New debugging primitive: break whenever any instruction writes to a
given general-purpose register (0-31), regardless of which address
executes the write. Requested for continuing the reboot.bin trace,
where the actual blocker is "what sets $s3 to this bad value", not
"what happens at a specific address" - existing address/memory
breakpoints can't express that directly.
- GPRBreakpoint (Core/Debugger/Breakpoints.h) mirrors the existing
BreakPoint/MemCheck shape (result/condition/logFormat/hit count),
keyed by register index instead of address/range.
- BreakpointManager keeps a u32 bitmask (bit i = register i has an
active breakpoint) alongside the GPRBreakpoint vector, so the
interpreter loop can test "would this write trip anything" with a
single shift+and against a value already cached in a local.
- RunUntilDowncountZeroWithChecks (Core/MIPS/MIPSTables.cpp) computes
the about-to-be-written register from the current instruction's
OUT_RT/OUT_RD/OUT_RA flags (GetGPRWriteTarget()) and checks it
against the mask, same convention as the existing memcheck handling
right above it (checked before the instruction executes, bails via
CORE_STEPPING_CPU without running it if tripped).
- New BreakReason::GPRBreakpoint ("cpu.gprBreakpoint") for Core_Break.
- WebSocket API: cpu.gprBreakpoint.add/update/remove/list, accepting
either a 0-31 'register' index or a case-insensitive 'name' (e.g.
"s3"), documented in docs/WebSocketDebugger.md.
Interpreter-only for now, deliberately.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GZq8ZtJmFY7bkX5FVkr3P9
WebSocketMemoryBreakpointParams::Parse() (used by add/update) checks
for address + size wrapping around before computing the end address,
but memory.breakpoint.remove computed it inline without that check.
Apply the same check for consistency - a crafted size could otherwise
wrap the computed end below address, causing RemoveMemCheck to operate
on an unintended range.
CPUCoreSubscriber through the CPU thread
Continues the pattern started with SteppingSubscriber: route breakpoint,
disassembly, symbol, and register access through Core_RunOnCPUThread()
instead of touching that state directly from the WebSocket handler thread.
Two intentional exceptions, matching the reasoning already used for
cpu.stepInto's "not currently stepping" branch:
- cpu.stepping's Core_Break() call stays unqueued - it's what makes the CPU
thread start reaching the queue drain point in the first place.
- cpu.status stays unqueued - it's meant to be a cheap, frequently-pollable
status check, and its "pc" field is already documented as inaccurate unless
stepping. Matches how SteppingBroadcaster already reads the same state
directly from the WebSocket thread.
Where a handler's response doesn't depend on anything the queued lambda
computed (plain add/remove endpoints), moved req.Respond() back out after
the Core_RunOnCPUThread() call for readability - the JSON building and
socket write happen later in Finish() regardless of where Respond() is
called, so there's no thread-safety difference either way, just clarity
about what actually needs to run on the CPU thread.
memory.searchDisasm carries the same caveat flagged for memory.search: its
scan range has no size cap, so if the CPU is stepping, a very large range
will now block the CPU thread's own frame pump for the scan's duration
rather than running unqueued on the WebSocket thread as before. Not fixed
here - noted in a comment at the call site.
Replaced remaining `auto` locals in these three files with concrete types.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hqm11k99viLfbJm2MkH4BH
