• Clemens Backes's avatar
    Revert "[arm64][wasm] Use NEON S/Usra for Wasm SIMD add(shr(x, imm), y)" · 55e6a51f
    Clemens Backes authored
    This reverts commit 2261e053.
    
    Reason for revert: No issues with the CL, but it is taking the
    last two available opcodes on arm64 (we use 9 bits to encode it,
    so we are limited to 512 opcodes). We need to land a security fix
    which includes the addition of two opcodes. Before relanding this,
    we need to figure out a strategy to either reduce opcodes, or use
    one more bit to encode them.
    
    Original change's description:
    > [arm64][wasm] Use NEON S/Usra for Wasm SIMD add(shr(x, imm), y)
    >
    > A single AArch64 SIMD signed/unsigned Shift Right and Accumulate can be
    > used to implement Wasm SIMD add(shr(x, imm), y). This gives a 1-1.5%
    > improvement on some compute intensive Wasm benchmarks on Neoverse-N1.
    >
    > Mla and Adalp optimisations were refactored to match the style of the
    > added code.
    >
    > Change-Id: Id5959a31ca267e02b7d60e7ff6f942adb029b41e
    > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3089157
    > Reviewed-by: Zhi An Ng <zhin@chromium.org>
    > Commit-Queue: Martyn Capewell <martyn.capewell@arm.com>
    > Cr-Commit-Position: refs/heads/master@{#76280}
    
    Change-Id: Ifad0625ed8a6b66e7a7a74da11ad7d60941207e5
    No-Presubmit: true
    No-Tree-Checks: true
    No-Try: true
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3094014
    Auto-Submit: Clemens Backes <clemensb@chromium.org>
    Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
    Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
    Cr-Commit-Position: refs/heads/master@{#76282}
    55e6a51f
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