llvm::computeKnownBits

Synopses

Declared in <llvm/Analysis/ValueTracking.h>

Compute known bits for V using the simplify query Q.

KnownBits
computeKnownBits(
    Value const* V,
    SimplifyQuery const& Q,
    unsigned int Depth = 0);

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Compute known bits for V into Known using the simplify query Q.

void
computeKnownBits(
    Value const* V,
    KnownBits& Known,
    SimplifyQuery const& Q,
    unsigned int Depth = 0);

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Compute known bits for the demanded elements of V using Q.

KnownBits
computeKnownBits(
    Value const* V,
    APInt const& DemandedElts,
    SimplifyQuery const& Q,
    unsigned int Depth = 0);

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Returns the known bits rather than passing by reference.

KnownBits
computeKnownBits(
    Value const* V,
    DataLayout const& DL,
    AssumptionCache* AC = nullptr,
    Instruction const* CxtI = nullptr,
    DominatorTree const* DT = nullptr,
    bool UseInstrInfo = true,
    unsigned int Depth = 0);

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Determine which bits of V are known to be either zero or one and return them in the KnownZero/KnownOne bit sets.

void
computeKnownBits(
    Value const* V,
    KnownBits& Known,
    DataLayout const& DL,
    AssumptionCache* AC = nullptr,
    Instruction const* CxtI = nullptr,
    DominatorTree const* DT = nullptr,
    bool UseInstrInfo = true,
    unsigned int Depth = 0);

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Returns the known bits rather than passing by reference.

KnownBits
computeKnownBits(
    Value const* V,
    APInt const& DemandedElts,
    DataLayout const& DL,
    AssumptionCache* AC = nullptr,
    Instruction const* CxtI = nullptr,
    DominatorTree const* DT = nullptr,
    bool UseInstrInfo = true,
    unsigned int Depth = 0);

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Return Value

Known-zero and known-one bits for V.
Known-zero and known-one bits for the demanded elements of V.

Parameters

Name	Description
V	Value to analyze.
Q	Simplify query providing context for the analysis.
Depth	Current recursion depth for this query.
Known	Output known-zero and known-one bits.
DemandedElts	Demanded vector elements for the query.
DL	Data layout used for type sizes and pointer widths.
AC	Optional assumption cache for context-sensitive facts.
CxtI	Optional context instruction for local analysis.
DT	Optional dominator tree for context-sensitive analysis.
UseInstrInfo	Whether to use instruction-level information.