LLVM: slpvectorizer::BoUpSLP::LookAheadHeuristics Class Reference (original) (raw)

A helper class used for scoring candidates for two consecutive lanes. More...

Public Member Functions
LookAheadHeuristics (const TargetLibraryInfo &TLI, const DataLayout &DL, ScalarEvolution &SE, const BoUpSLP &R, int NumLanes, int MaxLevel)
int getShallowScore (Value *V1, Value *V2, Instruction *U1, Instruction *U2, ArrayRef< Value * > MainAltOps) const
int getScoreAtLevelRec (Value *LHS, Value *RHS, Instruction *U1, Instruction *U2, int CurrLevel, ArrayRef< Value * > MainAltOps) const
Go through the operands of LHS and RHS recursively until MaxLevel, and return the cummulative score.
Static Public Attributes
static const int ScoreConsecutiveLoads = 4
Loads from consecutive memory addresses, e.g. load(A[i]), load(A[i+1]).
static const int ScoreSplatLoads = 3
The same load multiple times.
static const int ScoreReversedLoads = 3
Loads from reversed memory addresses, e.g. load(A[i+1]), load(A[i]).
static const int ScoreMaskedGatherCandidate = 1
A load candidate for masked gather.
static const int ScoreConsecutiveExtracts = 4
ExtractElementInst from same vector and consecutive indexes.
static const int ScoreReversedExtracts = 3
ExtractElementInst from same vector and reversed indices.
static const int ScoreConstants = 2
Constants.
static const int ScoreSameOpcode = 2
Instructions with the same opcode.
static const int ScoreAltOpcodes = 1
Instructions with alt opcodes (e.g, add + sub).
static const int ScoreSplat = 1
Identical instructions (a.k.a. splat or broadcast).
static const int ScoreUndef = 1
Matching with an undef is preferable to failing.
static const int ScoreFail = 0
Score for failing to find a decent match.
static const int ScoreAllUserVectorized = 1
Score if all users are vectorized.

A helper class used for scoring candidates for two consecutive lanes.

Definition at line 2371 of file SLPVectorizer.cpp.

◆ getScoreAtLevelRec()

Go through the operands of LHS and RHS recursively until MaxLevel, and return the cummulative score.

U1 and U2 are the users of LHS and RHS (that is LHS and RHS are operands of U1 and U2), except at the beginning of the recursion where these are set to nullptr.

For example:

/// A[0] B[0] A[1] B[1] C[0] D[0] B[1] A[1] /// \ / \ / \ / \ / /// + + + + /// G1 G2 G3 G4 ///

The getScoreAtLevelRec(G1, G2) function will try to match the nodes at each level recursively, accumulating the score. It starts from matching the additions at level 0, then moves on to the loads (level 1). The score of G1 and G2 is higher than G1 and G3, because {A[0],A[1]} and {B[0],B[1]} match with LookAheadHeuristics::ScoreConsecutiveLoads, while {A[0],C[0]} has a score of LookAheadHeuristics::ScoreFail. Please note that the order of the operands does not matter, as we evaluate the score of all profitable combinations of operands. In other words the score of G1 and G4 is the same as G1 and G2. This heuristic is based on ideas described in: Look-ahead SLP: Auto-vectorization in the presence of commutative operations, CGO 2018 by Vasileios Porpodas, Rodrigo C. O. Rocha, Luís F. W. Góes

Definition at line 2612 of file SLPVectorizer.cpp.

References assert(), llvm::SmallSet< T, N, C >::count(), llvm::dyn_cast(), getScoreAtLevelRec(), getShallowScore(), llvm::SmallSet< T, N, C >::insert(), llvm::isa(), isCommutative(), and ScoreFail.

Referenced by slpvectorizer::BoUpSLP::findBestRootPair(), and getScoreAtLevelRec().

◆ getShallowScore()

Returns

the score of placing V1 and V2 in consecutive lanes. U1 and U2 are the users of V1 and V2. Also, checks if V1 and V2 are compatible with instructions in MainAltOps.

Definition at line 2431 of file SLPVectorizer.cpp.

References AbstractManglingParser< Derived, Alloc >::Ops, llvm::all_of(), llvm::any_of(), llvm::cast(), llvm::dyn_cast(), llvm::ArrayRef< T >::empty(), llvm::from_range, llvm::ElementCount::getFixed(), llvm::getPointersDiff(), getSameOpcode(), llvm::Value::getType(), llvm::getUnderlyingObject(), getWidenedType(), llvm::ConstantInt::getZExtValue(), llvm::Value::hasNUsesOrMore(), llvm::isa(), isUndefVector(), isValidElementType(), llvm::PatternMatch::m_CombineOr(), llvm::PatternMatch::m_ConstantInt(), llvm::PatternMatch::m_ExtractElt(), llvm::PatternMatch::m_Undef(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), ScoreAltOpcodes, ScoreConsecutiveExtracts, ScoreConsecutiveLoads, ScoreConstants, ScoreFail, ScoreMaskedGatherCandidate, ScoreReversedExtracts, ScoreReversedLoads, ScoreSameOpcode, ScoreSplat, ScoreSplatLoads, ScoreUndef, and UsesLimit.

Referenced by getScoreAtLevelRec().

◆ ScoreAllUserVectorized

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreAllUserVectorized = 1 static

◆ ScoreAltOpcodes

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreAltOpcodes = 1 static

◆ ScoreConsecutiveExtracts

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreConsecutiveExtracts = 4 static

◆ ScoreConsecutiveLoads

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreConsecutiveLoads = 4 static

◆ ScoreConstants

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreConstants = 2 static

◆ ScoreFail

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreFail = 0 static

◆ ScoreMaskedGatherCandidate

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreMaskedGatherCandidate = 1 static

◆ ScoreReversedExtracts

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreReversedExtracts = 3 static

◆ ScoreReversedLoads

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreReversedLoads = 3 static

◆ ScoreSameOpcode

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreSameOpcode = 2 static

◆ ScoreSplat

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreSplat = 1 static

◆ ScoreSplatLoads

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreSplatLoads = 3 static

◆ ScoreUndef

const int slpvectorizer::BoUpSLP::LookAheadHeuristics::ScoreUndef = 1 static

The documentation for this class was generated from the following file: