dmd.sideeffect

Find side-effects of expressions.

Authors

Walter Bright

License

Boost License 1.0

Source: sideeffect.d

Documentation: https://dlang.org/phobos/dmd_sideeffect.html

Coverage: https://codecov.io/gh/dlang/dmd/src/master/src/dmd/sideeffect.d

  • isTrivialExp

    Declaration

    bool isTrivialExp(Expression e);

    Front-end expression rewriting should create temporary variables for non trivial sub-expressions in order to:

    1. save evaluation order
    2. prevent sharing of sub-expression in AST

  • hasSideEffect

    Declaration

    bool hasSideEffect(Expression e, bool assumeImpureCalls = false);

    Determine if Expression has any side effects.

    Parameters

    Expression e

    the expression

    bool assumeImpureCalls

    whether function calls should always be assumed to be impure (e.g. debug is allowed to violate purity)

  • callSideEffectLevel

    Declaration

    int callSideEffectLevel(FuncDeclaration f);

    Determine if the call of f, or function type or delegate type t1, has any side effects.

    Return Value

    0 has any side effects 1 nothrow + constant purity 2 nothrow + strong purity

  • discardValue

    Declaration

    bool discardValue(Expression e);

    The result of this expression will be discarded. Print error messages if the operation has no side effects (and hence is meaningless).

    Return Value

    true if expression has no side effects

  • copyToTemp

    Declaration

    VarDeclaration copyToTemp(StorageClass stc, const char[] name, Expression e);

    Build a temporary variable to copy the value of e into.

    Parameters

    StorageClass stc

    storage classes will be added to the made temporary variable

    char[] name

    name for temporary variable

    Expression e

    original expression

    Return Value

    Newly created temporary variable.

  • extractSideEffect

    Declaration

    Expression extractSideEffect(Scope* sc, const char[] name, ref Expression e0, Expression e, bool alwaysCopy = false);

    Build a temporary variable to extract e's evaluation, if e is not trivial.

    Parameters

    Scope* sc

    scope

    char[] name

    name for temporary variable

    Expression e0

    a new side effect part will be appended to it.

    Expression e

    original expression

    bool alwaysCopy

    if true, build new temporary variable even if e is trivial.

    Return Value

    When e is trivial and alwaysCopy == false, e itself is returned. Otherwise, a new VarExp is returned.

    Note: e's lvalue-ness will be handled well by STC.ref_ or STC.rvalue.