https://github.com/Michael137 created
https://github.com/llvm/llvm-project/pull/181127
These assertions would occasionally crash on macOS CI with following stacktrace:
```
06:53:31 Death test: { read_results = process_sp->ReadMemoryRanges(ranges,
buffer); }
06:53:31 Result: died but not with expected error.
06:53:31 Expected: contains regular expression "read more than requested
bytes"
06:53:31 Actual msg:
06:53:31 [ DEATH ] Stack dump without symbol names (ensure you have
llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH`
to point to it):
06:53:31 [ DEATH ] 0 TargetTests 0x000000010055bb80
llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
06:53:31 [ DEATH ] 1 TargetTests 0x0000000100559778
llvm::sys::RunSignalHandlers() + 64
06:53:31 [ DEATH ] 2 TargetTests 0x000000010055c668
SignalHandler(int, __siginfo*, void*) + 344
06:53:31 [ DEATH ] 3 libsystem_platform.dylib 0x0000000196993744 _sigtramp
+ 56
06:53:31 [ DEATH ] 4 libsystem_trace.dylib 0x00000001966b5180
_os_log_preferences_refresh + 36
06:53:31 [ DEATH ] 5 libsystem_trace.dylib 0x00000001966b5740
os_signpost_enabled + 300
06:53:31 [ DEATH ] 6 TargetTests 0x0000000100500930
llvm::SignpostEmitter::startInterval(void const*, llvm::StringRef) + 68
06:53:31 [ DEATH ] 7 TargetTests 0x0000000100782c24
lldb_private::Timer::Timer(lldb_private::Timer::Category&, char const*, ...) +
168
06:53:31 [ DEATH ] 8 TargetTests 0x000000010069cd44
lldb_private::Process::ReadMemoryFromInferior(unsigned long long, void*,
unsigned long, lldb_private::Status&) + 100
06:53:31 [ DEATH ] 9 TargetTests 0x000000010069cf68
lldb_private::Process::ReadMemoryRanges(llvm::ArrayRef<lldb_private::Range<unsigned
long long, unsigned long>>, llvm::MutableArrayRef<unsigned char>) + 300
06:53:31 [ DEATH ] 10 TargetTests 0x000000010045482c
MemoryDeathTest_TestReadMemoryRangesReturnsTooMuch_Test::TestBody() + 1748
```
By default, Google death-tests executes the code under test in a sub-process
(e.g., via `fork`, see [official
docs](https://google.github.io/googletest/reference/assertions.html#death)).
However, the os_log APIs are not safe across forks, and using the os_log
handles of a parent process is not guaranteed to work (read undefined). This is
why we sometimes non-deterministically crash.
On Darwin we compile with signposts enabled, and there's no mechanism of
avoiding calling into os_log once you've compiled with them enabled (e.g., in
our case we just check the runtime `os_signpost_enabled`).
GoogleTest provides an alternative mechanism to spawn the death tests. It
"re-executes the unit binary but only runs the death tests". This should avoid
sharing the os_log handles with the parent. This mode is called "threadsafe".
This patch sets this style for the only 2 death-tests currently in the LLDB
test-suite.
Since this is quite the foot-gun we should disable it for the entire LLDB
unit-test suite. But to make CI less flakey for now, do this for only the tests
in question.
>From d1bcb31e389d56d8f985d23a903bdb1f263c5a02 Mon Sep 17 00:00:00 2001
From: Michael Buch <[email protected]>
Date: Thu, 12 Feb 2026 11:57:36 +0000
Subject: [PATCH] [lldb][test] Make MemoryTest the threadsafe gtest death-test
style
These assertions would occasionally crash on macOS CI with following
stacktrace:
```
06:53:31 Death test: { read_results = process_sp->ReadMemoryRanges(ranges,
buffer); }
06:53:31 Result: died but not with expected error.
06:53:31 Expected: contains regular expression "read more than requested
bytes"
06:53:31 Actual msg:
06:53:31 [ DEATH ] Stack dump without symbol names (ensure you have
llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH`
to point to it):
06:53:31 [ DEATH ] 0 TargetTests 0x000000010055bb80
llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
06:53:31 [ DEATH ] 1 TargetTests 0x0000000100559778
llvm::sys::RunSignalHandlers() + 64
06:53:31 [ DEATH ] 2 TargetTests 0x000000010055c668
SignalHandler(int, __siginfo*, void*) + 344
06:53:31 [ DEATH ] 3 libsystem_platform.dylib 0x0000000196993744 _sigtramp
+ 56
06:53:31 [ DEATH ] 4 libsystem_trace.dylib 0x00000001966b5180
_os_log_preferences_refresh + 36
06:53:31 [ DEATH ] 5 libsystem_trace.dylib 0x00000001966b5740
os_signpost_enabled + 300
06:53:31 [ DEATH ] 6 TargetTests 0x0000000100500930
llvm::SignpostEmitter::startInterval(void const*, llvm::StringRef) + 68
06:53:31 [ DEATH ] 7 TargetTests 0x0000000100782c24
lldb_private::Timer::Timer(lldb_private::Timer::Category&, char const*, ...) +
168
06:53:31 [ DEATH ] 8 TargetTests 0x000000010069cd44
lldb_private::Process::ReadMemoryFromInferior(unsigned long long, void*,
unsigned long, lldb_private::Status&) + 100
06:53:31 [ DEATH ] 9 TargetTests 0x000000010069cf68
lldb_private::Process::ReadMemoryRanges(llvm::ArrayRef<lldb_private::Range<unsigned
long long, unsigned long>>, llvm::MutableArrayRef<unsigned char>) + 300
06:53:31 [ DEATH ] 10 TargetTests 0x000000010045482c
MemoryDeathTest_TestReadMemoryRangesReturnsTooMuch_Test::TestBody() + 1748
```
By default, Google death-tests executes the code under test in a sub-process
(e.g., via `fork`, see [official
docs](https://google.github.io/googletest/reference/assertions.html#death)).
However, the os_log APIs are not safe across forks, and using the os_log
handles of a parent process is not guaranteed to work (read undefined). This is
why we sometimes non-deterministically crash.
On Darwin we compile with signposts enabled, and there's no mechanism of
avoiding calling into os_log once you've compiled with them enabled (e.g., in
our case we just check the runtime `os_signpost_enabled`).
GoogleTest provides an alternative mechanism to spawn the death tests. It
"re-executes the unit binary but only runs the death tests". This should avoid
sharing the os_log handles with the parent. This mode is called "threadsafe".
This patch sets this style for the only 2 death-tests currently in the LLDB
test-suite.
Since this is quite the foot-gun we should disable it for the entire
LLDB unit-test suite. But to make CI less flakey for now, do this for
only the tests in question.
---
lldb/unittests/Target/MemoryTest.cpp | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/lldb/unittests/Target/MemoryTest.cpp
b/lldb/unittests/Target/MemoryTest.cpp
index 15b22a47e30e8..47aa105cdfecd 100644
--- a/lldb/unittests/Target/MemoryTest.cpp
+++ b/lldb/unittests/Target/MemoryTest.cpp
@@ -381,6 +381,13 @@ TEST_F(MemoryTest, TestReadMemoryRanges) {
using MemoryDeathTest = MemoryTest;
TEST_F(MemoryDeathTest, TestReadMemoryRangesReturnsTooMuch) {
+ // gtest death-tests execute in a sub-process (fork), which invalidates
+ // any signpost handles and would cause spurious crashes if used. Use the
+ // "threadsafe" style of death-test to work around this.
+ // FIXME: we should set this only if signposts are enabled, and do so
+ // for the entire test-suite.
+ GTEST_FLAG_SET(death_test_style, "threadsafe");
+
ArchSpec arch("x86_64-apple-macosx-");
Platform::SetHostPlatform(PlatformRemoteMacOSX::CreateInstance(true, &arch));
DebuggerSP debugger_sp = Debugger::CreateInstance();
@@ -409,6 +416,13 @@ TEST_F(MemoryDeathTest,
TestReadMemoryRangesReturnsTooMuch) {
}
TEST_F(MemoryDeathTest, TestReadMemoryRangesWithShortBuffer) {
+ // gtest death-tests execute in a sub-process (fork), which invalidates
+ // any signpost handles and would cause spurious crashes if used. Use the
+ // "threadsafe" style of death-test to work around this.
+ // FIXME: we should set this only if signposts are enabled, and do so
+ // for the entire test-suite.
+ GTEST_FLAG_SET(death_test_style, "threadsafe");
+
ArchSpec arch("x86_64-apple-macosx-");
Platform::SetHostPlatform(PlatformRemoteMacOSX::CreateInstance(true, &arch));
DebuggerSP debugger_sp = Debugger::CreateInstance();
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