Struct rustc_mir_transform::match_branches::SimplifyToIf

struct SimplifyToIf;

Trait Implementations

impl<'tcx> SimplifyMatch<'tcx> for SimplifyToIf

If a source block is found that switches between two blocks that are exactly the same modulo const bool assignments (e.g., one assigns true another false to the same place), merge a target block statements into the source block, using Eq / Ne comparison with switch value where const bools value differ.

For example:

bb0: {
    switchInt(move _3) -> [42_isize: bb1, otherwise: bb2];
}

bb1: {
    _2 = const true;
    goto -> bb3;
}

bb2: {
    _2 = const false;
    goto -> bb3;
}

into:

bb0: {
   _2 = Eq(move _3, const 42_isize);
   goto -> bb3;
}

fn can_simplify( &mut self, tcx: TyCtxt<'tcx>, targets: &SwitchTargets, param_env: ParamEnv<'tcx>, bbs: &IndexSlice<BasicBlock, BasicBlockData<'tcx>>, _discr_ty: Ty<'tcx>, ) -> Option<()>

Check that the BBs to be simplified satisfies all distinct and that the terminator are the same. There are also conditions for different ways of simplification.

fn new_stmts( &self, tcx: TyCtxt<'tcx>, targets: &SwitchTargets, param_env: ParamEnv<'tcx>, patch: &mut MirPatch<'tcx>, parent_end: Location, bbs: &IndexSlice<BasicBlock, BasicBlockData<'tcx>>, discr_local: Local, discr_ty: Ty<'tcx>, )

fn simplify( &mut self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, switch_bb_idx: BasicBlock, param_env: ParamEnv<'tcx>, ) -> Option<()>

Simplifies a match statement, returning true if the simplification succeeds, false otherwise. Generic code is written here, and we generally don’t need a custom implementation.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 0 bytes