• Clemens Backes's avatar
    [wasm] Use a single source of truth for feedback vector size · c582eb4e
    Clemens Backes authored
    The number of feedback vector slots is currently stored in the
    {WasmFunction}, returned in the {WasmCompilationResult}, and implicitly
    stored as the size of the {call_targets} vector in
    {FunctionTypeFeedback}.
    
    This CL uses the latter as the source of truth, encapsulated in a new
    {NumFeedbackSlots} function. This can be updated when adding new kinds
    of feedback that need additional slots.
    For now, the implementation of {NumFeedbackSlots} requires taking a
    mutex, which we can hopefully avoid when productionizing speculative
    inlining. We also take the mutex on every Liftoff compilation, which
    adds synchronization between concurrent compilation which we previously
    tried very hard to avoid (because it introduced significant overhead for
    eager compilation).
    
    As a nice side-effect, this CL reduces the per-function overhead by 8
    bytes, independent of enabled features.
    
    R=jkummerow@chromium.org
    
    Bug: v8:13209
    Change-Id: I2fe5f7fe73154328032a3f0961e88d068c5d07ae
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3899299Reviewed-by: 's avatarJakob Kummerow <jkummerow@chromium.org>
    Commit-Queue: Clemens Backes <clemensb@chromium.org>
    Cr-Commit-Position: refs/heads/main@{#83253}
    c582eb4e
module-decoder-impl.h 92.3 KB