[webkit-changes] [WebKit/WebKit] a0d948: Implement B3 Sub/Mul of Int64 values on 32-bits

[aoikonomopoulos]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: a0d948c191f504a1e62387400dc69e7d0b24ca32
      https://github.com/WebKit/WebKit/commit/a0d948c191f504a1e62387400dc69e7d0b24ca32
  Author: Angelos Oikonomopoulos <angelos at igalia.com>
  Date:   2024-07-15 (Mon, 15 Jul 2024)

  Changed paths:
    M Source/JavaScriptCore/b3/B3LowerInt64.cpp
    M Source/JavaScriptCore/b3/B3LowerToAir32_64.cpp

  Log Message:
  -----------
  Implement B3 Sub/Mul of Int64 values on 32-bits
https://bugs.webkit.org/show_bug.cgi?id=276482

Reviewed by Yusuke Suzuki.

Implement both Sub and Mul of Int64 values in B3LowerToAir32_64.cpp.

We cannot easily lower Sub on Int64s in B3LowerInt64 since the
performant implementation requires two subtractions, the latter using
the carry bit produced by the former. Similar to Add, make use of the
already available Sub64 form.

A performant implementation of Mul on Int64 on ARMv7 needs to make use
of the UMull air form (taking 2 32-bit values and producing one 64-bit
output). Technically we could define a B3 op for that just on
ARMv7, but this feels more straightforward. Mul is the last arithmetic
that should need special handling in B3LowerToAir32_64 (as opposed to
being lowered in B3LowerInt64).

* Source/JavaScriptCore/b3/B3LowerInt64.cpp:
* Source/JavaScriptCore/b3/B3LowerToAir32_64.cpp:

Canonical link: https://commits.webkit.org/280964@main



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