From: Erik Eckstein Date: Tue, 13 Jan 2015 11:37:51 +0000 (+0000) Subject: SLPVectorizer: Cache results from memory alias checking. X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=5b23df7cd81cafba2aa0c609dd30731ec1111331;hp=f416c108a1457ea566086278add7b8534bb1f7b5 SLPVectorizer: Cache results from memory alias checking. This speeds up the dependency calculations for blocks with many load/store/call instructions. Beside the improved runtime, there is no functional change. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225786 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Transforms/Vectorize/SLPVectorizer.cpp b/lib/Transforms/Vectorize/SLPVectorizer.cpp index 9281bcb2c51..8fb87b80954 100644 --- a/lib/Transforms/Vectorize/SLPVectorizer.cpp +++ b/lib/Transforms/Vectorize/SLPVectorizer.cpp @@ -19,6 +19,7 @@ #include "llvm/ADT/MapVector.h" #include "llvm/ADT/PostOrderIterator.h" #include "llvm/ADT/SetVector.h" +#include "llvm/ADT/Optional.h" #include "llvm/ADT/Statistic.h" #include "llvm/Analysis/AliasAnalysis.h" #include "llvm/Analysis/AssumptionCache.h" @@ -388,6 +389,15 @@ static bool InTreeUserNeedToExtract(Value *Scalar, Instruction *UserInst, } } +/// \returns the AA location that is being access by the instruction. +static AliasAnalysis::Location getLocation(Instruction *I, AliasAnalysis *AA) { + if (StoreInst *SI = dyn_cast(I)) + return AA->getLocation(SI); + if (LoadInst *LI = dyn_cast(I)) + return AA->getLocation(LI); + return AliasAnalysis::Location(); +} + /// Bottom Up SLP Vectorizer. class BoUpSLP { public: @@ -555,6 +565,35 @@ private: }; typedef SmallVector UserList; + /// Checks if two instructions may access the same memory. + /// + /// \p Loc1 is the location of \p Inst1. It is passed explicitly because it + /// is invariant in the calling loop. + bool isAliased(const AliasAnalysis::Location &Loc1, Instruction *Inst1, + Instruction *Inst2) { + + // First check if the result is already in the cache. + AliasCacheKey key = std::make_pair(Inst1, Inst2); + Optional &result = AliasCache[key]; + if (result.hasValue()) { + return result.getValue(); + } + AliasAnalysis::Location Loc2 = getLocation(Inst2, AA); + bool aliased = true; + if (Loc1.Ptr && Loc2.Ptr) { + // Do the alias check. + aliased = AA->alias(Loc1, Loc2); + } + // Store the result in the cache. + result = aliased; + return aliased; + } + + typedef std::pair AliasCacheKey; + + /// Cache for alias results. + DenseMap> AliasCache; + /// A list of values that need to extracted out of the tree. /// This list holds pairs of (Internal Scalar : External User). UserList ExternalUses; @@ -791,7 +830,7 @@ private: /// Checks if a bundle of instructions can be scheduled, i.e. has no /// cyclic dependencies. This is only a dry-run, no instructions are /// actually moved at this stage. - bool tryScheduleBundle(ArrayRef VL, AliasAnalysis *AA); + bool tryScheduleBundle(ArrayRef VL, BoUpSLP *SLP); /// Un-bundles a group of instructions. void cancelScheduling(ArrayRef VL); @@ -808,7 +847,7 @@ private: /// Updates the dependency information of a bundle and of all instructions/ /// bundles which depend on the original bundle. void calculateDependencies(ScheduleData *SD, bool InsertInReadyList, - AliasAnalysis *AA); + BoUpSLP *SLP); /// Sets all instruction in the scheduling region to un-scheduled. void resetSchedule(); @@ -1069,7 +1108,7 @@ void BoUpSLP::buildTree_rec(ArrayRef VL, unsigned Depth) { } BlockScheduling &BS = *BSRef.get(); - if (!BS.tryScheduleBundle(VL, AA)) { + if (!BS.tryScheduleBundle(VL, this)) { DEBUG(dbgs() << "SLP: We are not able to schedule this bundle!\n"); BS.cancelScheduling(VL); newTreeEntry(VL, false); @@ -2460,7 +2499,7 @@ void BoUpSLP::optimizeGatherSequence() { // Groups the instructions to a bundle (which is then a single scheduling entity) // and schedules instructions until the bundle gets ready. bool BoUpSLP::BlockScheduling::tryScheduleBundle(ArrayRef VL, - AliasAnalysis *AA) { + BoUpSLP *SLP) { if (isa(VL[0])) return true; @@ -2517,7 +2556,7 @@ bool BoUpSLP::BlockScheduling::tryScheduleBundle(ArrayRef VL, DEBUG(dbgs() << "SLP: try schedule bundle " << *Bundle << " in block " << BB->getName() << "\n"); - calculateDependencies(Bundle, true, AA); + calculateDependencies(Bundle, true, SLP); // Now try to schedule the new bundle. As soon as the bundle is "ready" it // means that there are no cyclic dependencies and we can schedule it. @@ -2648,18 +2687,9 @@ void BoUpSLP::BlockScheduling::initScheduleData(Instruction *FromI, } } -/// \returns the AA location that is being access by the instruction. -static AliasAnalysis::Location getLocation(Instruction *I, AliasAnalysis *AA) { - if (StoreInst *SI = dyn_cast(I)) - return AA->getLocation(SI); - if (LoadInst *LI = dyn_cast(I)) - return AA->getLocation(LI); - return AliasAnalysis::Location(); -} - void BoUpSLP::BlockScheduling::calculateDependencies(ScheduleData *SD, bool InsertInReadyList, - AliasAnalysis *AA) { + BoUpSLP *SLP) { assert(SD->isSchedulingEntity()); SmallVector WorkList; @@ -2704,14 +2734,14 @@ void BoUpSLP::BlockScheduling::calculateDependencies(ScheduleData *SD, // Handle the memory dependencies. ScheduleData *DepDest = BundleMember->NextLoadStore; if (DepDest) { - AliasAnalysis::Location SrcLoc = getLocation(BundleMember->Inst, AA); + Instruction *SrcInst = BundleMember->Inst; + AliasAnalysis::Location SrcLoc = getLocation(SrcInst, SLP->AA); bool SrcMayWrite = BundleMember->Inst->mayWriteToMemory(); while (DepDest) { assert(isInSchedulingRegion(DepDest)); if (SrcMayWrite || DepDest->Inst->mayWriteToMemory()) { - AliasAnalysis::Location DstLoc = getLocation(DepDest->Inst, AA); - if (!SrcLoc.Ptr || !DstLoc.Ptr || AA->alias(SrcLoc, DstLoc)) { + if (SLP->isAliased(SrcLoc, SrcInst, DepDest->Inst)) { DepDest->MemoryDependencies.push_back(BundleMember); BundleMember->Dependencies++; ScheduleData *DestBundle = DepDest->FirstInBundle; @@ -2779,7 +2809,7 @@ void BoUpSLP::scheduleBlock(BlockScheduling *BS) { "scheduler and vectorizer have different opinion on what is a bundle"); SD->FirstInBundle->SchedulingPriority = Idx++; if (SD->isSchedulingEntity()) { - BS->calculateDependencies(SD, false, AA); + BS->calculateDependencies(SD, false, this); NumToSchedule++; } }