step-over, step-out and run-until plant a one-shot breakpoint at the address
they want execution to return to. Keeping it in breakPoints_ alongside the
user's own meant the two kept colliding:
- Adding a log-only user breakpoint at the same address hijacked the temporary
one. AddBreakPoint() didn't match across temp-ness so both existed, and then
ChangeBreakPoint() looked up "the first enabled breakpoint at this address" -
a log-only breakpoint isn't enabled, so the temporary one won and had its
action overwritten to log-only. It lost PAUSE and the step never came back.
- RemoveBreakPoint() erased up to two entries per address to catch an
overlapping temporary one, so deleting either deleted both - including the
interpreter's cleanup path in CheckExecBreakpoints() taking the user's
breakpoint with it.
- ExecBreakPoint() handled one breakpoint per address, so with both at the same
address only one of them did anything: the step completed but the user's log
line never printed.
- Nothing dropped it when something *else* stopped us first, so an interrupted
step left a breakpoint armed at an address nobody was waiting for anymore,
which later fired as a phantom stop.
It's a single TempBreakPoint member now, invisible to the breakpoint lists and
untouched by user edits. One is enough: step over/out and cross-thread step into
all require the CPU to already be stepping and resume it immediately, so only
one can be in flight, and run-until now replaces rather than stacking (two
pending run-untils had no coherent meaning, and the loser stayed armed).
Behavior follows what other debuggers do. Both breakpoints at an address are
evaluated independently and their actions combine, so a log-only breakpoint
logs without stopping and still lets the step finish. Core_Break() drops the
temporary breakpoint on any stop, whatever the reason - the same way gdb deletes
its step-resume breakpoint and lldb discards the thread plan.
Two things to be careful of, both covered by the new TempBreakpoints test:
HasBreakPoints() has to account for it, or the interpreter's checked run loop
and the JIT skip breakpoint checking entirely and a step with no user
breakpoints set never returns; and IsAddressBreakPoint() (user-facing, for the
lists and disassembly markers) is now separate from NeedsBreakCheckAt() (what
the JIT frontends and interpreter ask), since only the latter should see it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GZq8ZtJmFY7bkX5FVkr3P9
Into()'s same-thread branch called Core_RequestCPUStep(CPUStepType::Into, 1)
without checking its return value. Core_RequestCPUStep() can genuinely
fail (a step/run request is already queued this host frame - see its own
"Can't submit two steps in one host frame" ERROR_LOG) - on failure, no
step happens and no cpu.stepping event ever fires, but cpu.stepInto's own
contract is "no immediate response, a cpu.stepping event follows", so a
rejected request looked identical to a request still in flight: nothing
to distinguish "wait longer" from "this silently failed, nothing is ever
coming." This is part of the same failure family as the delay-slot race
just fixed in PrepareResume() (previous commit) - Core_RequestCPUStep()'s
one-at-a-time guard rejecting a step no caller in this file checked for.
Now calls req.Fail() on rejection so the client gets an explicit answer
instead of an indefinite wait. Updated the cpu.stepInto doc comment to
note the new (retryable) failure mode.
Verified via UnitTest.exe all (49/49).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GZq8ZtJmFY7bkX5FVkr3P9
PrepareResume() used Core_RequestCPUStep(CPUStepType::Into, 1) to step past a
delay slot instruction before deciding whether to add a breakpoint and call
Core_Resume() - but Core_RequestCPUStep() only queues that step for
Core_ProcessStepping() to perform later (on the next iteration of the normal
stepping-mode loop). Every caller (Into's cross-thread branch, Over, Out,
RunUntil, HLE) immediately inspected currentMIPS->pc/inDelaySlot right after
PrepareResume() returned to decide what to do next - reading stale,
pre-step state, since the queued step hadn't run yet.
Worse: those callers then call Core_Resume(), which sets coreState back to
CORE_RUNNING_CPU. Core_ProcessStepping() only processes g_cpuStepCommand
when coreState is CORE_STEPPING_CPU/STEPPING_GE/RUNNING_GE, so once resumed,
the queued step is never processed at all - not just late, silently dropped,
leaving g_cpuStepCommand permanently set until the next Core_Break() resets
it. Any cpu.step*/cpu.runUntil request a client issues in that window (CPU
resumed running, breakpoint not yet hit again) hits
Core_RequestCPUStep()'s "Can't submit two steps in one host frame" guard and
is silently ignored, since none of these call sites check its return value -
this is the "step-out sometimes just doesn't do anything" flakiness reported
against this file.
PrepareResume() is only ever called from within a Core_RunOnCPUThread()
callback, so it's always already running on the CPU thread - safe to
single-step synchronously (currentMIPS->SingleStep(), matching how
Core_PerformCPUStep()'s own CPUStepType::Into case does it) instead of
queuing an async request whose completion every caller then assumes without
verifying.
Verified via UnitTest.exe all (49/49). Attempted to force a live repro via
wsdbg against a delay-slot jal in a demo ELF; wasn't able to reliably
trigger the failure window externally (by the time a client's next command
arrives, the CPU has typically already reached its next breakpoint and
Core_Break() has cleaned up the stale state first) - the race window is
real per the code trace above but appears to be narrow enough that it
mainly shows up under real usage timing (a slow-to-reach next breakpoint,
or a fast follow-up command from a script/UI), not simple synchronous
scripting. The fix is unconditionally more correct regardless: it replaces
a fire-and-forget async request every caller immediately assumed had
already completed with a direct synchronous call that actually has by the
time the next line runs.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GZq8ZtJmFY7bkX5FVkr3P9
Extends the cpu.stepInto treatment to cpu.stepOver, cpu.stepOut, cpu.runUntil,
and cpu.nextHLE: each now routes its breakpoint/stepping manipulation through
Core_RunOnCPUThread() instead of touching it directly from the WebSocket
handler thread. cpu.runUntil didn't have an explicit "must be stepping"
guard to begin with; since the CPU-thread queue is now drained unconditionally
at the top of every Core_RunLoopUntil() iteration (not just while stepping),
queuing from it is safe regardless of current core state.
Also corrects a stale comment on Core_RunOnCPUThread() left over from before
the drain point moved from Core_ProcessStepping() to the top of
Core_RunLoopUntil() - it's not limited to the stepping/paused case.
Replaced remaining `auto` locals in this file with concrete types.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hqm11k99viLfbJm2MkH4BH
The WebSocket debugger's cpu.stepInto handler ran entirely on the WebSocket
handler thread, directly manipulating breakpoints and stepping state (via
Core_RequestCPUStep, g_breakpoints.SetSkipFirst, etc.) that's otherwise only
ever touched from the CPU thread (the one that calls Core_RunLoopUntil, and
thus indirectly NativeFrame).
Adds Core_RunOnCPUThread() - queues a function to run on the CPU thread and
blocks the caller until it's done. The queue is drained at the top of
Core_RunLoopUntil()'s loop, so it's reached continuously (in a tight spin)
while the CPU is stepping/paused, and at least once per call even while fully
running.
cpu.stepInto is the first consumer: once the CPU is already stepping, the
breakpoint/stepping manipulation is now routed through Core_RunOnCPUThread
instead of happening directly on the WebSocket thread. The "not currently
stepping" path still calls Core_Break() directly from the WebSocket thread,
since it's already documented free-threaded and is what makes the CPU thread
start reaching the queue-drain point in the first place.
More WebSocket debugger commands can be converted the same way going forward.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hqm11k99viLfbJm2MkH4BH
DisassemblyManager used to fuse lui+addiu/load/store into single pseudo-
instructions ("li", fused loads/stores) for display. This only applied to a
handful of opcodes, complicated DisassemblyManager, and was the root cause of
a stepping bug: Core_PerformCPUStep's Into/Over cases treated stepSize as a
byte count, while the WebSocket cpu.stepInto handler computed it as an
instruction count (needed to step over a whole fused macro in one go) - so a
plain, non-fused stepInto silently executed zero instructions.
Removed the fusion logic entirely (DisassemblyMacro, DISTYPE_MACRO) - every
disassembly line is now exactly one 4-byte instruction. With that,
"how many instructions does this line span" is always 1, so the
getInstructionSizeAt() byte-size queries in the legacy Windows and ImGui
debuggers are gone too; step requests just pass 1. Core_RequestCPUStep's
stepSize is now consistently in instructions everywhere.
Also fixes the PPSSPPHeadless build, broken since 0ed1f3e added
OpenWebDebugger() (which calls System_LaunchUrl) without a headless stub.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hqm11k99viLfbJm2MkH4BH
