[llvm] [DependenceAnalysis] Extending SIV to handle fusable loops (PR #128782)
Alireza Torabian via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 24 09:57:22 PDT 2025
https://github.com/1997alireza updated https://github.com/llvm/llvm-project/pull/128782
>From 151bc5e99a79351afad5e1f1a871ede8475271b5 Mon Sep 17 00:00:00 2001
From: Alireza Torabian <alireza.torabian at huawei.com>
Date: Mon, 24 Feb 2025 11:53:53 -0500
Subject: [PATCH 1/2] [DependenceAnalysis] Extending SIV to handle fusable
loops
When there is a dependency between two memory instructions in separate
fusable loops, SIV will be able to test them and compute the direction
and the distance of the dependency. Two loop levels are considered
fusable if they have the same tripcount and depth.
---
.../llvm/Analysis/DependenceAnalysis.h | 213 +++++---
llvm/lib/Analysis/DependenceAnalysis.cpp | 474 +++++++++++-------
.../DependenceAnalysis/SIVFusableLoops.ll | 145 ++++++
3 files changed, 595 insertions(+), 237 deletions(-)
create mode 100644 llvm/test/Analysis/DependenceAnalysis/SIVFusableLoops.ll
diff --git a/llvm/include/llvm/Analysis/DependenceAnalysis.h b/llvm/include/llvm/Analysis/DependenceAnalysis.h
index f98bd684149f9..73a3a528909db 100644
--- a/llvm/include/llvm/Analysis/DependenceAnalysis.h
+++ b/llvm/include/llvm/Analysis/DependenceAnalysis.h
@@ -82,6 +82,17 @@ namespace llvm {
/// Dependence::DVEntry - Each level in the distance/direction vector
/// has a direction (or perhaps a union of several directions), and
/// perhaps a distance.
+ /// The dependency information could be across a single loop level or across
+ /// two separate levels that are candidates for fusion. Two levels are
+ /// considered fusable if they can be interpreted as a single fused loop,
+ /// i.e., have the same trip count and the same nesting depth.
+ /// For example, loops b and c are similar and considered as fusable loops:
+ /// for (a = ...) {
+ /// for (b = 0; b < 10; b++) {
+ /// }
+ /// for (c = 0; c < 10; c++) {
+ /// }
+ /// }
struct DVEntry {
enum : unsigned char {
NONE = 0,
@@ -153,13 +164,26 @@ namespace llvm {
/// source and destination of the dependence.
virtual unsigned getLevels() const { return 0; }
+ /// getFusableLevels - Returns the number of fusable loops surrounding
+ /// the source and destination of the dependence.
+ virtual unsigned getFusableLevels() const { return 0; }
+
+ /// getDVEntry - Returns the DV entry associated with a regular or a
+ /// fusable level
+ DVEntry getDVEntry(unsigned Level, bool Fusable) const;
+
/// getDirection - Returns the direction associated with a particular
- /// level.
- virtual unsigned getDirection(unsigned Level) const { return DVEntry::ALL; }
+ /// common or fusable level.
+ virtual unsigned getDirection(unsigned Level, bool Fusable = false) const {
+ return DVEntry::ALL;
+ }
/// getDistance - Returns the distance (or NULL) associated with a
- /// particular level.
- virtual const SCEV *getDistance(unsigned Level) const { return nullptr; }
+ /// particular common or fusable level.
+ virtual const SCEV *getDistance(unsigned Level,
+ bool Fusable = false) const {
+ return nullptr;
+ }
/// Check if the direction vector is negative. A negative direction
/// vector means Src and Dst are reversed in the actual program.
@@ -172,21 +196,32 @@ namespace llvm {
virtual bool normalize(ScalarEvolution *SE) { return false; }
/// isPeelFirst - Returns true if peeling the first iteration from
- /// this loop will break this dependence.
- virtual bool isPeelFirst(unsigned Level) const { return false; }
+ /// this regular or fusable loop level will break this dependence.
+ virtual bool isPeelFirst(unsigned Level, bool Fusable = false) const {
+ return false;
+ }
/// isPeelLast - Returns true if peeling the last iteration from
- /// this loop will break this dependence.
- virtual bool isPeelLast(unsigned Level) const { return false; }
+ /// this regular or fusable loop level will break this dependence.
+ virtual bool isPeelLast(unsigned Level, bool Fusable = false) const {
+ return false;
+ }
- /// isSplitable - Returns true if splitting this loop will break
+ /// isSplitable - Returns true if splitting the loop will break
/// the dependence.
- virtual bool isSplitable(unsigned Level) const { return false; }
+ virtual bool isSplitable(unsigned Level, bool Fusable = false) const {
+ return false;
+ }
+
+ /// inFusableLoops - Returns true if this level is a fusable level, i.e.,
+ /// performed across two separate loop nests that are treated like a single
+ /// fused loop.
+ virtual bool inFusableLoops(unsigned Level) const { return false; }
- /// isScalar - Returns true if a particular level is scalar; that is,
- /// if no subscript in the source or destination mention the induction
- /// variable associated with the loop at this level.
- virtual bool isScalar(unsigned Level) const;
+ /// isScalar - Returns true if a particular regular or fusable level is
+ /// scalar; that is, if no subscript in the source or destination mention
+ /// the induction variable associated with the loop at this level.
+ virtual bool isScalar(unsigned Level, bool Fusable = false) const;
/// getNextPredecessor - Returns the value of the NextPredecessor
/// field.
@@ -212,6 +247,10 @@ namespace llvm {
///
void dump(raw_ostream &OS) const;
+ /// dumpImp - For debugging purposes. Dumps a dependence to OS with or
+ /// without considering the fusable levels.
+ void dumpImp(raw_ostream &OS, bool Fusable = false) const;
+
protected:
Instruction *Src, *Dst;
@@ -252,13 +291,31 @@ namespace llvm {
/// source and destination of the dependence.
unsigned getLevels() const override { return Levels; }
+ /// getFusableLevels - Returns the number of fusable loops surrounding
+ /// the source and destination of the dependence.
+ unsigned getFusableLevels() const override { return FusableLevels; }
+
+ /// getDVEntry - Returns the DV entry associated with a regular or a
+ /// fusable level
+ DVEntry getDVEntry(unsigned Level, bool Fusable) const {
+ if (!Fusable) {
+ assert(0 < Level && Level <= Levels && "Level out of range");
+ return DV[Level - 1];
+ } else {
+ assert(Levels < Level && Level <= Levels + FusableLevels &&
+ "Fusable level out of range");
+ return DVFusable[Level - Levels - 1];
+ }
+ }
+
/// getDirection - Returns the direction associated with a particular
- /// level.
- unsigned getDirection(unsigned Level) const override;
+ /// common or fusable level.
+ unsigned getDirection(unsigned Level, bool Fusable = false) const override;
/// getDistance - Returns the distance (or NULL) associated with a
- /// particular level.
- const SCEV *getDistance(unsigned Level) const override;
+ /// particular common or fusable level.
+ const SCEV *getDistance(unsigned Level,
+ bool Fusable = false) const override;
/// Check if the direction vector is negative. A negative direction
/// vector means Src and Dst are reversed in the actual program.
@@ -271,27 +328,34 @@ namespace llvm {
bool normalize(ScalarEvolution *SE) override;
/// isPeelFirst - Returns true if peeling the first iteration from
- /// this loop will break this dependence.
- bool isPeelFirst(unsigned Level) const override;
+ /// this regular or fusable loop level will break this dependence.
+ bool isPeelFirst(unsigned Level, bool Fusable = false) const override;
/// isPeelLast - Returns true if peeling the last iteration from
- /// this loop will break this dependence.
- bool isPeelLast(unsigned Level) const override;
+ /// this regular or fusable loop level will break this dependence.
+ bool isPeelLast(unsigned Level, bool Fusable = false) const override;
/// isSplitable - Returns true if splitting the loop will break
/// the dependence.
- bool isSplitable(unsigned Level) const override;
+ bool isSplitable(unsigned Level, bool Fusable = false) const override;
- /// isScalar - Returns true if a particular level is scalar; that is,
- /// if no subscript in the source or destination mention the induction
- /// variable associated with the loop at this level.
- bool isScalar(unsigned Level) const override;
+ /// inFusableLoops - Returns true if this level is a fusable level, i.e.,
+ /// performed across two fusable loop nests that are treated like a single
+ /// fused loop.
+ bool inFusableLoops(unsigned Level) const override;
+
+ /// isScalar - Returns true if a particular regular or fusable level is
+ /// scalar; that is, if no subscript in the source or destination mention
+ /// the induction variable associated with the loop at this level.
+ bool isScalar(unsigned Level, bool Fusable = false) const override;
private:
unsigned short Levels;
+ unsigned short FusableLevels;
bool LoopIndependent;
bool Consistent; // Init to true, then refine.
std::unique_ptr<DVEntry[]> DV;
+ std::unique_ptr<DVEntry[]> DVFusable;
friend class DependenceInfo;
};
@@ -423,7 +487,8 @@ namespace llvm {
const SCEV *A;
const SCEV *B;
const SCEV *C;
- const Loop *AssociatedLoop;
+ const Loop *AssociatedSrcLoop;
+ const Loop *AssociatedDstLoop;
public:
/// isEmpty - Return true if the constraint is of kind Empty.
@@ -467,19 +532,27 @@ namespace llvm {
/// Otherwise assert.
LLVM_ABI const SCEV *getD() const;
- /// getAssociatedLoop - Returns the loop associated with this constraint.
- LLVM_ABI const Loop *getAssociatedLoop() const;
+ /// getAssociatedSrcLoop - Returns the source loop associated with this
+ /// constraint.
+ LLVM_ABI const Loop *getAssociatedSrcLoop() const;
+
+ /// getAssociatedDstLoop - Returns the destination loop associated with
+ /// this constraint.
+ LLVM_ABI const Loop *getAssociatedDstLoop() const;
/// setPoint - Change a constraint to Point.
LLVM_ABI void setPoint(const SCEV *X, const SCEV *Y,
- const Loop *CurrentLoop);
+ const Loop *CurrentSrcLoop,
+ const Loop *CurrentDstLoop);
/// setLine - Change a constraint to Line.
LLVM_ABI void setLine(const SCEV *A, const SCEV *B, const SCEV *C,
- const Loop *CurrentLoop);
+ const Loop *CurrentSrcLoop,
+ const Loop *CurrentDstLoop);
/// setDistance - Change a constraint to Distance.
- LLVM_ABI void setDistance(const SCEV *D, const Loop *CurrentLoop);
+ LLVM_ABI void setDistance(const SCEV *D, const Loop *CurrentSrcLoop,
+ const Loop *CurrentDstLoop);
/// setEmpty - Change a constraint to Empty.
LLVM_ABI void setEmpty();
@@ -492,6 +565,10 @@ namespace llvm {
LLVM_ABI void dump(raw_ostream &OS) const;
};
+ /// Returns true if two loops are the same or they have the same tripcount
+ /// and depth
+ bool areLoopsSimilar(const Loop *SrcLoop, const Loop *DstLoop) const;
+
/// establishNestingLevels - Examines the loop nesting of the Src and Dst
/// instructions and establishes their shared loops. Sets the variables
/// CommonLevels, SrcLevels, and MaxLevels.
@@ -542,10 +619,23 @@ namespace llvm {
/// e - 5
/// f - 6
/// g - 7 = MaxLevels
- void establishNestingLevels(const Instruction *Src,
- const Instruction *Dst);
-
- unsigned CommonLevels, SrcLevels, MaxLevels;
+ /// FusableLevels counts the number of levels after common levels that are
+ /// not common but are similar, meaning that they have the same tripcount
+ /// and depth. Assume that in this code fragment, levels c and e are
+ /// similar. In this case only the loop nests at the next level after
+ /// common levels are similar, and FusableLevels is set to 1.
+ /// If there are similar loop nests, we could use the APIs with considering
+ /// them as fused loops. In that case the level numbers for the previous
+ /// code look like
+ /// a - 1
+ /// b - 2
+ /// c,e - 3 = CommonLevels
+ /// d - 4 = SrcLevels
+ /// f - 5
+ /// g - 6 = MaxLevels
+ void establishNestingLevels(const Instruction *Src, const Instruction *Dst);
+
+ unsigned CommonLevels, SrcLevels, MaxLevels, FusableLevels;
/// mapSrcLoop - Given one of the loops containing the source, return
/// its level index in our numbering scheme.
@@ -684,13 +774,10 @@ namespace llvm {
/// Returns true if any possible dependence is disproved.
/// If there might be a dependence, returns false.
/// Sets appropriate direction and distance.
- bool strongSIVtest(const SCEV *Coeff,
- const SCEV *SrcConst,
- const SCEV *DstConst,
- const Loop *CurrentLoop,
- unsigned Level,
- FullDependence &Result,
- Constraint &NewConstraint) const;
+ bool strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
+ const SCEV *DstConst, const Loop *CurrentSrcLoop,
+ const Loop *CurrentDstLoop, unsigned Level,
+ FullDependence &Result, Constraint &NewConstraint) const;
/// weakCrossingSIVtest - Tests the weak-crossing SIV subscript pair
/// (Src and Dst) for dependence.
@@ -702,13 +789,10 @@ namespace llvm {
/// Sets appropriate direction entry.
/// Set consistent to false.
/// Marks the dependence as splitable.
- bool weakCrossingSIVtest(const SCEV *SrcCoeff,
- const SCEV *SrcConst,
- const SCEV *DstConst,
- const Loop *CurrentLoop,
- unsigned Level,
- FullDependence &Result,
- Constraint &NewConstraint,
+ bool weakCrossingSIVtest(const SCEV *SrcCoeff, const SCEV *SrcConst,
+ const SCEV *DstConst, const Loop *CurrentSrcLoop,
+ const Loop *CurrentDstLoop, unsigned Level,
+ FullDependence &Result, Constraint &NewConstraint,
const SCEV *&SplitIter) const;
/// ExactSIVtest - Tests the SIV subscript pair
@@ -720,13 +804,10 @@ namespace llvm {
/// If there might be a dependence, returns false.
/// Sets appropriate direction entry.
/// Set consistent to false.
- bool exactSIVtest(const SCEV *SrcCoeff,
- const SCEV *DstCoeff,
- const SCEV *SrcConst,
- const SCEV *DstConst,
- const Loop *CurrentLoop,
- unsigned Level,
- FullDependence &Result,
+ bool exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
+ const SCEV *SrcConst, const SCEV *DstConst,
+ const Loop *CurrentSrcLoop, const Loop *CurrentDstLoop,
+ unsigned Level, FullDependence &Result,
Constraint &NewConstraint) const;
/// weakZeroSrcSIVtest - Tests the weak-zero SIV subscript pair
@@ -739,11 +820,9 @@ namespace llvm {
/// Sets appropriate direction entry.
/// Set consistent to false.
/// If loop peeling will break the dependence, mark appropriately.
- bool weakZeroSrcSIVtest(const SCEV *DstCoeff,
- const SCEV *SrcConst,
- const SCEV *DstConst,
- const Loop *CurrentLoop,
- unsigned Level,
+ bool weakZeroSrcSIVtest(const SCEV *DstCoeff, const SCEV *SrcConst,
+ const SCEV *DstConst, const Loop *CurrentSrcLoop,
+ const Loop *CurrentDstLoop, unsigned Level,
FullDependence &Result,
Constraint &NewConstraint) const;
@@ -757,11 +836,9 @@ namespace llvm {
/// Sets appropriate direction entry.
/// Set consistent to false.
/// If loop peeling will break the dependence, mark appropriately.
- bool weakZeroDstSIVtest(const SCEV *SrcCoeff,
- const SCEV *SrcConst,
- const SCEV *DstConst,
- const Loop *CurrentLoop,
- unsigned Level,
+ bool weakZeroDstSIVtest(const SCEV *SrcCoeff, const SCEV *SrcConst,
+ const SCEV *DstConst, const Loop *CurrentSrcLoop,
+ const Loop *CurrentDstLoop, unsigned Level,
FullDependence &Result,
Constraint &NewConstraint) const;
diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index dd9a44b9aecac..042f5b83800f5 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -104,6 +104,7 @@ STATISTIC(GCDindependence, "GCD independence");
STATISTIC(BanerjeeApplications, "Banerjee applications");
STATISTIC(BanerjeeIndependence, "Banerjee independence");
STATISTIC(BanerjeeSuccesses, "Banerjee successes");
+STATISTIC(FusableLoopsConsidered, "Fusable loops considered");
static cl::opt<bool>
Delinearize("da-delinearize", cl::init(true), cl::Hidden,
@@ -272,10 +273,7 @@ bool Dependence::isAnti() const {
// if no subscript in the source or destination mention the induction
// variable associated with the loop at this level.
// Leave this out of line, so it will serve as a virtual method anchor
-bool Dependence::isScalar(unsigned level) const {
- return false;
-}
-
+bool Dependence::isScalar(unsigned level, bool Fusable) const { return false; }
//===----------------------------------------------------------------------===//
// FullDependence methods
@@ -287,6 +285,7 @@ FullDependence::FullDependence(Instruction *Source, Instruction *Destination,
: Dependence(Source, Destination, Assumes), Levels(CommonLevels),
LoopIndependent(PossiblyLoopIndependent) {
Consistent = true;
+ FusableLevels = 0;
if (CommonLevels)
DV = std::make_unique<DVEntry[]>(CommonLevels);
}
@@ -349,51 +348,49 @@ bool FullDependence::normalize(ScalarEvolution *SE) {
// The rest are simple getters that hide the implementation.
-// getDirection - Returns the direction associated with a particular level.
-unsigned FullDependence::getDirection(unsigned Level) const {
- assert(0 < Level && Level <= Levels && "Level out of range");
- return DV[Level - 1].Direction;
+// getDirection - Returns the direction associated with a particular common or
+// fusable level.
+unsigned FullDependence::getDirection(unsigned Level, bool Fusable) const {
+ return getDVEntry(Level, Fusable).Direction;
}
-
-// Returns the distance (or NULL) associated with a particular level.
-const SCEV *FullDependence::getDistance(unsigned Level) const {
- assert(0 < Level && Level <= Levels && "Level out of range");
- return DV[Level - 1].Distance;
+// Returns the distance (or NULL) associated with a particular common or
+// fusable level.
+const SCEV *FullDependence::getDistance(unsigned Level, bool Fusable) const {
+ return getDVEntry(Level, Fusable).Distance;
}
-
-// Returns true if a particular level is scalar; that is,
-// if no subscript in the source or destination mention the induction
-// variable associated with the loop at this level.
-bool FullDependence::isScalar(unsigned Level) const {
- assert(0 < Level && Level <= Levels && "Level out of range");
- return DV[Level - 1].Scalar;
+// Returns true if a particular regular or fusable level is scalar; that is,
+// if no subscript in the source or destination mention the induction variable
+// associated with the loop at this level.
+bool FullDependence::isScalar(unsigned Level, bool Fusable) const {
+ return getDVEntry(Level, Fusable).Scalar;
}
-
-// Returns true if peeling the first iteration from this loop
-// will break this dependence.
-bool FullDependence::isPeelFirst(unsigned Level) const {
- assert(0 < Level && Level <= Levels && "Level out of range");
- return DV[Level - 1].PeelFirst;
+// Returns true if peeling the first iteration from this regular or fusable
+// loop level will break this dependence.
+bool FullDependence::isPeelFirst(unsigned Level, bool Fusable) const {
+ return getDVEntry(Level, Fusable).PeelFirst;
}
-
-// Returns true if peeling the last iteration from this loop
-// will break this dependence.
-bool FullDependence::isPeelLast(unsigned Level) const {
- assert(0 < Level && Level <= Levels && "Level out of range");
- return DV[Level - 1].PeelLast;
+// Returns true if peeling the last iteration from this regular or fusable
+// loop level will break this dependence.
+bool FullDependence::isPeelLast(unsigned Level, bool Fusable) const {
+ return getDVEntry(Level, Fusable).PeelLast;
}
-
-// Returns true if splitting this loop will break the dependence.
-bool FullDependence::isSplitable(unsigned Level) const {
- assert(0 < Level && Level <= Levels && "Level out of range");
- return DV[Level - 1].Splitable;
+// Returns true if splitting loop will break the dependence.
+bool FullDependence::isSplitable(unsigned Level, bool Fusable) const {
+ return getDVEntry(Level, Fusable).Splitable;
}
+// inFusableLoops - Returns true if this level is a fusable level, i.e.,
+// performed across two separate loop nests that are treated like a single
+// fused loop.
+bool FullDependence::inFusableLoops(unsigned Level) const {
+ assert(0 < Level && Level <= Levels + FusableLevels && "Level out of range");
+ return Level > Levels;
+}
//===----------------------------------------------------------------------===//
// DependenceInfo::Constraint methods
@@ -448,38 +445,50 @@ const SCEV *DependenceInfo::Constraint::getD() const {
return SE->getNegativeSCEV(C);
}
+// Returns the source loop associated with this constraint.
+const Loop *DependenceInfo::Constraint::getAssociatedSrcLoop() const {
+ assert((Kind == Distance || Kind == Line || Kind == Point) &&
+ "Kind should be Distance, Line, or Point");
+ return AssociatedSrcLoop;
+}
-// Returns the loop associated with this constraint.
-const Loop *DependenceInfo::Constraint::getAssociatedLoop() const {
+// Returns the destination loop associated with this constraint.
+const Loop *DependenceInfo::Constraint::getAssociatedDstLoop() const {
assert((Kind == Distance || Kind == Line || Kind == Point) &&
"Kind should be Distance, Line, or Point");
- return AssociatedLoop;
+ return AssociatedDstLoop;
}
void DependenceInfo::Constraint::setPoint(const SCEV *X, const SCEV *Y,
- const Loop *CurLoop) {
+ const Loop *CurSrcLoop,
+ const Loop *CurDstLoop) {
Kind = Point;
A = X;
B = Y;
- AssociatedLoop = CurLoop;
+ AssociatedSrcLoop = CurSrcLoop;
+ AssociatedDstLoop = CurDstLoop;
}
void DependenceInfo::Constraint::setLine(const SCEV *AA, const SCEV *BB,
- const SCEV *CC, const Loop *CurLoop) {
+ const SCEV *CC, const Loop *CurSrcLoop,
+ const Loop *CurDstLoop) {
Kind = Line;
A = AA;
B = BB;
C = CC;
- AssociatedLoop = CurLoop;
+ AssociatedSrcLoop = CurSrcLoop;
+ AssociatedDstLoop = CurDstLoop;
}
void DependenceInfo::Constraint::setDistance(const SCEV *D,
- const Loop *CurLoop) {
+ const Loop *CurSrcLoop,
+ const Loop *CurDstLoop) {
Kind = Distance;
A = SE->getOne(D->getType());
B = SE->getNegativeSCEV(A);
C = SE->getNegativeSCEV(D);
- AssociatedLoop = CurLoop;
+ AssociatedSrcLoop = CurSrcLoop;
+ AssociatedDstLoop = CurDstLoop;
}
void DependenceInfo::Constraint::setEmpty() { Kind = Empty; }
@@ -626,8 +635,8 @@ bool DependenceInfo::intersectConstraints(Constraint *X, const Constraint *Y) {
++DeltaSuccesses;
return true;
}
- if (const SCEVConstant *CUB =
- collectConstantUpperBound(X->getAssociatedLoop(), Prod1->getType())) {
+ if (const SCEVConstant *CUB = collectConstantUpperBound(
+ X->getAssociatedSrcLoop(), Prod1->getType())) {
const APInt &UpperBound = CUB->getAPInt();
LLVM_DEBUG(dbgs() << "\t\tupper bound = " << UpperBound << "\n");
if (Xq.sgt(UpperBound) || Yq.sgt(UpperBound)) {
@@ -636,9 +645,8 @@ bool DependenceInfo::intersectConstraints(Constraint *X, const Constraint *Y) {
return true;
}
}
- X->setPoint(SE->getConstant(Xq),
- SE->getConstant(Yq),
- X->getAssociatedLoop());
+ X->setPoint(SE->getConstant(Xq), SE->getConstant(Yq),
+ X->getAssociatedSrcLoop(), X->getAssociatedDstLoop());
++DeltaSuccesses;
return true;
}
@@ -673,7 +681,6 @@ bool DependenceInfo::intersectConstraints(Constraint *X, const Constraint *Y) {
// For debugging purposes. Dumps a dependence to OS.
void Dependence::dump(raw_ostream &OS) const {
- bool Splitable = false;
if (isConfused())
OS << "confused";
else {
@@ -687,41 +694,12 @@ void Dependence::dump(raw_ostream &OS) const {
OS << "anti";
else if (isInput())
OS << "input";
- unsigned Levels = getLevels();
- OS << " [";
- for (unsigned II = 1; II <= Levels; ++II) {
- if (isSplitable(II))
- Splitable = true;
- if (isPeelFirst(II))
- OS << 'p';
- const SCEV *Distance = getDistance(II);
- if (Distance)
- OS << *Distance;
- else if (isScalar(II))
- OS << "S";
- else {
- unsigned Direction = getDirection(II);
- if (Direction == DVEntry::ALL)
- OS << "*";
- else {
- if (Direction & DVEntry::LT)
- OS << "<";
- if (Direction & DVEntry::EQ)
- OS << "=";
- if (Direction & DVEntry::GT)
- OS << ">";
- }
- }
- if (isPeelLast(II))
- OS << 'p';
- if (II < Levels)
- OS << " ";
+ dumpImp(OS);
+ unsigned FusableLevels = getFusableLevels();
+ if (FusableLevels > 0) {
+ OS << "! / assuming " << FusableLevels << " fused loop(s): ";
+ dumpImp(OS, true);
}
- if (isLoopIndependent())
- OS << "|<";
- OS << "]";
- if (Splitable)
- OS << " splitable";
}
OS << "!\n";
@@ -732,6 +710,54 @@ void Dependence::dump(raw_ostream &OS) const {
}
}
+// For debugging purposes. Dumps a dependence to OS with or without considering
+// the fusable levels.
+void Dependence::dumpImp(raw_ostream &OS, bool Fusable) const {
+ bool Splitable = false;
+ unsigned Levels = getLevels();
+ unsigned FusableLevels = getFusableLevels();
+ bool OnFusable = false;
+ unsigned LevelNum = Levels;
+ if (Fusable)
+ LevelNum += FusableLevels;
+ OS << " [";
+ for (unsigned II = 1; II <= LevelNum; ++II) {
+ if (!OnFusable && inFusableLoops(II))
+ OnFusable = true;
+ if (isSplitable(II, OnFusable))
+ Splitable = true;
+ if (isPeelFirst(II, OnFusable))
+ OS << 'p';
+ const SCEV *Distance = getDistance(II, OnFusable);
+ if (Distance)
+ OS << *Distance;
+ else if (isScalar(II, OnFusable))
+ OS << "S";
+ else {
+ unsigned Direction = getDirection(II, OnFusable);
+ if (Direction == DVEntry::ALL)
+ OS << "*";
+ else {
+ if (Direction & DVEntry::LT)
+ OS << "<";
+ if (Direction & DVEntry::EQ)
+ OS << "=";
+ if (Direction & DVEntry::GT)
+ OS << ">";
+ }
+ }
+ if (isPeelLast(II, OnFusable))
+ OS << 'p';
+ if (II < LevelNum)
+ OS << " ";
+ }
+ if (isLoopIndependent())
+ OS << "|<";
+ OS << "]";
+ if (Splitable)
+ OS << " splitable";
+}
+
// Returns NoAlias/MayAliass/MustAlias for two memory locations based upon their
// underlaying objects. If LocA and LocB are known to not alias (for any reason:
// tbaa, non-overlapping regions etc), then it is known there is no dependecy.
@@ -782,6 +808,34 @@ bool isLoadOrStore(const Instruction *I) {
return false;
}
+// Returns true if two loops are the same or they have the same tripcount and
+// depth
+bool DependenceInfo::areLoopsSimilar(const Loop *SrcLoop,
+ const Loop *DstLoop) const {
+ if (SrcLoop == DstLoop)
+ return true;
+
+ if (SrcLoop->getLoopDepth() != DstLoop->getLoopDepth())
+ return false;
+
+ if (!SrcLoop || !SrcLoop->getLoopLatch() || !DstLoop ||
+ !DstLoop->getLoopLatch())
+ return false;
+
+ const SCEV *SrcUB, *DstUP;
+ if (SE->hasLoopInvariantBackedgeTakenCount(SrcLoop))
+ SrcUB = SE->getBackedgeTakenCount(SrcLoop);
+ if (SE->hasLoopInvariantBackedgeTakenCount(DstLoop))
+ DstUP = SE->getBackedgeTakenCount(DstLoop);
+
+ if (SrcUB == nullptr || DstUP == nullptr)
+ return false;
+
+ if (SE->isKnownPredicate(ICmpInst::ICMP_EQ, SrcUB, DstUP))
+ return true;
+
+ return false;
+}
// Examines the loop nesting of the Src and Dst
// instructions and establishes their shared loops. Sets the variables
@@ -833,6 +887,20 @@ bool isLoadOrStore(const Instruction *I) {
// e - 5
// f - 6
// g - 7 = MaxLevels
+// FusableLevels counts the number of levels after common levels that are
+// not common but are similar, meaning that they have the same tripcount
+// and depth. Assume that in this code fragment, levels c and e are
+// similar. In this case only the loop nests at the next level after
+// common levels are similar, and FusableLevels is set to 1.
+// If there are similar loop nests, we could use the APIs with considering them
+// as fused loops. In that case the level numbers for the previous code look
+// like
+// a - 1
+// b - 2
+// c,e - 3 = CommonLevels
+// d - 4 = SrcLevels
+// f - 5
+// g - 6 = MaxLevels
void DependenceInfo::establishNestingLevels(const Instruction *Src,
const Instruction *Dst) {
const BasicBlock *SrcBlock = Src->getParent();
@@ -843,6 +911,7 @@ void DependenceInfo::establishNestingLevels(const Instruction *Src,
const Loop *DstLoop = LI->getLoopFor(DstBlock);
SrcLevels = SrcLevel;
MaxLevels = SrcLevel + DstLevel;
+ FusableLevels = 0;
while (SrcLevel > DstLevel) {
SrcLoop = SrcLoop->getParentLoop();
SrcLevel--;
@@ -851,7 +920,12 @@ void DependenceInfo::establishNestingLevels(const Instruction *Src,
DstLoop = DstLoop->getParentLoop();
DstLevel--;
}
+
+ // find the first common level and count the fusable levels leading to it
while (SrcLoop != DstLoop) {
+ FusableLevels++;
+ if (!areLoopsSimilar(SrcLoop, DstLoop))
+ FusableLevels = 0;
SrcLoop = SrcLoop->getParentLoop();
DstLoop = DstLoop->getParentLoop();
SrcLevel--;
@@ -860,7 +934,6 @@ void DependenceInfo::establishNestingLevels(const Instruction *Src,
MaxLevels -= CommonLevels;
}
-
// Given one of the loops containing the source, return
// its level index in our numbering scheme.
unsigned DependenceInfo::mapSrcLoop(const Loop *SrcLoop) const {
@@ -1247,8 +1320,9 @@ bool DependenceInfo::testZIV(const SCEV *Src, const SCEV *Dst,
//
// Return true if dependence disproved.
bool DependenceInfo::strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
- const SCEV *DstConst, const Loop *CurLoop,
- unsigned Level, FullDependence &Result,
+ const SCEV *DstConst, const Loop *CurSrcLoop,
+ const Loop *CurDstLoop, unsigned Level,
+ FullDependence &Result,
Constraint &NewConstraint) const {
LLVM_DEBUG(dbgs() << "\tStrong SIV test\n");
LLVM_DEBUG(dbgs() << "\t Coeff = " << *Coeff);
@@ -1266,7 +1340,8 @@ bool DependenceInfo::strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
LLVM_DEBUG(dbgs() << ", " << *Delta->getType() << "\n");
// check that |Delta| < iteration count
- if (const SCEV *UpperBound = collectUpperBound(CurLoop, Delta->getType())) {
+ if (const SCEV *UpperBound =
+ collectUpperBound(CurSrcLoop, Delta->getType())) {
LLVM_DEBUG(dbgs() << "\t UpperBound = " << *UpperBound);
LLVM_DEBUG(dbgs() << ", " << *UpperBound->getType() << "\n");
const SCEV *AbsDelta =
@@ -1299,7 +1374,8 @@ bool DependenceInfo::strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
return true;
}
Result.DV[Level].Distance = SE->getConstant(Distance);
- NewConstraint.setDistance(SE->getConstant(Distance), CurLoop);
+ NewConstraint.setDistance(SE->getConstant(Distance), CurSrcLoop,
+ CurDstLoop);
if (Distance.sgt(0))
Result.DV[Level].Direction &= Dependence::DVEntry::LT;
else if (Distance.slt(0))
@@ -1311,7 +1387,7 @@ bool DependenceInfo::strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
else if (Delta->isZero()) {
// since 0/X == 0
Result.DV[Level].Distance = Delta;
- NewConstraint.setDistance(Delta, CurLoop);
+ NewConstraint.setDistance(Delta, CurSrcLoop, CurDstLoop);
Result.DV[Level].Direction &= Dependence::DVEntry::EQ;
++StrongSIVsuccesses;
}
@@ -1319,13 +1395,12 @@ bool DependenceInfo::strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
if (Coeff->isOne()) {
LLVM_DEBUG(dbgs() << "\t Distance = " << *Delta << "\n");
Result.DV[Level].Distance = Delta; // since X/1 == X
- NewConstraint.setDistance(Delta, CurLoop);
+ NewConstraint.setDistance(Delta, CurSrcLoop, CurDstLoop);
}
else {
Result.Consistent = false;
- NewConstraint.setLine(Coeff,
- SE->getNegativeSCEV(Coeff),
- SE->getNegativeSCEV(Delta), CurLoop);
+ NewConstraint.setLine(Coeff, SE->getNegativeSCEV(Coeff),
+ SE->getNegativeSCEV(Delta), CurSrcLoop, CurDstLoop);
}
// maybe we can get a useful direction
@@ -1353,7 +1428,6 @@ bool DependenceInfo::strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
return false;
}
-
// weakCrossingSIVtest -
// From the paper, Practical Dependence Testing, Section 4.2.2
//
@@ -1384,8 +1458,9 @@ bool DependenceInfo::strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
// Return true if dependence disproved.
bool DependenceInfo::weakCrossingSIVtest(
const SCEV *Coeff, const SCEV *SrcConst, const SCEV *DstConst,
- const Loop *CurLoop, unsigned Level, FullDependence &Result,
- Constraint &NewConstraint, const SCEV *&SplitIter) const {
+ const Loop *CurSrcLoop, const Loop *CurDstLoop, unsigned Level,
+ FullDependence &Result, Constraint &NewConstraint,
+ const SCEV *&SplitIter) const {
LLVM_DEBUG(dbgs() << "\tWeak-Crossing SIV test\n");
LLVM_DEBUG(dbgs() << "\t Coeff = " << *Coeff << "\n");
LLVM_DEBUG(dbgs() << "\t SrcConst = " << *SrcConst << "\n");
@@ -1396,7 +1471,7 @@ bool DependenceInfo::weakCrossingSIVtest(
Result.Consistent = false;
const SCEV *Delta = SE->getMinusSCEV(DstConst, SrcConst);
LLVM_DEBUG(dbgs() << "\t Delta = " << *Delta << "\n");
- NewConstraint.setLine(Coeff, Coeff, Delta, CurLoop);
+ NewConstraint.setLine(Coeff, Coeff, Delta, CurSrcLoop, CurDstLoop);
if (Delta->isZero()) {
Result.DV[Level].Direction &= ~Dependence::DVEntry::LT;
Result.DV[Level].Direction &= ~Dependence::DVEntry::GT;
@@ -1444,7 +1519,8 @@ bool DependenceInfo::weakCrossingSIVtest(
// We're certain that Delta > 0 and ConstCoeff > 0.
// Check Delta/(2*ConstCoeff) against upper loop bound
- if (const SCEV *UpperBound = collectUpperBound(CurLoop, Delta->getType())) {
+ if (const SCEV *UpperBound =
+ collectUpperBound(CurSrcLoop, Delta->getType())) {
LLVM_DEBUG(dbgs() << "\t UpperBound = " << *UpperBound << "\n");
const SCEV *ConstantTwo = SE->getConstant(UpperBound->getType(), 2);
const SCEV *ML = SE->getMulExpr(SE->getMulExpr(ConstCoeff, UpperBound),
@@ -1498,7 +1574,6 @@ bool DependenceInfo::weakCrossingSIVtest(
return false;
}
-
// Kirch's algorithm, from
//
// Optimizing Supercompilers for Supercomputers
@@ -1584,7 +1659,8 @@ static APInt ceilingOfQuotient(const APInt &A, const APInt &B) {
// returns all the dependencies that exist between Dst and Src.
bool DependenceInfo::exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
const SCEV *SrcConst, const SCEV *DstConst,
- const Loop *CurLoop, unsigned Level,
+ const Loop *CurSrcLoop,
+ const Loop *CurDstLoop, unsigned Level,
FullDependence &Result,
Constraint &NewConstraint) const {
LLVM_DEBUG(dbgs() << "\tExact SIV test\n");
@@ -1599,7 +1675,7 @@ bool DependenceInfo::exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
const SCEV *Delta = SE->getMinusSCEV(DstConst, SrcConst);
LLVM_DEBUG(dbgs() << "\t Delta = " << *Delta << "\n");
NewConstraint.setLine(SrcCoeff, SE->getNegativeSCEV(DstCoeff), Delta,
- CurLoop);
+ CurSrcLoop, CurDstLoop);
const SCEVConstant *ConstDelta = dyn_cast<SCEVConstant>(Delta);
const SCEVConstant *ConstSrcCoeff = dyn_cast<SCEVConstant>(SrcCoeff);
const SCEVConstant *ConstDstCoeff = dyn_cast<SCEVConstant>(DstCoeff);
@@ -1626,7 +1702,7 @@ bool DependenceInfo::exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
bool UMValid = false;
// UM is perhaps unavailable, let's check
if (const SCEVConstant *CUB =
- collectConstantUpperBound(CurLoop, Delta->getType())) {
+ collectConstantUpperBound(CurSrcLoop, Delta->getType())) {
UM = CUB->getAPInt();
LLVM_DEBUG(dbgs() << "\t UM = " << UM << "\n");
UMValid = true;
@@ -1733,7 +1809,6 @@ bool DependenceInfo::exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
return Result.DV[Level].Direction == Dependence::DVEntry::NONE;
}
-
// Return true if the divisor evenly divides the dividend.
static
bool isRemainderZero(const SCEVConstant *Dividend,
@@ -1778,7 +1853,8 @@ bool isRemainderZero(const SCEVConstant *Dividend,
bool DependenceInfo::weakZeroSrcSIVtest(const SCEV *DstCoeff,
const SCEV *SrcConst,
const SCEV *DstConst,
- const Loop *CurLoop, unsigned Level,
+ const Loop *CurSrcLoop,
+ const Loop *CurDstLoop, unsigned Level,
FullDependence &Result,
Constraint &NewConstraint) const {
// For the WeakSIV test, it's possible the loop isn't common to
@@ -1794,7 +1870,7 @@ bool DependenceInfo::weakZeroSrcSIVtest(const SCEV *DstCoeff,
Result.Consistent = false;
const SCEV *Delta = SE->getMinusSCEV(SrcConst, DstConst);
NewConstraint.setLine(SE->getZero(Delta->getType()), DstCoeff, Delta,
- CurLoop);
+ CurSrcLoop, CurDstLoop);
LLVM_DEBUG(dbgs() << "\t Delta = " << *Delta << "\n");
if (isKnownPredicate(CmpInst::ICMP_EQ, SrcConst, DstConst)) {
if (Level < CommonLevels) {
@@ -1815,7 +1891,8 @@ bool DependenceInfo::weakZeroSrcSIVtest(const SCEV *DstCoeff,
// check that Delta/SrcCoeff < iteration count
// really check NewDelta < count*AbsCoeff
- if (const SCEV *UpperBound = collectUpperBound(CurLoop, Delta->getType())) {
+ if (const SCEV *UpperBound =
+ collectUpperBound(CurSrcLoop, Delta->getType())) {
LLVM_DEBUG(dbgs() << "\t UpperBound = " << *UpperBound << "\n");
const SCEV *Product = SE->getMulExpr(AbsCoeff, UpperBound);
if (isKnownPredicate(CmpInst::ICMP_SGT, NewDelta, Product)) {
@@ -1853,7 +1930,6 @@ bool DependenceInfo::weakZeroSrcSIVtest(const SCEV *DstCoeff,
return false;
}
-
// weakZeroDstSIVtest -
// From the paper, Practical Dependence Testing, Section 4.2.2
//
@@ -1888,7 +1964,8 @@ bool DependenceInfo::weakZeroSrcSIVtest(const SCEV *DstCoeff,
bool DependenceInfo::weakZeroDstSIVtest(const SCEV *SrcCoeff,
const SCEV *SrcConst,
const SCEV *DstConst,
- const Loop *CurLoop, unsigned Level,
+ const Loop *CurSrcLoop,
+ const Loop *CurDstLoop, unsigned Level,
FullDependence &Result,
Constraint &NewConstraint) const {
// For the WeakSIV test, it's possible the loop isn't common to the
@@ -1903,7 +1980,7 @@ bool DependenceInfo::weakZeroDstSIVtest(const SCEV *SrcCoeff,
Result.Consistent = false;
const SCEV *Delta = SE->getMinusSCEV(DstConst, SrcConst);
NewConstraint.setLine(SrcCoeff, SE->getZero(Delta->getType()), Delta,
- CurLoop);
+ CurSrcLoop, CurDstLoop);
LLVM_DEBUG(dbgs() << "\t Delta = " << *Delta << "\n");
if (isKnownPredicate(CmpInst::ICMP_EQ, DstConst, SrcConst)) {
if (Level < CommonLevels) {
@@ -1924,7 +2001,8 @@ bool DependenceInfo::weakZeroDstSIVtest(const SCEV *SrcCoeff,
// check that Delta/SrcCoeff < iteration count
// really check NewDelta < count*AbsCoeff
- if (const SCEV *UpperBound = collectUpperBound(CurLoop, Delta->getType())) {
+ if (const SCEV *UpperBound =
+ collectUpperBound(CurSrcLoop, Delta->getType())) {
LLVM_DEBUG(dbgs() << "\t UpperBound = " << *UpperBound << "\n");
const SCEV *Product = SE->getMulExpr(AbsCoeff, UpperBound);
if (isKnownPredicate(CmpInst::ICMP_SGT, NewDelta, Product)) {
@@ -2254,43 +2332,47 @@ bool DependenceInfo::testSIV(const SCEV *Src, const SCEV *Dst, unsigned &Level,
const SCEV *DstConst = DstAddRec->getStart();
const SCEV *SrcCoeff = SrcAddRec->getStepRecurrence(*SE);
const SCEV *DstCoeff = DstAddRec->getStepRecurrence(*SE);
- const Loop *CurLoop = SrcAddRec->getLoop();
- assert(CurLoop == DstAddRec->getLoop() &&
- "both loops in SIV should be same");
- Level = mapSrcLoop(CurLoop);
+ const Loop *CurSrcLoop = SrcAddRec->getLoop();
+ const Loop *CurDstLoop = DstAddRec->getLoop();
+ assert(areLoopsSimilar(CurSrcLoop, CurDstLoop) &&
+ "both loops in SIV should be the same or have the same tripcount "
+ "and depth");
+ Level = mapSrcLoop(CurSrcLoop);
bool disproven;
if (SrcCoeff == DstCoeff)
- disproven = strongSIVtest(SrcCoeff, SrcConst, DstConst, CurLoop,
- Level, Result, NewConstraint);
+ disproven = strongSIVtest(SrcCoeff, SrcConst, DstConst, CurSrcLoop,
+ CurDstLoop, Level, Result, NewConstraint);
else if (SrcCoeff == SE->getNegativeSCEV(DstCoeff))
- disproven = weakCrossingSIVtest(SrcCoeff, SrcConst, DstConst, CurLoop,
- Level, Result, NewConstraint, SplitIter);
+ disproven = weakCrossingSIVtest(SrcCoeff, SrcConst, DstConst, CurSrcLoop,
+ CurDstLoop, Level, Result, NewConstraint,
+ SplitIter);
else
- disproven = exactSIVtest(SrcCoeff, DstCoeff, SrcConst, DstConst, CurLoop,
- Level, Result, NewConstraint);
- return disproven ||
- gcdMIVtest(Src, Dst, Result) ||
- symbolicRDIVtest(SrcCoeff, DstCoeff, SrcConst, DstConst, CurLoop, CurLoop);
+ disproven =
+ exactSIVtest(SrcCoeff, DstCoeff, SrcConst, DstConst, CurSrcLoop,
+ CurDstLoop, Level, Result, NewConstraint);
+ return disproven || gcdMIVtest(Src, Dst, Result) ||
+ symbolicRDIVtest(SrcCoeff, DstCoeff, SrcConst, DstConst, CurSrcLoop,
+ CurDstLoop);
}
if (SrcAddRec) {
const SCEV *SrcConst = SrcAddRec->getStart();
const SCEV *SrcCoeff = SrcAddRec->getStepRecurrence(*SE);
const SCEV *DstConst = Dst;
- const Loop *CurLoop = SrcAddRec->getLoop();
- Level = mapSrcLoop(CurLoop);
- return weakZeroDstSIVtest(SrcCoeff, SrcConst, DstConst, CurLoop,
- Level, Result, NewConstraint) ||
- gcdMIVtest(Src, Dst, Result);
+ const Loop *CurSrcLoop = SrcAddRec->getLoop();
+ Level = mapSrcLoop(CurSrcLoop);
+ return weakZeroDstSIVtest(SrcCoeff, SrcConst, DstConst, CurSrcLoop,
+ CurSrcLoop, Level, Result, NewConstraint) ||
+ gcdMIVtest(Src, Dst, Result);
}
if (DstAddRec) {
const SCEV *DstConst = DstAddRec->getStart();
const SCEV *DstCoeff = DstAddRec->getStepRecurrence(*SE);
const SCEV *SrcConst = Src;
- const Loop *CurLoop = DstAddRec->getLoop();
- Level = mapDstLoop(CurLoop);
- return weakZeroSrcSIVtest(DstCoeff, SrcConst, DstConst,
- CurLoop, Level, Result, NewConstraint) ||
- gcdMIVtest(Src, Dst, Result);
+ const Loop *CurDstLoop = DstAddRec->getLoop();
+ Level = mapDstLoop(CurDstLoop);
+ return weakZeroSrcSIVtest(DstCoeff, SrcConst, DstConst, CurDstLoop,
+ CurDstLoop, Level, Result, NewConstraint) ||
+ gcdMIVtest(Src, Dst, Result);
}
llvm_unreachable("SIV test expected at least one AddRec");
return false;
@@ -3187,19 +3269,20 @@ bool DependenceInfo::propagate(const SCEV *&Src, const SCEV *&Dst,
bool DependenceInfo::propagateDistance(const SCEV *&Src, const SCEV *&Dst,
Constraint &CurConstraint,
bool &Consistent) {
- const Loop *CurLoop = CurConstraint.getAssociatedLoop();
+ const Loop *CurSrcLoop = CurConstraint.getAssociatedSrcLoop();
+ const Loop *CurDstLoop = CurConstraint.getAssociatedDstLoop();
LLVM_DEBUG(dbgs() << "\t\tSrc is " << *Src << "\n");
- const SCEV *A_K = findCoefficient(Src, CurLoop);
+ const SCEV *A_K = findCoefficient(Src, CurSrcLoop);
if (A_K->isZero())
return false;
const SCEV *DA_K = SE->getMulExpr(A_K, CurConstraint.getD());
Src = SE->getMinusSCEV(Src, DA_K);
- Src = zeroCoefficient(Src, CurLoop);
+ Src = zeroCoefficient(Src, CurSrcLoop);
LLVM_DEBUG(dbgs() << "\t\tnew Src is " << *Src << "\n");
LLVM_DEBUG(dbgs() << "\t\tDst is " << *Dst << "\n");
- Dst = addToCoefficient(Dst, CurLoop, SE->getNegativeSCEV(A_K));
+ Dst = addToCoefficient(Dst, CurDstLoop, SE->getNegativeSCEV(A_K));
LLVM_DEBUG(dbgs() << "\t\tnew Dst is " << *Dst << "\n");
- if (!findCoefficient(Dst, CurLoop)->isZero())
+ if (!findCoefficient(Dst, CurDstLoop)->isZero())
Consistent = false;
return true;
}
@@ -3213,7 +3296,8 @@ bool DependenceInfo::propagateDistance(const SCEV *&Src, const SCEV *&Dst,
bool DependenceInfo::propagateLine(const SCEV *&Src, const SCEV *&Dst,
Constraint &CurConstraint,
bool &Consistent) {
- const Loop *CurLoop = CurConstraint.getAssociatedLoop();
+ const Loop *CurSrcLoop = CurConstraint.getAssociatedSrcLoop();
+ const Loop *CurDstLoop = CurConstraint.getAssociatedDstLoop();
const SCEV *A = CurConstraint.getA();
const SCEV *B = CurConstraint.getB();
const SCEV *C = CurConstraint.getC();
@@ -3229,11 +3313,11 @@ bool DependenceInfo::propagateLine(const SCEV *&Src, const SCEV *&Dst,
APInt Charlie = Cconst->getAPInt();
APInt CdivB = Charlie.sdiv(Beta);
assert(Charlie.srem(Beta) == 0 && "C should be evenly divisible by B");
- const SCEV *AP_K = findCoefficient(Dst, CurLoop);
+ const SCEV *AP_K = findCoefficient(Dst, CurDstLoop);
// Src = SE->getAddExpr(Src, SE->getMulExpr(AP_K, SE->getConstant(CdivB)));
Src = SE->getMinusSCEV(Src, SE->getMulExpr(AP_K, SE->getConstant(CdivB)));
- Dst = zeroCoefficient(Dst, CurLoop);
- if (!findCoefficient(Src, CurLoop)->isZero())
+ Dst = zeroCoefficient(Dst, CurDstLoop);
+ if (!findCoefficient(Src, CurSrcLoop)->isZero())
Consistent = false;
}
else if (B->isZero()) {
@@ -3244,10 +3328,10 @@ bool DependenceInfo::propagateLine(const SCEV *&Src, const SCEV *&Dst,
APInt Charlie = Cconst->getAPInt();
APInt CdivA = Charlie.sdiv(Alpha);
assert(Charlie.srem(Alpha) == 0 && "C should be evenly divisible by A");
- const SCEV *A_K = findCoefficient(Src, CurLoop);
+ const SCEV *A_K = findCoefficient(Src, CurSrcLoop);
Src = SE->getAddExpr(Src, SE->getMulExpr(A_K, SE->getConstant(CdivA)));
- Src = zeroCoefficient(Src, CurLoop);
- if (!findCoefficient(Dst, CurLoop)->isZero())
+ Src = zeroCoefficient(Src, CurSrcLoop);
+ if (!findCoefficient(Dst, CurDstLoop)->isZero())
Consistent = false;
}
else if (isKnownPredicate(CmpInst::ICMP_EQ, A, B)) {
@@ -3258,22 +3342,22 @@ bool DependenceInfo::propagateLine(const SCEV *&Src, const SCEV *&Dst,
APInt Charlie = Cconst->getAPInt();
APInt CdivA = Charlie.sdiv(Alpha);
assert(Charlie.srem(Alpha) == 0 && "C should be evenly divisible by A");
- const SCEV *A_K = findCoefficient(Src, CurLoop);
+ const SCEV *A_K = findCoefficient(Src, CurSrcLoop);
Src = SE->getAddExpr(Src, SE->getMulExpr(A_K, SE->getConstant(CdivA)));
- Src = zeroCoefficient(Src, CurLoop);
- Dst = addToCoefficient(Dst, CurLoop, A_K);
- if (!findCoefficient(Dst, CurLoop)->isZero())
+ Src = zeroCoefficient(Src, CurSrcLoop);
+ Dst = addToCoefficient(Dst, CurDstLoop, A_K);
+ if (!findCoefficient(Dst, CurDstLoop)->isZero())
Consistent = false;
}
else {
// paper is incorrect here, or perhaps just misleading
- const SCEV *A_K = findCoefficient(Src, CurLoop);
+ const SCEV *A_K = findCoefficient(Src, CurSrcLoop);
Src = SE->getMulExpr(Src, A);
Dst = SE->getMulExpr(Dst, A);
Src = SE->getAddExpr(Src, SE->getMulExpr(A_K, C));
- Src = zeroCoefficient(Src, CurLoop);
- Dst = addToCoefficient(Dst, CurLoop, SE->getMulExpr(A_K, B));
- if (!findCoefficient(Dst, CurLoop)->isZero())
+ Src = zeroCoefficient(Src, CurSrcLoop);
+ Dst = addToCoefficient(Dst, CurDstLoop, SE->getMulExpr(A_K, B));
+ if (!findCoefficient(Dst, CurDstLoop)->isZero())
Consistent = false;
}
LLVM_DEBUG(dbgs() << "\t\tnew Src = " << *Src << "\n");
@@ -3287,17 +3371,18 @@ bool DependenceInfo::propagateLine(const SCEV *&Src, const SCEV *&Dst,
// Return true if some simplification occurs.
bool DependenceInfo::propagatePoint(const SCEV *&Src, const SCEV *&Dst,
Constraint &CurConstraint) {
- const Loop *CurLoop = CurConstraint.getAssociatedLoop();
- const SCEV *A_K = findCoefficient(Src, CurLoop);
- const SCEV *AP_K = findCoefficient(Dst, CurLoop);
+ const Loop *CurSrcLoop = CurConstraint.getAssociatedSrcLoop();
+ const Loop *CurDstLoop = CurConstraint.getAssociatedDstLoop();
+ const SCEV *A_K = findCoefficient(Src, CurSrcLoop);
+ const SCEV *AP_K = findCoefficient(Dst, CurDstLoop);
const SCEV *XA_K = SE->getMulExpr(A_K, CurConstraint.getX());
const SCEV *YAP_K = SE->getMulExpr(AP_K, CurConstraint.getY());
LLVM_DEBUG(dbgs() << "\t\tSrc is " << *Src << "\n");
Src = SE->getAddExpr(Src, SE->getMinusSCEV(XA_K, YAP_K));
- Src = zeroCoefficient(Src, CurLoop);
+ Src = zeroCoefficient(Src, CurSrcLoop);
LLVM_DEBUG(dbgs() << "\t\tnew Src is " << *Src << "\n");
LLVM_DEBUG(dbgs() << "\t\tDst is " << *Dst << "\n");
- Dst = zeroCoefficient(Dst, CurLoop);
+ Dst = zeroCoefficient(Dst, CurDstLoop);
LLVM_DEBUG(dbgs() << "\t\tnew Dst is " << *Dst << "\n");
return true;
}
@@ -3694,14 +3779,6 @@ DependenceInfo::depends(Instruction *Src, Instruction *Dst,
}
}
- establishNestingLevels(Src, Dst);
- LLVM_DEBUG(dbgs() << " common nesting levels = " << CommonLevels << "\n");
- LLVM_DEBUG(dbgs() << " maximum nesting levels = " << MaxLevels << "\n");
-
- FullDependence Result(Src, Dst, SCEVUnionPredicate(Assume, *SE),
- PossiblyLoopIndependent, CommonLevels);
- ++TotalArrayPairs;
-
unsigned Pairs = 1;
SmallVector<Subscript, 2> Pair(Pairs);
Pair[0].Src = SrcSCEV;
@@ -3714,6 +3791,46 @@ DependenceInfo::depends(Instruction *Src, Instruction *Dst,
}
}
+ // Establish loop nesting levels considering fusable loops as common
+ establishNestingLevels(Src, Dst);
+
+ LLVM_DEBUG(dbgs() << " common nesting levels = " << CommonLevels << "\n");
+ LLVM_DEBUG(dbgs() << " maximum nesting levels = " << MaxLevels << "\n");
+ LLVM_DEBUG(dbgs() << " fusable nesting levels = " << FusableLevels
+ << "\n");
+
+ // Modify common levels to consider the fusable levels in the tests
+ CommonLevels += FusableLevels;
+ MaxLevels -= FusableLevels;
+ if (FusableLevels > 0) {
+ // Not all tests are handled yet over fusable loops
+ // Revoke if there are any tests other than ZIV, SIV or RDIV
+ for (unsigned P = 0; P < Pairs; ++P) {
+ Pair[P].Loops.resize(MaxLevels + 1);
+ Subscript::ClassificationKind TestClass = classifyPair(
+ Pair[P].Src, LI->getLoopFor(Src->getParent()), Pair[P].Dst,
+ LI->getLoopFor(Dst->getParent()), Pair[P].Loops);
+
+ if (TestClass != Subscript::ZIV && TestClass != Subscript::SIV &&
+ TestClass != Subscript::RDIV) {
+ // Revert the levels to not consider the fusable levels
+ CommonLevels -= FusableLevels;
+ MaxLevels += FusableLevels;
+ FusableLevels = 0;
+ break;
+ }
+ }
+ }
+
+ FullDependence Result(Src, Dst, SCEVUnionPredicate(Assume, *SE),
+ PossiblyLoopIndependent, CommonLevels);
+ ++TotalArrayPairs;
+
+ if (FusableLevels > 0) {
+ Result.Consistent = false;
+ FusableLoopsConsidered++;
+ }
+
for (unsigned P = 0; P < Pairs; ++P) {
Pair[P].Loops.resize(MaxLevels + 1);
Pair[P].GroupLoops.resize(MaxLevels + 1);
@@ -4025,6 +4142,25 @@ DependenceInfo::depends(Instruction *Src, Instruction *Dst,
#endif
}
+ if (FusableLevels > 0) {
+ // Extracting fusable levels from the common levels
+ // Reverting CommonLevels and MaxLevels to their original values
+ assert(CommonLevels >= FusableLevels);
+ CommonLevels -= FusableLevels;
+ MaxLevels += FusableLevels;
+ std::unique_ptr<FullDependence::DVEntry[]> DV, DVFusable;
+ DV = std::make_unique<FullDependence::DVEntry[]>(CommonLevels);
+ DVFusable = std::make_unique<FullDependence::DVEntry[]>(FusableLevels);
+ for (unsigned level = 0; level < CommonLevels; ++level)
+ DV[level] = Result.DV[level];
+ for (unsigned level = 0; level < FusableLevels; ++level)
+ DVFusable[level] = Result.DV[CommonLevels + level];
+ Result.DV = std::move(DV);
+ Result.DVFusable = std::move(DVFusable);
+ Result.Levels = CommonLevels;
+ Result.FusableLevels = FusableLevels;
+ }
+
if (PossiblyLoopIndependent) {
// Make sure the LoopIndependent flag is set correctly.
// All directions must include equal, otherwise no
diff --git a/llvm/test/Analysis/DependenceAnalysis/SIVFusableLoops.ll b/llvm/test/Analysis/DependenceAnalysis/SIVFusableLoops.ll
new file mode 100644
index 0000000000000..8bc248372a690
--- /dev/null
+++ b/llvm/test/Analysis/DependenceAnalysis/SIVFusableLoops.ll
@@ -0,0 +1,145 @@
+; RUN: opt < %s -disable-output "-passes=print<da>" -aa-pipeline=basic-aa 2>&1 \
+; RUN: -da-disable-delinearization-checks | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.6.0"
+
+;; for (long int i = 0; i < n; i++) {
+;; for (long int j = 0; j < n; j++) {
+;; for (long int k = 0; k < n; k++) {
+;; for (long int l = 0; l < n; l++)
+;; A[i][j][k][l] = i;
+;; }
+;; for (long int k = 1; k < n+1; k++) {
+;; for (long int l = 0; l < n; l++)
+;; *B++ = A[i + 4][j + 3][k + 2][l + 1];
+
+define void @SIVFusable(i64 %n, ptr %A, ptr %B) nounwind uwtable ssp {
+entry:
+ %cmp10 = icmp sgt i64 %n, 0
+ br i1 %cmp10, label %for.cond1.preheader.preheader, label %for.end35
+
+; CHECK-LABEL: SIVFusable
+; CHECK: da analyze - none!
+; CHECK: da analyze - flow [-4 -3]! / assuming 2 fused loop(s): [-4 -3 -3 -1]!
+; CHECK: da analyze - confused!
+; CHECK: da analyze - none!
+; CHECK: da analyze - confused!
+; CHECK: da analyze - output [* * * *]!
+
+for.cond1.preheader.preheader: ; preds = %entry
+ br label %for.cond1.preheader
+
+for.cond1.preheader: ; preds = %for.cond1.preheader.preheader, %for.inc33
+ %B.addr.014 = phi ptr [ %B.addr.1.lcssa, %for.inc33 ], [ %B, %for.cond1.preheader.preheader ]
+ %i.013 = phi i64 [ %inc34, %for.inc33 ], [ 0, %for.cond1.preheader.preheader ]
+ %cmp28 = icmp sgt i64 %n, 0
+ br i1 %cmp28, label %for.cond4.preheader.preheader, label %for.inc33
+
+for.cond4.preheader.preheader: ; preds = %for.cond1.preheader
+ br label %for.cond4.preheader
+
+for.cond4.preheader: ; preds = %for.cond4.preheader.preheader, %for.inc30
+ %B.addr.110 = phi ptr [ %B.addr.2.lcssa, %for.inc30 ], [ %B.addr.014, %for.cond4.preheader.preheader ]
+ %j.09 = phi i64 [ %inc31, %for.inc30 ], [ 0, %for.cond4.preheader.preheader ]
+ %cmp53 = icmp sgt i64 %n, 0
+ br i1 %cmp53, label %for.cond7.preheader.preheader, label %for.cond15.loopexit
+
+for.cond7.preheader.preheader: ; preds = %for.cond4.preheader
+ br label %for.cond7.preheader
+
+for.cond7.preheader: ; preds = %for.cond7.preheader.preheader, %for.inc12
+ %k.07 = phi i64 [ %inc13, %for.inc12 ], [ 0, %for.cond7.preheader.preheader ]
+ %cmp81 = icmp sgt i64 %n, 0
+ br i1 %cmp81, label %for.body9.preheader, label %for.inc12
+
+for.body9.preheader: ; preds = %for.cond7.preheader
+ br label %for.body9
+
+for.body9: ; preds = %for.body9.preheader, %for.body9
+ %l.02 = phi i64 [ %inc11, %for.body9 ], [ 0, %for.body9.preheader ]
+ %arrayidx12 = getelementptr inbounds [100 x [100 x [100 x i64]]], ptr %A, i64 %i.013, i64 %j.09, i64 %k.07, i64 %l.02
+ store i64 %i.013, ptr %arrayidx12, align 8
+ %inc11 = add nsw i64 %l.02, 1
+ %exitcond15 = icmp ne i64 %inc11, %n
+ br i1 %exitcond15, label %for.body9, label %for.inc12.loopexit
+
+for.inc12.loopexit: ; preds = %for.body9
+ br label %for.inc12
+
+for.inc12: ; preds = %for.inc12.loopexit, %for.cond7.preheader
+ %inc13 = add nsw i64 %k.07, 1
+ %exitcond16 = icmp ne i64 %inc13, %n
+ br i1 %exitcond16, label %for.cond7.preheader, label %for.cond15.loopexit.loopexit
+
+for.cond15.loopexit.loopexit: ; preds = %for.inc12
+ br label %for.cond15.loopexit
+
+for.cond15.loopexit: ; preds = %for.cond15.loopexit.loopexit, %for.cond4.preheader
+ %cmp163 = icmp sgt i64 %n, 0
+ br i1 %cmp163, label %for.cond18.preheader.preheader, label %for.inc30
+
+for.cond18.preheader.preheader: ; preds = %for.cond15.loopexit
+ br label %for.cond18.preheader
+
+for.cond18.preheader: ; preds = %for.cond18.preheader.preheader, %for.inc27
+ %k14.06 = phi i64 [ %inc28, %for.inc27 ], [ 1, %for.cond18.preheader.preheader ]
+ %B.addr.25 = phi ptr [ %B.addr.3.lcssa, %for.inc27 ], [ %B.addr.110, %for.cond18.preheader.preheader ]
+ %cmp191 = icmp sgt i64 %n, 0
+ br i1 %cmp191, label %for.body20.preheader, label %for.inc27
+
+for.body20.preheader: ; preds = %for.cond18.preheader
+ br label %for.body20
+
+for.body20: ; preds = %for.body20.preheader, %for.body20
+ %l17.04 = phi i64 [ %inc25, %for.body20 ], [ 0, %for.body20.preheader ]
+ %B.addr.34 = phi ptr [ %incdec.ptr, %for.body20 ], [ %B.addr.25, %for.body20.preheader ]
+ %add = add nsw i64 %l17.04, 1
+ %add21 = add nsw i64 %k14.06, 2
+ %add22 = add nsw i64 %j.09, 3
+ %add23 = add nsw i64 %i.013, 4
+ %arrayidx24 = getelementptr inbounds [100 x [100 x [100 x i64]]], ptr %A, i64 %add23, i64 %add22, i64 %add21, i64 %add
+ %0 = load i64, ptr %arrayidx24, align 8
+ %incdec.ptr = getelementptr inbounds i64, ptr %B.addr.34, i64 1
+ store i64 %0, ptr %B.addr.34, align 8
+ %inc25 = add nsw i64 %l17.04, 1
+ %exitcond = icmp ne i64 %inc25, %n
+ br i1 %exitcond, label %for.body20, label %for.inc27.loopexit
+
+for.inc27.loopexit: ; preds = %for.body20
+ %scevgep = getelementptr i64, ptr %B.addr.25, i64 %n
+ br label %for.inc27
+
+for.inc27: ; preds = %for.inc27.loopexit, %for.cond18.preheader
+ %B.addr.3.lcssa = phi ptr [ %B.addr.25, %for.cond18.preheader ], [ %scevgep, %for.inc27.loopexit ]
+ %inc28 = add nsw i64 %k14.06, 1
+ %inc29 = add nsw i64 %n, 1
+ %exitcond17 = icmp ne i64 %inc28, %inc29
+ br i1 %exitcond17, label %for.cond18.preheader, label %for.inc30.loopexit
+
+for.inc30.loopexit: ; preds = %for.inc27
+ %B.addr.3.lcssa.lcssa = phi ptr [ %B.addr.3.lcssa, %for.inc27 ]
+ br label %for.inc30
+
+for.inc30: ; preds = %for.inc30.loopexit, %for.cond15.loopexit
+ %B.addr.2.lcssa = phi ptr [ %B.addr.110, %for.cond15.loopexit ], [ %B.addr.3.lcssa.lcssa, %for.inc30.loopexit ]
+ %inc31 = add nsw i64 %j.09, 1
+ %exitcond18 = icmp ne i64 %inc31, %n
+ br i1 %exitcond18, label %for.cond4.preheader, label %for.inc33.loopexit
+
+for.inc33.loopexit: ; preds = %for.inc30
+ %B.addr.2.lcssa.lcssa = phi ptr [ %B.addr.2.lcssa, %for.inc30 ]
+ br label %for.inc33
+
+for.inc33: ; preds = %for.inc33.loopexit, %for.cond1.preheader
+ %B.addr.1.lcssa = phi ptr [ %B.addr.014, %for.cond1.preheader ], [ %B.addr.2.lcssa.lcssa, %for.inc33.loopexit ]
+ %inc34 = add nsw i64 %i.013, 1
+ %exitcond19 = icmp ne i64 %inc34, %n
+ br i1 %exitcond19, label %for.cond1.preheader, label %for.end35.loopexit
+
+for.end35.loopexit: ; preds = %for.inc33
+ br label %for.end35
+
+for.end35: ; preds = %for.end35.loopexit, %entry
+ ret void
+}
>From 3b2e4167c928c2ccf9bddef0eaabf2c0982b5403 Mon Sep 17 00:00:00 2001
From: Alireza Torabian <alireza.torabian at huawei.com>
Date: Thu, 29 May 2025 13:56:18 -0400
Subject: [PATCH 2/2] [NFC] Applying clang-format
---
.../llvm/Analysis/DependenceAnalysis.h | 4 ++--
llvm/lib/Analysis/DependenceAnalysis.cpp | 23 +++++++------------
2 files changed, 10 insertions(+), 17 deletions(-)
diff --git a/llvm/include/llvm/Analysis/DependenceAnalysis.h b/llvm/include/llvm/Analysis/DependenceAnalysis.h
index 73a3a528909db..0022967d5c9e3 100644
--- a/llvm/include/llvm/Analysis/DependenceAnalysis.h
+++ b/llvm/include/llvm/Analysis/DependenceAnalysis.h
@@ -580,8 +580,8 @@ namespace llvm {
/// This lets us allocate vectors MaxLevels in length, with room for every
/// distinct loop referenced in both the source and destination subscripts.
/// The variable SrcLevels is the nesting depth of the source instruction.
- /// It's used to help calculate distinct loops referenced by the destination.
- /// Here's the map from loops to levels:
+ /// It's used to help calculate distinct loops referenced by the
+ /// destination. Here's the map from loops to levels:
/// 0 - unused
/// 1 - outermost common loop
/// ... - other common loops
diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index 042f5b83800f5..07f112f65fa45 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -1850,13 +1850,10 @@ bool isRemainderZero(const SCEVConstant *Dividend,
// (see also weakZeroDstSIVtest)
//
// Return true if dependence disproved.
-bool DependenceInfo::weakZeroSrcSIVtest(const SCEV *DstCoeff,
- const SCEV *SrcConst,
- const SCEV *DstConst,
- const Loop *CurSrcLoop,
- const Loop *CurDstLoop, unsigned Level,
- FullDependence &Result,
- Constraint &NewConstraint) const {
+bool DependenceInfo::weakZeroSrcSIVtest(
+ const SCEV *DstCoeff, const SCEV *SrcConst, const SCEV *DstConst,
+ const Loop *CurSrcLoop, const Loop *CurDstLoop, unsigned Level,
+ FullDependence &Result, Constraint &NewConstraint) const {
// For the WeakSIV test, it's possible the loop isn't common to
// the Src and Dst loops. If it isn't, then there's no need to
// record a direction.
@@ -1961,13 +1958,10 @@ bool DependenceInfo::weakZeroSrcSIVtest(const SCEV *DstCoeff,
// (see also weakZeroSrcSIVtest)
//
// Return true if dependence disproved.
-bool DependenceInfo::weakZeroDstSIVtest(const SCEV *SrcCoeff,
- const SCEV *SrcConst,
- const SCEV *DstConst,
- const Loop *CurSrcLoop,
- const Loop *CurDstLoop, unsigned Level,
- FullDependence &Result,
- Constraint &NewConstraint) const {
+bool DependenceInfo::weakZeroDstSIVtest(
+ const SCEV *SrcCoeff, const SCEV *SrcConst, const SCEV *DstConst,
+ const Loop *CurSrcLoop, const Loop *CurDstLoop, unsigned Level,
+ FullDependence &Result, Constraint &NewConstraint) const {
// For the WeakSIV test, it's possible the loop isn't common to the
// Src and Dst loops. If it isn't, then there's no need to record a direction.
LLVM_DEBUG(dbgs() << "\tWeak-Zero (dst) SIV test\n");
@@ -2040,7 +2034,6 @@ bool DependenceInfo::weakZeroDstSIVtest(const SCEV *SrcCoeff,
return false;
}
-
// exactRDIVtest - Tests the RDIV subscript pair for dependence.
// Things of the form [c1 + a*i] and [c2 + b*j],
// where i and j are induction variable, c1 and c2 are loop invariant,
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