9, %bb
+ %indvars.iv3 = phi i64 [ %indvars.iv.next4, %bb9 ], [ 0, %bb ]
+ %.01 = phi i32 [ 0, %bb ], [ %tmp11, %bb9 ]
+ %exitcond5 = icmp ne i64 %indvars.iv3, 100
+ br i1 %exitcond5, label %bb9, label %bb13
+
+bb9: ; preds = %bb6
+ %tmp = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv3
+ %tmp10 = load i32, i32* %tmp, align 4
+ %tmp11 = add nsw i32 %.01, %tmp10
+ %indvars.iv.next4 = add nuw nsw i64 %indvars.iv3, 1
+ br label %bb6
+
+bb13: ; preds = %bb20, %bb6
+ %.01.lcssa = phi i32 [ %.01, %bb6 ], [ %.01.lcssa, %bb20 ]
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb20 ], [ 0, %bb6 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb15, label %bb14
+
+bb14: ; preds = %bb13
+ br label %bb21
+
+bb15: ; preds = %bb13
+ %tmp16 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv
+ %tmp17 = load i32, i32* %tmp16, align 4
+ %tmp18 = sdiv i32 %tmp17, %.01.lcssa
+ %tmp19 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
+ store i32 %tmp18, i32* %tmp19, align 4
+ br label %bb20
+
+bb20: ; preds = %bb15
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ br label %bb13
+
+bb21: ; preds = %bb14
+ ret i32 %.01.lcssa
+}
+
+; Similar to sumTest above. The first loop computes %add and must
+; complete before it is used in the second loop. Thus, these two loops
+; also cannot be fused.
+
+; CHECK: Performing Loop Fusion on function test
+; CHECK: Fusion Candidates:
+; CHECK: *** Fusion Candidate Set ***
+; CHECK-NEXT: [[LOOP1PREHEADER:for.body[0-9]*.preheader]]
+; CHECK-NEXT: [[LOOP2PREHEADER:for.body[0-9]*.preheader]]
+; CHECK-NEXT: ****************************
+; CHECK: Attempting fusion on Candidate Set:
+; CHECK-NEXT: [[LOOP1PREHEADER]]
+; CHECK-NEXT: [[LOOP2PREHEADER]]
+; CHECK: Memory dependencies do not allow fusion!
+; CHECK: Loop Fusion complete
+define float @test(float* nocapture %a, i32 %n) {
+entry:
+ %conv = zext i32 %n to i64
+ %cmp32 = icmp eq i32 %n, 0
+ br i1 %cmp32, label %for.cond.cleanup7, label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.034 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
+ %sum1.033 = phi float [ %add, %for.body ], [ 0.000000e+00, %entry ]
+ %idxprom = trunc i64 %i.034 to i32
+ %arrayidx = getelementptr inbounds float, float* %a, i32 %idxprom
+ %0 = load float, float* %arrayidx, align 4
+ %add = fadd float %sum1.033, %0
+ %inc = add nuw nsw i64 %i.034, 1
+ %cmp = icmp ult i64 %inc, %conv
+ br i1 %cmp, label %for.body, label %for.body8
+
+for.body8: ; preds = %for.body, %for.body8
+ %i2.031 = phi i64 [ %inc14, %for.body8 ], [ 0, %for.body ]
+ %idxprom9 = trunc i64 %i2.031 to i32
+ %arrayidx10 = getelementptr inbounds float, float* %a, i32 %idxprom9
+ %1 = load float, float* %arrayidx10, align 4
+ %div = fdiv float %1, %add
+ store float %div, float* %arrayidx10, align 4
+ %inc14 = add nuw nsw i64 %i2.031, 1
+ %cmp5 = icmp ult i64 %inc14, %conv
+ br i1 %cmp5, label %for.body8, label %for.cond.cleanup7
+
+for.cond.cleanup7: ; preds = %for.body8, %entry
+ %sum1.0.lcssa36 = phi float [ 0.000000e+00, %entry ], [ %add, %for.body8 ]
+ ret float %sum1.0.lcssa36
+}
--- /dev/null
+; RUN: opt -S -loop-fusion < %s | FileCheck %s
+
+@A = common global [1024 x i32] zeroinitializer, align 16
+@B = common global [1024 x i32] zeroinitializer, align 16
+@C = common global [1024 x i32] zeroinitializer, align 16
+@D = common global [1024 x i32] zeroinitializer, align 16
+
+; CHECK: void @dep_free
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %[[LOOP1HEADER:bb[0-9]+]]
+; CHECK: [[LOOP1HEADER]]
+; CHECK: br i1 %exitcond12, label %[[LOOP1BODY:bb[0-9]+]], label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP1BODY]]
+; CHECK: br label %[[LOOP1LATCH:bb[0-9]+]]
+; CHECK: [[LOOP1LATCH]]
+; CHECK: br label %[[LOOP2PREHEADER]]
+; CHECK: [[LOOP2PREHEADER]]
+; CHECK: br i1 %exitcond9, label %[[LOOP2HEADER:bb[0-9]+]], label %[[LOOP3PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP2HEADER]]
+; CHECK: br label %[[LOOP2LATCH:bb[0-9]+]]
+; CHECK: [[LOOP2LATCH]]
+; CHECK: br label %[[LOOP3PREHEADER]]
+; CHECK: [[LOOP3PREHEADER]]
+; CHECK: br i1 %exitcond6, label %[[LOOP3HEADER:bb[0-9]+]], label %[[LOOP4PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP3HEADER]]
+; CHECK: br label %[[LOOP3LATCH:bb[0-9]+]]
+; CHECK: [[LOOP3LATCH]]
+; CHECK: br label %[[LOOP4PREHEADER]]
+; CHECK: [[LOOP4PREHEADER]]
+; CHECK: br i1 %exitcond, label %[[LOOP4HEADER:bb[0-9]+]], label %[[LOOP4EXIT:bb[0-9]+]]
+; CHECK: [[LOOP4EXIT]]
+; CHECK: br label %[[FUNCEXIT:bb[0-9]+]]
+; CHECK: [[LOOP4HEADER]]
+; CHECK: br label %[[LOOP4LATCH:bb[0-9]+]]
+; CHECK: [[LOOP4LATCH]]
+; CHECK: br label %[[LOOP1HEADER]]
+; CHECK: [[FUNCEXIT]]
+; CHECK: ret void
+define void @dep_free() {
+bb:
+ br label %bb13
+
+bb13: ; preds = %bb22, %bb
+ %indvars.iv10 = phi i64 [ %indvars.iv.next11, %bb22 ], [ 0, %bb ]
+ %.0 = phi i32 [ 0, %bb ], [ %tmp23, %bb22 ]
+ %exitcond12 = icmp ne i64 %indvars.iv10, 100
+ br i1 %exitcond12, label %bb15, label %bb25
+
+bb15: ; preds = %bb13
+ %tmp = add nsw i32 %.0, -3
+ %tmp16 = add nuw nsw i64 %indvars.iv10, 3
+ %tmp17 = trunc i64 %tmp16 to i32
+ %tmp18 = mul nsw i32 %tmp, %tmp17
+ %tmp19 = trunc i64 %indvars.iv10 to i32
+ %tmp20 = srem i32 %tmp18, %tmp19
+ %tmp21 = getelementptr inbounds [1024 x i32], [1024 x i32]* @A, i64 0, i64 %indvars.iv10
+ store i32 %tmp20, i32* %tmp21, align 4
+ br label %bb22
+
+bb22: ; preds = %bb15
+ %indvars.iv.next11 = add nuw nsw i64 %indvars.iv10, 1
+ %tmp23 = add nuw nsw i32 %.0, 1
+ br label %bb13
+
+bb25: ; preds = %bb35, %bb13
+ %indvars.iv7 = phi i64 [ %indvars.iv.next8, %bb35 ], [ 0, %bb13 ]
+ %.01 = phi i32 [ 0, %bb13 ], [ %tmp36, %bb35 ]
+ %exitcond9 = icmp ne i64 %indvars.iv7, 100
+ br i1 %exitcond9, label %bb27, label %bb38
+
+bb27: ; preds = %bb25
+ %tmp28 = add nsw i32 %.01, -3
+ %tmp29 = add nuw nsw i64 %indvars.iv7, 3
+ %tmp30 = trunc i64 %tmp29 to i32
+ %tmp31 = mul nsw i32 %tmp28, %tmp30
+ %tmp32 = trunc i64 %indvars.iv7 to i32
+ %tmp33 = srem i32 %tmp31, %tmp32
+ %tmp34 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv7
+ store i32 %tmp33, i32* %tmp34, align 4
+ br label %bb35
+
+bb35: ; preds = %bb27
+ %indvars.iv.next8 = add nuw nsw i64 %indvars.iv7, 1
+ %tmp36 = add nuw nsw i32 %.01, 1
+ br label %bb25
+
+bb38: ; preds = %bb48, %bb25
+ %indvars.iv4 = phi i64 [ %indvars.iv.next5, %bb48 ], [ 0, %bb25 ]
+ %.02 = phi i32 [ 0, %bb25 ], [ %tmp49, %bb48 ]
+ %exitcond6 = icmp ne i64 %indvars.iv4, 100
+ br i1 %exitcond6, label %bb40, label %bb51
+
+bb40: ; preds = %bb38
+ %tmp41 = add nsw i32 %.02, -3
+ %tmp42 = add nuw nsw i64 %indvars.iv4, 3
+ %tmp43 = trunc i64 %tmp42 to i32
+ %tmp44 = mul nsw i32 %tmp41, %tmp43
+ %tmp45 = trunc i64 %indvars.iv4 to i32
+ %tmp46 = srem i32 %tmp44, %tmp45
+ %tmp47 = getelementptr inbounds [1024 x i32], [1024 x i32]* @C, i64 0, i64 %indvars.iv4
+ store i32 %tmp46, i32* %tmp47, align 4
+ br label %bb48
+
+bb48: ; preds = %bb40
+ %indvars.iv.next5 = add nuw nsw i64 %indvars.iv4, 1
+ %tmp49 = add nuw nsw i32 %.02, 1
+ br label %bb38
+
+bb51: ; preds = %bb61, %bb38
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb61 ], [ 0, %bb38 ]
+ %.03 = phi i32 [ 0, %bb38 ], [ %tmp62, %bb61 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb53, label %bb52
+
+bb52: ; preds = %bb51
+ br label %bb63
+
+bb53: ; preds = %bb51
+ %tmp54 = add nsw i32 %.03, -3
+ %tmp55 = add nuw nsw i64 %indvars.iv, 3
+ %tmp56 = trunc i64 %tmp55 to i32
+ %tmp57 = mul nsw i32 %tmp54, %tmp56
+ %tmp58 = trunc i64 %indvars.iv to i32
+ %tmp59 = srem i32 %tmp57, %tmp58
+ %tmp60 = getelementptr inbounds [1024 x i32], [1024 x i32]* @D, i64 0, i64 %indvars.iv
+ store i32 %tmp59, i32* %tmp60, align 4
+ br label %bb61
+
+bb61: ; preds = %bb53
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ %tmp62 = add nuw nsw i32 %.03, 1
+ br label %bb51
+
+bb63: ; preds = %bb52
+ ret void
+}
--- /dev/null
+; RUN: opt -S -loop-fusion < %s 2>&1 | FileCheck %s
+
+@A = common global [1024 x [1024 x i32]] zeroinitializer, align 16
+@B = common global [1024 x [1024 x i32]] zeroinitializer, align 16
+
+; CHECK: void @dep_free
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %[[LOOP1HEADER:bb[0-9]*]]
+; CHECK: [[LOOP1HEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP1BODY:bb[0-9]*]], label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP1BODY]]
+; CHECK: br label %[[LOOP1LATCH:bb[0-9]*]]
+; CHECK: [[LOOP1LATCH]]
+; CHECK: br label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP2PREHEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP2BODY:bb[0-9]*]], label %[[LOOP2EXIT:bb[0-9]*]]
+; CHECK: [[LOOP2BODY]]
+; CHECK: br label %[[LOOP2LATCH:bb[0-9]+]]
+; CHECK: [[LOOP2LATCH]]
+; CHECK: br label %[[LOOP1HEADER]]
+; CHECK: ret void
+
+define void @dep_free() {
+bb:
+ br label %bb9
+
+bb9: ; preds = %bb35, %bb
+ %indvars.iv6 = phi i64 [ %indvars.iv.next7, %bb35 ], [ 0, %bb ]
+ %.0 = phi i32 [ 0, %bb ], [ %tmp36, %bb35 ]
+ %exitcond8 = icmp ne i64 %indvars.iv6, 100
+ br i1 %exitcond8, label %bb11, label %bb10
+
+bb10: ; preds = %bb9
+ br label %bb37
+
+bb11: ; preds = %bb9
+ br label %bb12
+
+bb12: ; preds = %bb21, %bb11
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb21 ], [ 0, %bb11 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb14, label %bb23
+
+bb14: ; preds = %bb12
+ %tmp = add nsw i32 %.0, -3
+ %tmp15 = add nuw nsw i64 %indvars.iv6, 3
+ %tmp16 = trunc i64 %tmp15 to i32
+ %tmp17 = mul nsw i32 %tmp, %tmp16
+ %tmp18 = trunc i64 %indvars.iv6 to i32
+ %tmp19 = srem i32 %tmp17, %tmp18
+ %tmp20 = getelementptr inbounds [1024 x [1024 x i32]], [1024 x [1024 x i32]]* @A, i64 0, i64 %indvars.iv6, i64 %indvars.iv
+ store i32 %tmp19, i32* %tmp20, align 4
+ br label %bb21
+
+bb21: ; preds = %bb14
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ br label %bb12
+
+bb23: ; preds = %bb33, %bb12
+ %indvars.iv3 = phi i64 [ %indvars.iv.next4, %bb33 ], [ 0, %bb12 ]
+ %exitcond5 = icmp ne i64 %indvars.iv3, 100
+ br i1 %exitcond5, label %bb25, label %bb35
+
+bb25: ; preds = %bb23
+ %tmp26 = add nsw i32 %.0, -3
+ %tmp27 = add nuw nsw i64 %indvars.iv6, 3
+ %tmp28 = trunc i64 %tmp27 to i32
+ %tmp29 = mul nsw i32 %tmp26, %tmp28
+ %tmp30 = trunc i64 %indvars.iv6 to i32
+ %tmp31 = srem i32 %tmp29, %tmp30
+ %tmp32 = getelementptr inbounds [1024 x [1024 x i32]], [1024 x [1024 x i32]]* @B, i64 0, i64 %indvars.iv6, i64 %indvars.iv3
+ store i32 %tmp31, i32* %tmp32, align 4
+ br label %bb33
+
+bb33: ; preds = %bb25
+ %indvars.iv.next4 = add nuw nsw i64 %indvars.iv3, 1
+ br label %bb23
+
+bb35: ; preds = %bb23
+ %indvars.iv.next7 = add nuw nsw i64 %indvars.iv6, 1
+ %tmp36 = add nuw nsw i32 %.0, 1
+ br label %bb9
+
+bb37: ; preds = %bb10
+ ret void
+}
--- /dev/null
+; RUN: opt -S -loop-fusion < %s | FileCheck %s
+;
+; int A[1024][1024];
+; int B[1024][1024];
+;
+; #define EXPENSIVE_PURE_COMPUTATION(i) ((i - 3) * (i + 3) % i)
+;
+; void dep_free() {
+;
+; for (int i = 0; i < 100; i++)
+; for (int j = 0; j < 100; j++)
+; A[i][j] = EXPENSIVE_PURE_COMPUTATION(i);
+;
+; for (int i = 0; i < 100; i++)
+; for (int j = 0; j < 100; j++)
+; B[i][j] = EXPENSIVE_PURE_COMPUTATION(i);
+; }
+;
+@A = common global [1024 x [1024 x i32]] zeroinitializer, align 16
+@B = common global [1024 x [1024 x i32]] zeroinitializer, align 16
+
+; CHECK: void @dep_free
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %[[LOOP1HEADER:bb[0-9]+]]
+; CHECK: [[LOOP1HEADER]]
+; CHECK: br i1 %exitcond12, label %[[LOOP3PREHEADER:bb[0-9]+.preheader]], label %[[LOOP2HEADER:bb[0-9]+]]
+; CHECK: [[LOOP3PREHEADER]]
+; CHECK: br label %[[LOOP3HEADER:bb[0-9]+]]
+; CHECK: [[LOOP3HEADER]]
+; CHECK: br i1 %exitcond9, label %[[LOOP3BODY:bb[0-9]+]], label %[[LOOP1LATCH:bb[0-9]+]]
+; CHECK: [[LOOP1LATCH]]
+; CHECK: br label %[[LOOP2HEADER:bb[0-9]+]]
+; CHECK: [[LOOP2HEADER]]
+; CHECK: br i1 %exitcond6, label %[[LOOP4PREHEADER:bb[0-9]+.preheader]], label %[[LOOP2EXITBLOCK:bb[0-9]+]]
+; CHECK: [[LOOP4PREHEADER]]
+; CHECK: br label %[[LOOP4HEADER:bb[0-9]+]]
+; CHECK: [[LOOP2EXITBLOCK]]
+; CHECK-NEXT: br label %[[FUNCEXIT:bb[0-9]+]]
+; CHECK: [[LOOP4HEADER]]
+; CHECK: br i1 %exitcond, label %[[LOOP4BODY:bb[0-9]+]], label %[[LOOP2LATCH:bb[0-9]+]]
+; CHECK: [[LOOP2LATCH]]
+; CHECK: br label %[[LOOP1HEADER:bb[0-9]+]]
+; CHECK: [[FUNCEXIT]]
+; CHECK: ret void
+
+; TODO: The current version of loop fusion does not allow the inner loops to be
+; fused because they are not control flow equivalent and adjacent. These are
+; limitations that can be addressed in future improvements to fusion.
+define void @dep_free() {
+bb:
+ br label %bb13
+
+bb13: ; preds = %bb27, %bb
+ %indvars.iv10 = phi i64 [ %indvars.iv.next11, %bb27 ], [ 0, %bb ]
+ %.0 = phi i32 [ 0, %bb ], [ %tmp28, %bb27 ]
+ %exitcond12 = icmp ne i64 %indvars.iv10, 100
+ br i1 %exitcond12, label %bb16, label %bb30
+
+bb16: ; preds = %bb25, %bb13
+ %indvars.iv7 = phi i64 [ %indvars.iv.next8, %bb25 ], [ 0, %bb13 ]
+ %exitcond9 = icmp ne i64 %indvars.iv7, 100
+ br i1 %exitcond9, label %bb18, label %bb27
+
+bb18: ; preds = %bb16
+ %tmp = add nsw i32 %.0, -3
+ %tmp19 = add nuw nsw i64 %indvars.iv10, 3
+ %tmp20 = trunc i64 %tmp19 to i32
+ %tmp21 = mul nsw i32 %tmp, %tmp20
+ %tmp22 = trunc i64 %indvars.iv10 to i32
+ %tmp23 = srem i32 %tmp21, %tmp22
+ %tmp24 = getelementptr inbounds [1024 x [1024 x i32]], [1024 x [1024 x i32]]* @A, i64 0, i64 %indvars.iv10, i64 %indvars.iv7
+ store i32 %tmp23, i32* %tmp24, align 4
+ br label %bb25
+
+bb25: ; preds = %bb18
+ %indvars.iv.next8 = add nuw nsw i64 %indvars.iv7, 1
+ br label %bb16
+
+bb27: ; preds = %bb16
+ %indvars.iv.next11 = add nuw nsw i64 %indvars.iv10, 1
+ %tmp28 = add nuw nsw i32 %.0, 1
+ br label %bb13
+
+bb30: ; preds = %bb45, %bb13
+ %indvars.iv4 = phi i64 [ %indvars.iv.next5, %bb45 ], [ 0, %bb13 ]
+ %.02 = phi i32 [ 0, %bb13 ], [ %tmp46, %bb45 ]
+ %exitcond6 = icmp ne i64 %indvars.iv4, 100
+ br i1 %exitcond6, label %bb33, label %bb31
+
+bb31: ; preds = %bb30
+ br label %bb47
+
+bb33: ; preds = %bb43, %bb30
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb43 ], [ 0, %bb30 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb35, label %bb45
+
+bb35: ; preds = %bb33
+ %tmp36 = add nsw i32 %.02, -3
+ %tmp37 = add nuw nsw i64 %indvars.iv4, 3
+ %tmp38 = trunc i64 %tmp37 to i32
+ %tmp39 = mul nsw i32 %tmp36, %tmp38
+ %tmp40 = trunc i64 %indvars.iv4 to i32
+ %tmp41 = srem i32 %tmp39, %tmp40
+ %tmp42 = getelementptr inbounds [1024 x [1024 x i32]], [1024 x [1024 x i32]]* @B, i64 0, i64 %indvars.iv4, i64 %indvars.iv
+ store i32 %tmp41, i32* %tmp42, align 4
+ br label %bb43
+
+bb43: ; preds = %bb35
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ br label %bb33
+
+bb45: ; preds = %bb33
+ %indvars.iv.next5 = add nuw nsw i64 %indvars.iv4, 1
+ %tmp46 = add nuw nsw i32 %.02, 1
+ br label %bb30
+
+bb47: ; preds = %bb31
+ ret void
+}
--- /dev/null
+; RUN: opt -S -loop-fusion < %s | FileCheck %s
+
+@B = common global [1024 x i32] zeroinitializer, align 16
+
+; CHECK: void @dep_free
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %[[LOOP1HEADER:bb[0-9]*]]
+; CHECK: [[LOOP1HEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP1BODY:bb[0-9]*]], label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP1BODY]]
+; CHECK: br label %[[LOOP1LATCH:bb[0-9]*]]
+; CHECK: [[LOOP1LATCH]]
+; CHECK: br label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP2PREHEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP2BODY:bb[0-9]*]], label %[[LOOP2EXIT:bb[0-9]*]]
+; CHECK: [[LOOP2BODY]]
+; CHECK: br label %[[LOOP2LATCH:bb[0-9]+]]
+; CHECK: [[LOOP2LATCH]]
+; CHECK: br label %[[LOOP1HEADER]]
+; CHECK: ret void
+define void @dep_free(i32* noalias %arg) {
+bb:
+ br label %bb5
+
+bb5: ; preds = %bb14, %bb
+ %indvars.iv2 = phi i64 [ %indvars.iv.next3, %bb14 ], [ 0, %bb ]
+ %.01 = phi i32 [ 0, %bb ], [ %tmp15, %bb14 ]
+ %exitcond4 = icmp ne i64 %indvars.iv2, 100
+ br i1 %exitcond4, label %bb7, label %bb17
+
+bb7: ; preds = %bb5
+ %tmp = add nsw i32 %.01, -3
+ %tmp8 = add nuw nsw i64 %indvars.iv2, 3
+ %tmp9 = trunc i64 %tmp8 to i32
+ %tmp10 = mul nsw i32 %tmp, %tmp9
+ %tmp11 = trunc i64 %indvars.iv2 to i32
+ %tmp12 = srem i32 %tmp10, %tmp11
+ %tmp13 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv2
+ store i32 %tmp12, i32* %tmp13, align 4
+ br label %bb14
+
+bb14: ; preds = %bb7
+ %indvars.iv.next3 = add nuw nsw i64 %indvars.iv2, 1
+ %tmp15 = add nuw nsw i32 %.01, 1
+ br label %bb5
+
+bb17: ; preds = %bb27, %bb5
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb27 ], [ 0, %bb5 ]
+ %.0 = phi i32 [ 0, %bb5 ], [ %tmp28, %bb27 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb19, label %bb18
+
+bb18: ; preds = %bb17
+ br label %bb29
+
+bb19: ; preds = %bb17
+ %tmp20 = add nsw i32 %.0, -3
+ %tmp21 = add nuw nsw i64 %indvars.iv, 3
+ %tmp22 = trunc i64 %tmp21 to i32
+ %tmp23 = mul nsw i32 %tmp20, %tmp22
+ %tmp24 = trunc i64 %indvars.iv to i32
+ %tmp25 = srem i32 %tmp23, %tmp24
+ %tmp26 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
+ store i32 %tmp25, i32* %tmp26, align 4
+ br label %bb27
+
+bb27: ; preds = %bb19
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ %tmp28 = add nuw nsw i32 %.0, 1
+ br label %bb17
+
+bb29: ; preds = %bb18
+ ret void
+}
+
+; CHECK: void @dep_free_parametric
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %[[LOOP1HEADER:bb[0-9]*]]
+; CHECK: [[LOOP1HEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP1BODY:bb[0-9]*]], label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP1BODY]]
+; CHECK: br label %[[LOOP1LATCH:bb[0-9]*]]
+; CHECK: [[LOOP1LATCH]]
+; CHECK: br label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP2PREHEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP2BODY:bb[0-9]*]], label %[[LOOP2EXIT:bb[0-9]*]]
+; CHECK: [[LOOP2BODY]]
+; CHECK: br label %[[LOOP2LATCH:bb[0-9]+]]
+; CHECK: [[LOOP2LATCH]]
+; CHECK: br label %[[LOOP1HEADER]]
+; CHECK: ret void
+define void @dep_free_parametric(i32* noalias %arg, i64 %arg2) {
+bb:
+ br label %bb3
+
+bb3: ; preds = %bb12, %bb
+ %.01 = phi i64 [ 0, %bb ], [ %tmp13, %bb12 ]
+ %tmp = icmp slt i64 %.01, %arg2
+ br i1 %tmp, label %bb5, label %bb15
+
+bb5: ; preds = %bb3
+ %tmp6 = add nsw i64 %.01, -3
+ %tmp7 = add nuw nsw i64 %.01, 3
+ %tmp8 = mul nsw i64 %tmp6, %tmp7
+ %tmp9 = srem i64 %tmp8, %.01
+ %tmp10 = trunc i64 %tmp9 to i32
+ %tmp11 = getelementptr inbounds i32, i32* %arg, i64 %.01
+ store i32 %tmp10, i32* %tmp11, align 4
+ br label %bb12
+
+bb12: ; preds = %bb5
+ %tmp13 = add nuw nsw i64 %.01, 1
+ br label %bb3
+
+bb15: ; preds = %bb25, %bb3
+ %.0 = phi i64 [ 0, %bb3 ], [ %tmp26, %bb25 ]
+ %tmp16 = icmp slt i64 %.0, %arg2
+ br i1 %tmp16, label %bb18, label %bb17
+
+bb17: ; preds = %bb15
+ br label %bb27
+
+bb18: ; preds = %bb15
+ %tmp19 = add nsw i64 %.0, -3
+ %tmp20 = add nuw nsw i64 %.0, 3
+ %tmp21 = mul nsw i64 %tmp19, %tmp20
+ %tmp22 = srem i64 %tmp21, %.0
+ %tmp23 = trunc i64 %tmp22 to i32
+ %tmp24 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %.0
+ store i32 %tmp23, i32* %tmp24, align 4
+ br label %bb25
+
+bb25: ; preds = %bb18
+ %tmp26 = add nuw nsw i64 %.0, 1
+ br label %bb15
+
+bb27: ; preds = %bb17
+ ret void
+}
+
+; CHECK: void @raw_only
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %[[LOOP1HEADER:bb[0-9]*]]
+; CHECK: [[LOOP1HEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP1BODY:bb[0-9]*]], label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP1BODY]]
+; CHECK: br label %[[LOOP1LATCH:bb[0-9]*]]
+; CHECK: [[LOOP1LATCH]]
+; CHECK: br label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP2PREHEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP2BODY:bb[0-9]*]], label %[[LOOP2EXIT:bb[0-9]*]]
+; CHECK: [[LOOP2BODY]]
+; CHECK: br label %[[LOOP2LATCH:bb[0-9]+]]
+; CHECK: [[LOOP2LATCH]]
+; CHECK: br label %[[LOOP1HEADER]]
+; CHECK: ret void
+define void @raw_only(i32* noalias %arg) {
+bb:
+ br label %bb5
+
+bb5: ; preds = %bb9, %bb
+ %indvars.iv2 = phi i64 [ %indvars.iv.next3, %bb9 ], [ 0, %bb ]
+ %exitcond4 = icmp ne i64 %indvars.iv2, 100
+ br i1 %exitcond4, label %bb7, label %bb11
+
+bb7: ; preds = %bb5
+ %tmp = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv2
+ %tmp8 = trunc i64 %indvars.iv2 to i32
+ store i32 %tmp8, i32* %tmp, align 4
+ br label %bb9
+
+bb9: ; preds = %bb7
+ %indvars.iv.next3 = add nuw nsw i64 %indvars.iv2, 1
+ br label %bb5
+
+bb11: ; preds = %bb18, %bb5
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb18 ], [ 0, %bb5 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb13, label %bb19
+
+bb13: ; preds = %bb11
+ %tmp14 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv
+ %tmp15 = load i32, i32* %tmp14, align 4
+ %tmp16 = shl nsw i32 %tmp15, 1
+ %tmp17 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
+ store i32 %tmp16, i32* %tmp17, align 4
+ br label %bb18
+
+bb18: ; preds = %bb13
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ br label %bb11
+
+bb19: ; preds = %bb11
+ ret void
+}
+
+; CHECK: void @raw_only_parametric
+; CHECK-NEXT: bb:
+; CHECK: br label %[[LOOP1HEADER:bb[0-9]*]]
+; CHECK: [[LOOP1HEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP1BODY:bb[0-9]*]], label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP1BODY]]
+; CHECK: br label %[[LOOP1LATCH:bb[0-9]*]]
+; CHECK: [[LOOP1LATCH]]
+; CHECK: br label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP2PREHEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP2BODY:bb[0-9]*]], label %[[LOOP2EXIT:bb[0-9]*]]
+; CHECK: [[LOOP2BODY]]
+; CHECK: br label %[[LOOP2LATCH:bb[0-9]+]]
+; CHECK: [[LOOP2LATCH]]
+; CHECK: br label %[[LOOP1HEADER]]
+; CHECK: ret void
+define void @raw_only_parametric(i32* noalias %arg, i32 %arg4) {
+bb:
+ br label %bb5
+
+bb5: ; preds = %bb11, %bb
+ %indvars.iv2 = phi i64 [ %indvars.iv.next3, %bb11 ], [ 0, %bb ]
+ %tmp = sext i32 %arg4 to i64
+ %tmp6 = icmp slt i64 %indvars.iv2, %tmp
+ br i1 %tmp6, label %bb8, label %bb14
+
+bb8: ; preds = %bb5
+ %tmp9 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv2
+ %tmp10 = trunc i64 %indvars.iv2 to i32
+ store i32 %tmp10, i32* %tmp9, align 4
+ br label %bb11
+
+bb11: ; preds = %bb8
+ %indvars.iv.next3 = add nuw nsw i64 %indvars.iv2, 1
+ br label %bb5
+
+bb14: ; preds = %bb22, %bb5
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb22 ], [ 0, %bb5 ]
+ %tmp13 = sext i32 %arg4 to i64
+ %tmp15 = icmp slt i64 %indvars.iv, %tmp13
+ br i1 %tmp15, label %bb17, label %bb23
+
+bb17: ; preds = %bb14
+ %tmp18 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv
+ %tmp19 = load i32, i32* %tmp18, align 4
+ %tmp20 = shl nsw i32 %tmp19, 1
+ %tmp21 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
+ store i32 %tmp20, i32* %tmp21, align 4
+ br label %bb22
+
+bb22: ; preds = %bb17
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ br label %bb14
+
+bb23: ; preds = %bb14
+ ret void
+}
+
+; CHECK: void @forward_dep
+; CHECK-NEXT: bb:
+; CHECK: br label %[[LOOP1HEADER:bb[0-9]*]]
+; CHECK: [[LOOP1HEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP1BODY:bb[0-9]*]], label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP1BODY]]
+; CHECK: br label %[[LOOP1LATCH:bb[0-9]*]]
+; CHECK: [[LOOP1LATCH]]
+; CHECK: br label %[[LOOP2PREHEADER:bb[0-9]+]]
+; CHECK: [[LOOP2PREHEADER]]
+; CHECK: br i1 %{{.*}}, label %[[LOOP2BODY:bb[0-9]*]], label %[[LOOP2EXIT:bb[0-9]*]]
+; CHECK: [[LOOP2BODY]]
+; CHECK: br label %[[LOOP2LATCH:bb[0-9]+]]
+; CHECK: [[LOOP2LATCH]]
+; CHECK: br label %[[LOOP1HEADER]]
+; CHECK: ret void
+define void @forward_dep(i32* noalias %arg) {
+bb:
+ br label %bb5
+
+bb5: ; preds = %bb14, %bb
+ %indvars.iv2 = phi i64 [ %indvars.iv.next3, %bb14 ], [ 0, %bb ]
+ %.01 = phi i32 [ 0, %bb ], [ %tmp15, %bb14 ]
+ %exitcond4 = icmp ne i64 %indvars.iv2, 100
+ br i1 %exitcond4, label %bb7, label %bb17
+
+bb7: ; preds = %bb5
+ %tmp = add nsw i32 %.01, -3
+ %tmp8 = add nuw nsw i64 %indvars.iv2, 3
+ %tmp9 = trunc i64 %tmp8 to i32
+ %tmp10 = mul nsw i32 %tmp, %tmp9
+ %tmp11 = trunc i64 %indvars.iv2 to i32
+ %tmp12 = srem i32 %tmp10, %tmp11
+ %tmp13 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv2
+ store i32 %tmp12, i32* %tmp13, align 4
+ br label %bb14
+
+bb14: ; preds = %bb7
+ %indvars.iv.next3 = add nuw nsw i64 %indvars.iv2, 1
+ %tmp15 = add nuw nsw i32 %.01, 1
+ br label %bb5
+
+bb17: ; preds = %bb25, %bb5
+ %indvars.iv = phi i64 [ %indvars.iv.next, %bb25 ], [ 0, %bb5 ]
+ %exitcond = icmp ne i64 %indvars.iv, 100
+ br i1 %exitcond, label %bb19, label %bb26
+
+bb19: ; preds = %bb17
+ %tmp20 = add nsw i64 %indvars.iv, -3
+ %tmp21 = getelementptr inbounds i32, i32* %arg, i64 %tmp20
+ %tmp22 = load i32, i32* %tmp21, align 4
+ %tmp23 = mul nsw i32 %tmp22, 3
+ %tmp24 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv
+ store i32 %tmp23, i32* %tmp24, align 4
+ br label %bb25
+
+bb25: ; preds = %bb19
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ br label %bb17
+
+bb26: ; preds = %bb17
+ ret void
+}
projects / llvm / commitdiff