[webkit-changes] [WebKit/WebKit] 47e3ba: BBQJIT Splat 0/-1 should emit only one instruction

[Keith Miller]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 47e3bae743c547cf4172e785763a4c55a045be39
      https://github.com/WebKit/WebKit/commit/47e3bae743c547cf4172e785763a4c55a045be39
  Author: Keith Miller <keith_miller at apple.com>
  Date:   2023-05-19 (Fri, 19 May 2023)

  Changed paths:
    M Source/JavaScriptCore/wasm/WasmBBQJIT.cpp

  Log Message:
  -----------
  BBQJIT Splat 0/-1 should emit only one instruction
https://bugs.webkit.org/show_bug.cgi?id=257051

Reviewed by Yusuke Suzuki.

According to https://github.com/WebAssembly/design/issues/1476 at least one person wants to encode vector 0 as Splat i32.const 0 since the former's encoding is 18 bytes whereas the latter is 5 bytes. As such, we should emit Splat i32.const 0/-1 as the optimal code in BBQJIT.

* Source/JavaScriptCore/wasm/WasmBBQJIT.cpp:
(JSC::Wasm::BBQJIT::addSIMDSplat):

Canonical link: https://commits.webkit.org/264280@main