Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: e51159c6bbedb25e0e9eeb217917dce4eb7bf327
https://github.com/WebKit/WebKit/commit/e51159c6bbedb25e0e9eeb217917dce4eb7bf327
Author: Yijia Huang <[email protected]>
Date: 2026-01-06 (Tue, 06 Jan 2026)
Changed paths:
M JSTests/wasm/debugger/lib/core/base.py
A
JSTests/wasm/debugger/resources/wasm/multi-vm-same-module-different-funcs.js
A JSTests/wasm/debugger/resources/wasm/multi-vm-same-module-same-func.js
A JSTests/wasm/debugger/resources/wasm/system-call.js
M JSTests/wasm/debugger/test-wasm-debugger.py
M JSTests/wasm/debugger/tests/tests.py
M Source/JavaScriptCore/API/tests/VMManagerStopTheWorldTest.cpp
M Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj
M Source/JavaScriptCore/jsc.cpp
M Source/JavaScriptCore/llint/InPlaceInterpreter.asm
M Source/JavaScriptCore/runtime/InitializeThreading.cpp
M Source/JavaScriptCore/runtime/JSCConfig.h
M Source/JavaScriptCore/runtime/Options.cpp
M Source/JavaScriptCore/runtime/StopTheWorldCallback.h
M Source/JavaScriptCore/runtime/VM.cpp
M Source/JavaScriptCore/runtime/VM.h
M Source/JavaScriptCore/runtime/VMManager.cpp
M Source/JavaScriptCore/runtime/VMManager.h
M Source/JavaScriptCore/shell/CMakeLists.txt
M Source/JavaScriptCore/wasm/WasmIPIntSlowPaths.cpp
M Source/JavaScriptCore/wasm/WasmInstanceAnchor.h
A Source/JavaScriptCore/wasm/debugger/Debugger-Mutator-Protocol.md
M Source/JavaScriptCore/wasm/debugger/README.md
M Source/JavaScriptCore/wasm/debugger/RWI_ARCHITECTURE.md
M Source/JavaScriptCore/wasm/debugger/WasmBreakpointManager.cpp
M Source/JavaScriptCore/wasm/debugger/WasmBreakpointManager.h
M Source/JavaScriptCore/wasm/debugger/WasmDebugServer.cpp
M Source/JavaScriptCore/wasm/debugger/WasmDebugServer.h
M Source/JavaScriptCore/wasm/debugger/WasmDebugServerUtilities.cpp
M Source/JavaScriptCore/wasm/debugger/WasmDebugServerUtilities.h
M Source/JavaScriptCore/wasm/debugger/WasmExecutionHandler.cpp
M Source/JavaScriptCore/wasm/debugger/WasmExecutionHandler.h
M Source/JavaScriptCore/wasm/debugger/WasmModuleManager.cpp
M Source/JavaScriptCore/wasm/debugger/WasmModuleManager.h
M Source/JavaScriptCore/wasm/debugger/WasmQueryHandler.cpp
M Source/JavaScriptCore/wasm/debugger/WasmVirtualAddress.h
A Source/JavaScriptCore/wasm/debugger/tests/ExecutionHandlerTest.cpp
A Source/JavaScriptCore/wasm/debugger/tests/ExecutionHandlerTest.h
A Source/JavaScriptCore/wasm/debugger/tests/ExecutionHandlerTestSupport.cpp
A Source/JavaScriptCore/wasm/debugger/tests/ExecutionHandlerTestSupport.h
A Source/JavaScriptCore/wasm/debugger/tests/TestScripts.cpp
A Source/JavaScriptCore/wasm/debugger/tests/TestScripts.h
M Source/JavaScriptCore/wasm/debugger/tests/TestUtilities.cpp
M Source/JavaScriptCore/wasm/debugger/testwasmdebugger.cpp
M Source/JavaScriptCore/wasm/js/JSWebAssemblyInstance.cpp
M Source/WebKit/WebProcess/WebProcess.cpp
Log Message:
-----------
[JSC][Wasm][Debugger] Implement multi-VM stop-the-world debugging
https://bugs.webkit.org/show_bug.cgi?id=302699
rdar://164945623
Reviewed by Keith Miller.
Implements comprehensive multi-VM stop-the-world Wasm debugger that stops ALL
VMs
in the process when any VM hits a breakpoint or receives an interrupt.
Architecture:
* VMManager world modes coordinate multi-VM execution:
- Running: Normal execution (all VMs running).
- Stopped: All VMs paused at safe points for inspection.
- RunOne: Single-step mode (target VM runs, others stopped).
* Two-phase callback system:
- wasmDebuggerOnStop(): VMManager calls with ALL VMs stopped; returns
resume mode.
- wasmDebuggerOnResume(): VMManager calls after ALL VMs resume; releases
barriers.
* Per-VM DebugState tracks execution state:
- Running vs Stopped with stop reason (Prologue/Breakpoint/SystemCall).
- StopData snapshot: PC, locals, stack, call frame for inspection.
- Step-into event flags for cross-function stepping (call/throw).
* ExecutionHandler bridges LLDB commands to VM execution:
- Detailed design in Debugger-Mutator-Protocol.md.
- Two condition variables orchestrate debugger-mutator communication.
- State machine
(Replied/InterruptRequested/ContinueRequested/StepRequested/SwitchRequested).
- Resume barrier prevents overlapping stop-the-world operations.
- Target VM selection: prefers VM at prologue, falls back to triggering VM.
* Step-into design minimizes runtime changes:
- step() sets event flag instead of resolving callee/handler immediately
- Runtime resolves target naturally during execution (call dispatch,
exception unwinding)
- Callback sets breakpoint using resolved target, avoiding duplicate
resolution logic
- Reuses existing runtime mechanisms rather than duplicating complex
resolution in debugger
Testing:
* Unit tests: ExecutionHandlerTest validates coordination logic.
* Integration tests: multi-vm test cases for same/different modules and
functions.
Note that the WebAssembly debugger currently supports ARM64 platforms only.
Canonical link: https://commits.webkit.org/305160@main
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