[llvm] r231458 - Add a new pass "Loop Interchange"
Aaron Ballman
aaron at aaronballman.com
Fri Apr 24 09:17:56 PDT 2015
Ah, I hadn't noticed that patch! Yes, it looks good to me to commit it, but
we may still want to consider whether the removal api is the best approach.
-Aaron
On Apr 24, 2015 11:53 AM, "Karthik Bhat" <blitz.opensource at gmail.com> wrote:
> Hi Aaron,
> Sorry for the delay..
>
> Kyler had proposed a fix which looks good to me.. I have added my comments
> on the same.. I think it would be submitted shortly.
>
>
> http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20150420/273084.html
>
> Shall i go ahead and make those changes?
>
> Thanks and Regards
>
> Karthik Bhat
>
>
>
> On 24-Apr-2015 8:25 pm, "Aaron Ballman" <aaron at aaronballman.com> wrote:
>
> I am still seeing these failures on Windows; can you please address
> them (I suspect reversion would be a horribly painful option I would
> like to avoid).
>
> Thanks!
>
> ~Aaron
>
> On Thu, Apr 23, 2015 at 11:07 AM, Aaron Ballman <aaron at aaronballman.com>
> wrote:
> > On Fri, Mar 6, 2015 at 5:11 AM, Karthik Bhat <kv.bhat at samsung.com>
> wrote:
> >> Author: karthik
> >> Date: Fri Mar 6 04:11:25 2015
> >> New Revision: 231458
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=231458&view=rev
> >> Log:
> >> Add a new pass "Loop Interchange"
> >> This pass interchanges loops to provide a more cache-friendly memory
> access.
> >>
> >> For e.g. given a loop like -
> >> for(int i=0;i<N;i++)
> >> for(int j=0;j<N;j++)
> >> A[j][i] = A[j][i]+B[j][i];
> >>
> >> is interchanged to -
> >> for(int j=0;j<N;j++)
> >> for(int i=0;i<N;i++)
> >> A[j][i] = A[j][i]+B[j][i];
> >>
> >> This pass is currently disabled by default.
> >>
> >> To give a brief introduction it consists of 3 stages-
> >>
> >> LoopInterchangeLegality : Checks the legality of loop interchange based
> on Dependency matrix.
> >> LoopInterchangeProfitability: A very basic heuristic has been added to
> check for profitibility. This will evolve over time.
> >> LoopInterchangeTransform : Which does the actual transform.
> >>
> >> LNT Performance tests shows improvement in
> Polybench/linear-algebra/kernels/mvt and
> Polybench/linear-algebra/kernels/gemver becnmarks.
> >>
> >> TODO:
> >> 1) Add support for reductions and lcssa phi.
> >> 2) Improve profitability model.
> >> 3) Improve loop selection algorithm to select best loop for
> interchange. Currently the innermost loop is selected for interchange.
> >> 4) Improve compile time regression found in llvm lnt due to this pass.
> >> 5) Fix issues in Dependency Analysis module.
> >>
> >> A special thanks to Hal for reviewing this code.
> >> Review: http://reviews.llvm.org/D7499
> >>
> >>
> >>
> >> Added:
> >> llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp
> >> llvm/trunk/test/Transforms/LoopInterchange/
> >> llvm/trunk/test/Transforms/LoopInterchange/currentLimitation.ll
> >> llvm/trunk/test/Transforms/LoopInterchange/interchange.ll
> >> llvm/trunk/test/Transforms/LoopInterchange/profitability.ll
> >> Modified:
> >> llvm/trunk/include/llvm/InitializePasses.h
> >> llvm/trunk/include/llvm/LinkAllPasses.h
> >> llvm/trunk/include/llvm/Transforms/Scalar.h
> >> llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> >> llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt
> >> llvm/trunk/lib/Transforms/Scalar/Scalar.cpp
> >>
> >> Modified: llvm/trunk/include/llvm/InitializePasses.h
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=231458&r1=231457&r2=231458&view=diff
> >>
> ==============================================================================
> >> --- llvm/trunk/include/llvm/InitializePasses.h (original)
> >> +++ llvm/trunk/include/llvm/InitializePasses.h Fri Mar 6 04:11:25 2015
> >> @@ -166,6 +166,7 @@ void initializeLocalStackSlotPassPass(Pa
> >> void initializeLoopDeletionPass(PassRegistry&);
> >> void initializeLoopExtractorPass(PassRegistry&);
> >> void initializeLoopInfoWrapperPassPass(PassRegistry&);
> >> +void initializeLoopInterchangePass(PassRegistry &);
> >> void initializeLoopInstSimplifyPass(PassRegistry&);
> >> void initializeLoopRotatePass(PassRegistry&);
> >> void initializeLoopSimplifyPass(PassRegistry&);
> >>
> >> Modified: llvm/trunk/include/llvm/LinkAllPasses.h
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/LinkAllPasses.h?rev=231458&r1=231457&r2=231458&view=diff
> >>
> ==============================================================================
> >> --- llvm/trunk/include/llvm/LinkAllPasses.h (original)
> >> +++ llvm/trunk/include/llvm/LinkAllPasses.h Fri Mar 6 04:11:25 2015
> >> @@ -95,6 +95,7 @@ namespace {
> >> (void) llvm::createLICMPass();
> >> (void) llvm::createLazyValueInfoPass();
> >> (void) llvm::createLoopExtractorPass();
> >> + (void)llvm::createLoopInterchangePass();
> >> (void) llvm::createLoopSimplifyPass();
> >> (void) llvm::createLoopStrengthReducePass();
> >> (void) llvm::createLoopRerollPass();
> >>
> >> Modified: llvm/trunk/include/llvm/Transforms/Scalar.h
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Scalar.h?rev=231458&r1=231457&r2=231458&view=diff
> >>
> ==============================================================================
> >> --- llvm/trunk/include/llvm/Transforms/Scalar.h (original)
> >> +++ llvm/trunk/include/llvm/Transforms/Scalar.h Fri Mar 6 04:11:25 2015
> >> @@ -140,6 +140,13 @@ Pass *createLICMPass();
> >>
> >>
> //===----------------------------------------------------------------------===//
> >> //
> >> +// LoopInterchange - This pass interchanges loops to provide a more
> >> +// cache-friendly memory access patterns.
> >> +//
> >> +Pass *createLoopInterchangePass();
> >> +
> >>
> +//===----------------------------------------------------------------------===//
> >> +//
> >> // LoopStrengthReduce - This pass is strength reduces GEP instructions
> that use
> >> // a loop's canonical induction variable as one of their indices.
> >> //
> >>
> >> Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=231458&r1=231457&r2=231458&view=diff
> >>
> ==============================================================================
> >> --- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
> >> +++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Fri Mar 6
> 04:11:25 2015
> >> @@ -77,6 +77,10 @@ static cl::opt<bool>
> >> EnableMLSM("mlsm", cl::init(true), cl::Hidden,
> >> cl::desc("Enable motion of merged load and store"));
> >>
> >> +static cl::opt<bool> EnableLoopInterchange(
> >> + "enable-loopinterchange", cl::init(false), cl::Hidden,
> >> + cl::desc("Enable the new, experimental LoopInterchange Pass"));
> >> +
> >> PassManagerBuilder::PassManagerBuilder() {
> >> OptLevel = 2;
> >> SizeLevel = 0;
> >> @@ -239,6 +243,8 @@ void PassManagerBuilder::populateModuleP
> >> MPM.add(createIndVarSimplifyPass()); // Canonicalize indvars
> >> MPM.add(createLoopIdiomPass()); // Recognize idioms like
> memset.
> >> MPM.add(createLoopDeletionPass()); // Delete dead loops
> >> + if (EnableLoopInterchange)
> >> + MPM.add(createLoopInterchangePass()); // Interchange loops
> >>
> >> if (!DisableUnrollLoops)
> >> MPM.add(createSimpleLoopUnrollPass()); // Unroll small loops
> >> @@ -454,6 +460,9 @@ void PassManagerBuilder::addLTOOptimizat
> >> // More loops are countable; try to optimize them.
> >> PM.add(createIndVarSimplifyPass());
> >> PM.add(createLoopDeletionPass());
> >> + if (EnableLoopInterchange)
> >> + PM.add(createLoopInterchangePass());
> >> +
> >> PM.add(createLoopVectorizePass(true, LoopVectorize));
> >>
> >> // More scalar chains could be vectorized due to more alias
> information
> >>
> >> Modified: llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt?rev=231458&r1=231457&r2=231458&view=diff
> >>
> ==============================================================================
> >> --- llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt (original)
> >> +++ llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt Fri Mar 6 04:11:25
> 2015
> >> @@ -18,6 +18,7 @@ add_llvm_library(LLVMScalarOpts
> >> LoopDeletion.cpp
> >> LoopIdiomRecognize.cpp
> >> LoopInstSimplify.cpp
> >> + LoopInterchange.cpp
> >> LoopRerollPass.cpp
> >> LoopRotation.cpp
> >> LoopStrengthReduce.cpp
> >>
> >> Added: llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp?rev=231458&view=auto
> >>
> ==============================================================================
> >> --- llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp (added)
> >> +++ llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp Fri Mar 6
> 04:11:25 2015
> >> @@ -0,0 +1,1193 @@
> >> +//===- LoopInterchange.cpp - Loop interchange
> pass------------------------===//
> >> +//
> >> +// The LLVM Compiler Infrastructure
> >> +//
> >> +// This file is distributed under the University of Illinois Open
> Source
> >> +// License. See LICENSE.TXT for details.
> >> +//
> >>
> +//===----------------------------------------------------------------------===//
> >> +//
> >> +// This Pass handles loop interchange transform.
> >> +// This pass interchanges loops to provide a more cache-friendly
> memory access
> >> +// patterns.
> >> +//
> >>
> +//===----------------------------------------------------------------------===//
> >> +
> >> +#include "llvm/ADT/SmallVector.h"
> >> +#include "llvm/Analysis/AliasAnalysis.h"
> >> +#include "llvm/Analysis/AliasSetTracker.h"
> >> +#include "llvm/Analysis/AssumptionCache.h"
> >> +#include "llvm/Analysis/BlockFrequencyInfo.h"
> >> +#include "llvm/Analysis/CodeMetrics.h"
> >> +#include "llvm/Analysis/DependenceAnalysis.h"
> >> +#include "llvm/Analysis/LoopInfo.h"
> >> +#include "llvm/Analysis/LoopIterator.h"
> >> +#include "llvm/Analysis/LoopPass.h"
> >> +#include "llvm/Analysis/ScalarEvolution.h"
> >> +#include "llvm/Analysis/ScalarEvolutionExpander.h"
> >> +#include "llvm/Analysis/ScalarEvolutionExpressions.h"
> >> +#include "llvm/Analysis/TargetTransformInfo.h"
> >> +#include "llvm/Analysis/ValueTracking.h"
> >> +#include "llvm/Transforms/Scalar.h"
> >> +#include "llvm/IR/Function.h"
> >> +#include "llvm/IR/IRBuilder.h"
> >> +#include "llvm/IR/IntrinsicInst.h"
> >> +#include "llvm/IR/InstIterator.h"
> >> +#include "llvm/IR/Dominators.h"
> >> +#include "llvm/Pass.h"
> >> +#include "llvm/Support/Debug.h"
> >> +#include "llvm/Transforms/Utils/SSAUpdater.h"
> >> +#include "llvm/Support/raw_ostream.h"
> >> +#include "llvm/Transforms/Utils/LoopUtils.h"
> >> +#include "llvm/Transforms/Utils/BasicBlockUtils.h"
> >> +using namespace llvm;
> >> +
> >> +#define DEBUG_TYPE "loop-interchange"
> >> +
> >> +namespace {
> >> +
> >> +typedef SmallVector<Loop *, 8> LoopVector;
> >> +
> >> +// TODO: Check if we can use a sparse matrix here.
> >> +typedef std::vector<std::vector<char>> CharMatrix;
> >> +
> >> +// Maximum number of dependencies that can be handled in the
> dependency matrix.
> >> +static const unsigned MaxMemInstrCount = 100;
> >> +
> >> +// Maximum loop depth supported.
> >> +static const unsigned MaxLoopNestDepth = 10;
> >> +
> >> +struct LoopInterchange;
> >> +
> >> +#ifdef DUMP_DEP_MATRICIES
> >> +void printDepMatrix(CharMatrix &DepMatrix) {
> >> + for (auto I = DepMatrix.begin(), E = DepMatrix.end(); I != E; ++I) {
> >> + std::vector<char> Vec = *I;
> >> + for (auto II = Vec.begin(), EE = Vec.end(); II != EE; ++II)
> >> + DEBUG(dbgs() << *II << " ");
> >> + DEBUG(dbgs() << "\n");
> >> + }
> >> +}
> >> +#endif
> >> +
> >> +bool populateDependencyMatrix(CharMatrix &DepMatrix, unsigned Level,
> Loop *L,
> >> + DependenceAnalysis *DA) {
> >> + typedef SmallVector<Value *, 16> ValueVector;
> >> + ValueVector MemInstr;
> >> +
> >> + if (Level > MaxLoopNestDepth) {
> >> + DEBUG(dbgs() << "Cannot handle loops of depth greater than "
> >> + << MaxLoopNestDepth << "\n");
> >> + return false;
> >> + }
> >> +
> >> + // For each block.
> >> + for (Loop::block_iterator BB = L->block_begin(), BE = L->block_end();
> >> + BB != BE; ++BB) {
> >> + // Scan the BB and collect legal loads and stores.
> >> + for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I
> != E;
> >> + ++I) {
> >> + Instruction *Ins = dyn_cast<Instruction>(I);
> >> + if (!Ins)
> >> + return false;
> >> + LoadInst *Ld = dyn_cast<LoadInst>(I);
> >> + StoreInst *St = dyn_cast<StoreInst>(I);
> >> + if (!St && !Ld)
> >> + continue;
> >> + if (Ld && !Ld->isSimple())
> >> + return false;
> >> + if (St && !St->isSimple())
> >> + return false;
> >> + MemInstr.push_back(I);
> >> + }
> >> + }
> >> +
> >> + DEBUG(dbgs() << "Found " << MemInstr.size()
> >> + << " Loads and Stores to analyze\n");
> >> +
> >> + ValueVector::iterator I, IE, J, JE;
> >> +
> >> + for (I = MemInstr.begin(), IE = MemInstr.end(); I != IE; ++I) {
> >> + for (J = I, JE = MemInstr.end(); J != JE; ++J) {
> >> + std::vector<char> Dep;
> >> + Instruction *Src = dyn_cast<Instruction>(*I);
> >> + Instruction *Des = dyn_cast<Instruction>(*J);
> >> + if (Src == Des)
> >> + continue;
> >> + if (isa<LoadInst>(Src) && isa<LoadInst>(Des))
> >> + continue;
> >> + if (auto D = DA->depends(Src, Des, true)) {
> >> + DEBUG(dbgs() << "Found Dependency between Src=" << Src << "
> Des=" << Des
> >> + << "\n");
> >> + if (D->isFlow()) {
> >> + // TODO: Handle Flow dependence.Check if it is sufficient to
> populate
> >> + // the Dependence Matrix with the direction reversed.
> >> + DEBUG(dbgs() << "Flow dependence not handled");
> >> + return false;
> >> + }
> >> + if (D->isAnti()) {
> >> + DEBUG(dbgs() << "Found Anti dependence \n");
> >> + unsigned Levels = D->getLevels();
> >> + char Direction;
> >> + for (unsigned II = 1; II <= Levels; ++II) {
> >> + const SCEV *Distance = D->getDistance(II);
> >> + const SCEVConstant *SCEVConst =
> >> + dyn_cast_or_null<SCEVConstant>(Distance);
> >> + if (SCEVConst) {
> >> + const ConstantInt *CI = SCEVConst->getValue();
> >> + if (CI->isNegative())
> >> + Direction = '<';
> >> + else if (CI->isZero())
> >> + Direction = '=';
> >> + else
> >> + Direction = '>';
> >> + Dep.push_back(Direction);
> >> + } else if (D->isScalar(II)) {
> >> + Direction = 'S';
> >> + Dep.push_back(Direction);
> >> + } else {
> >> + unsigned Dir = D->getDirection(II);
> >> + if (Dir == Dependence::DVEntry::LT ||
> >> + Dir == Dependence::DVEntry::LE)
> >> + Direction = '<';
> >> + else if (Dir == Dependence::DVEntry::GT ||
> >> + Dir == Dependence::DVEntry::GE)
> >> + Direction = '>';
> >> + else if (Dir == Dependence::DVEntry::EQ)
> >> + Direction = '=';
> >> + else
> >> + Direction = '*';
> >> + Dep.push_back(Direction);
> >> + }
> >> + }
> >> + while (Dep.size() != Level) {
> >> + Dep.push_back('I');
> >> + }
> >> +
> >> + DepMatrix.push_back(Dep);
> >> + if (DepMatrix.size() > MaxMemInstrCount) {
> >> + DEBUG(dbgs() << "Cannot handle more than " <<
> MaxMemInstrCount
> >> + << " dependencies inside loop\n");
> >> + return false;
> >> + }
> >> + }
> >> + }
> >> + }
> >> + }
> >> +
> >> + // We don't have a DepMatrix to check legality return false
> >> + if (DepMatrix.size() == 0)
> >> + return false;
> >> + return true;
> >> +}
> >> +
> >> +// A loop is moved from index 'from' to an index 'to'. Update the
> Dependence
> >> +// matrix by exchanging the two columns.
> >> +void interChangeDepedencies(CharMatrix &DepMatrix, unsigned FromIndx,
> >> + unsigned ToIndx) {
> >> + unsigned numRows = DepMatrix.size();
> >> + for (unsigned i = 0; i < numRows; ++i) {
> >> + char TmpVal = DepMatrix[i][ToIndx];
> >> + DepMatrix[i][ToIndx] = DepMatrix[i][FromIndx];
> >> + DepMatrix[i][FromIndx] = TmpVal;
> >> + }
> >> +}
> >> +
> >> +// Checks if outermost non '=','S'or'I' dependence in the dependence
> matrix is
> >> +// '>'
> >> +bool isOuterMostDepPositive(CharMatrix &DepMatrix, unsigned Row,
> >> + unsigned Column) {
> >> + for (unsigned i = 0; i <= Column; ++i) {
> >> + if (DepMatrix[Row][i] == '<')
> >> + return false;
> >> + if (DepMatrix[Row][i] == '>')
> >> + return true;
> >> + }
> >> + // All dependencies were '=','S' or 'I'
> >> + return false;
> >> +}
> >> +
> >> +// Checks if no dependence exist in the dependency matrix in Row
> before Column.
> >> +bool containsNoDependence(CharMatrix &DepMatrix, unsigned Row,
> >> + unsigned Column) {
> >> + for (unsigned i = 0; i < Column; ++i) {
> >> + if (DepMatrix[Row][i] != '=' || DepMatrix[Row][i] != 'S' ||
> >> + DepMatrix[Row][i] != 'I')
> >> + return false;
> >> + }
> >> + return true;
> >> +}
> >> +
> >> +bool validDepInterchange(CharMatrix &DepMatrix, unsigned Row,
> >> + unsigned OuterLoopId, char InnerDep, char
> OuterDep) {
> >> +
> >> + if (isOuterMostDepPositive(DepMatrix, Row, OuterLoopId))
> >> + return false;
> >> +
> >> + if (InnerDep == OuterDep)
> >> + return true;
> >> +
> >> + // It is legal to interchange if and only if after interchange no
> row has a
> >> + // '>' direction as the leftmost non-'='.
> >> +
> >> + if (InnerDep == '=' || InnerDep == 'S' || InnerDep == 'I')
> >> + return true;
> >> +
> >> + if (InnerDep == '<')
> >> + return true;
> >> +
> >> + if (InnerDep == '>') {
> >> + // If OuterLoopId represents outermost loop then interchanging
> will make the
> >> + // 1st dependency as '>'
> >> + if (OuterLoopId == 0)
> >> + return false;
> >> +
> >> + // If all dependencies before OuterloopId are '=','S'or 'I'. Then
> >> + // interchanging will result in this row having an outermost non
> '='
> >> + // dependency of '>'
> >> + if (!containsNoDependence(DepMatrix, Row, OuterLoopId))
> >> + return true;
> >> + }
> >> +
> >> + return false;
> >> +}
> >> +
> >> +// Checks if it is legal to interchange 2 loops.
> >> +// [Theorm] A permutation of the loops in a perfect nest is legal if
> and only if
> >> +// the direction matrix, after the same permutation is applied to its
> columns,
> >> +// has no ">" direction as the leftmost non-"=" direction in any row.
> >> +bool isLegalToInterChangeLoops(CharMatrix &DepMatrix, unsigned
> InnerLoopId,
> >> + unsigned OuterLoopId) {
> >> +
> >> + unsigned NumRows = DepMatrix.size();
> >> + // For each row check if it is valid to interchange.
> >> + for (unsigned Row = 0; Row < NumRows; ++Row) {
> >> + char InnerDep = DepMatrix[Row][InnerLoopId];
> >> + char OuterDep = DepMatrix[Row][OuterLoopId];
> >> + if (InnerDep == '*' || OuterDep == '*')
> >> + return false;
> >> + else if (!validDepInterchange(DepMatrix, Row, OuterLoopId,
> InnerDep,
> >> + OuterDep))
> >> + return false;
> >> + }
> >> + return true;
> >> +}
> >> +
> >> +static void populateWorklist(Loop &L, SmallVector<LoopVector, 8> &V) {
> >> +
> >> + DEBUG(dbgs() << "Calling populateWorklist called\n");
> >> + LoopVector LoopList;
> >> + Loop *CurrentLoop = &L;
> >> + std::vector<Loop *> vec = CurrentLoop->getSubLoopsVector();
> >> + while (vec.size() != 0) {
> >> + // The current loop has multiple subloops in it hence it is not
> tightly
> >> + // nested.
> >> + // Discard all loops above it added into Worklist.
> >> + if (vec.size() != 1) {
> >> + LoopList.clear();
> >> + return;
> >> + }
> >> + LoopList.push_back(CurrentLoop);
> >> + CurrentLoop = *(vec.begin());
> >> + vec = CurrentLoop->getSubLoopsVector();
> >> + }
> >> + LoopList.push_back(CurrentLoop);
> >> + V.push_back(LoopList);
> >> +}
> >> +
> >> +static PHINode *getInductionVariable(Loop *L, ScalarEvolution *SE) {
> >> + PHINode *InnerIndexVar = L->getCanonicalInductionVariable();
> >> + if (InnerIndexVar)
> >> + return InnerIndexVar;
> >> + if (L->getLoopLatch() == nullptr || L->getLoopPredecessor() ==
> nullptr)
> >> + return nullptr;
> >> + for (BasicBlock::iterator I = L->getHeader()->begin();
> isa<PHINode>(I); ++I) {
> >> + PHINode *PhiVar = cast<PHINode>(I);
> >> + Type *PhiTy = PhiVar->getType();
> >> + if (!PhiTy->isIntegerTy() && !PhiTy->isFloatingPointTy() &&
> >> + !PhiTy->isPointerTy())
> >> + return nullptr;
> >> + const SCEVAddRecExpr *AddRec =
> >> + dyn_cast<SCEVAddRecExpr>(SE->getSCEV(PhiVar));
> >> + if (!AddRec || !AddRec->isAffine())
> >> + continue;
> >> + const SCEV *Step = AddRec->getStepRecurrence(*SE);
> >> + const SCEVConstant *C = dyn_cast<SCEVConstant>(Step);
> >> + if (!C)
> >> + continue;
> >> + // Found the induction variable.
> >> + // FIXME: Handle loops with more than one induction variable. Note
> that,
> >> + // currently, legality makes sure we have only one induction
> variable.
> >> + return PhiVar;
> >> + }
> >> + return nullptr;
> >> +}
> >> +
> >> +/// LoopInterchangeLegality checks if it is legal to interchange the
> loop.
> >> +class LoopInterchangeLegality {
> >> +public:
> >> + LoopInterchangeLegality(Loop *Outer, Loop *Inner, ScalarEvolution
> *SE,
> >> + LoopInterchange *Pass)
> >> + : OuterLoop(Outer), InnerLoop(Inner), SE(SE), CurrentPass(Pass)
> {}
> >> +
> >> + /// Check if the loops can be interchanged.
> >> + bool canInterchangeLoops(unsigned InnerLoopId, unsigned OuterLoopId,
> >> + CharMatrix &DepMatrix);
> >> + /// Check if the loop structure is understood. We do not handle
> triangular
> >> + /// loops for now.
> >> + bool isLoopStructureUnderstood(PHINode *InnerInductionVar);
> >> +
> >> + bool currentLimitations();
> >> +
> >> +private:
> >> + bool tightlyNested(Loop *Outer, Loop *Inner);
> >> +
> >> + Loop *OuterLoop;
> >> + Loop *InnerLoop;
> >> +
> >> + /// Scev analysis.
> >> + ScalarEvolution *SE;
> >> + LoopInterchange *CurrentPass;
> >> +};
> >> +
> >> +/// LoopInterchangeProfitability checks if it is profitable to
> interchange the
> >> +/// loop.
> >> +class LoopInterchangeProfitability {
> >> +public:
> >> + LoopInterchangeProfitability(Loop *Outer, Loop *Inner,
> ScalarEvolution *SE)
> >> + : OuterLoop(Outer), InnerLoop(Inner), SE(SE) {}
> >> +
> >> + /// Check if the loop interchange is profitable
> >> + bool isProfitable(unsigned InnerLoopId, unsigned OuterLoopId,
> >> + CharMatrix &DepMatrix);
> >> +
> >> +private:
> >> + int getInstrOrderCost();
> >> +
> >> + Loop *OuterLoop;
> >> + Loop *InnerLoop;
> >> +
> >> + /// Scev analysis.
> >> + ScalarEvolution *SE;
> >> +};
> >> +
> >> +/// LoopInterchangeTransform interchanges the loop
> >> +class LoopInterchangeTransform {
> >> +public:
> >> + LoopInterchangeTransform(Loop *Outer, Loop *Inner, ScalarEvolution
> *SE,
> >> + LoopInfo *LI, DominatorTree *DT,
> >> + LoopInterchange *Pass, BasicBlock
> *LoopNestExit)
> >> + : OuterLoop(Outer), InnerLoop(Inner), SE(SE), LI(LI), DT(DT),
> >> + LoopExit(LoopNestExit) {
> >> + initialize();
> >> + }
> >> +
> >> + /// Interchange OuterLoop and InnerLoop.
> >> + bool transform();
> >> + void restructureLoops(Loop *InnerLoop, Loop *OuterLoop);
> >> + void removeChildLoop(Loop *OuterLoop, Loop *InnerLoop);
> >> + void initialize();
> >> +
> >> +private:
> >> + void splitInnerLoopLatch(Instruction *);
> >> + void splitOuterLoopLatch();
> >> + void splitInnerLoopHeader();
> >> + bool adjustLoopLinks();
> >> + void adjustLoopPreheaders();
> >> + void adjustOuterLoopPreheader();
> >> + void adjustInnerLoopPreheader();
> >> + bool adjustLoopBranches();
> >> +
> >> + Loop *OuterLoop;
> >> + Loop *InnerLoop;
> >> +
> >> + /// Scev analysis.
> >> + ScalarEvolution *SE;
> >> + LoopInfo *LI;
> >> + DominatorTree *DT;
> >> + BasicBlock *LoopExit;
> >> +};
> >> +
> >> +// Main LoopInterchange Pass
> >> +struct LoopInterchange : public FunctionPass {
> >> + static char ID;
> >> + ScalarEvolution *SE;
> >> + LoopInfo *LI;
> >> + DependenceAnalysis *DA;
> >> + DominatorTree *DT;
> >> + LoopInterchange()
> >> + : FunctionPass(ID), SE(nullptr), LI(nullptr), DA(nullptr),
> DT(nullptr) {
> >> + initializeLoopInterchangePass(*PassRegistry::getPassRegistry());
> >> + }
> >> +
> >> + void getAnalysisUsage(AnalysisUsage &AU) const override {
> >> + AU.addRequired<ScalarEvolution>();
> >> + AU.addRequired<AliasAnalysis>();
> >> + AU.addRequired<DominatorTreeWrapperPass>();
> >> + AU.addRequired<LoopInfoWrapperPass>();
> >> + AU.addRequired<DependenceAnalysis>();
> >> + AU.addRequiredID(LoopSimplifyID);
> >> + AU.addRequiredID(LCSSAID);
> >> + }
> >> +
> >> + bool runOnFunction(Function &F) override {
> >> + SE = &getAnalysis<ScalarEvolution>();
> >> + LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
> >> + DA = &getAnalysis<DependenceAnalysis>();
> >> + auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
> >> + DT = DTWP ? &DTWP->getDomTree() : nullptr;
> >> + // Build up a worklist of loop pairs to analyze.
> >> + SmallVector<LoopVector, 8> Worklist;
> >> +
> >> + for (Loop *L : *LI)
> >> + populateWorklist(*L, Worklist);
> >> +
> >> + DEBUG(dbgs() << "Worklist size = " << Worklist.size() << "\n");
> >> + bool Changed = true;
> >> + while (!Worklist.empty()) {
> >> + LoopVector LoopList = Worklist.pop_back_val();
> >> + Changed = processLoopList(LoopList);
> >> + }
> >> + return Changed;
> >> + }
> >> +
> >> + bool isComputableLoopNest(LoopVector LoopList) {
> >> + for (auto I = LoopList.begin(), E = LoopList.end(); I != E; ++I) {
> >> + Loop *L = *I;
> >> + const SCEV *ExitCountOuter = SE->getBackedgeTakenCount(L);
> >> + if (ExitCountOuter == SE->getCouldNotCompute()) {
> >> + DEBUG(dbgs() << "Couldn't compute Backedge count\n");
> >> + return false;
> >> + }
> >> + if (L->getNumBackEdges() != 1) {
> >> + DEBUG(dbgs() << "NumBackEdges is not equal to 1\n");
> >> + return false;
> >> + }
> >> + if (!L->getExitingBlock()) {
> >> + DEBUG(dbgs() << "Loop Doesn't have unique exit block\n");
> >> + return false;
> >> + }
> >> + }
> >> + return true;
> >> + }
> >> +
> >> + unsigned selectLoopForInterchange(LoopVector LoopList) {
> >> + // TODO: Add a better heuristic to select the loop to be
> interchanged based
> >> + // on the dependece matrix. Currently we select the innermost loop.
> >> + return LoopList.size() - 1;
> >> + }
> >> +
> >> + bool processLoopList(LoopVector LoopList) {
> >> + bool Changed = false;
> >> + bool containsLCSSAPHI = false;
> >> + CharMatrix DependencyMatrix;
> >> + if (LoopList.size() < 2) {
> >> + DEBUG(dbgs() << "Loop doesn't contain minimum nesting level.\n");
> >> + return false;
> >> + }
> >> + if (!isComputableLoopNest(LoopList)) {
> >> + DEBUG(dbgs() << "Not vaild loop candidate for interchange\n");
> >> + return false;
> >> + }
> >> + Loop *OuterMostLoop = *(LoopList.begin());
> >> +
> >> + DEBUG(dbgs() << "Processing LoopList of size = " << LoopList.size()
> >> + << "\n");
> >> +
> >> + if (!populateDependencyMatrix(DependencyMatrix, LoopList.size(),
> >> + OuterMostLoop, DA)) {
> >> + DEBUG(dbgs() << "Populating Dependency matrix failed\n");
> >> + return false;
> >> + }
> >> +#ifdef DUMP_DEP_MATRICIES
> >> + DEBUG(dbgs() << "Dependence before inter change \n");
> >> + printDepMatrix(DependencyMatrix);
> >> +#endif
> >> +
> >> + BasicBlock *OuterMostLoopLatch = OuterMostLoop->getLoopLatch();
> >> + BranchInst *OuterMostLoopLatchBI =
> >> + dyn_cast<BranchInst>(OuterMostLoopLatch->getTerminator());
> >> + if (!OuterMostLoopLatchBI)
> >> + return false;
> >> +
> >> + // Since we currently do not handle LCSSA PHI's any failure in loop
> >> + // condition will now branch to LoopNestExit.
> >> + // TODO: This should be removed once we handle LCSSA PHI nodes.
> >> +
> >> + // Get the Outermost loop exit.
> >> + BasicBlock *LoopNestExit;
> >> + if (OuterMostLoopLatchBI->getSuccessor(0) ==
> OuterMostLoop->getHeader())
> >> + LoopNestExit = OuterMostLoopLatchBI->getSuccessor(1);
> >> + else
> >> + LoopNestExit = OuterMostLoopLatchBI->getSuccessor(0);
> >> +
> >> + for (auto I = LoopList.begin(), E = LoopList.end(); I != E; ++I) {
> >> + Loop *L = *I;
> >> + BasicBlock *Latch = L->getLoopLatch();
> >> + BasicBlock *Header = L->getHeader();
> >> + if (Latch && Latch != Header && isa<PHINode>(Latch->begin())) {
> >> + containsLCSSAPHI = true;
> >> + break;
> >> + }
> >> + }
> >> +
> >> + // TODO: Handle lcssa PHI's. Currently LCSSA PHI's are not
> handled. Handle
> >> + // the same by splitting the loop latch and adjusting loop links
> >> + // accordingly.
> >> + if (containsLCSSAPHI)
> >> + return false;
> >> +
> >> + unsigned SelecLoopId = selectLoopForInterchange(LoopList);
> >> + // Move the selected loop outwards to the best posible position.
> >> + for (unsigned i = SelecLoopId; i > 0; i--) {
> >> + bool Interchanged =
> >> + processLoop(LoopList, i, i - 1, LoopNestExit,
> DependencyMatrix);
> >> + if (!Interchanged)
> >> + return Changed;
> >> + // Loops interchanged reflect the same in LoopList
> >> + Loop *OldOuterLoop = LoopList[i - 1];
> >> + LoopList[i - 1] = LoopList[i];
> >> + LoopList[i] = OldOuterLoop;
> >> +
> >> + // Update the DependencyMatrix
> >> + interChangeDepedencies(DependencyMatrix, i, i - 1);
> >> +
> >> +#ifdef DUMP_DEP_MATRICIES
> >> + DEBUG(dbgs() << "Dependence after inter change \n");
> >> + printDepMatrix(DependencyMatrix);
> >> +#endif
> >> + Changed |= Interchanged;
> >> + }
> >> + return Changed;
> >> + }
> >> +
> >> + bool processLoop(LoopVector LoopList, unsigned InnerLoopId,
> >> + unsigned OuterLoopId, BasicBlock *LoopNestExit,
> >> + std::vector<std::vector<char>> &DependencyMatrix) {
> >> +
> >> + DEBUG(dbgs() << "Processing Innder Loop Id = " << InnerLoopId
> >> + << " and OuterLoopId = " << OuterLoopId << "\n");
> >> + Loop *InnerLoop = LoopList[InnerLoopId];
> >> + Loop *OuterLoop = LoopList[OuterLoopId];
> >> +
> >> + LoopInterchangeLegality LIL(OuterLoop, InnerLoop, SE, this);
> >> + if (!LIL.canInterchangeLoops(InnerLoopId, OuterLoopId,
> DependencyMatrix)) {
> >> + DEBUG(dbgs() << "Not interchanging Loops. Cannot prove
> legality\n");
> >> + return false;
> >> + }
> >> + DEBUG(dbgs() << "Loops are legal to interchange\n");
> >> + LoopInterchangeProfitability LIP(OuterLoop, InnerLoop, SE);
> >> + if (!LIP.isProfitable(InnerLoopId, OuterLoopId, DependencyMatrix))
> {
> >> + DEBUG(dbgs() << "Interchanging Loops not profitable\n");
> >> + return false;
> >> + }
> >> +
> >> + LoopInterchangeTransform LIT(OuterLoop, InnerLoop, SE, LI, DT,
> this,
> >> + LoopNestExit);
> >> + LIT.transform();
> >> + DEBUG(dbgs() << "Loops interchanged\n");
> >> + return true;
> >> + }
> >> +};
> >> +
> >> +} // end of namespace
> >> +
> >> +static bool containsUnsafeInstructions(BasicBlock *BB) {
> >> + for (auto I = BB->begin(), E = BB->end(); I != E; ++I) {
> >> + if (I->mayHaveSideEffects() || I->mayReadFromMemory())
> >> + return true;
> >> + }
> >> + return false;
> >> +}
> >> +
> >> +bool LoopInterchangeLegality::tightlyNested(Loop *OuterLoop, Loop
> *InnerLoop) {
> >> + BasicBlock *OuterLoopHeader = OuterLoop->getHeader();
> >> + BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
> >> + BasicBlock *OuterLoopLatch = OuterLoop->getLoopLatch();
> >> +
> >> + DEBUG(dbgs() << "Checking if Loops are Tightly Nested\n");
> >> +
> >> + // A perfectly nested loop will not have any branch in between the
> outer and
> >> + // inner block i.e. outer header will branch to either inner
> preheader and
> >> + // outerloop latch.
> >> + BranchInst *outerLoopHeaderBI =
> >> + dyn_cast<BranchInst>(OuterLoopHeader->getTerminator());
> >> + if (!outerLoopHeaderBI)
> >> + return false;
> >> + unsigned num = outerLoopHeaderBI->getNumSuccessors();
> >> + for (unsigned i = 0; i < num; i++) {
> >> + if (outerLoopHeaderBI->getSuccessor(i) != InnerLoopPreHeader &&
> >> + outerLoopHeaderBI->getSuccessor(i) != OuterLoopLatch)
> >> + return false;
> >> + }
> >> +
> >> + DEBUG(dbgs() << "Checking instructions in Loop header and Loop latch
> \n");
> >> + // We do not have any basic block in between now make sure the outer
> header
> >> + // and outer loop latch doesnt contain any unsafe instructions.
> >> + if (containsUnsafeInstructions(OuterLoopHeader) ||
> >> + containsUnsafeInstructions(OuterLoopLatch))
> >> + return false;
> >> +
> >> + DEBUG(dbgs() << "Loops are perfectly nested \n");
> >> + // We have a perfect loop nest.
> >> + return true;
> >> +}
> >> +
> >> +static unsigned getPHICount(BasicBlock *BB) {
> >> + unsigned PhiCount = 0;
> >> + for (auto I = BB->begin(); isa<PHINode>(I); ++I)
> >> + PhiCount++;
> >> + return PhiCount;
> >> +}
> >> +
> >> +bool LoopInterchangeLegality::isLoopStructureUnderstood(
> >> + PHINode *InnerInduction) {
> >> +
> >> + unsigned Num = InnerInduction->getNumOperands();
> >> + BasicBlock *InnerLoopPreheader = InnerLoop->getLoopPreheader();
> >> + for (unsigned i = 0; i < Num; ++i) {
> >> + Value *Val = InnerInduction->getOperand(i);
> >> + if (isa<Constant>(Val))
> >> + continue;
> >> + Instruction *I = dyn_cast<Instruction>(Val);
> >> + if (!I)
> >> + return false;
> >> + // TODO: Handle triangular loops.
> >> + // e.g. for(int i=0;i<N;i++)
> >> + // for(int j=i;j<N;j++)
> >> + unsigned IncomBlockIndx =
> PHINode::getIncomingValueNumForOperand(i);
> >> + if (InnerInduction->getIncomingBlock(IncomBlockIndx) ==
> >> + InnerLoopPreheader &&
> >> + !OuterLoop->isLoopInvariant(I)) {
> >> + return false;
> >> + }
> >> + }
> >> + return true;
> >> +}
> >> +
> >> +// This function indicates the current limitations in the transform as
> a result
> >> +// of which we do not proceed.
> >> +bool LoopInterchangeLegality::currentLimitations() {
> >> +
> >> + BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
> >> + BasicBlock *InnerLoopHeader = InnerLoop->getHeader();
> >> + BasicBlock *OuterLoopHeader = OuterLoop->getHeader();
> >> + BasicBlock *InnerLoopLatch = InnerLoop->getLoopLatch();
> >> + BasicBlock *OuterLoopLatch = OuterLoop->getLoopLatch();
> >> +
> >> + PHINode *InnerInductionVar;
> >> + PHINode *OuterInductionVar;
> >> +
> >> + // We currently handle only 1 induction variable inside the loop. We
> also do
> >> + // not handle reductions as of now.
> >> + if (getPHICount(InnerLoopHeader) > 1)
> >> + return true;
> >> +
> >> + if (getPHICount(OuterLoopHeader) > 1)
> >> + return true;
> >> +
> >> + InnerInductionVar = getInductionVariable(InnerLoop, SE);
> >> + OuterInductionVar = getInductionVariable(OuterLoop, SE);
> >> +
> >> + if (!OuterInductionVar || !InnerInductionVar) {
> >> + DEBUG(dbgs() << "Induction variable not found\n");
> >> + return true;
> >> + }
> >> +
> >> + // TODO: Triangular loops are not handled for now.
> >> + if (!isLoopStructureUnderstood(InnerInductionVar)) {
> >> + DEBUG(dbgs() << "Loop structure not understood by pass\n");
> >> + return true;
> >> + }
> >> +
> >> + // TODO: Loops with LCSSA PHI's are currently not handled.
> >> + if (isa<PHINode>(OuterLoopLatch->begin())) {
> >> + DEBUG(dbgs() << "Found and LCSSA PHI in outer loop latch\n");
> >> + return true;
> >> + }
> >> + if (InnerLoopLatch != InnerLoopHeader &&
> >> + isa<PHINode>(InnerLoopLatch->begin())) {
> >> + DEBUG(dbgs() << "Found and LCSSA PHI in inner loop latch\n");
> >> + return true;
> >> + }
> >> +
> >> + // TODO: Current limitation: Since we split the inner loop latch at
> the point
> >> + // were induction variable is incremented (induction.next); We
> cannot have
> >> + // more than 1 user of induction.next since it would result in
> broken code
> >> + // after split.
> >> + // e.g.
> >> + // for(i=0;i<N;i++) {
> >> + // for(j = 0;j<M;j++) {
> >> + // A[j+1][i+2] = A[j][i]+k;
> >> + // }
> >> + // }
> >> + bool FoundInduction = false;
> >> + Instruction *InnerIndexVarInc = nullptr;
> >> + if (InnerInductionVar->getIncomingBlock(0) == InnerLoopPreHeader)
> >> + InnerIndexVarInc =
> >> + dyn_cast<Instruction>(InnerInductionVar->getIncomingValue(1));
> >> + else
> >> + InnerIndexVarInc =
> >> + dyn_cast<Instruction>(InnerInductionVar->getIncomingValue(0));
> >> +
> >> + if (!InnerIndexVarInc)
> >> + return true;
> >> +
> >> + // Since we split the inner loop latch on this induction variable.
> Make sure
> >> + // we do not have any instruction between the induction variable and
> branch
> >> + // instruction.
> >> +
> >> + for (auto I = InnerLoopLatch->rbegin(), E = InnerLoopLatch->rend();
> >> + I != E && !FoundInduction; ++I) {
> >> + if (isa<BranchInst>(*I) || isa<CmpInst>(*I) || isa<TruncInst>(*I))
> >> + continue;
> >> + const Instruction &Ins = *I;
> >> + // We found an instruction. If this is not induction variable then
> it is not
> >> + // safe to split this loop latch.
> >> + if (!Ins.isIdenticalTo(InnerIndexVarInc))
> >> + return true;
> >> + else
> >> + FoundInduction = true;
> >> + }
> >> + // The loop latch ended and we didnt find the induction variable
> return as
> >> + // current limitation.
> >> + if (!FoundInduction)
> >> + return true;
> >> +
> >> + return false;
> >> +}
> >> +
> >> +bool LoopInterchangeLegality::canInterchangeLoops(unsigned InnerLoopId,
> >> + unsigned OuterLoopId,
> >> + CharMatrix
> &DepMatrix) {
> >> +
> >> + if (!isLegalToInterChangeLoops(DepMatrix, InnerLoopId, OuterLoopId))
> {
> >> + DEBUG(dbgs() << "Failed interchange InnerLoopId = " << InnerLoopId
> >> + << "and OuterLoopId = " << OuterLoopId
> >> + << "due to dependence\n");
> >> + return false;
> >> + }
> >> +
> >> + // Create unique Preheaders if we already do not have one.
> >> + BasicBlock *OuterLoopPreHeader = OuterLoop->getLoopPreheader();
> >> + BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
> >> +
> >> + // Create a unique outer preheader -
> >> + // 1) If OuterLoop preheader is not present.
> >> + // 2) If OuterLoop Preheader is same as OuterLoop Header
> >> + // 3) If OuterLoop Preheader is same as Header of the previous loop.
> >> + // 4) If OuterLoop Preheader is Entry node.
> >> + if (!OuterLoopPreHeader || OuterLoopPreHeader ==
> OuterLoop->getHeader() ||
> >> + isa<PHINode>(OuterLoopPreHeader->begin()) ||
> >> + !OuterLoopPreHeader->getUniquePredecessor()) {
> >> + OuterLoopPreHeader = InsertPreheaderForLoop(OuterLoop,
> CurrentPass);
> >> + }
> >> +
> >> + if (!InnerLoopPreHeader || InnerLoopPreHeader ==
> InnerLoop->getHeader() ||
> >> + InnerLoopPreHeader == OuterLoop->getHeader()) {
> >> + InnerLoopPreHeader = InsertPreheaderForLoop(InnerLoop,
> CurrentPass);
> >> + }
> >> +
> >> + // Check if the loops are tightly nested.
> >> + if (!tightlyNested(OuterLoop, InnerLoop)) {
> >> + DEBUG(dbgs() << "Loops not tightly nested\n");
> >> + return false;
> >> + }
> >> +
> >> + // TODO: The loops could not be interchanged due to current
> limitations in the
> >> + // transform module.
> >> + if (currentLimitations()) {
> >> + DEBUG(dbgs() << "Not legal because of current transform
> limitation\n");
> >> + return false;
> >> + }
> >> +
> >> + return true;
> >> +}
> >> +
> >> +int LoopInterchangeProfitability::getInstrOrderCost() {
> >> + unsigned GoodOrder, BadOrder;
> >> + BadOrder = GoodOrder = 0;
> >> + for (auto BI = InnerLoop->block_begin(), BE = InnerLoop->block_end();
> >> + BI != BE; ++BI) {
> >> + for (auto I = (*BI)->begin(), E = (*BI)->end(); I != E; ++I) {
> >> + const Instruction &Ins = *I;
> >> + if (const GetElementPtrInst *GEP =
> dyn_cast<GetElementPtrInst>(&Ins)) {
> >> + unsigned NumOp = GEP->getNumOperands();
> >> + bool FoundInnerInduction = false;
> >> + bool FoundOuterInduction = false;
> >> + for (unsigned i = 0; i < NumOp; ++i) {
> >> + const SCEV *OperandVal = SE->getSCEV(GEP->getOperand(i));
> >> + const SCEVAddRecExpr *AR =
> dyn_cast<SCEVAddRecExpr>(OperandVal);
> >> + if (!AR)
> >> + continue;
> >> +
> >> + // If we find the inner induction after an outer induction
> e.g.
> >> + // for(int i=0;i<N;i++)
> >> + // for(int j=0;j<N;j++)
> >> + // A[i][j] = A[i-1][j-1]+k;
> >> + // then it is a good order.
> >> + if (AR->getLoop() == InnerLoop) {
> >> + // We found an InnerLoop induction after OuterLoop
> induction. It is
> >> + // a good order.
> >> + FoundInnerInduction = true;
> >> + if (FoundOuterInduction) {
> >> + GoodOrder++;
> >> + break;
> >> + }
> >> + }
> >> + // If we find the outer induction after an inner induction
> e.g.
> >> + // for(int i=0;i<N;i++)
> >> + // for(int j=0;j<N;j++)
> >> + // A[j][i] = A[j-1][i-1]+k;
> >> + // then it is a bad order.
> >> + if (AR->getLoop() == OuterLoop) {
> >> + // We found an OuterLoop induction after InnerLoop
> induction. It is
> >> + // a bad order.
> >> + FoundOuterInduction = true;
> >> + if (FoundInnerInduction) {
> >> + BadOrder++;
> >> + break;
> >> + }
> >> + }
> >> + }
> >> + }
> >> + }
> >> + }
> >> + return GoodOrder - BadOrder;
> >> +}
> >> +
> >> +bool isProfitabileForVectorization(unsigned InnerLoopId, unsigned
> OuterLoopId,
> >> + CharMatrix &DepMatrix) {
> >> + // TODO: Improve this heuristic to catch more cases.
> >> + // If the inner loop is loop independent or doesn't carry any
> dependency it is
> >> + // profitable to move this to outer position.
> >> + unsigned Row = DepMatrix.size();
> >> + for (unsigned i = 0; i < Row; ++i) {
> >> + if (DepMatrix[i][InnerLoopId] != 'S' && DepMatrix[i][InnerLoopId]
> != 'I')
> >> + return false;
> >> + // TODO: We need to improve this heuristic.
> >> + if (DepMatrix[i][OuterLoopId] != '=')
> >> + return false;
> >> + }
> >> + // If outer loop has dependence and inner loop is loop independent
> then it is
> >> + // profitable to interchange to enable parallelism.
> >> + return true;
> >> +}
> >> +
> >> +bool LoopInterchangeProfitability::isProfitable(unsigned InnerLoopId,
> >> + unsigned OuterLoopId,
> >> + CharMatrix &DepMatrix)
> {
> >> +
> >> + // TODO: Add Better Profitibility checks.
> >> + // e.g
> >> + // 1) Construct dependency matrix and move the one with no loop
> carried dep
> >> + // inside to enable vectorization.
> >> +
> >> + // This is rough cost estimation algorithm. It counts the good and
> bad order
> >> + // of induction variables in the instruction and allows reordering
> if number
> >> + // of bad orders is more than good.
> >> + int Cost = 0;
> >> + Cost += getInstrOrderCost();
> >> + DEBUG(dbgs() << "Cost = " << Cost << "\n");
> >> + if (Cost < 0)
> >> + return true;
> >> +
> >> + // It is not profitable as per current cache profitibility model.
> But check if
> >> + // we can move this loop outside to improve parallelism.
> >> + bool ImprovesPar =
> >> + isProfitabileForVectorization(InnerLoopId, OuterLoopId,
> DepMatrix);
> >> + return ImprovesPar;
> >> +}
> >> +
> >> +void LoopInterchangeTransform::removeChildLoop(Loop *OuterLoop,
> >> + Loop *InnerLoop) {
> >> + for (Loop::iterator I = OuterLoop->begin(), E = OuterLoop->end();;
> ++I) {
> >> + assert(I != E && "Couldn't find loop");
> >> + if (*I == InnerLoop) {
> >> + OuterLoop->removeChildLoop(I);
> >> + return;
> >> + }
> >> + }
> >> +}
> >> +void LoopInterchangeTransform::restructureLoops(Loop *InnerLoop,
> >> + Loop *OuterLoop) {
> >> + Loop *OuterLoopParent = OuterLoop->getParentLoop();
> >> + if (OuterLoopParent) {
> >> + // Remove the loop from its parent loop.
> >> + removeChildLoop(OuterLoopParent, OuterLoop);
> >> + removeChildLoop(OuterLoop, InnerLoop);
> >> + OuterLoopParent->addChildLoop(InnerLoop);
> >> + } else {
> >> + removeChildLoop(OuterLoop, InnerLoop);
> >> + LI->changeTopLevelLoop(OuterLoop, InnerLoop);
> >> + }
> >> +
> >> + for (Loop::iterator I = InnerLoop->begin(), E = InnerLoop->end(); I
> != E; ++I)
> >> + OuterLoop->addChildLoop(InnerLoop->removeChildLoop(I));
> >
> > This for loop is causing failed assertions in debug builds with MSVC;
> > the iterator is invalidated when the child loop is removed on
> > InnerLoop, so when ++I is executed, the following assertion is
> > triggered. I don't think removeChildLoop() is a particularly safe API
> > design given how trivial it is for the underlying container to
> > invalidate all iterators.
> >
> > 63> FAIL: LLVM :: Transforms/LoopInterchange/reductions.ll (19260 of
> 22394)
> > 63> ******************** TEST 'LLVM ::
> > Transforms/LoopInterchange/reductions.ll' FAILED ********************
> > 63> Script:
> > 63> --
> > 63> E:/llvm/2013/Debug/bin\opt.EXE <
> > E:\llvm\llvm\test\Transforms\LoopInterchange\reductions.ll -basicaa
> > -loop-interchange -S | E:/llvm/2013/Debug/bin\FileCheck.EXE
> > E:\llvm\llvm\test\Transforms\LoopInterchange\reductions.ll
> > 63> --
> > 63> Exit Code: 2
> > 63>
> > 63> Command Output (stdout):
> > 63> --
> > 63> Command 0: "E:/llvm/2013/Debug/bin\opt.EXE" "-basicaa"
> > "-loop-interchange" "-S"
> > 63> Command 0 Result: -2147483645
> > 63> Command 0 Output:
> > 63>
> > 63>
> > 63> Command 0 Stderr:
> > 63> 0x0F4FCEE6 (0x02AB16A0 0x02AACBD0 0x00000065 0x00322278),
> > ?_Debug_message at std@@YAXPB_W0I at Z() + 0x26 bytes(s)
> > 63>
> > 63> 0x0108C5AB (0x0421EE7C 0xCCCCCCCC 0xCCCCCCCC 0x00000000),
> >
> std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<llvm::Loop
> > *> > >::operator++() + 0x4B bytes(s), d:\program files (x86)\microsoft
> > visual studio 12.0\vc\include\vector, line 101 + 0x14 byte(s)
> > 63>
> > 63> 0x01D974CF (0x00331A38 0x00337B40 0x00000000 0xCCCCCCCC),
> > `anonymous namespace'::LoopInterchangeTransform::restructureLoops() +
> > 0x9F bytes(s), e:\llvm\llvm\lib\transforms\scalar\loopinterchange.cpp,
> > line 1015 + 0xA byte(s)
> > 63>
> > 63> 0x01D9741E (0x0421EF20 0xCCCCCCCC 0xCCCCCCCC 0x00337B40),
> > `anonymous namespace'::LoopInterchangeTransform::transform() + 0x22E
> > bytes(s), e:\llvm\llvm\lib\transforms\scalar\loopinterchange.cpp, line
> > 1060
> > 63>
> > 63> 0x01D9C9BC (0x0421EE90 0x0421EE9C 0x0421EEB0 0x00337B40),
> > `anonymous namespace'::LoopInterchange::processLoop() + 0x20C
> > bytes(s), e:\llvm\llvm\lib\transforms\scalar\loopinterchange.cpp, line
> > 592
> > 63>
> > 63> 0x01D9CD64 (0x0421EF34 0x0421EF40 0x0421EF54 0x00337B40),
> > `anonymous namespace'::LoopInterchange::processLoopList() + 0x304
> > bytes(s), e:\llvm\llvm\lib\transforms\scalar\loopinterchange.cpp, line
> > 550 + 0x29 byte(s)
> > 63>
> > 63> 0x01D9D4F0 (0x003213C0 0x0421F2B4 0x0421F1F8 0x00000001),
> > `anonymous namespace'::LoopInterchange::runOnFunction() + 0x1D0
> > bytes(s), e:\llvm\llvm\lib\transforms\scalar\loopinterchange.cpp, line
> > 465 + 0x1D byte(s)
> > 63>
> > 63> 0x0191E1D5 (0x003213C0 0x00000000 0xCCCCCCCC 0x002F53DC),
> > llvm::FPPassManager::runOnFunction() + 0x105 bytes(s),
> > e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1538 + 0x17 byte(s)
> > 63>
> > 63> 0x0191E365 (0x002F5408 0x0421F77C 0x0421F2C0 0x00000001),
> > llvm::FPPassManager::runOnModule() + 0x75 bytes(s),
> > e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1558 + 0x15 byte(s)
> > 63>
> > 63> 0x0191F2D9 (0x002F5408 0x0421F304 0x7EFDE000 0xCCCCCCCC),
> > `anonymous namespace'::MPPassManager::runOnModule() + 0x1C9 bytes(s),
> > e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1616 + 0x17 byte(s)
> > 63>
> > 63> 0x0191F971 (0x002F5408 0x0421F570 0x0421F77C 0x00B90A06),
> > llvm::legacy::PassManagerImpl::run() + 0x101 bytes(s),
> > e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1723 + 0x1B byte(s)
> > 63>
> > 63> 0x0191A3ED (0x002F5408 0x00000000 0x00000000 0xCCCCCCCC),
> > llvm::legacy::PassManager::run() + 0x1D bytes(s),
> > e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1757
> > 63>
> > 63> 0x00B90A06 (0x00000004 0x002EA2A0 0x002EFF88 0x75B36014), main()
> > + 0x1696 bytes(s), e:\llvm\llvm\tools\opt\opt.cpp, line 614
> > 63>
> > 63> 0x024017A9 (0x0421F7E0 0x778D336A 0x7EFDE000 0x0421F820),
> > __tmainCRTStartup() + 0x199 bytes(s),
> > f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c, line 626 + 0x19 byte(s)
> > 63>
> > 63> 0x024018ED (0x7EFDE000 0x0421F820 0x77E992B2 0x7EFDE000),
> > mainCRTStartup() + 0xD bytes(s),
> > f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c, line 466
> > 63>
> > 63> 0x778D336A (0x7EFDE000 0x7AB5E46A 0x00000000 0x00000000),
> > BaseThreadInitThunk() + 0x12 bytes(s)
> > 63>
> > 63> 0x77E992B2 (0x024018E0 0x7EFDE000 0x00000000 0x00000000),
> > RtlInitializeExceptionChain() + 0x63 bytes(s)
> > 63>
> > 63> 0x77E99285 (0x024018E0 0x7EFDE000 0x00000000 0x00000000),
> > RtlInitializeExceptionChain() + 0x36 bytes(s)
> > 63>
> > 63>
> > 63>
> > 63> Command 1: "E:/llvm/2013/Debug/bin\FileCheck.EXE"
> > "E:\llvm\llvm\test\Transforms\LoopInterchange\reductions.ll"
> > 63> Command 1 Result: 2
> > 63> Command 1 Output:
> > 63>
> > 63>
> > 63> Command 1 Stderr:
> > 63>CUSTOMBUILD : FileCheck error : '-' is empty.
> > 63>
> > 63>
> > 63>
> > 63>
> > 63> --
> > 63>
> >
> > ~Aaron
> >
> >> +
> >> + InnerLoop->addChildLoop(OuterLoop);
> >> +}
> >> +
> >> +bool LoopInterchangeTransform::transform() {
> >> +
> >> + DEBUG(dbgs() << "transform\n");
> >> + bool Transformed = false;
> >> + Instruction *InnerIndexVar;
> >> +
> >> + if (InnerLoop->getSubLoops().size() == 0) {
> >> + BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
> >> + DEBUG(dbgs() << "Calling Split Inner Loop\n");
> >> + PHINode *InductionPHI = getInductionVariable(InnerLoop, SE);
> >> + if (!InductionPHI) {
> >> + DEBUG(dbgs() << "Failed to find the point to split loop latch
> \n");
> >> + return false;
> >> + }
> >> +
> >> + if (InductionPHI->getIncomingBlock(0) == InnerLoopPreHeader)
> >> + InnerIndexVar =
> dyn_cast<Instruction>(InductionPHI->getIncomingValue(1));
> >> + else
> >> + InnerIndexVar =
> dyn_cast<Instruction>(InductionPHI->getIncomingValue(0));
> >> +
> >> + //
> >> + // Split at the place were the induction variable is
> >> + // incremented/decremented.
> >> + // TODO: This splitting logic may not work always. Fix this.
> >> + splitInnerLoopLatch(InnerIndexVar);
> >> + DEBUG(dbgs() << "splitInnerLoopLatch Done\n");
> >> +
> >> + // Splits the inner loops phi nodes out into a seperate basic
> block.
> >> + splitInnerLoopHeader();
> >> + DEBUG(dbgs() << "splitInnerLoopHeader Done\n");
> >> + }
> >> +
> >> + Transformed |= adjustLoopLinks();
> >> + if (!Transformed) {
> >> + DEBUG(dbgs() << "adjustLoopLinks Failed\n");
> >> + return false;
> >> + }
> >> +
> >> + restructureLoops(InnerLoop, OuterLoop);
> >> + return true;
> >> +}
> >> +
> >> +void LoopInterchangeTransform::initialize() {}
> >> +
> >> +void LoopInterchangeTransform::splitInnerLoopLatch(Instruction *inc) {
> >> +
> >> + BasicBlock *InnerLoopLatch = InnerLoop->getLoopLatch();
> >> + BasicBlock::iterator I = InnerLoopLatch->begin();
> >> + BasicBlock::iterator E = InnerLoopLatch->end();
> >> + for (; I != E; ++I) {
> >> + if (inc == I)
> >> + break;
> >> + }
> >> +
> >> + BasicBlock *InnerLoopLatchPred = InnerLoopLatch;
> >> + InnerLoopLatch = SplitBlock(InnerLoopLatchPred, I, DT, LI);
> >> +}
> >> +
> >> +void LoopInterchangeTransform::splitOuterLoopLatch() {
> >> + BasicBlock *OuterLoopLatch = OuterLoop->getLoopLatch();
> >> + BasicBlock *OuterLatchLcssaPhiBlock = OuterLoopLatch;
> >> + OuterLoopLatch = SplitBlock(OuterLatchLcssaPhiBlock,
> >> + OuterLoopLatch->getFirstNonPHI(), DT,
> LI);
> >> +}
> >> +
> >> +void LoopInterchangeTransform::splitInnerLoopHeader() {
> >> +
> >> + // Split the inner loop header out.
> >> + BasicBlock *InnerLoopHeader = InnerLoop->getHeader();
> >> + SplitBlock(InnerLoopHeader, InnerLoopHeader->getFirstNonPHI(), DT,
> LI);
> >> +
> >> + DEBUG(dbgs() << "Output of splitInnerLoopHeader InnerLoopHeaderSucc
> & "
> >> + "InnerLoopHeader \n");
> >> +}
> >> +
> >> +void LoopInterchangeTransform::adjustOuterLoopPreheader() {
> >> + BasicBlock *OuterLoopPreHeader = OuterLoop->getLoopPreheader();
> >> + SmallVector<Instruction *, 8> Inst;
> >> + for (auto I = OuterLoopPreHeader->begin(), E =
> OuterLoopPreHeader->end();
> >> + I != E; ++I) {
> >> + if (isa<BranchInst>(*I))
> >> + break;
> >> + Inst.push_back(I);
> >> + }
> >> +
> >> + BasicBlock *InnerPreHeader = InnerLoop->getLoopPreheader();
> >> + for (auto I = Inst.begin(), E = Inst.end(); I != E; ++I) {
> >> + Instruction *Ins = cast<Instruction>(*I);
> >> + Ins->moveBefore(InnerPreHeader->getTerminator());
> >> + }
> >> +}
> >> +
> >> +void LoopInterchangeTransform::adjustInnerLoopPreheader() {
> >> +
> >> + BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
> >> + SmallVector<Instruction *, 8> Inst;
> >> + for (auto I = InnerLoopPreHeader->begin(), E =
> InnerLoopPreHeader->end();
> >> + I != E; ++I) {
> >> + if (isa<BranchInst>(*I))
> >> + break;
> >> + Inst.push_back(I);
> >> + }
> >> + BasicBlock *OuterHeader = OuterLoop->getHeader();
> >> + for (auto I = Inst.begin(), E = Inst.end(); I != E; ++I) {
> >> + Instruction *Ins = cast<Instruction>(*I);
> >> + Ins->moveBefore(OuterHeader->getTerminator());
> >> + }
> >> +}
> >> +
> >> +bool LoopInterchangeTransform::adjustLoopBranches() {
> >> +
> >> + DEBUG(dbgs() << "adjustLoopBranches called\n");
> >> + // Adjust the loop preheader
> >> + BasicBlock *InnerLoopHeader = InnerLoop->getHeader();
> >> + BasicBlock *OuterLoopHeader = OuterLoop->getHeader();
> >> + BasicBlock *InnerLoopLatch = InnerLoop->getLoopLatch();
> >> + BasicBlock *OuterLoopLatch = OuterLoop->getLoopLatch();
> >> + BasicBlock *OuterLoopPreHeader = OuterLoop->getLoopPreheader();
> >> + BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
> >> + BasicBlock *OuterLoopPredecessor =
> OuterLoopPreHeader->getUniquePredecessor();
> >> + BasicBlock *InnerLoopLatchPredecessor =
> >> + InnerLoopLatch->getUniquePredecessor();
> >> + BasicBlock *InnerLoopLatchSuccessor;
> >> + BasicBlock *OuterLoopLatchSuccessor;
> >> +
> >> + BranchInst *OuterLoopLatchBI =
> >> + dyn_cast<BranchInst>(OuterLoopLatch->getTerminator());
> >> + BranchInst *InnerLoopLatchBI =
> >> + dyn_cast<BranchInst>(InnerLoopLatch->getTerminator());
> >> + BranchInst *OuterLoopHeaderBI =
> >> + dyn_cast<BranchInst>(OuterLoopHeader->getTerminator());
> >> + BranchInst *InnerLoopHeaderBI =
> >> + dyn_cast<BranchInst>(InnerLoopHeader->getTerminator());
> >> +
> >> + if (!OuterLoopPredecessor || !InnerLoopLatchPredecessor ||
> >> + !OuterLoopLatchBI || !InnerLoopLatchBI || !OuterLoopHeaderBI ||
> >> + !InnerLoopHeaderBI)
> >> + return false;
> >> +
> >> + BranchInst *InnerLoopLatchPredecessorBI =
> >> + dyn_cast<BranchInst>(InnerLoopLatchPredecessor->getTerminator());
> >> + BranchInst *OuterLoopPredecessorBI =
> >> + dyn_cast<BranchInst>(OuterLoopPredecessor->getTerminator());
> >> +
> >> + if (!OuterLoopPredecessorBI || !InnerLoopLatchPredecessorBI)
> >> + return false;
> >> + BasicBlock *InnerLoopHeaderSucessor =
> InnerLoopHeader->getUniqueSuccessor();
> >> + if (!InnerLoopHeaderSucessor)
> >> + return false;
> >> +
> >> + // Adjust Loop Preheader and headers
> >> +
> >> + unsigned NumSucc = OuterLoopPredecessorBI->getNumSuccessors();
> >> + for (unsigned i = 0; i < NumSucc; ++i) {
> >> + if (OuterLoopPredecessorBI->getSuccessor(i) == OuterLoopPreHeader)
> >> + OuterLoopPredecessorBI->setSuccessor(i, InnerLoopPreHeader);
> >> + }
> >> +
> >> + NumSucc = OuterLoopHeaderBI->getNumSuccessors();
> >> + for (unsigned i = 0; i < NumSucc; ++i) {
> >> + if (OuterLoopHeaderBI->getSuccessor(i) == OuterLoopLatch)
> >> + OuterLoopHeaderBI->setSuccessor(i, LoopExit);
> >> + else if (OuterLoopHeaderBI->getSuccessor(i) == InnerLoopPreHeader)
> >> + OuterLoopHeaderBI->setSuccessor(i, InnerLoopHeaderSucessor);
> >> + }
> >> +
> >> + BranchInst::Create(OuterLoopPreHeader, InnerLoopHeaderBI);
> >> + InnerLoopHeaderBI->eraseFromParent();
> >> +
> >> + // -------------Adjust loop latches-----------
> >> + if (InnerLoopLatchBI->getSuccessor(0) == InnerLoopHeader)
> >> + InnerLoopLatchSuccessor = InnerLoopLatchBI->getSuccessor(1);
> >> + else
> >> + InnerLoopLatchSuccessor = InnerLoopLatchBI->getSuccessor(0);
> >> +
> >> + NumSucc = InnerLoopLatchPredecessorBI->getNumSuccessors();
> >> + for (unsigned i = 0; i < NumSucc; ++i) {
> >> + if (InnerLoopLatchPredecessorBI->getSuccessor(i) == InnerLoopLatch)
> >> + InnerLoopLatchPredecessorBI->setSuccessor(i,
> InnerLoopLatchSuccessor);
> >> + }
> >> +
> >> + if (OuterLoopLatchBI->getSuccessor(0) == OuterLoopHeader)
> >> + OuterLoopLatchSuccessor = OuterLoopLatchBI->getSuccessor(1);
> >> + else
> >> + OuterLoopLatchSuccessor = OuterLoopLatchBI->getSuccessor(0);
> >> +
> >> + if (InnerLoopLatchBI->getSuccessor(1) == InnerLoopLatchSuccessor)
> >> + InnerLoopLatchBI->setSuccessor(1, OuterLoopLatchSuccessor);
> >> + else
> >> + InnerLoopLatchBI->setSuccessor(0, OuterLoopLatchSuccessor);
> >> +
> >> + if (OuterLoopLatchBI->getSuccessor(0) == OuterLoopLatchSuccessor) {
> >> + OuterLoopLatchBI->setSuccessor(0, InnerLoopLatch);
> >> + } else {
> >> + OuterLoopLatchBI->setSuccessor(1, InnerLoopLatch);
> >> + }
> >> +
> >> + return true;
> >> +}
> >> +void LoopInterchangeTransform::adjustLoopPreheaders() {
> >> +
> >> + // We have interchanged the preheaders so we need to interchange the
> data in
> >> + // the preheader as well.
> >> + // This is because the content of inner preheader was previously
> executed
> >> + // inside the outer loop.
> >> + BasicBlock *OuterLoopPreHeader = OuterLoop->getLoopPreheader();
> >> + BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
> >> + BasicBlock *OuterLoopHeader = OuterLoop->getHeader();
> >> + BranchInst *InnerTermBI =
> >> + cast<BranchInst>(InnerLoopPreHeader->getTerminator());
> >> +
> >> + SmallVector<Value *, 16> OuterPreheaderInstr;
> >> + SmallVector<Value *, 16> InnerPreheaderInstr;
> >> +
> >> + for (auto I = OuterLoopPreHeader->begin(); !isa<BranchInst>(I); ++I)
> >> + OuterPreheaderInstr.push_back(I);
> >> +
> >> + for (auto I = InnerLoopPreHeader->begin(); !isa<BranchInst>(I); ++I)
> >> + InnerPreheaderInstr.push_back(I);
> >> +
> >> + BasicBlock *HeaderSplit =
> >> + SplitBlock(OuterLoopHeader, OuterLoopHeader->getTerminator(),
> DT, LI);
> >> + Instruction *InsPoint = HeaderSplit->getFirstNonPHI();
> >> + // These instructions should now be executed inside the loop.
> >> + // Move instruction into a new block after outer header.
> >> + for (auto I = InnerPreheaderInstr.begin(), E =
> InnerPreheaderInstr.end();
> >> + I != E; ++I) {
> >> + Instruction *Ins = cast<Instruction>(*I);
> >> + Ins->moveBefore(InsPoint);
> >> + }
> >> + // These instructions were not executed previously in the loop so
> move them to
> >> + // the older inner loop preheader.
> >> + for (auto I = OuterPreheaderInstr.begin(), E =
> OuterPreheaderInstr.end();
> >> + I != E; ++I) {
> >> + Instruction *Ins = cast<Instruction>(*I);
> >> + Ins->moveBefore(InnerTermBI);
> >> + }
> >> +}
> >> +
> >> +bool LoopInterchangeTransform::adjustLoopLinks() {
> >> +
> >> + // Adjust all branches in the inner and outer loop.
> >> + bool Changed = adjustLoopBranches();
> >> + if (Changed)
> >> + adjustLoopPreheaders();
> >> + return Changed;
> >> +}
> >> +
> >> +char LoopInterchange::ID = 0;
> >> +INITIALIZE_PASS_BEGIN(LoopInterchange, "loop-interchange",
> >> + "Interchanges loops for cache reuse", false,
> false)
> >> +INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
> >> +INITIALIZE_PASS_DEPENDENCY(DependenceAnalysis)
> >> +INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
> >> +INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
> >> +INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
> >> +INITIALIZE_PASS_DEPENDENCY(LCSSA)
> >> +INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
> >> +
> >> +INITIALIZE_PASS_END(LoopInterchange, "loop-interchange",
> >> + "Interchanges loops for cache reuse", false, false)
> >> +
> >> +Pass *llvm::createLoopInterchangePass() { return new
> LoopInterchange(); }
> >>
> >> Modified: llvm/trunk/lib/Transforms/Scalar/Scalar.cpp
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/Scalar.cpp?rev=231458&r1=231457&r2=231458&view=diff
> >>
> ==============================================================================
> >> --- llvm/trunk/lib/Transforms/Scalar/Scalar.cpp (original)
> >> +++ llvm/trunk/lib/Transforms/Scalar/Scalar.cpp Fri Mar 6 04:11:25 2015
> >> @@ -48,6 +48,7 @@ void llvm::initializeScalarOpts(PassRegi
> >> initializeLoopDeletionPass(Registry);
> >> initializeLoopAccessAnalysisPass(Registry);
> >> initializeLoopInstSimplifyPass(Registry);
> >> + initializeLoopInterchangePass(Registry);
> >> initializeLoopRotatePass(Registry);
> >> initializeLoopStrengthReducePass(Registry);
> >> initializeLoopRerollPass(Registry);
> >>
> >> Added: llvm/trunk/test/Transforms/LoopInterchange/currentLimitation.ll
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopInterchange/currentLimitation.ll?rev=231458&view=auto
> >>
> ==============================================================================
> >> --- llvm/trunk/test/Transforms/LoopInterchange/currentLimitation.ll
> (added)
> >> +++ llvm/trunk/test/Transforms/LoopInterchange/currentLimitation.ll Fri
> Mar 6 04:11:25 2015
> >> @@ -0,0 +1,58 @@
> >> +; RUN: opt < %s -basicaa -loop-interchange -S | FileCheck %s
> >> +;; These are test that fail to interchange due to current limitation.
> This will go off once we extend the loop interchange pass.
> >> +
> >> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> >> +target triple = "x86_64-unknown-linux-gnu"
> >> +
> >> + at A = common global [100 x [100 x i32]] zeroinitializer
> >> + at B = common global [100 x [100 x [100 x i32]]] zeroinitializer
> >> +
> >> +;;--------------------------------------Test case
> 01------------------------------------
> >> +;; [FIXME] This loop though valid is currently not interchanged due to
> the limitation that we cannot split the inner loop latch due to multiple
> use of inner induction
> >> +;; variable.(used to increment the loop counter and to access
> A[j+1][i+1]
> >> +;; for(int i=0;i<N-1;i++)
> >> +;; for(int j=1;j<N-1;j++)
> >> +;; A[j+1][i+1] = A[j+1][i+1] + k;
> >> +
> >> +define void @interchange_01(i32 %k, i32 %N) {
> >> + entry:
> >> + %sub = add nsw i32 %N, -1
> >> + %cmp26 = icmp sgt i32 %N, 1
> >> + br i1 %cmp26, label %for.cond1.preheader.lr.ph, label %for.end17
> >> +
> >> + for.cond1.preheader.lr.ph:
> >> + %cmp324 = icmp sgt i32 %sub, 1
> >> + %0 = add i32 %N, -2
> >> + %1 = sext i32 %sub to i64
> >> + br label %for.cond1.preheader
> >> +
> >> + for.cond.loopexit:
> >> + %cmp = icmp slt i64 %indvars.iv.next29, %1
> >> + br i1 %cmp, label %for.cond1.preheader, label %for.end17
> >> +
> >> + for.cond1.preheader:
> >> + %indvars.iv28 = phi i64 [ 0, %for.cond1.preheader.lr.ph ], [
> %indvars.iv.next29, %for.cond.loopexit ]
> >> + %indvars.iv.next29 = add nuw nsw i64 %indvars.iv28, 1
> >> + br i1 %cmp324, label %for.body4, label %for.cond.loopexit
> >> +
> >> + for.body4:
> >> + %indvars.iv = phi i64 [ %indvars.iv.next, %for.body4 ], [ 1,
> %for.cond1.preheader ]
> >> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> + %arrayidx7 = getelementptr inbounds [100 x [100 x i32]], [100 x
> [100 x i32]]* @A, i64 0, i64 %indvars.iv.next, i64 %indvars.iv.next29
> >> + %2 = load i32, i32* %arrayidx7
> >> + %add8 = add nsw i32 %2, %k
> >> + store i32 %add8, i32* %arrayidx7
> >> + %lftr.wideiv = trunc i64 %indvars.iv to i32
> >> + %exitcond = icmp eq i32 %lftr.wideiv, %0
> >> + br i1 %exitcond, label %for.cond.loopexit, label %for.body4
> >> +
> >> + for.end17:
> >> + ret void
> >> +}
> >> +;; Inner loop not split so it is not interchanged.
> >> +; CHECK-LABEL: @interchange_01
> >> +; CHECK: for.body4:
> >> +; CHECK-NEXT: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body4
> ], [ 1, %for.body4.preheader ]
> >> +; CHECK-NEXT: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> +; CHECK-NEXT: %arrayidx7 = getelementptr inbounds [100 x [100 x
> i32]], [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv.next, i64
> %indvars.iv.next29
> >> +
> >>
> >> Added: llvm/trunk/test/Transforms/LoopInterchange/interchange.ll
> >> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopInterchange/interchange.ll?rev=231458&view=auto
> >>
> ==============================================================================
> >> --- llvm/trunk/test/Transforms/LoopInterchange/interchange.ll (added)
> >> +++ llvm/trunk/test/Transforms/LoopInterchange/interchange.ll Fri Mar
> 6 04:11:25 2015
> >> @@ -0,0 +1,557 @@
> >> +; RUN: opt < %s -basicaa -loop-interchange -S | FileCheck %s
> >> +;; We test the complete .ll for adjustment in outer loop header/latch
> and inner loop header/latch.
> >> +
> >> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> >> +target triple = "x86_64-unknown-linux-gnu"
> >> +
> >> + at A = common global [100 x [100 x i32]] zeroinitializer
> >> + at B = common global [100 x i32] zeroinitializer
> >> + at C = common global [100 x [100 x i32]] zeroinitializer
> >> + at D = common global [100 x [100 x [100 x i32]]] zeroinitializer
> >> +
> >> +declare void @foo(...)
> >> +
> >> +;;--------------------------------------Test case
> 01------------------------------------
> >> +;; for(int i=0;i<N;i++)
> >> +;; for(int j=1;j<N;j++)
> >> +;; A[j][i] = A[j][i]+k;
> >> +
> >> +define void @interchange_01(i32 %k, i32 %N) {
> >> +entry:
> >> + %cmp21 = icmp sgt i32 %N, 0
> >> + br i1 %cmp21, label %for.cond1.preheader.lr.ph, label %for.end12
> >> +
> >> +for.cond1.preheader.lr.ph:
> >> + %cmp219 = icmp sgt i32 %N, 1
> >> + %0 = add i32 %N, -1
> >> + br label %for.cond1.preheader
> >> +
> >> +for.cond1.preheader:
> >> + %indvars.iv23 = phi i64 [ 0, %for.cond1.preheader.lr.ph ], [
> %indvars.iv.next24, %for.inc10 ]
> >> + br i1 %cmp219, label %for.body3, label %for.inc10
> >> +
> >> +for.body3:
> >> + %indvars.iv = phi i64 [ %indvars.iv.next, %for.body3 ], [ 1,
> %for.cond1.preheader ]
> >> + %arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100
> x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv23
> >> + %1 = load i32, i32* %arrayidx5
> >> + %add = add nsw i32 %1, %k
> >> + store i32 %add, i32* %arrayidx5
> >> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> + %lftr.wideiv = trunc i64 %indvars.iv to i32
> >> + %exitcond = icmp eq i32 %lftr.wideiv, %0
> >> + br i1 %exitcond, label %for.inc10, label %for.body3
> >> +
> >> +for.inc10:
> >> + %indvars.iv.next24 = add nuw nsw i64 %indvars.iv23, 1
> >> + %lftr.wideiv25 = trunc i64 %indvars.iv23 to i32
> >> + %exitcond26 = icmp eq i32 %lftr.wideiv25, %0
> >> + br i1 %exitcond26, label %for.end12, label %for.cond1.preheader
> >> +
> >> +for.end12:
> >> + ret void
> >> +}
> >> +
> >> +; CHECK-LABEL: @interchange_01
> >> +; CHECK: entry:
> >> +; CHECK: %cmp21 = icmp sgt i32 %N, 0
> >> +; CHECK: br i1 %cmp21, label %for.body3.preheader, label %for.end12
> >> +; CHECK: for.cond1.preheader.lr.ph:
> >> +; CHECK: br label %for.cond1.preheader
> >> +; CHECK: for.cond1.preheader:
> >> +; CHECK: %indvars.iv23 = phi i64 [ 0, %for.cond1.preheader.lr.ph ],
> [ %indvars.iv.next24, %for.inc10 ]
> >> +; CHECK: br i1 %cmp219, label %for.body3.split1, label
> %for.end12.loopexit
> >> +; CHECK: for.body3.preheader:
> >> +; CHECK: %cmp219 = icmp sgt i32 %N, 1
> >> +; CHECK: %0 = add i32 %N, -1
> >> +; CHECK: br label %for.body3
> >> +; CHECK: for.body3:
> >> +; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body3.split
> ], [ 1, %for.body3.preheader ]
> >> +; CHECK: br label %for.cond1.preheader.lr.ph
> >> +; CHECK: for.body3.split1:
> >> +; CHECK: %arrayidx5 = getelementptr inbounds [100 x [100 x i32]],
> [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv23
> >> +; CHECK: %1 = load i32, i32* %arrayidx5
> >> +; CHECK: %add = add nsw i32 %1, %k
> >> +; CHECK: store i32 %add, i32* %arrayidx5
> >> +; CHECK: br label %for.inc10.loopexit
> >> +; CHECK: for.body3.split:
> >> +; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> +; CHECK: %lftr.wideiv = trunc i64 %indvars.iv to i32
> >> +; CHECK: %exitcond = icmp eq i32 %lftr.wideiv, %0
> >> +; CHECK: br i1 %exitcond, label %for.end12.loopexit, label %for.body3
> >> +; CHECK: for.inc10.loopexit:
> >> +; CHECK: br label %for.inc10
> >> +; CHECK: for.inc10:
> >> +; CHECK: %indvars.iv.next24 = add nuw nsw i64 %indvars.iv23, 1
> >> +; CHECK: %lftr.wideiv25 = trunc i64 %indvars.iv23 to i32
> >> +; CHECK: %exitcond26 = icmp eq i32 %lftr.wideiv25, %0
> >> +; CHECK: br i1 %exitcond26, label %for.body3.split, label
> %for.cond1.preheader
> >> +; CHECK: for.end12.loopexit:
> >> +; CHECK: br label %for.end12
> >> +; CHECK: for.end12:
> >> +; CHECK: ret void
> >> +
> >> +;;--------------------------------------Test case
> 02-------------------------------------
> >> +
> >> +;; for(int i=0;i<100;i++)
> >> +;; for(int j=100;j>=0;j--)
> >> +;; A[j][i] = A[j][i]+k;
> >> +
> >> +define void @interchange_02(i32 %k) {
> >> +entry:
> >> + br label %for.cond1.preheader
> >> +
> >> +for.cond1.preheader:
> >> + %indvars.iv19 = phi i64 [ 0, %entry ], [ %indvars.iv.next20,
> %for.inc10 ]
> >> + br label %for.body3
> >> +
> >> +for.body3:
> >> + %indvars.iv = phi i64 [ 100, %for.cond1.preheader ], [
> %indvars.iv.next, %for.body3 ]
> >> + %arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100
> x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv19
> >> + %0 = load i32, i32* %arrayidx5
> >> + %add = add nsw i32 %0, %k
> >> + store i32 %add, i32* %arrayidx5
> >> + %indvars.iv.next = add nsw i64 %indvars.iv, -1
> >> + %cmp2 = icmp sgt i64 %indvars.iv, 0
> >> + br i1 %cmp2, label %for.body3, label %for.inc10
> >> +
> >> +for.inc10:
> >> + %indvars.iv.next20 = add nuw nsw i64 %indvars.iv19, 1
> >> + %exitcond = icmp eq i64 %indvars.iv.next20, 100
> >> + br i1 %exitcond, label %for.end11, label %for.cond1.preheader
> >> +
> >> +for.end11:
> >> + ret void
> >> +}
> >> +
> >> +; CHECK-LABEL: @interchange_02
> >> +; CHECK: entry:
> >> +; CHECK: br label %for.body3.preheader
> >> +; CHECK: for.cond1.preheader.preheader:
> >> +; CHECK: br label %for.cond1.preheader
> >> +; CHECK: for.cond1.preheader:
> >> +; CHECK: %indvars.iv19 = phi i64 [ %indvars.iv.next20, %for.inc10 ],
> [ 0, %for.cond1.preheader.preheader ]
> >> +; CHECK: br label %for.body3.split1
> >> +; CHECK: for.body3.preheader:
> >> +; CHECK: br label %for.body3
> >> +; CHECK: for.body3:
> >> +; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body3.split
> ], [ 100, %for.body3.preheader ]
> >> +; CHECK: br label %for.cond1.preheader.preheader
> >> +; CHECK: for.body3.split1: ; preds =
> %for.cond1.preheader
> >> +; CHECK: %arrayidx5 = getelementptr inbounds [100 x [100 x i32]],
> [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv19
> >> +; CHECK: %0 = load i32, i32* %arrayidx5
> >> +; CHECK: %add = add nsw i32 %0, %k
> >> +; CHECK: store i32 %add, i32* %arrayidx5
> >> +; CHECK: br label %for.inc10
> >> +; CHECK: for.body3.split:
> >> +; CHECK: %indvars.iv.next = add nsw i64 %indvars.iv, -1
> >> +; CHECK: %cmp2 = icmp sgt i64 %indvars.iv, 0
> >> +; CHECK: br i1 %cmp2, label %for.body3, label %for.end11
> >> +; CHECK: for.inc10:
> >> +; CHECK: %indvars.iv.next20 = add nuw nsw i64 %indvars.iv19, 1
> >> +; CHECK: %exitcond = icmp eq i64 %indvars.iv.next20, 100
> >> +; CHECK: br i1 %exitcond, label %for.body3.split, label
> %for.cond1.preheader
> >> +; CHECK: for.end11:
> >> +; CHECK: ret void
> >> +
> >> +;;--------------------------------------Test case
> 03-------------------------------------
> >> +;; Loops should not be interchanged in this case as it is not
> profitable.
> >> +;; for(int i=0;i<100;i++)
> >> +;; for(int j=0;j<100;j++)
> >> +;; A[i][j] = A[i][j]+k;
> >> +
> >> +define void @interchange_03(i32 %k) {
> >> +entry:
> >> + br label %for.cond1.preheader
> >> +
> >> +for.cond1.preheader:
> >> + %indvars.iv21 = phi i64 [ 0, %entry ], [ %indvars.iv.next22,
> %for.inc10 ]
> >> + br label %for.body3
> >> +
> >> +for.body3:
> >> + %indvars.iv = phi i64 [ 0, %for.cond1.preheader ], [
> %indvars.iv.next, %for.body3 ]
> >> + %arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100
> x i32]]* @A, i64 0, i64 %indvars.iv21, i64 %indvars.iv
> >> + %0 = load i32, i32* %arrayidx5
> >> + %add = add nsw i32 %0, %k
> >> + store i32 %add, i32* %arrayidx5
> >> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> + %exitcond = icmp eq i64 %indvars.iv.next, 100
> >> + br i1 %exitcond, label %for.inc10, label %for.body3
> >> +
> >> +for.inc10:
> >> + %indvars.iv.next22 = add nuw nsw i64 %indvars.iv21, 1
> >> + %exitcond23 = icmp eq i64 %indvars.iv.next22, 100
> >> + br i1 %exitcond23, label %for.end12, label %for.cond1.preheader
> >> +
> >> +for.end12:
> >> + ret void
> >> +}
> >> +
> >> +; CHECK-LABEL: @interchange_03
> >> +; CHECK: entry:
> >> +; CHECK: br label %for.cond1.preheader.preheader
> >> +; CHECK: for.cond1.preheader.preheader: ; preds =
> %entry
> >> +; CHECK: br label %for.cond1.preheader
> >> +; CHECK: for.cond1.preheader: ; preds =
> %for.cond1.preheader.preheader, %for.inc10
> >> +; CHECK: %indvars.iv21 = phi i64 [ %indvars.iv.next22, %for.inc10 ],
> [ 0, %for.cond1.preheader.preheader ]
> >> +; CHECK: br label %for.body3.preheader
> >> +; CHECK: for.body3.preheader: ; preds =
> %for.cond1.preheader
> >> +; CHECK: br label %for.body3
> >> +; CHECK: for.body3: ; preds =
> %for.body3.preheader, %for.body3
> >> +; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body3 ], [
> 0, %for.body3.preheader ]
> >> +; CHECK: %arrayidx5 = getelementptr inbounds [100 x [100 x i32]],
> [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv21, i64 %indvars.iv
> >> +; CHECK: %0 = load i32, i32* %arrayidx5
> >> +; CHECK: %add = add nsw i32 %0, %k
> >> +; CHECK: store i32 %add, i32* %arrayidx5
> >> +; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> +; CHECK: %exitcond = icmp eq i64 %indvars.iv.next, 100
> >> +; CHECK: br i1 %exitcond, label %for.inc10, label %for.body3
> >> +; CHECK: for.inc10: ; preds =
> %for.body3
> >> +; CHECK: %indvars.iv.next22 = add nuw nsw i64 %indvars.iv21, 1
> >> +; CHECK: %exitcond23 = icmp eq i64 %indvars.iv.next22, 100
> >> +; CHECK: br i1 %exitcond23, label %for.end12, label
> %for.cond1.preheader
> >> +; CHECK: for.end12: ; preds =
> %for.inc10
> >> +; CHECK: ret void
> >> +
> >> +
> >> +;;--------------------------------------Test case
> 04-------------------------------------
> >> +;; Loops should not be interchanged in this case as it is not legal
> due to dependency.
> >> +;; for(int j=0;j<99;j++)
> >> +;; for(int i=0;i<99;i++)
> >> +;; A[j][i+1] = A[j+1][i]+k;
> >> +
> >> +define void @interchange_04(i32 %k){
> >> +entry:
> >> + br label %for.cond1.preheader
> >> +
> >> +for.cond1.preheader:
> >> + %indvars.iv23 = phi i64 [ 0, %entry ], [ %indvars.iv.next24,
> %for.inc12 ]
> >> + %indvars.iv.next24 = add nuw nsw i64 %indvars.iv23, 1
> >> + br label %for.body3
> >> +
> >> +for.body3:
> >> + %indvars.iv = phi i64 [ 0, %for.cond1.preheader ], [
> %indvars.iv.next, %for.body3 ]
> >> + %arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100
> x i32]]* @A, i64 0, i64 %indvars.iv.next24, i64 %indvars.iv
> >> + %0 = load i32, i32* %arrayidx5
> >> + %add6 = add nsw i32 %0, %k
> >> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> + %arrayidx11 = getelementptr inbounds [100 x [100 x i32]], [100 x
> [100 x i32]]* @A, i64 0, i64 %indvars.iv23, i64 %indvars.iv.next
> >> + store i32 %add6, i32* %arrayidx11
> >> + %exitcond = icmp eq i64 %indvars.iv.next, 99
> >> + br i1 %exitcond, label %for.inc12, label %for.body3
> >> +
> >> +for.inc12:
> >> + %exitcond25 = icmp eq i64 %indvars.iv.next24, 99
> >> + br i1 %exitcond25, label %for.end14, label %for.cond1.preheader
> >> +
> >> +for.end14:
> >> + ret void
> >> +}
> >> +
> >> +; CHECK-LABEL: @interchange_04
> >> +; CHECK: entry:
> >> +; CHECK: br label %for.cond1.preheader
> >> +; CHECK: for.cond1.preheader: ; preds =
> %for.inc12, %entry
> >> +; CHECK: %indvars.iv23 = phi i64 [ 0, %entry ], [
> %indvars.iv.next24, %for.inc12 ]
> >> +; CHECK: %indvars.iv.next24 = add nuw nsw i64 %indvars.iv23, 1
> >> +; CHECK: br label %for.body3
> >> +; CHECK: for.body3: ; preds =
> %for.body3, %for.cond1.preheader
> >> +; CHECK: %indvars.iv = phi i64 [ 0, %for.cond1.preheader ], [
> %indvars.iv.next, %for.body3 ]
> >> +; CHECK: %arrayidx5 = getelementptr inbounds [100 x [100 x i32]],
> [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv.next24, i64 %indvars.iv
> >> +; CHECK: %0 = load i32, i32* %arrayidx5
> >> +; CHECK: %add6 = add nsw i32 %0, %k
> >> +; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> +; CHECK: %arrayidx11 = getelementptr inbounds [100 x [100 x i32]],
> [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv23, i64 %indvars.iv.next
> >> +; CHECK: store i32 %add6, i32* %arrayidx11
> >> +; CHECK: %exitcond = icmp eq i64 %indvars.iv.next, 99
> >>
>
> ...
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