llvm-project.git/lldb/source/Plugins/Process/scripted/ScriptedThread.cpp, branch users/mingmingl-llvm/samplefdo-profile-format

[lldb] Introduce ScriptedFrame affordance (#149622)

2025-09-04T22:07:11+00:00

This patch introduces a new scripting affordance in lldb:
`ScriptedFrame`.

This allows user to produce mock stackframes in scripted threads and
scripted processes from a python script.

With this change, StackFrame can be synthetized from different sources:
- Either from a dictionary containing a load address, and a frame index,
  which is the legacy way.
- Or by creating a ScriptedFrame python object.

One particularity of synthezising stackframes from the ScriptedFrame
python object, is that these frame have an optional PC, meaning that
they don't have a report a valid PC and they can act as shells that just
contain static information, like the frame function name, the list of
variables or registers, etc. It can also provide a symbol context.

rdar://157260006

Signed-off-by: Med Ismail Bennani 

Signed-off-by: Med Ismail Bennani

[lldb] Mark scripted frames as synthetic instead of artificial (#153117)

2025-09-03T22:58:14+00:00

This patch changes the way frames created from scripted affordances like
Scripted Threads are displayed. Currently, they're marked artificial
which is used usually for compiler generated frames.

This patch changes that behaviour by introducing a new synthetic
StackFrame kind and moves 'artificial' to be a distinct StackFrame
attribut.

On top of making these frames less confusing, this allows us to know
when a frame was created from a scripted affordance.

rdar://155949703

Signed-off-by: Med Ismail Bennani

[lldb] Change lldb's breakpoint handling behavior, reland (#126988)

2025-02-13T19:30:10+00:00

lldb today has two rules: When a thread stops at a BreakpointSite, we
set the thread's StopReason to be "breakpoint hit" (regardless if we've
actually hit the breakpoint, or if we've merely stopped *at* the
breakpoint instruction/point and haven't tripped it yet). And second,
when resuming a process, any thread sitting at a BreakpointSite is
silently stepped over the BreakpointSite -- because we've already
flagged the breakpoint hit when we stopped there originally.

In this patch, I change lldb to only set a thread's stop reason to
breakpoint-hit when we've actually executed the instruction/triggered
the breakpoint. When we resume, we only silently step past a
BreakpointSite that we've registered as hit. We preserve this state
across inferior function calls that the user may do while stopped, etc.

Also, when a user adds a new breakpoint at $pc while stopped, or changes
$pc to be the address of a BreakpointSite, we will silently step past
that breakpoint when the process resumes. This is purely a UX call, I
don't think there's any person who wants to set a breakpoint at $pc and
then hit it immediately on resuming.

One non-intuitive UX from this change, butt is necessary: If you're
stopped at a BreakpointSite that has not yet executed, you `stepi`, you
will hit the breakpoint and the pc will not yet advance. This thread has
not completed its stepi, and the ThreadPlanStepInstruction is still on
the stack. If you then `continue` the thread, lldb will now stop and
say, "instruction step completed", one instruction past the
BreakpointSite. You can continue a second time to resume execution.

The bugs driving this change are all from lldb dropping the real stop
reason for a thread and setting it to breakpoint-hit when that was not
the case. Jim hit one where we have an aarch64 watchpoint that triggers
one instruction before a BreakpointSite. On this arch we are notified of
the watchpoint hit after the instruction has been unrolled -- we disable
the watchpoint, instruction step, re-enable the watchpoint and collect
the new value. But now we're on a BreakpointSite so the watchpoint-hit
stop reason is lost.

Another was reported by ZequanWu in
https://discourse.llvm.org/t/lldb-unable-to-break-at-start/78282 we
attach to/launch a process with the pc at a BreakpointSite and
misbehave. Caroline Tice mentioned it is also a problem they've had with
putting a breakpoint on _dl_debug_state.

The change to each Process plugin that does execution control is that

1. If we've stopped at a BreakpointSite that has not been executed yet,
we will call Thread::SetThreadStoppedAtUnexecutedBP(pc) to record that.
When the thread resumes, if the pc is still at the same site, we will
continue, hit the breakpoint, and stop again.

2. When we've actually hit a breakpoint (enabled for this thread or
not), the Process plugin should call
Thread::SetThreadHitBreakpointSite(). When we go to resume the thread,
we will push a step-over-breakpoint ThreadPlan before resuming.

The biggest set of changes is to StopInfoMachException where we
translate a Mach Exception into a stop reason. The Mach exception codes
differ in a few places depending on the target (unambiguously), and I
didn't want to duplicate the new code for each target so I've tested
what mach exceptions we get for each action on each target, and
reorganized StopInfoMachException::CreateStopReasonWithMachException to
document these possible values, and handle them without specializing
based on the target arch.

I first landed this patch in July 2024 via
https://github.com/llvm/llvm-project/pull/96260

but the CI bots and wider testing found a number of test case failures
that needed to be updated, I reverted it. I've fixed all of those issues
in separate PRs and this change should run cleanly on all the CI bots
now.

rdar://123942164

Revert "[lldb] Change lldb's breakpoint handling behavior (#96260)"

2024-07-20T01:43:53+00:00

This reverts commit 05f0e86cc895181b3d2210458c78938f83353002.

The debuginfo dexter tests are failing, probably because the way
stepping over breakpoints has changed with my patches.  And there
are two API tests fails on the ubuntu-arm (32-bit) bot. I'll need
to investigate both of these, neither has an obvious failure reason.

[lldb] Change lldb's breakpoint handling behavior (#96260)

2024-07-20T00:26:13+00:00

lldb today has two rules: When a thread stops at a BreakpointSite, we
set the thread's StopReason to be "breakpoint hit" (regardless if we've
actually hit the breakpoint, or if we've merely stopped *at* the
breakpoint instruction/point and haven't tripped it yet). And second,
when resuming a process, any thread sitting at a BreakpointSite is
silently stepped over the BreakpointSite -- because we've already
flagged the breakpoint hit when we stopped there originally.

In this patch, I change lldb to only set a thread's stop reason to
breakpoint-hit when we've actually executed the instruction/triggered
the breakpoint. When we resume, we only silently step past a
BreakpointSite that we've registered as hit. We preserve this state
across inferior function calls that the user may do while stopped, etc.

Also, when a user adds a new breakpoint at $pc while stopped, or changes
$pc to be the address of a BreakpointSite, we will silently step past
that breakpoint when the process resumes. This is purely a UX call, I
don't think there's any person who wants to set a breakpoint at $pc and
then hit it immediately on resuming.

One non-intuitive UX from this change, but I'm convinced it is
necessary: If you're stopped at a BreakpointSite that has not yet
executed, you `stepi`, you will hit the breakpoint and the pc will not
yet advance. This thread has not completed its stepi, and the thread
plan is still on the stack. If you then `continue` the thread, lldb will
now stop and say, "instruction step completed", one instruction past the
BreakpointSite. You can continue a second time to resume execution. I
discussed this with Jim, and trying to paper over this behavior will
lead to more complicated scenarios behaving non-intuitively. And mostly
it's the testsuite that was trying to instruction step past a breakpoint
and getting thrown off -- and I changed those tests to expect the new
behavior.

The bugs driving this change are all from lldb dropping the real stop
reason for a thread and setting it to breakpoint-hit when that was not
the case. Jim hit one where we have an aarch64 watchpoint that triggers
one instruction before a BreakpointSite. On this arch we are notified of
the watchpoint hit after the instruction has been unrolled -- we disable
the watchpoint, instruction step, re-enable the watchpoint and collect
the new value. But now we're on a BreakpointSite so the watchpoint-hit
stop reason is lost.

Another was reported by ZequanWu in
https://discourse.llvm.org/t/lldb-unable-to-break-at-start/78282 we
attach to/launch a process with the pc at a BreakpointSite and
misbehave. Caroline Tice mentioned it is also a problem they've had with
putting a breakpoint on _dl_debug_state.

The change to each Process plugin that does execution control is that

1. If we've stopped at a BreakpointSite that has not been executed yet,
we will call Thread::SetThreadStoppedAtUnexecutedBP(pc) to record
that.  When the thread resumes, if the pc is still at the same site, we
will continue, hit the breakpoint, and stop again.

2. When we've actually hit a breakpoint (enabled for this thread or not),
the Process plugin should call Thread::SetThreadHitBreakpointSite().
When we go to resume the thread, we will push a step-over-breakpoint
ThreadPlan before resuming.

The biggest set of changes is to StopInfoMachException where we
translate a Mach Exception into a stop reason. The Mach exception codes
differ in a few places depending on the target (unambiguously), and I
didn't want to duplicate the new code for each target so I've tested
what mach exceptions we get for each action on each target, and
reorganized StopInfoMachException::CreateStopReasonWithMachException to
document these possible values, and handle them without specializing
based on the target arch.

rdar://123942164

[lldb] Change interface of StructuredData::Array::GetItemAtIndexAsDictionary (#71961)

2023-11-10T20:47:43+00:00

Similar to my previous patch (#71613) where I changed
`GetItemAtIndexAsString`, this patch makes the same change to
`GetItemAtIndexAsDictionary`.

`GetItemAtIndexAsDictionary` now returns a std::optional that is either
`std::nullopt` or is a valid pointer. Therefore, if the optional is
populated, we consider the pointer to always be valid (i.e. no need to
check pointer validity).

[lldb] Fix assertions caused by un-checked errors in ScriptedProcess

2023-10-26T00:31:02+00:00

This patch should fix some assertion that started getting hit after f22d82c.

That commit changed the scripted object plugin creation to use
`llvm::Expected` as a return type to enforce error handling, however
I forgot to handle the error which caused the assert.

The interesting  part about this, is that since that assert was triggered
in the ScriptedProcess constructor (where the `llvm::Error` wasn't
handled), that impacted every test that launched any kind of process,
since the process plugin manager would eventually also iterate over the
`ScriptedProcess::Create` factory method.

This patch should fix the assertions by handling the errors.

Signed-off-by: Med Ismail Bennani

[lldb/Interpreter] Make ScriptedInterface Object creation more generic (#68052)

2023-10-25T17:05:54+00:00

This patch changes the way plugin objects used with Scripted Interfaces
are created.

Instead of implementing a different SWIG method to create the object for
every scripted interface, this patch makes the creation more generic by
re-using some of the ScriptedPythonInterface templated Dispatch code.

This patch also improves error handling of the object creation by
returning an `llvm::Expected`.

Signed-off-by: Med Ismail Bennani 

Signed-off-by: Med Ismail Bennani

[lldb] Fix failure in TestStackCoreScriptedProcess on x86_64

2023-06-21T17:57:13+00:00

This patch should address the failure of TestStackCoreScriptedProcess
that is happening specifically on x86_64.

It turns out that in 1370a1cb5b97, I changed the way we extract integers
from a `StructuredData::Dictionary` and in order to get a stop info from
the scripted process, we call a method that returns a `SBStructuredData`
containing the stop reason data.

TestStackCoreScriptedProcess` was failing specifically on x86_64 because
the stop info dictionary contains the signal number, that the `Scripted
Thread` was trying to extract as a signed integer where it was actually
parsed as an unsigned integer. That caused `GetValueForKeyAsInteger` to
return the default value parameter, `LLDB_INVALID_SIGNAL_NUMBER`.

This patch address the issue by extracting the signal number with the
appropriate type and re-enables the test.

Differential Revision: https://reviews.llvm.org/D152848

Signed-off-by: Med Ismail Bennani

[lldb] Introduce DynamicRegisterInfo::CreateFromDict

2023-06-15T17:51:17+00:00

I want to add some error handling to DynamicRegisterInfo because there
are many operations that can fail and many of these operations do not
give meaningful information back to the caller.

To begin that process, I want to add a static method that is responsible
for creating a DynamicRegisterInfo from a StructuredData::Dictionary
(and ArchSpec). This is meant to replace the equivalent constructor
because constructors are ill-equipped to perform error handling.

Differential Revision: https://reviews.llvm.org/D152594