• Manos Koukoutos's avatar
    [turbofan] Disallow floating control in wasm · 02ac71e2
    Manos Koukoutos authored
    Loop unrolling did not work properly with floating control. Seeing as
    very few spots in the wasm compiler introduced floating control, we
    decided to disallow it altogether.
    Changes:
    - When lowering 64-bit rol/ror/clz/ctz in 32-bit platforms, we use a
      diamond operator, which used to introduce floating control. This CL
      adds a control edge to these operators so that the diamond can be
      chained to that control instead.
    - During loop analysis, as an additional safety check, we check that the
      explored loop does not have floating control. Exceptionally, floating
      control pointing directly do start() is allowed.
    - Change wasm-compiler so that generated floating projections point to
      start() even after stack check patch-in.
    
    Bug: chromium:1184929, v8:11298
    Change-Id: I1ee063f5250037ae6c84d2f16b0bd8fff3923117
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2876851Reviewed-by: 's avatarGeorg Neis <neis@chromium.org>
    Reviewed-by: 's avatarNico Hartmann <nicohartmann@chromium.org>
    Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#74527}
    02ac71e2
loop-unrolling.js 5.58 KB