Bug 258057

Summary: Fix WasmBBQJIT failing to preserve locations in ScratchScope
Product: WebKit Reporter: David Degazio <d_degazio>
Component: WebAssemblyAssignee: David Degazio <d_degazio>
Status: RESOLVED DUPLICATE    
Severity: Normal CC: webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   

Description David Degazio 2023-06-13 19:02:33 PDT 
rdar://110747242

The ScratchScope abstraction used by the new WebAssembly BBQ JIT implementation is supposed to allow for the preservation of certain registers throughout its scope, preventing them from being chosen as scratches or used for newly allocated values. However, we don't actually do this when locations that are already in use are passed to ScratchScope, which largely defeats the purpose of being able to preserve live registers. It's not clear if this can be reproduced by actual WebAssembly sources, but it's definitely not how this class is supposed to work.
Comment 1 David Degazio 2023-06-14 09:26:26 PDT 
Pull request: https://github.com/WebKit/WebKit/pull/14958
Comment 2 David Degazio 2023-06-14 09:42:59 PDT 
https://bugs.webkit.org/show_bug.cgi?id=258044 tracks the same issue, and was created earlier; resolving this as a dupe and closing my PR.

*** This bug has been marked as a duplicate of bug 258044 ***