[webkit-changes] [WebKit/WebKit] 3eb123: [JSC] Disable wasm tail-call because of several ne...

[Yusuke Suzuki]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 3eb123c1f36f03ab8b1f521de8f01aaf541854c8
      https://github.com/WebKit/WebKit/commit/3eb123c1f36f03ab8b1f521de8f01aaf541854c8
  Author: Yusuke Suzuki <ysuzuki at apple.com>
  Date:   2023-02-02 (Thu, 02 Feb 2023)

  Changed paths:
    M JSTests/wasm/stress/tail-call-should-not-clobber-caller-origin.js
    M JSTests/wasm/v8/indirect-call-non-zero-table.js
    M Source/JavaScriptCore/runtime/OptionsList.h

  Log Message:
  -----------
  [JSC] Disable wasm tail-call because of several necessary things
https://bugs.webkit.org/show_bug.cgi?id=251656
rdar://104987053

Reviewed by Mark Lam.

This change disables wasm tail-calls since we still need several things to make it work correctly.

1. All wasm function calls need to adjust stack-pointer after the call. This is necessary thing for the support of tail-call,
   but currently it is not done yet. Since tail-call can adjust the stack-pointer of the caller, the stack-pointer value can become
   different after the tail-call happens from the caller's view. Since B3 etc. are freely accessing to stack slots via stack-pointer,
   and since stack-pointer needs to be the same during the procedure, the adjustment is required to make things work.
   In JS world, we are doing this adjustment: BaselineJIT's resetSP for example. Previously, since wasm does not have tail-calls,
   wasm call is not doing this adjustment. Now, we should do that.
2. We should not change offset of StackSlots. This is not a supported operation by B3 / Air.

For now, we disable wasm tail-call.

* Source/JavaScriptCore/runtime/OptionsList.h:

Canonical link: https://commits.webkit.org/259801@main