[llvm] r235571 - Add support to interchange loops with reductions.
KARTHIK VENKATESH BHAT
kv.bhat at samsung.com
Wed Apr 22 23:31:53 PDT 2015
Hi Tilmann,
>From the log it seems like you missed svn revision r233352?
isInductionPHI was refactored out of LoopVectorizer and moved into LoopUtils.h in this changlelist.
I will recheck though.
Thanks and Regards
Karthik Bhat
------- Original Message -------
Sender : Tilmann Scheller<tilmann at osg.samsung.com>
Date : Apr 23, 2015 15:13 (GMT+09:00)
Title : Re: [llvm] r235571 - Add support to interchange loops with reductions.
Hi Karthik,
looks like this commit broke the build (-DCMAKE_BUILD_TYPE=Debug
-DBUILD_SHARED_LIBS=ON):
$ time make
[ 4%] Built target LLVMSupport
[ 6%] Built target LLVMTableGen
[ 8%] Built target llvm-tblgen
[ 8%] Built target intrinsics_gen
[ 10%] Built target LLVMCore
[ 10%] Built target LLVMAsmParser
[ 10%] Built target LLVMBitReader
[ 10%] Built target LLVMIRReader
[ 13%] Built target LLVMMC
[ 16%] Built target LLVMAnalysis
[ 16%] Built target LLVMTarget
[ 16%] Built target LLVMipa
[ 19%] Built target LLVMTransformUtils
[ 20%] Built target LLVMMCParser
[ 21%] Built target LLVMObject
[ 21%] Built target LLVMProfileData
[ 22%] Built target LLVMInstCombine
Linking CXX shared library ../../libLLVMScalarOpts.so
/home/t/work/arm/llvm/lib/Transforms/Scalar/LoopInterchange.cpp:703:
error: undefined reference to 'llvm::isInductionPHI(llvm::PHINode*,
llvm::ScalarEvolution*, llvm::ConstantInt*&)'
clang-3.7: error: linker command failed with exit code 1 (use -v to see
invocation)
lib/Transforms/Scalar/CMakeFiles/LLVMScalarOpts.dir/build.make:1266:
recipe for target 'lib/libLLVMScalarOpts.so.3.7.0svn' failed
make[2]: *** [lib/libLLVMScalarOpts.so.3.7.0svn] Error 1
CMakeFiles/Makefile2:1459: recipe for target
'lib/Transforms/Scalar/CMakeFiles/LLVMScalarOpts.dir/all' failed
make[1]: *** [lib/Transforms/Scalar/CMakeFiles/LLVMScalarOpts.dir/all]
Error 2
Makefile:137: recipe for target 'all' failed
make: *** [all] Error 2
Can you please have a look?
Thanks!
Regards,
Tilmann
On 04/23/2015 06:51 AM, Karthik Bhat wrote:
> Author: karthik
> Date: Wed Apr 22 23:51:44 2015
> New Revision: 235571
>
> URL: http://llvm.org/viewvc/llvm-project?rev=235571&view=rev
> Log:
> Add support to interchange loops with reductions.
> This patch enables interchanging of tightly nested loops with reductions.
> Differential Revision: http://reviews.llvm.org/D8314
>
> Added:
> llvm/trunk/test/Transforms/LoopInterchange/reductions.ll
> Modified:
> llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp
>
> Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=235571&r1=235570&r2=235571&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Wed Apr 22 23:51:44 2015
> @@ -246,9 +246,10 @@ void PassManagerBuilder::populateModuleP
> MPM.add(createIndVarSimplifyPass()); // Canonicalize indvars
> MPM.add(createLoopIdiomPass()); // Recognize idioms like memset.
> MPM.add(createLoopDeletionPass()); // Delete dead loops
> - if (EnableLoopInterchange)
> + if (EnableLoopInterchange) {
> MPM.add(createLoopInterchangePass()); // Interchange loops
> -
> + MPM.add(createCFGSimplificationPass());
> + }
> if (!DisableUnrollLoops)
> MPM.add(createSimpleLoopUnrollPass()); // Unroll small loops
> addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
>
> Modified: llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp?rev=235571&r1=235570&r2=235571&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp Wed Apr 22 23:51:44 2015
> @@ -33,6 +33,7 @@
> #include "llvm/IR/IRBuilder.h"
> #include "llvm/IR/InstIterator.h"
> #include "llvm/IR/IntrinsicInst.h"
> +#include "llvm/IR/Module.h"
> #include "llvm/Pass.h"
> #include "llvm/Support/Debug.h"
> #include "llvm/Support/raw_ostream.h"
> @@ -70,8 +71,8 @@ void printDepMatrix(CharMatrix &DepMatri
> }
> #endif
>
> -bool populateDependencyMatrix(CharMatrix &DepMatrix, unsigned Level, Loop *L,
> - DependenceAnalysis *DA) {
> +static bool populateDependencyMatrix(CharMatrix &DepMatrix, unsigned Level,
> + Loop *L, DependenceAnalysis *DA) {
> typedef SmallVector ValueVector;
> ValueVector MemInstr;
>
> @@ -183,8 +184,8 @@ bool populateDependencyMatrix(CharMatrix
>
> // 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) {
> +static void interChangeDepedencies(CharMatrix &DepMatrix, unsigned FromIndx,
> + unsigned ToIndx) {
> unsigned numRows = DepMatrix.size();
> for (unsigned i = 0; i < numRows; ++i) {
> char TmpVal = DepMatrix[i][ToIndx];
> @@ -195,8 +196,8 @@ void interChangeDepedencies(CharMatrix &
>
> // Checks if outermost non '=','S'or'I' dependence in the dependence matrix is
> // '>'
> -bool isOuterMostDepPositive(CharMatrix &DepMatrix, unsigned Row,
> - unsigned Column) {
> +static bool isOuterMostDepPositive(CharMatrix &DepMatrix, unsigned Row,
> + unsigned Column) {
> for (unsigned i = 0; i <= Column; ++i) {
> if (DepMatrix[Row][i] == '<')
> return false;
> @@ -208,8 +209,8 @@ bool isOuterMostDepPositive(CharMatrix &
> }
>
> // Checks if no dependence exist in the dependency matrix in Row before Column.
> -bool containsNoDependence(CharMatrix &DepMatrix, unsigned Row,
> - unsigned Column) {
> +static 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')
> @@ -218,8 +219,9 @@ bool containsNoDependence(CharMatrix &De
> return true;
> }
>
> -bool validDepInterchange(CharMatrix &DepMatrix, unsigned Row,
> - unsigned OuterLoopId, char InnerDep, char OuterDep) {
> +static bool validDepInterchange(CharMatrix &DepMatrix, unsigned Row,
> + unsigned OuterLoopId, char InnerDep,
> + char OuterDep) {
>
> if (isOuterMostDepPositive(DepMatrix, Row, OuterLoopId))
> return false;
> @@ -253,11 +255,13 @@ bool validDepInterchange(CharMatrix &Dep
> }
>
> // 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
> +// [Theorem] 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) {
> +static bool isLegalToInterChangeLoops(CharMatrix &DepMatrix,
> + unsigned InnerLoopId,
> + unsigned OuterLoopId) {
>
> unsigned NumRows = DepMatrix.size();
> // For each row check if it is valid to interchange.
> @@ -328,7 +332,8 @@ class LoopInterchangeLegality {
> public:
> LoopInterchangeLegality(Loop *Outer, Loop *Inner, ScalarEvolution *SE,
> LoopInterchange *Pass)
> - : OuterLoop(Outer), InnerLoop(Inner), SE(SE), CurrentPass(Pass) {}
> + : OuterLoop(Outer), InnerLoop(Inner), SE(SE), CurrentPass(Pass),
> + InnerLoopHasReduction(false) {}
>
> /// Check if the loops can be interchanged.
> bool canInterchangeLoops(unsigned InnerLoopId, unsigned OuterLoopId,
> @@ -339,15 +344,24 @@ public:
>
> bool currentLimitations();
>
> + bool hasInnerLoopReduction() { return InnerLoopHasReduction; }
> +
> private:
> bool tightlyNested(Loop *Outer, Loop *Inner);
> -
> + bool containsUnsafeInstructionsInHeader(BasicBlock *BB);
> + bool areAllUsesReductions(Instruction *Ins, Loop *L);
> + bool containsUnsafeInstructionsInLatch(BasicBlock *BB);
> + bool findInductionAndReductions(Loop *L,
> + SmallVector &Inductions,
> + SmallVector &Reductions);
> Loop *OuterLoop;
> Loop *InnerLoop;
>
> /// Scev analysis.
> ScalarEvolution *SE;
> LoopInterchange *CurrentPass;
> +
> + bool InnerLoopHasReduction;
> };
>
> /// LoopInterchangeProfitability checks if it is profitable to interchange the
> @@ -376,9 +390,11 @@ class LoopInterchangeTransform {
> public:
> LoopInterchangeTransform(Loop *Outer, Loop *Inner, ScalarEvolution *SE,
> LoopInfo *LI, DominatorTree *DT,
> - LoopInterchange *Pass, BasicBlock *LoopNestExit)
> + LoopInterchange *Pass, BasicBlock *LoopNestExit,
> + bool InnerLoopContainsReductions)
> : OuterLoop(Outer), InnerLoop(Inner), SE(SE), LI(LI), DT(DT),
> - LoopExit(LoopNestExit) {}
> + LoopExit(LoopNestExit),
> + InnerLoopHasReduction(InnerLoopContainsReductions) {}
>
> /// Interchange OuterLoop and InnerLoop.
> bool transform();
> @@ -394,6 +410,8 @@ private:
> void adjustOuterLoopPreheader();
> void adjustInnerLoopPreheader();
> bool adjustLoopBranches();
> + void updateIncomingBlock(BasicBlock *CurrBlock, BasicBlock *OldPred,
> + BasicBlock *NewPred);
>
> Loop *OuterLoop;
> Loop *InnerLoop;
> @@ -403,6 +421,7 @@ private:
> LoopInfo *LI;
> DominatorTree *DT;
> BasicBlock *LoopExit;
> + bool InnerLoopHasReduction;
> };
>
> // Main LoopInterchange Pass
> @@ -443,7 +462,7 @@ struct LoopInterchange : public Function
> bool Changed = true;
> while (!Worklist.empty()) {
> LoopVector LoopList = Worklist.pop_back_val();
> - Changed = processLoopList(LoopList);
> + Changed = processLoopList(LoopList, F);
> }
> return Changed;
> }
> @@ -474,9 +493,9 @@ struct LoopInterchange : public Function
> return LoopList.size() - 1;
> }
>
> - bool processLoopList(LoopVector LoopList) {
> + bool processLoopList(LoopVector LoopList, Function &F) {
> +
> bool Changed = false;
> - bool containsLCSSAPHI = false;
> CharMatrix DependencyMatrix;
> if (LoopList.size() < 2) {
> DEBUG(dbgs() << "Loop doesn't contain minimum nesting level.\n");
> @@ -518,21 +537,11 @@ struct LoopInterchange : public Function
> 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(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)
> + if (isa(LoopNestExit->begin())) {
> + DEBUG(dbgs() << "PHI Nodes in loop nest exit is not handled for now "
> + "since on failure all loops branch to loop nest exit.\n");
> return false;
> + }
>
> unsigned SelecLoopId = selectLoopForInterchange(LoopList);
> // Move the selected loop outwards to the best posible position.
> @@ -546,7 +555,7 @@ struct LoopInterchange : public Function
>
> // Update the DependencyMatrix
> interChangeDepedencies(DependencyMatrix, i, i - 1);
> -
> + DT->recalculate(F);
> #ifdef DUMP_DEP_MATRICIES
> DEBUG(dbgs() << "Dependence after inter change \n");
> printDepMatrix(DependencyMatrix);
> @@ -578,7 +587,7 @@ struct LoopInterchange : public Function
> }
>
> LoopInterchangeTransform LIT(OuterLoop, InnerLoop, SE, LI, DT, this,
> - LoopNestExit);
> + LoopNestExit, LIL.hasInnerLoopReduction());
> LIT.transform();
> DEBUG(dbgs() << "Loops interchanged\n");
> return true;
> @@ -586,10 +595,38 @@ struct LoopInterchange : public Function
> };
>
> } // end of namespace
> +bool LoopInterchangeLegality::areAllUsesReductions(Instruction *Ins, Loop *L) {
> + return !std::any_of(Ins->user_begin(), Ins->user_end(), [=](User *U) -> bool {
> + PHINode *UserIns = dyn_cast(U);
> + ReductionDescriptor RD;
> + return !UserIns || !ReductionDescriptor::isReductionPHI(UserIns, L, RD);
> + });
> +}
>
> -static bool containsUnsafeInstructions(BasicBlock *BB) {
> +bool LoopInterchangeLegality::containsUnsafeInstructionsInHeader(
> + BasicBlock *BB) {
> for (auto I = BB->begin(), E = BB->end(); I != E; ++I) {
> - if (I->mayHaveSideEffects() || I->mayReadFromMemory())
> + // Load corresponding to reduction PHI's are safe while concluding if
> + // tightly nested.
> + if (LoadInst *L = dyn_cast(I)) {
> + if (!areAllUsesReductions(L, InnerLoop))
> + return true;
> + } else if (I->mayHaveSideEffects() || I->mayReadFromMemory())
> + return true;
> + }
> + return false;
> +}
> +
> +bool LoopInterchangeLegality::containsUnsafeInstructionsInLatch(
> + BasicBlock *BB) {
> + for (auto I = BB->begin(), E = BB->end(); I != E; ++I) {
> + // Stores corresponding to reductions are safe while concluding if tightly
> + // nested.
> + if (StoreInst *L = dyn_cast(I)) {
> + PHINode *PHI = dyn_cast(L->getOperand(0));
> + if (!PHI)
> + return true;
> + } else if (I->mayHaveSideEffects() || I->mayReadFromMemory())
> return true;
> }
> return false;
> @@ -619,8 +656,8 @@ bool LoopInterchangeLegality::tightlyNes
> 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))
> + if (containsUnsafeInstructionsInHeader(OuterLoopHeader) ||
> + containsUnsafeInstructionsInLatch(OuterLoopLatch))
> return false;
>
> DEBUG(dbgs() << "Loops are perfectly nested \n");
> @@ -628,12 +665,6 @@ bool LoopInterchangeLegality::tightlyNes
> return true;
> }
>
> -static unsigned getPHICount(BasicBlock *BB) {
> - unsigned PhiCount = 0;
> - for (auto I = BB->begin(); isa(I); ++I)
> - PhiCount++;
> - return PhiCount;
> -}
>
> bool LoopInterchangeLegality::isLoopStructureUnderstood(
> PHINode *InnerInduction) {
> @@ -660,34 +691,96 @@ bool LoopInterchangeLegality::isLoopStru
> return true;
> }
>
> +bool LoopInterchangeLegality::findInductionAndReductions(
> + Loop *L, SmallVector &Inductions,
> + SmallVector &Reductions) {
> + if (!L->getLoopLatch() || !L->getLoopPredecessor())
> + return false;
> + for (BasicBlock::iterator I = L->getHeader()->begin(); isa(I); ++I) {
> + ReductionDescriptor RD;
> + PHINode *PHI = cast(I);
> + ConstantInt *StepValue = nullptr;
> + if (isInductionPHI(PHI, SE, StepValue))
> + Inductions.push_back(PHI);
> + else if (ReductionDescriptor::isReductionPHI(PHI, L, RD))
> + Reductions.push_back(PHI);
> + else {
> + DEBUG(
> + dbgs() << "Failed to recognize PHI as an induction or reduction.\n");
> + return false;
> + }
> + }
> + return true;
> +}
> +
> +static bool containsSafePHI(BasicBlock *Block, bool isOuterLoopExitBlock) {
> + for (auto I = Block->begin(); isa(I); ++I) {
> + PHINode *PHI = cast(I);
> + // Reduction lcssa phi will have only 1 incoming block that from loop latch.
> + if (PHI->getNumIncomingValues() > 1)
> + return false;
> + Instruction *Ins = dyn_cast(PHI->getIncomingValue(0));
> + if (!Ins)
> + return false;
> + // Incoming value for lcssa phi's in outer loop exit can only be inner loop
> + // exits lcssa phi else it would not be tightly nested.
> + if (!isa(Ins) && isOuterLoopExitBlock)
> + return false;
> + }
> + return true;
> +}
> +
> +static BasicBlock *getLoopLatchExitBlock(BasicBlock *LatchBlock,
> + BasicBlock *LoopHeader) {
> + if (BranchInst *BI = dyn_cast(LatchBlock->getTerminator())) {
> + unsigned Num = BI->getNumSuccessors();
> + assert(Num == 2);
> + for (unsigned i = 0; i < Num; ++i) {
> + if (BI->getSuccessor(i) == LoopHeader)
> + continue;
> + return BI->getSuccessor(i);
> + }
> + }
> + return nullptr;
> +}
> +
> // 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();
> + BasicBlock *OuterLoopHeader = OuterLoop->getHeader();
>
> 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)
> + SmallVector Inductions;
> + SmallVector Reductions;
> + if (!findInductionAndReductions(InnerLoop, Inductions, Reductions))
> return true;
>
> - if (getPHICount(OuterLoopHeader) > 1)
> + // TODO: Currently we handle only loops with 1 induction variable.
> + if (Inductions.size() != 1) {
> + DEBUG(dbgs() << "We currently only support loops with 1 induction variable."
> + << "Failed to interchange due to current limitation\n");
> return true;
> + }
> + if (Reductions.size() > 0)
> + InnerLoopHasReduction = true;
>
> - InnerInductionVar = getInductionVariable(InnerLoop, SE);
> - OuterInductionVar = getInductionVariable(OuterLoop, SE);
> + InnerInductionVar = Inductions.pop_back_val();
> + Reductions.clear();
> + if (!findInductionAndReductions(OuterLoop, Inductions, Reductions))
> + return true;
>
> - if (!OuterInductionVar || !InnerInductionVar) {
> - DEBUG(dbgs() << "Induction variable not found\n");
> + // Outer loop cannot have reduction because then loops will not be tightly
> + // nested.
> + if (!Reductions.empty())
> + return true;
> + // TODO: Currently we handle only loops with 1 induction variable.
> + if (Inductions.size() != 1)
> return true;
> - }
>
> // TODO: Triangular loops are not handled for now.
> if (!isLoopStructureUnderstood(InnerInductionVar)) {
> @@ -695,16 +788,15 @@ bool LoopInterchangeLegality::currentLim
> return true;
> }
>
> - // TODO: Loops with LCSSA PHI's are currently not handled.
> - if (isa(OuterLoopLatch->begin())) {
> - DEBUG(dbgs() << "Found and LCSSA PHI in outer loop latch\n");
> + // TODO: We only handle LCSSA PHI's corresponding to reduction for now.
> + BasicBlock *LoopExitBlock =
> + getLoopLatchExitBlock(OuterLoopLatch, OuterLoopHeader);
> + if (!LoopExitBlock || !containsSafePHI(LoopExitBlock, true))
> return true;
> - }
> - if (InnerLoopLatch != InnerLoopHeader &&
> - isa(InnerLoopLatch->begin())) {
> - DEBUG(dbgs() << "Found and LCSSA PHI in inner loop latch\n");
> +
> + LoopExitBlock = getLoopLatchExitBlock(InnerLoopLatch, InnerLoopHeader);
> + if (!LoopExitBlock || !containsSafePHI(LoopExitBlock, false))
> 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
> @@ -783,12 +875,6 @@ bool LoopInterchangeLegality::canInterch
> 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()) {
> @@ -796,6 +882,12 @@ bool LoopInterchangeLegality::canInterch
> return false;
> }
>
> + // Check if the loops are tightly nested.
> + if (!tightlyNested(OuterLoop, InnerLoop)) {
> + DEBUG(dbgs() << "Loops not tightly nested\n");
> + return false;
> + }
> +
> return true;
> }
>
> @@ -983,9 +1075,33 @@ void LoopInterchangeTransform::splitOute
>
> void LoopInterchangeTransform::splitInnerLoopHeader() {
>
> - // Split the inner loop header out.
> + // Split the inner loop header out. Here make sure that the reduction PHI's
> + // stay in the innerloop body.
> BasicBlock *InnerLoopHeader = InnerLoop->getHeader();
> - SplitBlock(InnerLoopHeader, InnerLoopHeader->getFirstNonPHI(), DT, LI);
> + BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
> + if (InnerLoopHasReduction) {
> + // FIXME: Check if the induction PHI will always be the first PHI.
> + BasicBlock *New = InnerLoopHeader->splitBasicBlock(
> + ++(InnerLoopHeader->begin()), InnerLoopHeader->getName() + ".split");
> + if (LI)
> + if (Loop *L = LI->getLoopFor(InnerLoopHeader))
> + L->addBasicBlockToLoop(New, *LI);
> +
> + // Adjust Reduction PHI's in the block.
> + SmallVector PHIVec;
> + for (auto I = New->begin(); isa(I); ++I) {
> + PHINode *PHI = dyn_cast(I);
> + Value *V = PHI->getIncomingValueForBlock(InnerLoopPreHeader);
> + PHI->replaceAllUsesWith(V);
> + PHIVec.push_back((PHI));
> + }
> + for (auto I = PHIVec.begin(), E = PHIVec.end(); I != E; ++I) {
> + PHINode *P = *I;
> + P->eraseFromParent();
> + }
> + } else {
> + SplitBlock(InnerLoopHeader, InnerLoopHeader->getFirstNonPHI(), DT, LI);
> + }
>
> DEBUG(dbgs() << "Output of splitInnerLoopHeader InnerLoopHeaderSucc & "
> "InnerLoopHeader \n");
> @@ -1015,6 +1131,19 @@ void LoopInterchangeTransform::adjustInn
> moveBBContents(InnerLoopPreHeader, OuterHeader->getTerminator());
> }
>
> +void LoopInterchangeTransform::updateIncomingBlock(BasicBlock *CurrBlock,
> + BasicBlock *OldPred,
> + BasicBlock *NewPred) {
> + for (auto I = CurrBlock->begin(); isa(I); ++I) {
> + PHINode *PHI = cast(I);
> + unsigned Num = PHI->getNumIncomingValues();
> + for (unsigned i = 0; i < Num; ++i) {
> + if (PHI->getIncomingBlock(i) == OldPred)
> + PHI->setIncomingBlock(i, NewPred);
> + }
> + }
> +}
> +
> bool LoopInterchangeTransform::adjustLoopBranches() {
>
> DEBUG(dbgs() << "adjustLoopBranches called\n");
> @@ -1072,6 +1201,10 @@ bool LoopInterchangeTransform::adjustLoo
> OuterLoopHeaderBI->setSuccessor(i, InnerLoopHeaderSucessor);
> }
>
> + // Adjust reduction PHI's now that the incoming block has changed.
> + updateIncomingBlock(InnerLoopHeaderSucessor, InnerLoopHeader,
> + OuterLoopHeader);
> +
> BranchInst::Create(OuterLoopPreHeader, InnerLoopHeaderBI);
> InnerLoopHeaderBI->eraseFromParent();
>
> @@ -1087,6 +1220,20 @@ bool LoopInterchangeTransform::adjustLoo
> InnerLoopLatchPredecessorBI->setSuccessor(i, InnerLoopLatchSuccessor);
> }
>
> + // Adjust PHI nodes in InnerLoopLatchSuccessor. Update all uses of PHI with
> + // the value and remove this PHI node from inner loop.
> + SmallVector LcssaVec;
> + for (auto I = InnerLoopLatchSuccessor->begin(); isa(I); ++I) {
> + PHINode *LcssaPhi = cast(I);
> + LcssaVec.push_back(LcssaPhi);
> + }
> + for (auto I = LcssaVec.begin(), E = LcssaVec.end(); I != E; ++I) {
> + PHINode *P = *I;
> + Value *Incoming = P->getIncomingValueForBlock(InnerLoopLatch);
> + P->replaceAllUsesWith(Incoming);
> + P->eraseFromParent();
> + }
> +
> if (OuterLoopLatchBI->getSuccessor(0) == OuterLoopHeader)
> OuterLoopLatchSuccessor = OuterLoopLatchBI->getSuccessor(1);
> else
> @@ -1097,6 +1244,8 @@ bool LoopInterchangeTransform::adjustLoo
> else
> InnerLoopLatchBI->setSuccessor(0, OuterLoopLatchSuccessor);
>
> + updateIncomingBlock(OuterLoopLatchSuccessor, OuterLoopLatch, InnerLoopLatch);
> +
> if (OuterLoopLatchBI->getSuccessor(0) == OuterLoopLatchSuccessor) {
> OuterLoopLatchBI->setSuccessor(0, InnerLoopLatch);
> } else {
> @@ -1117,12 +1266,9 @@ void LoopInterchangeTransform::adjustLoo
> BranchInst *InnerTermBI =
> cast(InnerLoopPreHeader->getTerminator());
>
> - 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.
> - moveBBContents(InnerLoopPreHeader, InsPoint);
> + moveBBContents(InnerLoopPreHeader, OuterLoopHeader->getTerminator());
> // These instructions were not executed previously in the loop so move them to
> // the older inner loop preheader.
> moveBBContents(OuterLoopPreHeader, InnerTermBI);
>
> Added: llvm/trunk/test/Transforms/LoopInterchange/reductions.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopInterchange/reductions.ll?rev=235571&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/LoopInterchange/reductions.ll (added)
> +++ llvm/trunk/test/Transforms/LoopInterchange/reductions.ll Wed Apr 22 23:51:44 2015
> @@ -0,0 +1,235 @@
> +; RUN: opt < %s -basicaa -loop-interchange -S | FileCheck %s
> +
> + at A = common global [500 x [500 x i32]] zeroinitializer
> + at X = common global i32 0
> + at B = common global [500 x [500 x i32]] zeroinitializer
> + at Y = common global i32 0
> +
> +;; for( int i=1;i> +;; for( int j=1;j> +;; X+=A[j][i];
> +
> +define void @reduction_01(i32 %N) {
> +entry:
> + %cmp16 = icmp sgt i32 %N, 1
> + br i1 %cmp16, label %for.body3.lr.ph, label %for.end8
> +
> +for.body3.lr.ph: ; preds = %entry, %for.cond1.for.inc6_crit_edge
> + %indvars.iv18 = phi i64 [ %indvars.iv.next19, %for.cond1.for.inc6_crit_edge ], [ 1, %entry ]
> + %X.promoted = load i32, i32* @X
> + br label %for.body3
> +
> +for.body3: ; preds = %for.body3, %for.body3.lr.ph
> + %indvars.iv = phi i64 [ 1, %for.body3.lr.ph ], [ %indvars.iv.next, %for.body3 ]
> + %add15 = phi i32 [ %X.promoted, %for.body3.lr.ph ], [ %add, %for.body3 ]
> + %arrayidx5 = getelementptr inbounds [500 x [500 x i32]], [500 x [500 x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv18
> + %0 = load i32, i32* %arrayidx5
> + %add = add nsw i32 %add15, %0
> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> + %lftr.wideiv = trunc i64 %indvars.iv.next to i32
> + %exitcond = icmp eq i32 %lftr.wideiv, %N
> + br i1 %exitcond, label %for.cond1.for.inc6_crit_edge, label %for.body3
> +
> +for.cond1.for.inc6_crit_edge: ; preds = %for.body3
> + store i32 %add, i32* @X
> + %indvars.iv.next19 = add nuw nsw i64 %indvars.iv18, 1
> + %lftr.wideiv20 = trunc i64 %indvars.iv.next19 to i32
> + %exitcond21 = icmp eq i32 %lftr.wideiv20, %N
> + br i1 %exitcond21, label %for.end8, label %for.body3.lr.ph
> +
> +for.end8: ; preds = %for.cond1.for.inc6_crit_edge, %entry
> + ret void
> +}
> +
> +;; Loop is interchanged check that the phi nodes are split and the promoted value is used instead of the reduction phi.
> +; CHECK-LABEL: @reduction_01
> +; CHECK: for.body3: ; preds = %for.body3.preheader, %for.body3.split
> +; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body3.split ], [ 1, %for.body3.preheader ]
> +; CHECK: br label %for.body3.lr.ph.preheader
> +; CHECK: %add = add nsw i32 %X.promoted
> +
> +
> +;; Test for more than 1 reductions inside a loop.
> +;; for( int i=1;i> +;; for( int j=1;j> +;; for( int k=1;k> +;; X+=A[k][j];
> +;; Y+=B[k][i];
> +;; }
> +
> +define void @reduction_02(i32 %N) {
> +entry:
> + %cmp34 = icmp sgt i32 %N, 1
> + br i1 %cmp34, label %for.cond4.preheader.preheader, label %for.end19
> +
> +for.cond4.preheader.preheader: ; preds = %entry, %for.inc17
> + %indvars.iv40 = phi i64 [ %indvars.iv.next41, %for.inc17 ], [ 1, %entry ]
> + br label %for.body6.lr.ph
> +
> +for.body6.lr.ph: ; preds = %for.cond4.for.inc14_crit_edge, %for.cond4.preheader.preheader
> + %indvars.iv36 = phi i64 [ %indvars.iv.next37, %for.cond4.for.inc14_crit_edge ], [ 1, %for.cond4.preheader.preheader ]
> + %X.promoted = load i32, i32* @X
> + %Y.promoted = load i32, i32* @Y
> + br label %for.body6
> +
> +for.body6: ; preds = %for.body6, %for.body6.lr.ph
> + %indvars.iv = phi i64 [ 1, %for.body6.lr.ph ], [ %indvars.iv.next, %for.body6 ]
> + %add1331 = phi i32 [ %Y.promoted, %for.body6.lr.ph ], [ %add13, %for.body6 ]
> + %add30 = phi i32 [ %X.promoted, %for.body6.lr.ph ], [ %add, %for.body6 ]
> + %arrayidx8 = getelementptr inbounds [500 x [500 x i32]], [500 x [500 x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv36
> + %0 = load i32, i32* %arrayidx8
> + %add = add nsw i32 %add30, %0
> + %arrayidx12 = getelementptr inbounds [500 x [500 x i32]], [500 x [500 x i32]]* @B, i64 0, i64 %indvars.iv, i64 %indvars.iv40
> + %1 = load i32, i32* %arrayidx12
> + %add13 = add nsw i32 %add1331, %1
> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> + %lftr.wideiv = trunc i64 %indvars.iv.next to i32
> + %exitcond = icmp eq i32 %lftr.wideiv, %N
> + br i1 %exitcond, label %for.cond4.for.inc14_crit_edge, label %for.body6
> +
> +for.cond4.for.inc14_crit_edge: ; preds = %for.body6
> + store i32 %add, i32* @X
> + store i32 %add13, i32* @Y
> + %indvars.iv.next37 = add nuw nsw i64 %indvars.iv36, 1
> + %lftr.wideiv38 = trunc i64 %indvars.iv.next37 to i32
> + %exitcond39 = icmp eq i32 %lftr.wideiv38, %N
> + br i1 %exitcond39, label %for.inc17, label %for.body6.lr.ph
> +
> +for.inc17: ; preds = %for.cond4.for.inc14_crit_edge
> + %indvars.iv.next41 = add nuw nsw i64 %indvars.iv40, 1
> + %lftr.wideiv42 = trunc i64 %indvars.iv.next41 to i32
> + %exitcond43 = icmp eq i32 %lftr.wideiv42, %N
> + br i1 %exitcond43, label %for.end19, label %for.cond4.preheader.preheader
> +
> +for.end19: ; preds = %for.inc17, %entry
> + ret void
> +}
> +
> +;; Loop is interchanged check that the phi nodes are split and the promoted value is used instead of the reduction phi.
> +; CHECK-LABEL: @reduction_02
> +; CHECK: for.body6: ; preds = %for.body6.preheader, %for.body6.split
> +; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body6.split ], [ 1, %for.body6.preheader ]
> +; CHECK: br label %for.cond4.preheader.preheader.preheader
> +; CHECK: %add13 = add nsw i32 %Y.promoted
> +
> +
> +;; Not tightly nested. Do not interchange.
> +;; for( int i=1;i> +;; for( int j=1;j> +;; for( int k=1;k> +;; X+=A[k][j];
> +;; }
> +;; Y+=B[j][i];
> +;; }
> +define void @reduction_03(i32 %N) {
> +entry:
> + %cmp35 = icmp sgt i32 %N, 1
> + br i1 %cmp35, label %for.cond4.preheader.lr.ph, label %for.end19
> +
> +for.cond4.preheader.lr.ph: ; preds = %entry, %for.cond1.for.inc17_crit_edge
> + %indvars.iv41 = phi i64 [ %indvars.iv.next42, %for.cond1.for.inc17_crit_edge ], [ 1, %entry ]
> + %Y.promoted = load i32, i32* @Y
> + br label %for.body6.lr.ph
> +
> +for.body6.lr.ph: ; preds = %for.cond4.preheader.lr.ph, %for.cond4.for.end_crit_edge
> + %indvars.iv37 = phi i64 [ 1, %for.cond4.preheader.lr.ph ], [ %indvars.iv.next38, %for.cond4.for.end_crit_edge ]
> + %add1334 = phi i32 [ %Y.promoted, %for.cond4.preheader.lr.ph ], [ %add13, %for.cond4.for.end_crit_edge ]
> + %X.promoted = load i32, i32* @X
> + br label %for.body6
> +
> +for.body6: ; preds = %for.body6, %for.body6.lr.ph
> + %indvars.iv = phi i64 [ 1, %for.body6.lr.ph ], [ %indvars.iv.next, %for.body6 ]
> + %add31 = phi i32 [ %X.promoted, %for.body6.lr.ph ], [ %add, %for.body6 ]
> + %arrayidx8 = getelementptr inbounds [500 x [500 x i32]], [500 x [500 x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv37
> + %0 = load i32, i32* %arrayidx8
> + %add = add nsw i32 %add31, %0
> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> + %lftr.wideiv = trunc i64 %indvars.iv.next to i32
> + %exitcond = icmp eq i32 %lftr.wideiv, %N
> + br i1 %exitcond, label %for.cond4.for.end_crit_edge, label %for.body6
> +
> +for.cond4.for.end_crit_edge: ; preds = %for.body6
> + store i32 %add, i32* @X
> + %arrayidx12 = getelementptr inbounds [500 x [500 x i32]], [500 x [500 x i32]]* @B, i64 0, i64 %indvars.iv37, i64 %indvars.iv41
> + %1 = load i32, i32* %arrayidx12
> + %add13 = add nsw i32 %add1334, %1
> + %indvars.iv.next38 = add nuw nsw i64 %indvars.iv37, 1
> + %lftr.wideiv39 = trunc i64 %indvars.iv.next38 to i32
> + %exitcond40 = icmp eq i32 %lftr.wideiv39, %N
> + br i1 %exitcond40, label %for.cond1.for.inc17_crit_edge, label %for.body6.lr.ph
> +
> +for.cond1.for.inc17_crit_edge: ; preds = %for.cond4.for.end_crit_edge
> + store i32 %add13, i32* @Y
> + %indvars.iv.next42 = add nuw nsw i64 %indvars.iv41, 1
> + %lftr.wideiv43 = trunc i64 %indvars.iv.next42 to i32
> + %exitcond44 = icmp eq i32 %lftr.wideiv43, %N
> + br i1 %exitcond44, label %for.end19, label %for.cond4.preheader.lr.ph
> +
> +for.end19: ; preds = %for.cond1.for.inc17_crit_edge, %entry
> + ret void
> +}
> +;; Not tightly nested. Do not interchange.
> +;; Not interchanged hence the phi's in the inner loop will not be split. Check for the same.
> +; CHECK-LABEL: @reduction_03
> +; CHECK: for.body6: ; preds = %for.body6.preheader, %for.body6
> +; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body6 ], [ 1, %for.body6.preheader ]
> +; CHECK: %add31 = phi i32 [ %add, %for.body6 ], [ %X.promoted, %for.body6.preheader ]
> +
> +
> +
> +;; Multiple use of reduction not safe. Do not interchange.
> +;; for( int i=1;i> +;; for( int j=1;j> +;; for( int k=1;k> +;; X+=A[k][j];
> +;; Y+=X;
> +;; }
> +define void @reduction_04(i32 %N) {
> +entry:
> + %cmp28 = icmp sgt i32 %N, 1
> + br i1 %cmp28, label %for.cond4.preheader.preheader, label %for.end15
> +
> +for.cond4.preheader.preheader: ; preds = %entry, %for.inc13
> + %i.029 = phi i32 [ %inc14, %for.inc13 ], [ 1, %entry ]
> + br label %for.body6.lr.ph
> +
> +for.body6.lr.ph: ; preds = %for.cond4.for.inc10_crit_edge, %for.cond4.preheader.preheader
> + %indvars.iv30 = phi i64 [ %indvars.iv.next31, %for.cond4.for.inc10_crit_edge ], [ 1, %for.cond4.preheader.preheader ]
> + %X.promoted = load i32, i32* @X
> + %Y.promoted = load i32, i32* @Y
> + br label %for.body6
> +
> +for.body6: ; preds = %for.body6, %for.body6.lr.ph
> + %indvars.iv = phi i64 [ 1, %for.body6.lr.ph ], [ %indvars.iv.next, %for.body6 ]
> + %add925 = phi i32 [ %Y.promoted, %for.body6.lr.ph ], [ %add9, %for.body6 ]
> + %add24 = phi i32 [ %X.promoted, %for.body6.lr.ph ], [ %add, %for.body6 ]
> + %arrayidx8 = getelementptr inbounds [500 x [500 x i32]], [500 x [500 x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv30
> + %0 = load i32, i32* %arrayidx8
> + %add = add nsw i32 %add24, %0
> + %add9 = add nsw i32 %add925, %add
> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> + %lftr.wideiv = trunc i64 %indvars.iv.next to i32
> + %exitcond = icmp eq i32 %lftr.wideiv, %N
> + br i1 %exitcond, label %for.cond4.for.inc10_crit_edge, label %for.body6
> +
> +for.cond4.for.inc10_crit_edge: ; preds = %for.body6
> + store i32 %add, i32* @X
> + store i32 %add9, i32* @Y
> + %indvars.iv.next31 = add nuw nsw i64 %indvars.iv30, 1
> + %lftr.wideiv32 = trunc i64 %indvars.iv.next31 to i32
> + %exitcond33 = icmp eq i32 %lftr.wideiv32, %N
> + br i1 %exitcond33, label %for.inc13, label %for.body6.lr.ph
> +
> +for.inc13: ; preds = %for.cond4.for.inc10_crit_edge
> + %inc14 = add nuw nsw i32 %i.029, 1
> + %exitcond34 = icmp eq i32 %inc14, %N
> + br i1 %exitcond34, label %for.end15, label %for.cond4.preheader.preheader
> +
> +for.end15: ; preds = %for.inc13, %entry
> + ret void
> +}
> +;; Not interchanged hence the phi's in the inner loop will not be split. Check for the same.
> +; CHECK-LABEL: @reduction_04
> +; CHECK: for.body6: ; preds = %for.body6.preheader, %for.body6
> +; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body6 ], [ 1, %for.body6.preheader ]
> +; CHECK: %add925 = phi i32 [ %add9, %for.body6 ], [ %Y.promoted, %for.body6.preheader ]
>
>
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