https://github.com/JDevlieghere created
https://github.com/llvm/llvm-project/pull/134343
The `lldbassert` macro in LLDB behaves like a regular `assert` when assertions
are enabled, and otherwise prints a pretty backtrace and prompts the user to
file a bug. By default, this is emitted as a diagnostic event, but vendors can
provide their own behavior, for example pre-populating a bug report.
Recently, we ran into an issue where an `lldbassert` (in the Swift language
plugin) would fire excessively, to the point that it was interfering with the
usability of the debugger.
Once an `lldbasser` has fired, there's no point in bothering the user over and
over again for the same problem. This PR solves the problem by introducing a
static `std::once_flag` in the macro. This way, every `lldbasser` will fire at
most once per lldb instance.
rdar://148520448
>From a19e0ce464b928ec55e6bf315626f3fb3f5c5a43 Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jo...@devlieghere.com>
Date: Thu, 3 Apr 2025 21:08:25 -0700
Subject: [PATCH] [lldb] Make lldbassert fire only once per instance
The `lldbassert` macro in LLDB behaves like a regular `assert` when
assertions are enabled, and otherwise prints a pretty backtrace and
prompts the user to file a bug. By default, this is emitted as a
diagnostic event, but vendors can provide their own behavior, for
example pre-populating a bug report.
Recently, we ran into an issue where an `lldbassert` (in the Swift
language plugin) would fire excessively, to the point that it was
interfering with the usability of the debugger.
Once an `lldbasser` has fired, there's no point in bothering the user
over and over again for the same problem. This PR solves the problem by
introducing a static `std::once_flag` in the macro. This way, every
`lldbasser` will fire at most once per lldb instance.
rdar://148520448
---
lldb/include/lldb/Utility/LLDBAssert.h | 11 +++++---
lldb/source/Utility/LLDBAssert.cpp | 37 +++++++++++++++-----------
2 files changed, 29 insertions(+), 19 deletions(-)
diff --git a/lldb/include/lldb/Utility/LLDBAssert.h
b/lldb/include/lldb/Utility/LLDBAssert.h
index 21dbdb3b3202d..cee30b81402ca 100644
--- a/lldb/include/lldb/Utility/LLDBAssert.h
+++ b/lldb/include/lldb/Utility/LLDBAssert.h
@@ -10,6 +10,7 @@
#define LLDB_UTILITY_LLDBASSERT_H
#include "llvm/ADT/StringRef.h"
+#include <mutex>
#ifndef NDEBUG
#define lldbassert(x) assert(x)
@@ -19,8 +20,11 @@
// __FILE__ but only renders the last path component (the filename) instead of
// an invocation dependent full path to that file.
#define lldbassert(x)
\
- lldb_private::_lldb_assert(static_cast<bool>(x), #x, __FUNCTION__,
\
- __FILE_NAME__, __LINE__)
+ do {
\
+ static std::once_flag _once_flag;
\
+ lldb_private::_lldb_assert(static_cast<bool>(x), #x, __FUNCTION__,
\
+ __FILE_NAME__, __LINE__, _once_flag)
\
+ } while (0)
#else
#define lldbassert(x)
\
lldb_private::_lldb_assert(static_cast<bool>(x), #x, __FUNCTION__, __FILE__,
\
@@ -33,7 +37,8 @@ namespace lldb_private {
/// Don't use _lldb_assert directly. Use the lldbassert macro instead so that
/// LLDB asserts become regular asserts in NDEBUG builds.
void _lldb_assert(bool expression, const char *expr_text, const char *func,
- const char *file, unsigned int line);
+ const char *file, unsigned int line,
+ std::once_flag &once_flag);
/// The default LLDB assert callback, which prints to stderr.
typedef void (*LLDBAssertCallback)(llvm::StringRef message,
diff --git a/lldb/source/Utility/LLDBAssert.cpp
b/lldb/source/Utility/LLDBAssert.cpp
index b84c581ccf822..611ad43cd071b 100644
--- a/lldb/source/Utility/LLDBAssert.cpp
+++ b/lldb/source/Utility/LLDBAssert.cpp
@@ -11,6 +11,7 @@
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/raw_ostream.h"
+#include <mutex>
#if LLVM_SUPPORT_XCODE_SIGNPOSTS
#include <os/log.h>
@@ -33,29 +34,33 @@ static std::atomic<LLDBAssertCallback>
g_lldb_assert_callback =
&DefaultAssertCallback;
void _lldb_assert(bool expression, const char *expr_text, const char *func,
- const char *file, unsigned int line) {
+ const char *file, unsigned int line,
+ std::once_flag &once_flag) {
if (LLVM_LIKELY(expression))
return;
+ std::call_once(once_flag, [&]() {
#if LLVM_SUPPORT_XCODE_SIGNPOSTS
- if (__builtin_available(macos 10.12, iOS 10, tvOS 10, watchOS 3, *)) {
- os_log_fault(OS_LOG_DEFAULT,
- "Assertion failed: (%s), function %s, file %s, line %u\n",
- expr_text, func, file, line);
- }
+ if (__builtin_available(macos 10.12, iOS 10, tvOS 10, watchOS 3, *)) {
+ os_log_fault(OS_LOG_DEFAULT,
+ "Assertion failed: (%s), function %s, file %s, line %u\n",
+ expr_text, func, file, line);
+ }
#endif
- std::string buffer;
- llvm::raw_string_ostream backtrace(buffer);
- llvm::sys::PrintStackTrace(backtrace);
+ std::string buffer;
+ llvm::raw_string_ostream backtrace(buffer);
+ llvm::sys::PrintStackTrace(backtrace);
- (*g_lldb_assert_callback.load())(
- llvm::formatv("Assertion failed: ({0}), function {1}, file {2}, line
{3}",
- expr_text, func, file, line)
- .str(),
- buffer,
- "Please file a bug report against lldb and include the backtrace, the "
- "version and as many details as possible.");
+ (*g_lldb_assert_callback.load())(
+ llvm::formatv(
+ "Assertion failed: ({0}), function {1}, file {2}, line {3}",
+ expr_text, func, file, line)
+ .str(),
+ buffer,
+ "Please file a bug report against lldb and include the backtrace, the "
+ "version and as many details as possible.");
+ });
}
void SetLLDBAssertCallback(LLDBAssertCallback callback) {
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