ic/dce

Source Edit

Dead code elimination (=DCE) for IC.

Imports

../ast, ../options, ../lineinfos, ../types, packed_ast, ic, bitabs

Types

AliveContext = object
  ## A stack for marking symbols as alive.
  ## We need a PackedDecoder for module ID address translations.
  ## The module we're currently analysing for DCE.
  ## The final result of our computation.

Purpose is to fill the 'alive' field. Source Edit

AliveSyms = seq[IntSet]

Source Edit

Procs

proc computeAliveSyms(g: PackedModuleGraph; conf: ConfigRef): AliveSyms {.
    ...raises: [KeyError, Exception], tags: [ReadDirEffect, RootEffect],
    forbids: [].}

Entry point for our DCE algorithm. Source Edit

proc isAlive(a: AliveSyms; module: int; item: int32): bool {....raises: [],
    tags: [], forbids: [].}

Backends use this to query if a symbol is alive which means we need to produce (C/C++/etc) code for it. Source Edit