1. 19 Jun, 2015 1 commit
    • bmeurer's avatar
      [turbofan] Proper dead code elimination as regular reducer. · 733a2463
      bmeurer authored
      The three different concerns that the ControlReducer used to deal with
      are now properly separated into
      
        a.) DeadCodeElimination, which is a regular AdvancedReducer, that
            propagates Dead via control edges,
        b.) CommonOperatorReducer, which does strength reduction on common
            operators (i.e. Branch, Phi, and friends), and
        c.) GraphTrimming, which removes dead->live edges from the graph.
      
      This will make it possible to run the DeadCodeElimination together with
      other passes that actually introduce Dead nodes, i.e. typed lowering;
      and it opens the door for general inlining without two stage fix point
      iteration.
      
      To make the DeadCodeElimination easier and more uniform, we basically
      reverted the introduction of DeadValue and DeadEffect, and changed the
      Dead operator to produce control, value and effect. Note however that
      this is not a requirement, but merely a way to make dead propagation
      easier and more uniform. We could always go back and decide to have
      different Dead operators if some other change requires that.
      
      Note that there are several additional opportunities for cleanup now,
      i.e. OSR deconstruction could be a regular reducer now, and we don't
      need to use TheHole as dead value marker in the GraphReducer. And we can
      actually run the dead code elimination together with the other passes
      instead of using separate passes over the graph.  We will do this in
      follow up CLs.
      
      R=jarin@chromium.org, mstarzinger@chromium.org
      
      Review URL: https://codereview.chromium.org/1193833002
      
      Cr-Commit-Position: refs/heads/master@{#29146}
      733a2463
  2. 18 Jun, 2015 1 commit
  3. 17 Jun, 2015 1 commit