[webkit-changes] [WebKit/WebKit] e960cd: Cherry-pick 265870.333 at safari-7616.1.27.10-branch ...

[Keith Miller]

  Branch: refs/heads/webkitglib/2.42
  Home:   https://github.com/WebKit/WebKit
  Commit: e960cdca544708c5eb699635438bf5e73c977c51
      https://github.com/WebKit/WebKit/commit/e960cdca544708c5eb699635438bf5e73c977c51
  Author: Keith Miller <keith_miller at apple.com>
  Date:   2023-09-21 (Thu, 21 Sep 2023)

  Changed paths:
    A JSTests/stress/getbyoffset-cse-consistency.js
    A JSTests/stress/multigetbyoffset-cse-consistency.js
    M Source/JavaScriptCore/dfg/DFGCSEPhase.cpp
    M Source/JavaScriptCore/dfg/DFGClobberize.h
    M Source/JavaScriptCore/dfg/DFGHeapLocation.h

  Log Message:
  -----------
  Cherry-pick 265870.333 at safari-7616.1.27.10-branch (ab5c6119c469). https://bugs.webkit.org/show_bug.cgi?id=261544

    Cherry-pick 47e039ffd689. rdar://115399657

        clobberize needs to be more precise with the *ByOffset nodes
        https://bugs.webkit.org/show_bug.cgi?id=261544
        rdar://115399657

        Reviewed by Yusuke Suzuki and Mark Lam.

        CSE phase uses clobberize to figure out if it's safe to merge two operations that
        def the same HeapLocation. Since HeapLocation does not currently have a way to
        track the offset used by the various *ByOffset nodes it can get confused and
        think that two ByOffset instructions produce the same value even if they don't
        use the same offset. This patch solves this by adding a new field to HeapLocation,
        which takes the metadata associated with the corresponding *ByOffset node. If two
        *ByOffset operations don't share the same metadata then they cannot be CSEed.

        * Source/JavaScriptCore/dfg/DFGCSEPhase.cpp:
        * Source/JavaScriptCore/dfg/DFGClobberize.h:
        (JSC::DFG::clobberize):
        * Source/JavaScriptCore/dfg/DFGHeapLocation.h:
        (JSC::DFG::HeapLocation::HeapLocation):
        (JSC::DFG::HeapLocation::extraState const):
        (JSC::DFG::HeapLocation::hash const):

        Canonical link: https://commits.webkit.org/265870.558@safari-7616-branch
    Identifier: 265423.780 at safari-7616.1.27.10-branch