LLVM: lib/CodeGen/SelectOptimize.cpp File Reference (original) (raw)

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Functions
STATISTIC (NumSelectOptAnalyzed, "Number of select groups considered for conversion to branch")
STATISTIC (NumSelectConvertedExpColdOperand, "Number of select groups converted due to expensive cold operand")
STATISTIC (NumSelectConvertedHighPred, "Number of select groups converted due to high-predictability")
STATISTIC (NumSelectUnPred, "Number of select groups not converted due to unpredictability")
STATISTIC (NumSelectColdBB, "Number of select groups not converted due to cold basic block")
STATISTIC (NumSelectConvertedLoop, "Number of select groups converted due to loop-level analysis")
STATISTIC (NumSelectsConverted, "Number of selects converted")
INITIALIZE_PASS_BEGIN (SelectOptimize, DEBUG_TYPE, "Optimize selects", false, false) INITIALIZE_PASS_END(SelectOptimize
static Value * getTrueOrFalseValue (SelectOptimizeImpl::SelectLike &SI, bool isTrue, SmallDenseMap< Instruction *, std::pair< Value *, Value * >, 2 > &OptSelects, BasicBlock *B)
Returns optimised value on IsTrue branch.
static void EmitAndPrintRemark (OptimizationRemarkEmitter *ORE, DiagnosticInfoOptimizationBase &Rem)
static InstructionCost divideNearest (InstructionCost Numerator, uint64_t Denominator)
static bool extractBranchWeights (const SelectOptimizeImpl::SelectLike SI, uint64_t &TrueVal, uint64_t &FalseVal)
static bool isSafeToSinkLoad (Instruction *LoadI, Instruction *SI)
Variables
static cl::opt< unsigned > ColdOperandThreshold ("cold-operand-threshold", cl::desc("Maximum frequency of path for an operand to be considered cold."), cl::init(20), cl::Hidden)
static cl::opt< unsigned > ColdOperandMaxCostMultiplier ("cold-operand-max-cost-multiplier", cl::desc("Maximum cost multiplier of TCC_expensive for the dependence " "slice of a cold operand to be considered inexpensive."), cl::init(1), cl::Hidden)
static cl::opt< unsigned > GainGradientThreshold ("select-opti-loop-gradient-gain-threshold", cl::desc("Gradient gain threshold (%)."), cl::init(25), cl::Hidden)
static cl::opt< unsigned > GainCycleThreshold ("select-opti-loop-cycle-gain-threshold", cl::desc("Minimum gain per loop (in cycles) threshold."), cl::init(4), cl::Hidden)
static cl::opt< unsigned > GainRelativeThreshold ("select-opti-loop-relative-gain-threshold", cl::desc("Minimum relative gain per loop threshold (1/X). Defaults to 12.5%"), cl::init(8), cl::Hidden)
static cl::opt< unsigned > MispredictDefaultRate ("mispredict-default-rate", cl::Hidden, cl::init(25), cl::desc("Default mispredict rate (initialized to 25%)."))
static cl::opt< bool > DisableLoopLevelHeuristics ("disable-loop-level-heuristics", cl::Hidden, cl::init(false), cl::desc("Disable loop-level heuristics."))
DEBUG_TYPE
Optimize selects
Optimize false

◆ DEBUG_TYPE

#define DEBUG_TYPE "select-optimize"

◆ divideNearest()

◆ EmitAndPrintRemark()

◆ extractBranchWeights()

◆ getTrueOrFalseValue()

Returns optimised value on IsTrue branch.

For SelectInst that would be either True or False value. For (BinaryOperator) instructions, where the condition may be skipped, the operation will use a non-conditional operand. For example, for or(V,zext(cond)) this function would return V. However, if the conditional operand on IsTrue branch matters, we create a clone of instruction at the end of that branch B and replace the condition operand with a constant.

Also /p OptSelects contains previously optimised select-like instructions. If the current value uses one of the optimised values, we can optimise it further by replacing it with the corresponding value on the given branch

Definition at line 480 of file SelectOptimize.cpp.

References assert(), B, and IV.

◆ INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN ( SelectOptimize ,
DEBUG_TYPE ,
"Optimize selects" ,
false ,
false
)

◆ isSafeToSinkLoad()

◆ STATISTIC() [1/7]

STATISTIC ( NumSelectColdBB ,
"Number of select groups not converted due to cold basic block"
)

◆ STATISTIC() [2/7]

STATISTIC ( NumSelectConvertedExpColdOperand ,
"Number of select groups converted due to expensive cold operand"
)

◆ STATISTIC() [3/7]

STATISTIC ( NumSelectConvertedHighPred ,
"Number of select groups converted due to high-predictability"
)

◆ STATISTIC() [4/7]

STATISTIC ( NumSelectConvertedLoop ,
"Number of select groups converted due to loop-level analysis"
)

◆ STATISTIC() [5/7]

STATISTIC ( NumSelectOptAnalyzed ,
"Number of select groups considered for conversion to branch"
)

◆ STATISTIC() [6/7]

STATISTIC ( NumSelectsConverted ,
"Number of selects converted"
)

◆ STATISTIC() [7/7]

STATISTIC ( NumSelectUnPred ,
"Number of select groups not converted due to unpredictability"
)

◆ ColdOperandMaxCostMultiplier

cl::opt< unsigned > ColdOperandMaxCostMultiplier("cold-operand-max-cost-multiplier", cl::desc("Maximum cost multiplier of TCC_expensive for the dependence " "slice of a cold operand to be considered inexpensive."), cl::init(1), cl::Hidden) ( "cold-operand-max-cost-multiplier" , cl::desc("Maximum cost multiplier of TCC_expensive for the dependence " "slice of a cold operand to be considered inexpensive.") , cl::init(1) , cl::Hidden ) static

◆ ColdOperandThreshold

cl::opt< unsigned > ColdOperandThreshold("cold-operand-threshold", cl::desc("Maximum frequency of path for an operand to be considered cold."), cl::init(20), cl::Hidden) ( "cold-operand-threshold" , cl::desc("Maximum frequency of path for an operand to be considered cold.") , cl::init(20) , cl::Hidden ) static

◆ DEBUG_TYPE

◆ DisableLoopLevelHeuristics

cl::opt< bool > DisableLoopLevelHeuristics("disable-loop-level-heuristics", cl::Hidden, cl::init(false), cl::desc("Disable loop-level heuristics.")) ( "disable-loop-level-heuristics" , cl::Hidden , cl::init(false) , cl::desc("Disable loop-level heuristics.") ) static

◆ false

◆ GainCycleThreshold

cl::opt< unsigned > GainCycleThreshold("select-opti-loop-cycle-gain-threshold", cl::desc("Minimum gain per loop (in cycles) threshold."), cl::init(4), cl::Hidden) ( "select-opti-loop-cycle-gain-threshold" , cl::desc("Minimum gain per loop (in cycles) threshold.") , cl::init(4) , cl::Hidden ) static

◆ GainGradientThreshold

cl::opt< unsigned > GainGradientThreshold("select-opti-loop-gradient-gain-threshold", cl::desc("Gradient gain threshold (%)."), cl::init(25), cl::Hidden) ( "select-opti-loop-gradient-gain-threshold" , cl::desc("Gradient gain threshold (%).") , cl::init(25) , cl::Hidden ) static

◆ GainRelativeThreshold

cl::opt< unsigned > GainRelativeThreshold("select-opti-loop-relative-gain-threshold", cl::desc( "Minimum relative gain per loop threshold (1/X). Defaults to 12.5%"), cl::init(8), cl::Hidden) ( "select-opti-loop-relative-gain-threshold" , cl::desc( "Minimum relative gain per loop threshold (1/X). Defaults to 12.5%") , cl::init(8) , cl::Hidden ) static

◆ MispredictDefaultRate

cl::opt< unsigned > MispredictDefaultRate("mispredict-default-rate", cl::Hidden, cl::init(25), cl::desc("Default mispredict rate (initialized to 25%).")) ( "mispredict-default-rate" , cl::Hidden , cl::init(25) , cl::desc("Default mispredict rate (initialized to 25%).") ) static

◆ selects