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authorAdrian Prantl <aprantl@apple.com>2024-08-20 16:01:22 -0700
committerGitHub <noreply@github.com>2024-08-20 16:01:22 -0700
commitf01f80ce6ca7640bb0e267b84b1ed0e89b57e2d9 (patch)
treec38a79f19b1eef07a0b315cc067035d380a83c80 /lldb/source/Commands/CommandObjectThread.cpp
parent1e9d0028d35ae69263aa848b4cb02245f442eb5c (diff)
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[lldb] Extend frame recognizers to hide frames from backtraces (#104523)
Compilers and language runtimes often use helper functions that are fundamentally uninteresting when debugging anything but the compiler/runtime itself. This patch introduces a user-extensible mechanism that allows for these frames to be hidden from backtraces and automatically skipped over when navigating the stack with `up` and `down`. This does not affect the numbering of frames, so `f <N>` will still provide access to the hidden frames. The `bt` output will also print a hint that frames have been hidden. My primary motivation for this feature is to hide thunks in the Swift programming language, but I'm including an example recognizer for `std::function::operator()` that I wished for myself many times while debugging LLDB. rdar://126629381 Example output. (Yes, my proof-of-concept recognizer could hide even more frames if we had a method that returned the function name without the return type or I used something that isn't based off regex, but it's really only meant as an example). before: ``` (lldb) thread backtrace --filtered=false * thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1 * frame #0: 0x0000000100001f04 a.out`foo(x=1, y=1) at main.cpp:4:10 frame #1: 0x0000000100003a00 a.out`decltype(std::declval<int (*&)(int, int)>()(std::declval<int>(), std::declval<int>())) std::__1::__invoke[abi:se200000]<int (*&)(int, int), int, int>(__f=0x000000016fdff280, __args=0x000000016fdff224, __args=0x000000016fdff220) at invoke.h:149:25 frame #2: 0x000000010000399c a.out`int std::__1::__invoke_void_return_wrapper<int, false>::__call[abi:se200000]<int (*&)(int, int), int, int>(__args=0x000000016fdff280, __args=0x000000016fdff224, __args=0x000000016fdff220) at invoke.h:216:12 frame #3: 0x0000000100003968 a.out`std::__1::__function::__alloc_func<int (*)(int, int), std::__1::allocator<int (*)(int, int)>, int (int, int)>::operator()[abi:se200000](this=0x000000016fdff280, __arg=0x000000016fdff224, __arg=0x000000016fdff220) at function.h:171:12 frame #4: 0x00000001000026bc a.out`std::__1::__function::__func<int (*)(int, int), std::__1::allocator<int (*)(int, int)>, int (int, int)>::operator()(this=0x000000016fdff278, __arg=0x000000016fdff224, __arg=0x000000016fdff220) at function.h:313:10 frame #5: 0x0000000100003c38 a.out`std::__1::__function::__value_func<int (int, int)>::operator()[abi:se200000](this=0x000000016fdff278, __args=0x000000016fdff224, __args=0x000000016fdff220) const at function.h:430:12 frame #6: 0x0000000100002038 a.out`std::__1::function<int (int, int)>::operator()(this= Function = foo(int, int) , __arg=1, __arg=1) const at function.h:989:10 frame #7: 0x0000000100001f64 a.out`main(argc=1, argv=0x000000016fdff4f8) at main.cpp:9:10 frame #8: 0x0000000183cdf154 dyld`start + 2476 (lldb) ``` after ``` (lldb) bt * thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1 * frame #0: 0x0000000100001f04 a.out`foo(x=1, y=1) at main.cpp:4:10 frame #1: 0x0000000100003a00 a.out`decltype(std::declval<int (*&)(int, int)>()(std::declval<int>(), std::declval<int>())) std::__1::__invoke[abi:se200000]<int (*&)(int, int), int, int>(__f=0x000000016fdff280, __args=0x000000016fdff224, __args=0x000000016fdff220) at invoke.h:149:25 frame #2: 0x000000010000399c a.out`int std::__1::__invoke_void_return_wrapper<int, false>::__call[abi:se200000]<int (*&)(int, int), int, int>(__args=0x000000016fdff280, __args=0x000000016fdff224, __args=0x000000016fdff220) at invoke.h:216:12 frame #6: 0x0000000100002038 a.out`std::__1::function<int (int, int)>::operator()(this= Function = foo(int, int) , __arg=1, __arg=1) const at function.h:989:10 frame #7: 0x0000000100001f64 a.out`main(argc=1, argv=0x000000016fdff4f8) at main.cpp:9:10 frame #8: 0x0000000183cdf154 dyld`start + 2476 Note: Some frames were hidden by frame recognizers ```
Diffstat (limited to 'lldb/source/Commands/CommandObjectThread.cpp')
-rw-r--r--lldb/source/Commands/CommandObjectThread.cpp19
1 files changed, 15 insertions, 4 deletions
diff --git a/lldb/source/Commands/CommandObjectThread.cpp b/lldb/source/Commands/CommandObjectThread.cpp
index 605f872..6a89c16 100644
--- a/lldb/source/Commands/CommandObjectThread.cpp
+++ b/lldb/source/Commands/CommandObjectThread.cpp
@@ -89,6 +89,9 @@ public:
"invalid boolean value for option '%c': %s", short_option,
option_arg.data());
} break;
+ case 'u':
+ m_filtered_backtrace = false;
+ break;
default:
llvm_unreachable("Unimplemented option");
}
@@ -99,6 +102,7 @@ public:
m_count = UINT32_MAX;
m_start = 0;
m_extended_backtrace = false;
+ m_filtered_backtrace = true;
}
llvm::ArrayRef<OptionDefinition> GetDefinitions() override {
@@ -109,6 +113,7 @@ public:
uint32_t m_count;
uint32_t m_start;
bool m_extended_backtrace;
+ bool m_filtered_backtrace;
};
CommandObjectThreadBacktrace(CommandInterpreter &interpreter)
@@ -121,7 +126,10 @@ public:
"call stacks.\n"
"Use 'settings set frame-format' to customize the printing of "
"frames in the backtrace and 'settings set thread-format' to "
- "customize the thread header.",
+ "customize the thread header.\n"
+ "Customizable frame recognizers may filter out less interesting "
+ "frames, which results in gaps in the numbering. "
+ "Use '-u' to see all frames.",
nullptr,
eCommandRequiresProcess | eCommandRequiresThread |
eCommandTryTargetAPILock | eCommandProcessMustBeLaunched |
@@ -199,7 +207,8 @@ protected:
strm.PutChar('\n');
if (ext_thread_sp->GetStatus(strm, m_options.m_start,
m_options.m_count,
- num_frames_with_source, stop_format)) {
+ num_frames_with_source, stop_format,
+ !m_options.m_filtered_backtrace)) {
DoExtendedBacktrace(ext_thread_sp.get(), result);
}
}
@@ -228,7 +237,8 @@ protected:
const uint32_t num_frames_with_source = 0;
const bool stop_format = true;
if (!thread->GetStatus(strm, m_options.m_start, m_options.m_count,
- num_frames_with_source, stop_format, only_stacks)) {
+ num_frames_with_source, stop_format,
+ !m_options.m_filtered_backtrace, only_stacks)) {
result.AppendErrorWithFormat(
"error displaying backtrace for thread: \"0x%4.4x\"\n",
thread->GetIndexID());
@@ -1392,7 +1402,8 @@ public:
const uint32_t num_frames_with_source = 0;
const bool stop_format = false;
exception_thread_sp->GetStatus(strm, 0, UINT32_MAX,
- num_frames_with_source, stop_format);
+ num_frames_with_source, stop_format,
+ /*filtered*/ false);
}
return true;