• Leszek Swirski's avatar
    Revert "[interpreter] Short Star bytecode" · 08a49bbe
    Leszek Swirski authored
    This reverts commit cf93071c.
    
    Reason for revert: Speculative revert because of Mac4 GC stress failure: https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Mac64%20GC%20Stress/16697/overview
    
    Original change's description:
    > [interpreter] Short Star bytecode
    >
    > Design doc:
    > https://docs.google.com/document/d/1g_NExMT78II_KnIYNa9MvyPYIj23qAiFUEsyemY5KRk/edit
    >
    > This change adds 16 new interpreter opcodes, kStar0 through kStar15, so
    > that we can use a single byte to represent the common operation of
    > storing to a low-numbered register. This generally reduces the quantity
    > of bytecode generated on web sites by 8-9%.
    >
    > In order to not degrade speed, a couple of other changes are required:
    >
    > The existing lookahead logic to check for Star after certain other
    > bytecode handlers is updated to check for these new short Star codes
    > instead. Furthermore, that lookahead logic is updated to contain its own
    > copy of the dispatch jump rather than merging control flow with the
    > lookahead-failed case, to improve branch prediction.
    >
    > A bunch of constants use bytecode size in bytes as a proxy for the size
    > or complexity of a function, and are adjusted downward proportionally to
    > the decrease in generated bytecode size.
    >
    > Other small drive-by fix: update generate-bytecode-expectations to emit
    > \n instead of \r\n on Windows.
    >
    > Change-Id: I6307c2b0f5794a3a1088bb0fb94f6e1615441ed5
    > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2641180
    > Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
    > Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
    > Cr-Commit-Position: refs/heads/master@{#72773}
    
    TBR=rmcilroy@chromium.org,mythria@chromium.org,seth.brenith@microsoft.com
    
    Change-Id: I0162b9400861b90bacef27cca9aebc8ab9d74c10
    No-Presubmit: true
    No-Tree-Checks: true
    No-Try: true
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2697350Reviewed-by: 's avatarLeszek Swirski <leszeks@chromium.org>
    Commit-Queue: Leszek Swirski <leszeks@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#72777}
    08a49bbe
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