From 86dbc2b6d32269712b3c777c7f4bacd6c776d6b6 Mon Sep 17 00:00:00 2001 From: Adam Nemet Date: Tue, 10 Mar 2015 18:54:26 +0000 Subject: [PATCH] [LAA-memchecks 3/3] Introduce pointer partitions for memchecks This is the final patch that actually introduces the new parameter of partition mapping to RuntimePointerCheck::needsChecking. Another API (LAI::getInstructionsForAccess) is also exposed that helps to map pointers to instructions because ultimately we partition instructions. The WIP version of the Loop Distribution pass in D6930 has been adapted to use all this. See for example, how InstrPartitionContainer::computePartitionSetForPointers sets up the partitions using the above API and then calls to LAI::addRuntimeCheck with the pointer partitions. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231818 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/LoopAccessAnalysis.h | 32 +++++++++++++-- lib/Analysis/LoopAccessAnalysis.cpp | 46 +++++++++++++++++----- 2 files changed, 65 insertions(+), 13 deletions(-) diff --git a/include/llvm/Analysis/LoopAccessAnalysis.h b/include/llvm/Analysis/LoopAccessAnalysis.h index d188327fbf4..0a9dc07102e 100644 --- a/include/llvm/Analysis/LoopAccessAnalysis.h +++ b/include/llvm/Analysis/LoopAccessAnalysis.h @@ -231,6 +231,10 @@ public: return InstMap; } + /// \brief Find the set of instructions that read or write via \p Ptr. + SmallVector getInstructionsForAccess(Value *Ptr, + bool isWrite) const; + private: ScalarEvolution *SE; const Loop *InnermostLoop; @@ -328,10 +332,20 @@ public: /// \brief Decide whether we need to issue a run-time check for pointer at /// index \p I and \p J to prove their independence. - bool needsChecking(unsigned I, unsigned J) const; + /// + /// If \p PtrPartition is set, it contains the partition number for + /// pointers (-1 if the pointer belongs to multiple partitions). In this + /// case omit checks between pointers belonging to the same partition. + bool needsChecking(unsigned I, unsigned J, + const SmallVectorImpl *PtrPartition) const; /// \brief Print the list run-time memory checks necessary. - void print(raw_ostream &OS, unsigned Depth = 0) const; + /// + /// If \p PtrPartition is set, it contains the partition number for + /// pointers (-1 if the pointer belongs to multiple partitions). In this + /// case omit checks between pointers belonging to the same partition. + void print(raw_ostream &OS, unsigned Depth = 0, + const SmallVectorImpl *PtrPartition = nullptr) const; /// This flag indicates if we need to add the runtime check. bool Need; @@ -383,8 +397,13 @@ public: /// Returns a pair of instructions where the first element is the first /// instruction generated in possibly a sequence of instructions and the /// second value is the final comparator value or NULL if no check is needed. + /// + /// If \p PtrPartition is set, it contains the partition number for pointers + /// (-1 if the pointer belongs to multiple partitions). In this case omit + /// checks between pointers belonging to the same partition. std::pair - addRuntimeCheck(Instruction *Loc) const; + addRuntimeCheck(Instruction *Loc, + const SmallVectorImpl *PtrPartition = nullptr) const; /// \brief The diagnostics report generated for the analysis. E.g. why we /// couldn't analyze the loop. @@ -394,6 +413,13 @@ public: /// loop-independent and loop-carried dependences between memory accesses. const MemoryDepChecker &getDepChecker() const { return DepChecker; } + /// \brief Return the list of instructions that use \p Ptr to read or write + /// memory. + SmallVector getInstructionsForAccess(Value *Ptr, + bool isWrite) const { + return DepChecker.getInstructionsForAccess(Ptr, isWrite); + } + /// \brief Print the information about the memory accesses in the loop. void print(raw_ostream &OS, unsigned Depth = 0) const; diff --git a/lib/Analysis/LoopAccessAnalysis.cpp b/lib/Analysis/LoopAccessAnalysis.cpp index d044bb008e9..4bedccf8d01 100644 --- a/lib/Analysis/LoopAccessAnalysis.cpp +++ b/lib/Analysis/LoopAccessAnalysis.cpp @@ -127,8 +127,8 @@ void LoopAccessInfo::RuntimePointerCheck::insert( AliasSetId.push_back(ASId); } -bool LoopAccessInfo::RuntimePointerCheck::needsChecking(unsigned I, - unsigned J) const { +bool LoopAccessInfo::RuntimePointerCheck::needsChecking( + unsigned I, unsigned J, const SmallVectorImpl *PtrPartition) const { // No need to check if two readonly pointers intersect. if (!IsWritePtr[I] && !IsWritePtr[J]) return false; @@ -141,11 +141,19 @@ bool LoopAccessInfo::RuntimePointerCheck::needsChecking(unsigned I, if (AliasSetId[I] != AliasSetId[J]) return false; + // If PtrPartition is set omit checks between pointers of the same partition. + // Partition number -1 means that the pointer is used in multiple partitions. + // In this case we can't omit the check. + if (PtrPartition && (*PtrPartition)[I] != -1 && + (*PtrPartition)[I] == (*PtrPartition)[J]) + return false; + return true; } -void LoopAccessInfo::RuntimePointerCheck::print(raw_ostream &OS, - unsigned Depth) const { +void LoopAccessInfo::RuntimePointerCheck::print( + raw_ostream &OS, unsigned Depth, + const SmallVectorImpl *PtrPartition) const { unsigned NumPointers = Pointers.size(); if (NumPointers == 0) return; @@ -154,10 +162,16 @@ void LoopAccessInfo::RuntimePointerCheck::print(raw_ostream &OS, unsigned N = 0; for (unsigned I = 0; I < NumPointers; ++I) for (unsigned J = I + 1; J < NumPointers; ++J) - if (needsChecking(I, J)) { + if (needsChecking(I, J, PtrPartition)) { OS.indent(Depth) << N++ << ":\n"; - OS.indent(Depth + 2) << *Pointers[I] << "\n"; - OS.indent(Depth + 2) << *Pointers[J] << "\n"; + OS.indent(Depth + 2) << *Pointers[I]; + if (PtrPartition) + OS << " (Partition: " << (*PtrPartition)[I] << ")"; + OS << "\n"; + OS.indent(Depth + 2) << *Pointers[J]; + if (PtrPartition) + OS << " (Partition: " << (*PtrPartition)[J] << ")"; + OS << "\n"; } } @@ -835,6 +849,18 @@ bool MemoryDepChecker::areDepsSafe(DepCandidates &AccessSets, return SafeForVectorization; } +SmallVector +MemoryDepChecker::getInstructionsForAccess(Value *Ptr, bool isWrite) const { + MemAccessInfo Access(Ptr, isWrite); + auto &IndexVector = Accesses.find(Access)->second; + + SmallVector Insts; + std::transform(IndexVector.begin(), IndexVector.end(), + std::back_inserter(Insts), + [&](unsigned Idx) { return this->InstMap[Idx]; }); + return Insts; +} + const char *MemoryDepChecker::Dependence::DepName[] = { "NoDep", "Unknown", "Forward", "ForwardButPreventsForwarding", "Backward", "BackwardVectorizable", "BackwardVectorizableButPreventsForwarding"}; @@ -1169,8 +1195,8 @@ static Instruction *getFirstInst(Instruction *FirstInst, Value *V, return nullptr; } -std::pair -LoopAccessInfo::addRuntimeCheck(Instruction *Loc) const { +std::pair LoopAccessInfo::addRuntimeCheck( + Instruction *Loc, const SmallVectorImpl *PtrPartition) const { Instruction *tnullptr = nullptr; if (!PtrRtCheck.Need) return std::pair(tnullptr, tnullptr); @@ -1211,7 +1237,7 @@ LoopAccessInfo::addRuntimeCheck(Instruction *Loc) const { Value *MemoryRuntimeCheck = nullptr; for (unsigned i = 0; i < NumPointers; ++i) { for (unsigned j = i+1; j < NumPointers; ++j) { - if (!PtrRtCheck.needsChecking(i, j)) + if (!PtrRtCheck.needsChecking(i, j, PtrPartition)) continue; unsigned AS0 = Starts[i]->getType()->getPointerAddressSpace();