Commit Graph

408 Commits

Author SHA1 Message Date
Med Ismail Bennani
46796762af [lldb/Plugins] Add ScriptedProcess Process Plugin
This patch introduces Scripted Processes to lldb.

The goal, here, is to be able to attach in the debugger to fake processes
that are backed by script files (in Python, Lua, Swift, etc ...) and
inspect them statically.

Scripted Processes can be used in cooperative multithreading environments
like the XNU Kernel or other real-time operating systems, but it can
also help us improve the debugger testing infrastructure by writting
synthetic tests that simulates hard-to-reproduce process/thread states.

Although ScriptedProcess is not feature-complete at the moment, it has
basic execution capabilities and will improve in the following patches.

rdar://65508855

Differential Revision: https://reviews.llvm.org/D95713

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2021-03-01 21:13:32 +01:00
Med Ismail Bennani
2cff3dec11 [lldb/bindings] Add Python ScriptedProcess base class to lldb module
In order to facilitate the writting of Scripted Processes, this patch
introduces a `ScriptedProcess` python base class in the lldb module.

The base class holds the python interface with all the - abstract -
methods that need to be implemented by the inherited class but also some
methods that can be overwritten.

This patch also provides an example of a Scripted Process with the
`MyScriptedProcess` class.

rdar://65508855

Differential Revision: https://reviews.llvm.org/D95712

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2021-03-01 21:13:32 +01:00
Michał Górny
15f067f1c7 [lldb] [test] Workaround symlink-related test failures
Use realpath() when spawning the executable create_after_attach
to workaround a FreeBSD plugin (and possibly others) problem.
If the executable is started via a path containing a symlink, it is
added to the module list twice -- via the real and apparent path.
This in turn cases the requested breakpoint to resolve twice.

Use realpath() for main program path in lldb-vscode breakpoint tests
to workaround a similar problem.  If the passed path does not match
the realpath, lldb-vscode does not report the breakpoints as verified
and causes tests to fail.

Since the underlying problems are non-trivial to fix and the purpose
of these tests is not to reproduce symlink problems, let's apply
trivial workarounds to make them pass.

Differential Revision: https://reviews.llvm.org/D97230
2021-03-01 16:23:36 +01:00
Dave Lee
3a677b29a3 [lldb] Add deref support to libc++ unique_ptr synthetic
Add frame variable dereference suppport to libc++ `std::unique_ptr`.

This change allows for commands like `v *thing_up` and `v thing_up->m_id`. These commands now work the same way they would with raw pointers, and as they would with expression. This is done by adding an unaccounted for child member named `$$dereference$$`.

Without this change, the command would have to be written as `v *thing_up.__value_` or v thing_up.__value_->m_id` which exposes internal structure and is more clumsy to type.

Additionally, the existing tests were updated. See also https://reviews.llvm.org/D97165 which added deref support for `std::shared_ptr`.

Differential Revision: https://reviews.llvm.org/D97524
2021-02-26 07:39:01 -08:00
Dave Lee
0ac42fd26d [lldb] Add deref support and tests to shared_ptr synthetic
Add `frame variable` dereference suppport to libc++ `std::shared_ptr`.

This change allows for commands like `v *thing_sp` and `v thing_sp->m_id`. These
commands now work the same way they do with raw pointers. This is done by adding an
unaccounted for child member named `$$dereference$$`.

Also, add API tests for `std::shared_ptr`, previously there were none.

Differential Revision: https://reviews.llvm.org/D97165
2021-02-23 09:03:46 -08:00
António Afonso
b19d3b092d Revert "Make sure the interpreter module was loaded before making checks against it"
This reverts commit a83a825e99.
2021-02-21 10:38:25 -08:00
António Afonso
a83a825e99 Make sure the interpreter module was loaded before making checks against it
This issue was introduced in https://reviews.llvm.org/D92187.
The guard I'm changing were is supposed to act when linux is loading the linker for the second time (due to differences in paths like symlinks).
This is done by checking `module_sp != m_interpreter_module.lock()` however this will be true when `m_interpreter_module` wasn't initialized, making linux unload the linker module (the most visible result here is that lldb will stop getting notified about new modules loaded by the process, because it can't set the rendezvous breakpoint again after the stepping over it once).
The `m_interpreter_module` is not getting initialize when it goes through this path: dbfdb139f7/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp (L332), which happens when lldb was able to read the address from the dynamic section of the executable.

What I'm not sure about though, is if when we go through this path if we still load the linker twice on linux. If that's the case then it means we need to somehow set the m_interpreter_module instead of the fix I provide here. I've only tested this on Android.

Differential Revision: https://reviews.llvm.org/D96637
2021-02-21 09:28:04 -08:00
Pavel Labath
004a264f8c [lldb] Fix shared library directory computation on windows
Our code for locating the shared library directory works via dladdr (or
the windows equivalent) to locate the path of an address known to reside
in liblldb. This works great for C++ programs, but there's a catch.

When (lib)lldb is used from python (like in our test suite), this dladdr
call will return a path to the _lldb.so (or such) file in the python
directory. To compensate for this, we have code which attempts to
resolve this symlink, to ensure we get the canonical location. However,
here's the second catch.

On windows, this file is not a symlink (but a copy), so this logic
fails. Since most of our other paths are derived from the liblldb
location, all of these paths will be wrong, when running the test suite.
One effect of this was the failure to find lldb-server in D96202.

To fix this issue, I add some windows-specific code to locate the
liblldb directory. Since it cannot rely on symlinks, it works by
manually walking the directory tree -- essentially doing the opposite of
what we do when computing the python directory.

To avoid python leaking back into the host code, I implement this with
the help of a callback which can be passed to HostInfo::Initialize in
order to assist with the directory location. The callback lives inside
the python plugin.

I also strenghten the existing path test to ensure the returned path is
the right one.

Differential Revision: https://reviews.llvm.org/D96779
2021-02-18 15:37:52 +01:00
Raphael Isemann
f88b502d9b [FileCollector] Fix that the file system case-sensitivity check was inverted
real_path returns an `std::error_code` which evaluates to `true` in case an
error happens and `false` if not. This code was checking the inverse, so
case-insensitive file systems ended up being detected as case sensitive.

Tested using an LLDB reproducer test as we anyway need a real file system and
also some matching logic to detect whether the respective file system is
case-sensitive (which the test is doing via some Python checks that we can't
really emulate with the usual FileCheck logic).

Fixes rdar://67003004

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D96795
2021-02-16 20:21:32 +01:00
Muhammad Omair Javaid
8561ad9296 Use remote regnums in expedited list, value regs and invalidate regs
Native register descriptions in LLDB specify lldb register numbers in
value_regs and invalidate_regs lists. These register numbers may not
match with Process gdb-remote register numbers which are generated by
native process after counting all registers in its register sets.

It was coincidentally not causing any problems as we never came across
a native target with dynamically changing register sets and register
numbers generated by counter matched with LLDB native register numbers.
This came up while testing target AArch64 SVE which can choose register
sets based on underlying hardware.

This patch fixes this behavior and always tries to use remote register
numbers while reading/writing registers over gdb-remote protocol.

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D77043
2021-02-08 14:09:15 +05:00
Djordje Todorovic
9abd8c1a4c [elf-core] Improve reading memory from core file
This patch tries to improve memory-read from core files
(in order to improve disassembly functionality).

I am using RHEL 7.7 (linux kernel 3.10) and for a lot of cases,
I was not able to disassemble some functions from backtrace when
debugging crashes from core files. It outputs some dummy code.

The cause of the problem was the fact we are returning all the zeros
from ProcessElfCore::ReadMemory() that is being called within
Disassembler::ParseInstructions() and it disassembles some dummy
opcodes from the buffer returned. Therefore, we are removing zero
bytes filling (padding) completely.

Differential Revision: https://reviews.llvm.org/D93939
2021-02-08 00:14:32 -08:00
Dave Lee
3cc3762292 [lldb] Use assertIn/NotIn over assertTrue/False (NFC)
For improved failure messages, use `assertIn` over `assertTrue`.

Differential Revision: https://reviews.llvm.org/D96095
2021-02-06 11:52:01 -08:00
Dave Lee
0ed758b260 [lldb] Convert more assertTrue to assertEqual (NFC)
Follow up to D95813, this converts multiline assertTrue to assertEqual.

Differential Revision: https://reviews.llvm.org/D95899
2021-02-03 21:15:08 -08:00
Dave Lee
619e2e095f [lldb] Convert assertTrue(a == b) to assertEqual(a, b)
Convert `assertTrue(a == b)` to `assertEqual(a, b)` to produce better failure messages.

These were mostly done via regex search & replace, with some manual fixes.

Differential Revision: https://reviews.llvm.org/D95813
2021-02-02 12:39:03 -08:00
Walter Erquinigo
4bb6244871 [ThreadPlan] fix exec on Linux 2021-01-25 11:30:48 -08:00
Shafik Yaghmour
dc057e87f6 [LLDB] Fix how ObjCBOOLSummaryProvider deals with BOOL
ObjCBOOLSummaryProvider was incorrectly treating BOOL as unsigned and this is now fixed.
Also adding tests for one bit bit-fields of BOOL and unsigned char.
2021-01-22 10:05:24 -08:00
Raphael Isemann
ed2853d2c8 Reland [lldb] Fix TestThreadStepOut.py after "Flush local value map on every instruction"
The original patch got reverted as a dependency of cf1c774d6a .
That patch got relanded so it's also necessary to reland this patch.

Original summary:

After cf1c774d6a, Clang seems to generate code
that is more similar to icc/Clang, so we can use the same line numbers for
all compilers in this test.
2021-01-21 13:35:13 +01:00
Raphael Isemann
060b51e052 [lldb] Make TestBSDArchives a no-debug-info-test
The DSYM variant of this test is failing since D94890. But as we explicitly
try to disable the DSYM generation in the makefile and build the archive on
our own, I don't see why we even need to run the DSYM version of the test.

This patch disables the generated derived versions of this test for the
different debug information containers (which includes the failing DSYM one).
2021-01-21 13:06:48 +01:00
Fangrui Song
6afdf13ae4 Makefile.rules: Avoid redundant .d generation (make restart) and inline archive rule to the only test
Take an example when `CXX_SOURCES` is main.cpp.

main.d is an included file. make will rebuild main.d, re-executes itself [1] to read
in the new main.d file, then rebuild main.o, finally link main.o into a.out.
main.cpp is parsed twice in this process.

This patch merges .d generation into .o generation [2], writes explicit rules
for .c/.m and deletes suffix rules for %.m and %.o. Since a target can be
satisfied by either of .c/.cpp/.m/.mm, we use multiple pattern rules. The
rule with the prerequisite (with VPATH considered) satisfied is used [3].

Since suffix rules are disabled, the implicit rule for archive member targets is
no long available [4]. Rewrite, simplify the archive rule and inline it into the
only test `test/API/functionalities/archives/Makefile`.

[1]: https://www.gnu.org/software/make/manual/html_node/Remaking-Makefiles.html
[2]: http://make.mad-scientist.net/papers/advanced-auto-dependency-generation/
[3]: https://www.gnu.org/software/make/manual/html_node/Pattern-Match.html
[4]: https://www.gnu.org/software/make/manual/html_node/Archive-Update.html

ObjC/ObjCXX tests only run on macOS. I don't have testing environment.  Hope
someone can do it for me.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D94890
2021-01-20 14:22:33 -08:00
Michał Górny
99562332e3 [lldb] [test] Update test status for NetBSD 2020-12-20 11:32:43 +01:00
Michał Górny
8666b9057f [lldb] [POSIX-DYLD] Add libraries from initial rendezvous brkpt hit
Explicitly consider the libraries reported on the initial rendezvous
breakpoint hit added.  This is necessary on FreeBSD since the dynamic
loader issues only a single 'consistent' state rendezvous breakpoint hit
for all the libraries present in DT_NEEDED.  It is also helpful on Linux
where it ensures that ld-linux is considered loaded as well
as the shared system libraries reported afterwards.

Reenable memory maps on FreeBSD since this fixed the issue triggered
by them.

Differential Revision: https://reviews.llvm.org/D92187
2020-12-17 09:31:10 +01:00
Med Ismail Bennani
dc82890a77 [lldb/API] Expose Target::CreateBreakpoint(..., move_to_nearest_code) overload
This patch exposes the Target::CreateBreakpoint overload with the
boolean argument to move to the neareast code to the SBAPI.

This is useful when creating column breakpoints to restrict lldb's
resolution to the pointed source location, preventing it to go to the next
line.

rdar://72196842

Differential Revision: https://reviews.llvm.org/D93266

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2020-12-15 06:18:04 +01:00
Med Ismail Bennani
1d3f1eb855 Revert "[lldb/API] Expose Target::CreateBreakpoint(..., move_to_nearest_code) overload"
This reverts commit 04696ff002e7d311887b7b7e6e171340a0623dd9.

Exposing the LazyBool private type in SBTarget.h breaks some tests.
2020-12-15 06:18:04 +01:00
Med Ismail Bennani
04701698eb [lldb/API] Expose Target::CreateBreakpoint(..., move_to_nearest_code) overload
This patch exposes the Target::CreateBreakpoint overload with the
boolean argument to move to the neareast code to the SBAPI.

This is useful when creating column breakpoints to restrict lldb's
resolution to the pointed source location, preventing it to go to the next
line.

rdar://72196842

Differential Revision: https://reviews.llvm.org/D93266

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2020-12-15 04:24:44 +01:00
Michał Górny
733e2ae8cd Revert "[lldb] [POSIX-DYLD] Add libraries from initial eTakeSnapshot action"
This reverts commit 09b08833f3.

This code is wrong on Linux, and causes ld-linux and linux-vdso to be
reported twice.  I need to work on it more.
2020-12-07 15:58:49 +01:00
Michał Górny
77f0ea4b5b [lldb] [test] Fix continue_to_breakpoint() args in TestThreadStepOut
The test is skipped/xfailing on all platforms, so it seems that the API
got out of sync.  Fix that so it returns to a 'proper' failure
on FreeBSD.

Differential Revision: https://reviews.llvm.org/D92746
2020-12-07 09:56:51 +01:00
Michał Górny
09b08833f3 [lldb] [POSIX-DYLD] Add libraries from initial eTakeSnapshot action
Explicitly consider the libraries reported on the initial eTakeSnapshot
action added, through adding them to the added soentry list
in DYLDRendezvous::SaveSOEntriesFromRemote().  This is necessary
on FreeBSD since the dynamic loader issues only a single 'consistent'
state rendezvous breakpoint hit for all the libraries present
in DT_NEEDED (while Linux issues an added-consistent event pair).

Reenable memory maps on FreeBSD since this fixed the issue triggered
by them.

Differential Revision: https://reviews.llvm.org/D92187
2020-12-07 09:56:51 +01:00
Michał Górny
1a1cc0ba7d [lldb] [Platform/POSIX] Use gdb-remote plugin when attaching
Force gdb-remote plugin when attaching using the derivatives
of PlatformPOSIX class.  This is consistent with the behavior
for launching processes (via DebugProcess() method) and guarantees
consistent plugin choice on FreeBSD.

Differential Revision: https://reviews.llvm.org/D92667
2020-12-07 09:56:51 +01:00
Michał Górny
266c90fec8 [lldb] [test] Link FreeBSD test failures to bugs
Differential Revision: https://reviews.llvm.org/D92740
2020-12-07 09:56:50 +01:00
David Blaikie
615f63e149 Revert "[FastISel] Flush local value map on ever instruction" and dependent patches
This reverts commit cf1c774d6a.

This change caused several regressions in the gdb test suite - at least
a sample of which was due to line zero instructions making breakpoints
un-lined. I think they're worth investigating/understanding more (&
possibly addressing) before moving forward with this change.

Revert "[FastISel] NFC: Clean up unnecessary bookkeeping"
This reverts commit 3fd39d3694.

Revert "[FastISel] NFC: Remove obsolete -fast-isel-sink-local-values option"
This reverts commit a474657e30.

Revert "Remove static function unused after cf1c774."
This reverts commit dc35368ccf.

Revert "[lldb] Fix TestThreadStepOut.py after "Flush local value map on every instruction""
This reverts commit 53a14a47ee.
2020-12-01 14:26:23 -08:00
Michał Górny
e1f613ce3c [lldb] [test] Reenable two passing tests on FreeBSD
[Reenable TestReproducerAttach and TestThreadSpecificBpPlusCondition
on FreeBSD -- both seem to pass correctly now.
2020-12-01 23:25:45 +01:00
Muhammad Omair Javaid
78cb4562fa Make offset field optional in RegisterInfo packet for Arm64
This patch carries forward our aim to remove offset field from qRegisterInfo
packets and XML register description. I have created a new function which
returns if offset fields are dynamic meaning client can calculate offset on
its own based on register number sequence and register size. For now this
function only returns true for NativeRegisterContextLinux_arm64 but we can
test this for other architectures and make it standard later.

As a consequence we do not send offset field from lldb-server (arm64 for now)
while other stubs dont have an offset field so it wont effect them for now.
On the client side we have replaced previous offset calculation algorithm
with a new scheme, where we sort all primary registers in increasing
order of remote regnum and then calculate offset incrementally.

This committ also includes a test to verify all of above functionality
on Arm64.

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D91241
2020-12-02 03:19:43 +05:00
Raphael Isemann
53a14a47ee [lldb] Fix TestThreadStepOut.py after "Flush local value map on every instruction"
After cf1c774d6a, Clang seems to generate code
that is more similar to icc/Clang, so we can use the same line numbers for
all compilers in this test.
2020-11-26 09:43:47 +01:00
Jonas Devlieghere
b20f3cc5b5 [lldb] Add platform select to TestProcessConnect.py
Extend TestProcessConnect to cover the scenario fixed by
6c0cd5676e. This replaces
command-process-connect.test which would fail if port 4321
was open.
2020-11-23 18:02:00 -08:00
Michał Górny
a8f6f4e873 [lldb] [test] Restore Windows-skip on 'process connect' tests 2020-11-23 14:27:32 +01:00
Michał Górny
18e4272a4f [lldb] Prevent 'process connect' from using local-only plugins
Add a 'can_connect' parameter to Process plugin initialization, and use
it to filter plugins to these capable of remote connections.  This is
used to prevent 'process connect' from picking up a plugin that can only
be used locally, e.g. the legacy FreeBSD plugin.

Differential Revision: https://reviews.llvm.org/D91810
2020-11-23 09:48:55 +01:00
Michał Górny
97a2eac3a9 [lldb] [test] Un-XFAIL tests on freebsd/i386
Restrict i386-specific XFAIL on a few tests to non-FreeBSD systems,
as they pass on FreeBSD.

Differential Revision: https://reviews.llvm.org/D91645
2020-11-18 12:09:11 +01:00
Jonas Devlieghere
406ad18748 [lldb/DataFormatters] Display null C++ pointers as nullptr
Display null pointer as `nullptr`, `nil` and `NULL` for C++,
Objective-C/Objective-C++ and C respectively. The original motivation
for this patch was to display a null std::string pointer as nullptr
instead of "", but the fix seemed generic enough to be done for all
summary providers.

Differential revision: https://reviews.llvm.org/D77153
2020-11-12 15:24:06 -08:00
Raphael Isemann
d85cc03c9c [lldb] Add expect_var_path to test variable path results
This adds `expect_var_path` to test variable paths so we no longer have to
use `frame var` and find substrs in the command output. The behaviour
is identical with `expect_expr` (and it also uses the same checking backend),
but it instead calls `GetValueForVariablePath` to evaluate the string as a variable
path.

Also rewrites a few of the tests that previously used `frame variable` to use
`expect_var_path`.

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D90450
2020-11-12 16:14:48 +01:00
Raphael Isemann
da121fff11 [lldb] Introduce a LLDB printing policy for Clang type names that suppressed inline namespaces
Commit 5f12f4ff90 made suppressing inline namespaces
when printing typenames default to true. As we're using the inline namespaces
in LLDB to construct internal type names (which need internal namespaces in them
to, for example, differentiate libc++'s std::__1::string from the std::string
from libstdc++), this broke most of the type formatting logic.
2020-11-12 14:00:33 +01:00
Raphael Isemann
66ae40ebfb [lldb][test] Remove not_remote_testsuite_ready in favor of skipIfRemote decorator
Those two decorators have identical behaviour. This removes
`not_remote_testsuite_ready` as `skipIfRemote` seems more consistent with the
other decorator names we have

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D89376
2020-11-11 09:14:54 +01:00
Michał Górny
f21e704d4a [lldb] [Process/NetBSD] Copy the recent improvements from FreeBSD
Copy the recent improvements from the FreeBSDRemote plugin, notably:

- moving event reporting setup into SetupTrace() helper

- adding more debug info into SIGTRAP handling

- handling user-generated (and unknown) SIGTRAP events

- adding missing error handling to the generic signal handler

- fixing attaching to processes

- switching watchpoint helpers to use llvm::Error

- minor style and formatting changes

This fixes a number of tests, mostly related to fixed attaching.

Differential Revision: https://reviews.llvm.org/D91167
2020-11-10 20:20:44 +01:00
Michał Górny
e637602e7a [lldb] [Process/FreeBSDRemote] Fix handling user-generated SIGTRAP
Update the SIGTRAP handler to account for the possibility of SIGTRAP
being generated by the user, i.e. not having any specific debugging
event associated with it, as well as receiving unknown SIGTRAPs.  These
instances of SIGTRAP are passed to the regular signal handler.

Differential Revision: https://reviews.llvm.org/D91007
2020-11-10 14:18:03 +01:00
Michał Górny
311cca8bbf [lldb] [test] Rename '.categories' to 'categories'
Make category-specifying files visible.  There is really no good reason
to keep them hidden, and having them visible increases the chances
that someone will actually spot them.

Differential Revision: https://reviews.llvm.org/D91065
2020-11-10 12:02:38 +01:00
Michał Górny
a852cf66ea [lldb] [test] Skip ObjC-based tests via 'objc' category
Replace the plethora of ObjC-implied 'skipUnlessDarwin' decorators
with marking tests as 'objc' category (whenever missing), and skip all
ObjC tests on non-Darwin platforms.  I have used '.categories' file
wherever it was present already or all (>1) tests were relying on ObjC,
and explicit add_test_categories() where there was only one test.

Differential Revision: https://reviews.llvm.org/D91056
2020-11-10 12:02:38 +01:00
Georgii Rymar
57f87977f5 [LLDB][test] - Update one more test after the yaml2obj change.
I've missed this one.
2020-11-09 14:56:07 +03:00
Michał Górny
9e1409aa1e [lldb] [Process/FreeBSDRemote] Handle exec() from inferior
Differential Revision: https://reviews.llvm.org/D90938
2020-11-09 11:35:11 +01:00
Michał Górny
93c9110c98 [lldb] [test] Use skipUnlessDarwin for tests specific to Darwin
Use skipUnlessDarwin decorator for tests that are specific to Darwin,
instead of skipIf... for all other platforms.  This should make it clear
that these tests are not supposed to work elsewhere.  It will also make
these tests stop repeatedly popping up while I look for tests that could
be fixed on the platform in question.

Differential Revision: https://reviews.llvm.org/D91003
2020-11-07 19:26:42 +01:00
Michał Górny
1ba9cedd0a [lldb] [test] Un-skip one of TestRaise signals on fbsd 2020-11-07 19:26:42 +01:00
Michał Górny
2c2eb5e670 [lldb] Enable FreeBSDRemote plugin by default and update test status
The new FreeBSDRemote plugin has reached feature parity on i386
and amd64 targets.  Use it by default on these architectures, while
allowing the use of the legacy plugin via FREEBSD_LEGACY_PLUGIN envvar.

Revisit the method of switching plugins.  Apparently, the return value
of PlatformFreeBSD::CanDebugProcess() is what really decides whether
the legacy or the new plugin is used.

Update the test status.  Reenable the tests that were previously
disabled on FreeBSD and do not cause hangs or are irrelevant to FreeBSD.
Mark all tests that fail reliably as expectedFailure.  For now, tests
that are flaky (i.e. produce unstable results) are left enabled
and cause unpredictable test failures.

Differential Revision: https://reviews.llvm.org/D90757
2020-11-05 17:49:46 +01:00