Bug 299166 – Missing llint op_instanceof handler in LowLevelInterpreter32_64.asm breaks 32-bit C-loop builds

• Status: NEW
• Component: New Bugs

Created attachment 476797 [details]
original compiler bug

Product: JavaScriptCore
Component: LLInt / OfflineASM
Version: 2.50.0
Platform: ARMv7 (32-bit, e.g. -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard) no NEON

Summary:
Building WebKitGTK 2.50.0 with ENABLE(C_LOOP)=ON on 32-bit ARM targets fails because the C loop interpreter now references the labels
    op_instanceof_return_location
    op_instanceof_return_location_wide16
    op_instanceof_return_location_wide32
but the 32-bit offlineasm file (LowLevelInterpreter32_64.asm) never defines them.

Steps to Reproduce:
1. Configure WebKitGTK 2.50.0 for armv7 with ENABLE(C_LOOP)=ON (Gentoo, gcc 13.2, -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard).
2. Run the build so that JavaScriptCore/llint/LowLevelInterpreter.cpp is compiled.

Expected Results:
Compilation succeeds; the LLInt C loop backend provides all required opcode return labels.

Actual Results:
Compilation stops with errors similar to:
    Source/JavaScriptCore/llint/LowLevelInterpreter.cpp:286: error: label 'op_instanceof_return_location' used but not defined
    ...
The new opcode return helper was added to BytecodeList.rb and LLIntOpcode.h, so LowLevelInterpreter.cpp assumes the labels exist, but LowLevelInterpreter32_64.asm still only has
    llintSlowPathOp(instanceof)
and therefore never emits the labels for the C loop build.

Additional Notes:
* LowLevelInterpreter64.asm in 2.50.0 already contains a full llintOpWithMetadata(op_instanceof, ...) implementation that generates the return labels.
* Copying/porting that block into LowLevelInterpreter32_64.asm restores the missing labels and fixes the build on armv7.
* The issue affects any 32-bit ARM build that enables the LLInt C loop (confirmed on Gentoo cross-distcc armv7 setup).

Suggested Fix:
Port the op_instanceof handler from LowLevelInterpreter64.asm into LowLevelInterpreter32_64.asm so that offlineasm emits _return_location labels for all operand widths in 32-bit builds.

Created attachment 476798 [details]
Bugfix for 32bit builds

Created attachment 476799 [details]
Bugfix for 32bit builds v2

Created attachment 476800 [details]
Bugfix for 32bit builds v3

[Radar WebKit Bug Importer]

<rdar://problem/161395111>