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# Lldb-server crash
We have seen stacks like the following in lldb-server core dumps:
```
[
"__GI___pthread_kill at pthread_kill.c:46",
"__GI_raise at raise.c:26",
"__GI_abort at abort.c:100",
"__assert_fail_base at assert.c:92",
"__GI___assert_fail at assert.c:101",
"lldb_private::NativeProcessProtocol::RemoveSoftwareBreakpoint(unsigned long) at /redacted/lldb-server:0"
]
```
# Hypothesis of root cause
In `NativeProcessProtocol::RemoveSoftwareBreakpoint()`
([code](https://github.com/llvm/llvm-project/blob/19b2dd9d798c124406b0124a1b8debb711675281/lldb/source/Host/common/NativeProcessProtocol.cpp#L359-L423)),
a `ref_count` is asserted and reduced. If it becomes zero, the code
first go through a series of memory reads and writes to remove the
breakpoint trap opcode and to restore the original process code, then,
if everything goes fine, removes the entry from the map
`m_software_breakpoints` at the end of the function.
However, if any of the validations for the above reads and writes goes
wrong, the code returns an error early, skipping the removal of the
entry. This leaves the entry behind with a `ref_count` of zero.
The next call to `NativeProcessProtocol::RemoveSoftwareBreakpoint()` for
the same breakpoint[*] would violate the assertion about `ref_count > 0`
([here](https://github.com/llvm/llvm-project/blob/19b2dd9d798c124406b0124a1b8debb711675281/lldb/source/Host/common/NativeProcessProtocol.cpp#L365)),
which would cause a crash.
[*] We haven't found a *regular* way to repro such a next call in lldb
or lldb-dap. This is because both of them remove the breakpoint from
their internal list when they get any response from the lldb-server (OK
or error). Asking the client to delete the breakpoint a second time
doesn't trigger the client to send the `$z` gdb packet to lldb-server.
We are able to trigger the crash by sending the `$z` packet directly,
see "Manual test" below.
# Fix
Lift the removal of the map entry to be immediately after the decrement
of `ref_count`, before the early returns. This ensures that the asserted
case will never happen. The validation errors can still happen, and
whether they happen or not, the breakpoint has been removed from the
perspective of the lldb-server (same as that of lldb and lldb-dap).
# Manual test & unit test
See PR.
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This patch uses *Set::insert_range and a range constructor of DenseSet
to clean up the code to populate sets.
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(#107163)
…ror() [NFC]
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This patch removes all of the Set.* methods from Status.
This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.
This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()
Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form
` ResultTy DoFoo(Status& error)
`
to
` llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?
The interesting changes are in Status.h and Status.cpp, all other
changes are mostly
` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.
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Add MSP430 to the list of available targets, implement MSP430 ABI, add support for debugging targets with 16-bit address size.
The update is intended for use with MSPDebug, a GDB server implementation for MSP430.
Reviewed By: bulbazord, DavidSpickett
Differential Revision: https://reviews.llvm.org/D146965
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This reverts commit 82c02b733c7736507a41a26bebd37d3f8e88bd4e.
Apparently, the original patch was not rebased onto `main
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Add MSP430 to the list of available targets, implement MSP430 ABI, add support for debugging targets with 16-bit address size.
The update is intended for use with MSPDebug, a GDB server implementation for MSP430.
Reviewed By: bulbazord, DavidSpickett
Differential Revision: https://reviews.llvm.org/D146965
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This is a follow-up to D116372, which had a rather unfortunate side
effect of making the processing of a single SIGCHLD quadratic in the
number of threads -- which does not matter for simple applications, but
can get really bad for applications with thousands of threads.
This patch fixes the problem by implementing the other possibility
mentioned in the first patch -- doing waitpid(-1) centrally and then
routing the events to the correct process instance. The "uncollected"
threads are held in the process factory class -- which I've renamed to
Manager for this purpose, as it now does more than creating processes.
Differential Revision: https://reviews.llvm.org/D146977
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Similar to how `makeArrayRef` is deprecated in favor of deduction guides, do the
same for `makeMutableArrayRef`.
Once all of the places in-tree are using the deduction guides for
`MutableArrayRef`, we can mark `makeMutableArrayRef` as deprecated.
Differential Revision: https://reviews.llvm.org/D141814
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This is a follow-up to https://reviews.llvm.org/D140896, split into
several parts as it touches a lot of files.
Differential Revision: https://reviews.llvm.org/D141298
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This patch replaces (llvm::|)Optional< with std::optional<. I'll post
a separate patch to clean up the "using" declarations, #include
"llvm/ADT/Optional.h", etc.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
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This patch adds #include <optional> to those files containing
llvm::Optional<...> or Optional<...>.
I'll post a separate patch to actually replace llvm::Optional with
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
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This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
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Use `break 0x5` for LoongArch software breakpoint traps.
The magic number 0x5 means `BRK_SSTEPBP` as defined in
the kernel header `asm/break.h` on LoongArch.
Reviewed By: SixWeining, xen0n
Differential Revision: https://reviews.llvm.org/D137519
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Add:
- RV64C instructions sets.
- corresponding unittests.
- `c.break` code for lldb and lldb-server
Fix:
- wrong decoding of imm in `DecodeSType`
Reviewed By: DavidSpickett
Differential Revision: https://reviews.llvm.org/D136362
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Added:
- Take RISC-V `ebreak` instruction as breakpoint trap code, so our breakpoint works as expected now.
Further work:
- RISC-V does not support hardware single stepping yet. A software implementation may come in future PR.
- Add support for RVC extension (the trap code, etc.).
Reviewed By: DavidSpickett
Differential Revision: https://reviews.llvm.org/D131566
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context switch traces
- Add collection of context switches per cpu grouped with the per-cpu intel pt traces.
- Move the state handling from the interl pt trace class to the PerfEvent one.
- Add support for stopping and enabling perf event groups.
- Return context switch entries as part of the jLLDBTraceGetState response.
- Move the triggers of whenever the process stopped or resumed. Now the will-resume notification is in a better location, which will ensure that we'll capture the instructions that will be executed.
- Remove IntelPTSingleBufferTraceUP. The unique pointer was useless.
- Add unit tests
Differential Revision: https://reviews.llvm.org/D125897
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NativeProcessLinux is not able to properly read libraries-svr4 data when
running with ld.so as the "main" executable. Normally, this is not a big
problem, as it returns an error message, and lldb can fallback to manual
library loading.
Unfortunately, lldb-server also does not clear cached svr4 data on exec,
which means that it does *not* return an error when the application
execs from the "regular" to the "ld.so" mode. Instead it returns
incorrect data (it is missing the main executable) and causes
TestDyldExecLinux to fail (but only when building with xml support
enabled).
This patch makes ensures that cached process data is cleared on exec,
fixing the test. Since TestDyldExecLinux has shown to be sensitive to
the way we read library info, I fork it into two (with svr4 enabled and
disabled).
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tracing based on the process state
When tracing on per-core mode, we are tracing all processes, which means
that after hitting a breakpoint, our process will stop running (thus
producing no more tracing data) but other processes will continue
writing to our trace buffers. This causes a big data loss for our trace.
As a way to remediate this, I'm adding some logic to pause and unpause
tracing based on the target's state. The earlier we do it the better,
however, I'm not adding the trigger at the earliest possible point for
simplicity of this diff. Later we can improve that part.
Differential Revision: https://reviews.llvm.org/D124962
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Most of our code was including Log.h even though that is not where the
"lldb" log channel is defined (Log.h defines the generic logging
infrastructure). This worked because Log.h included Logging.h, even
though it should.
After the recent refactor, it became impossible the two files include
each other in this direction (the opposite inclusion is needed), so this
patch removes the workaround that was put in place and cleans up all
files to include the right thing. It also renames the file to LLDBLog to
better reflect its purpose.
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This is implemented using the QMemTags packet, as specified
by GDB in:
https://sourceware.org/gdb/current/onlinedocs/gdb/General-Query-Packets.html#General-Query-Packets
(recall that qMemTags was previously added to read tags)
On receipt of a valid packet lldb-server will:
* align the given address and length to granules
(most of the time lldb will have already done this
but the specification doesn't guarantee it)
* Repeat the supplied tags as many times as needed to cover
the range. (if tags > range we just use as many as needed)
* Call ptrace POKEMTETAGS to write the tags.
The ptrace step will loop just like the tag read does,
until all tags are written or we get an error.
Meaning that if ptrace succeeds it could be a partial write.
So we call it again and if we then get an error, return an error to
lldb.
We are not going to attempt to restore tags after a partial
write followed by an error. This matches the behaviour of the
existing memory writes.
The lldb-server tests have been extended to include read and
write in the same test file. With some updated function names
since "qMemTags" vs "QMemTags" isn't very clear when they're
next to each other.
Reviewed By: omjavaid
Differential Revision: https://reviews.llvm.org/D105180
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This adds memory tag reading using the new "qMemTags"
packet and ptrace on AArch64 Linux.
This new packet is following the one used by GDB.
(https://sourceware.org/gdb/current/onlinedocs/gdb/General-Query-Packets.html)
On AArch64 Linux we use ptrace's PEEKMTETAGS to read
tags and we assume that lldb has already checked that the
memory region actually has tagging enabled.
We do not assume that lldb has expanded the requested range
to granules and expand it again to be sure.
(although lldb will be sending aligned ranges because it happens
to need them client side anyway)
Also we don't assume untagged addresses. So for AArch64 we'll
remove the top byte before using them. (the top byte includes
MTE and other non address data)
To do the ptrace read NativeProcessLinux will ask the native
register context for a memory tag manager based on the
type in the packet. This also gives you the ptrace numbers you need.
(it's called a register context but it also has non register data,
so it saves adding another per platform sub class)
The only supported platform for this is AArch64 Linux and the only
supported tag type is MTE allocation tags. Anything else will
error.
Ptrace can return a partial result but for lldb-server we will
be treating that as an error. To succeed we need to get all the tags
we expect.
(Note that the protocol leaves room for logical tags to be
read via qMemTags but this is not going to be implemented for lldb
at this time.)
Reviewed By: omjavaid
Differential Revision: https://reviews.llvm.org/D95601
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In all this time, we've never used more than one delegate. The logic to
support multiple delegates is therefore untested, and becomes
particularly unwieldy once we need to support multiple processes.
Just remove it.
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Introduce a minimal support for the 32-bit powerpc platform. This
includes support for GPR and FPR registers. I also needed to add
software breakpoint opcode for PPC32/PPC64 (big endian), and to fix
offsets in RegisterInfos_powerpc.h (used only by FreeBSD register
context to be globally unique rather than relative to each struct).
Differential Revision: https://reviews.llvm.org/D95947
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Differential Revision: https://reviews.llvm.org/D77460
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Summary:
A *.cpp file header in LLDB (and in LLDB) should like this:
```
//===-- TestUtilities.cpp -------------------------------------------------===//
```
However in LLDB most of our source files have arbitrary changes to this format and
these changes are spreading through LLDB as folks usually just use the existing
source files as templates for their new files (most notably the unnecessary
editor language indicator `-*- C++ -*-` is spreading and in every review
someone is pointing out that this is wrong, resulting in people pointing out that this
is done in the same way in other files).
This patch removes most of these inconsistencies including the editor language indicators,
all the different missing/additional '-' characters, files that center the file name, missing
trailing `===//` (mostly caused by clang-format breaking the line).
Reviewers: aprantl, espindola, jfb, shafik, JDevlieghere
Reviewed By: JDevlieghere
Subscribers: dexonsmith, wuzish, emaste, sdardis, nemanjai, kbarton, MaskRay, atanasyan, arphaman, jfb, abidh, jsji, JDevlieghere, usaxena95, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D73258
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Summary: There are a few places in LLDB where we do a `reinterpret_cast` for conversions that we could also do with `static_cast`. This patch moves all this code to `static_cast`.
Reviewers: shafik, JDevlieghere, labath
Reviewed By: labath
Subscribers: arphaman, usaxena95, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D72161
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that runs on arm64 ISA targets, specifically
Apple watches.
Differential Revision: https://reviews.llvm.org/D68858
llvm-svn: 375032
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This patch replaces explicit calls to log::Printf with the new LLDB_LOGF
macro. The macro is similar to LLDB_LOG but supports printf-style format
strings, instead of formatv-style format strings.
So instead of writing:
if (log)
log->Printf("%s\n", str);
You'd write:
LLDB_LOG(log, "%s\n", str);
This change was done mechanically with the command below. I replaced the
spurious if-checks with vim, since I know how to do multi-line
replacements with it.
find . -type f -name '*.cpp' -exec \
sed -i '' -E 's/log->Printf\(/LLDB_LOGF\(log, /g' "{}" +
Differential revision: https://reviews.llvm.org/D65128
llvm-svn: 366936
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This reverts commit 9c10b620c0619611dfe062216459431955ac4801.
llvm-svn: 366848
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This reverts commit a7335393f50246b59db450dc6005f7c8f29e73a6.
It seems this is breaking a bunch of tests (https://reviews.llvm.org/D62503#1549874) so reverting until I find the time to repro and fix.
llvm-svn: 364355
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Summary:
This is the fifth patch to improve module loading in a series that started here (where I explain the motivation and solution): D62499
Reading strings with ReadMemory is really slow when reading the path of the shared library. This is because we don't know the length of the path so use PATH_MAX (4096) and these strings are actually super close to the boundary of an unreadable page. So even though we use process_vm_readv it will usually fail because the read size spans to the unreadable page and we then default to read the string word by word with ptrace.
This new function is very similar to another ReadCStringFromMemory that already exists in lldb that makes sure it never reads cross page boundaries and checks if we already read the entire string by finding '\0'.
I was able to reduce the GetLoadedSharedLibraries call from 30ms to 4ms (or something of that order).
Reviewers: clayborg, xiaobai, labath
Reviewed By: labath
Subscribers: emaste, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D62503
llvm-svn: 363750
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A lot of comments in LLDB are surrounded by an ASCII line to delimit the
begging and end of the comment.
Its use is not really consistent across the code base, sometimes the
lines are longer, sometimes they are shorter and sometimes they are
omitted. Furthermore, it looks kind of weird with the 80 column limit,
where the comment actually extends past the line, but not by much.
Furthermore, when /// is used for Doxygen comments, it looks
particularly odd. And when // is used, it incorrectly gives the
impression that it's actually a Doxygen comment.
I assume these lines were added to improve distinguishing between
comments and code. However, given that todays editors and IDEs do a
great job at highlighting comments, I think it's worth to drop this for
the sake of consistency. The alternative is fixing all the
inconsistencies, which would create a lot more churn.
Differential revision: https://reviews.llvm.org/D60508
llvm-svn: 358135
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to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
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Thanks to Dávid Bolvanský for pointing that out.
llvm-svn: 346094
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Summary:
A fairly simple operation as setting a breakpoint (writing a breakpoint
opcode) at a given address was going through three classes:
NativeProcessProtocol which called NativeBreakpointList, which then
called SoftwareBrekpoint, only to end up again in NativeProcessProtocol
to do the actual writing itself. This is unnecessarily complex and can
be simplified by moving all of the logic into NativeProcessProtocol
class itself, removing a lot of boilerplate.
One of the reeasons for this complexity was that (it seems)
NativeBreakpointList class was meant to hold both software and hardware
breakpoints. However, that never materialized, and hardware breakpoints
are stored in a separate map holding only hardware breakpoints.
Essentially, this patch makes software breakpoints follow that approach
by replacing the heavy SoftwareBraekpoint with a light struct of the
same name, which holds only the data necessary to describe one
breakpoint. The rest of the logic is in the main class. As, at the
lldb-server level, handling software and hardware breakpoints is very
different, this seems like a reasonable state of things.
Reviewers: krytarowski, zturner, clayborg
Subscribers: mgorny, lldb-commits
Differential Revision: https://reviews.llvm.org/D52941
llvm-svn: 346093
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Summary:
This function existed (with identical code) in both NativeProcessLinux
and NativeProcessNetBSD, and it is likely that it would be useful to any
future implementation of NativeProcessProtocol.
Therefore I move it to the base class.
Reviewers: krytarowski
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D52719
llvm-svn: 343683
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Summary:
This function encodes the knowledge of whether the PC points to the
breakpoint instruction of the one following it after the breakpoint is
"hit". This behavior mainly(*) depends on the architecture and not on the
OS, so it makes sense for it to be implemented in the base class, where
it can be shared between different implementations (Linux and NetBSD
atm).
(*) It is possible for an OS to expose a different API, perhaps by doing
some fixups in the kernel. In this case, the implementation can override
this function to implement custom behavior.
Reviewers: krytarowski, zturner
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D52532
llvm-svn: 343409
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The two existing implementations have the function implemented
identically, and there's no reason to believe that this would be
different for other implementations.
llvm-svn: 342167
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llvm-svn: 341759
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This recommits r341487, which was reverted due to failing tests with
clang. It turned out I had incorrectly expected that the literal arrays
passed to ArrayRef constructor will have static (permanent) storage.
This was only the case with gcc, while clang was constructing them on
stack, leading to dangling pointers when the function returns.
The fix is to explicitly assign static storage duration to the opcode
arrays.
llvm-svn: 341758
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This reverts commit r341487. Jan Kratochvil reports it breaks LLDB when
compiling with clang.
llvm-svn: 341747
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return the opcode as a Expected<ArrayRef> instead of a
Status+pointer+size combo.
I also move the linux implementation to the base class, as the trap
opcodes are likely to be the same for all/most implementations of the
class (except the arm one, where linux chooses a different opcode than
what the arm spec recommends, which I keep linux-specific).
llvm-svn: 341487
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These three classes have no external dependencies, but they are used
from various low-level APIs. Moving them down to Utility improves
overall code layering (although it still does not break any particular
dependency completely).
The XCode project will need to be updated after this change.
Differential Revision: https://reviews.llvm.org/D49740
llvm-svn: 339127
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This re-lands r332250/D46395, after fixing Mac build errors.
llvm-svn: 332353
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The first fix wasn't enough, there is still a missing
ProcessInstanceInfo include in Host.mm. I won't be able to test a fix
before leaving work, so I am reverting both commits.
This reverts commit r332250 and the subsequent fix attempt.
llvm-svn: 332261
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The Process class was only being referenced because of the last-ditch
effort in the process launchers to set a process death callback in case
one isn't set already.
Although launching a process for debugging is the most important kind of
"launch" we are doing, it is by far not the only one, so assuming this
particular callback is the one to be used is not a good idea (besides
breaking layering). Instead of assuming a particular exit callback, I
change the launcher code to require the callback to be set by the user (and fix
up the two call sites which did not set the callback already).
Reviewers: jingham, davide
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D46395
llvm-svn: 332250
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