[PATCH] libstdc++: Implement C++26 <debugging> features (P2546R5)

[Peter0x44]

3 Jun 2024 4:14:28 pm Jonathan Wakely <jwakely@redhat.com>:

> On Mon, 3 Jun 2024 at 14:36, Peter0x44 wrote:
>>> +void
>>> +std::breakpoint() noexcept
>>> +{
>>> +#if _GLIBCXX_HAVE_DEBUGAPI_H && defined(_WIN32) &&
>>> !defined(__CYGWIN__)
>>> +  DebugBreak();
>>> +#elif __has_builtin(__builtin_debugtrap)
>>> +  __builtin_debugtrap(); // Clang
>>> +#elif defined(__i386__) || defined(__x86_64__)
>>> +  __asm__ volatile ("int3");
>> Worth noting, currently gcc has some bugs around its handling of int3,
>
> s/gcc/gdb/ ?
Yes, my bad
>
>> https://sourceware.org/bugzilla/show_bug.cgi?id=31194
>> int3;nop seems to work around it okay. __builtin_debugtrap() of clang
>> does run into the same issues.
>
> It seemed to work OK for me, maybe because there's no code after it?
I suspect it won't matter for the tests, the assertion failure is only if 
you step after hitting the int3. I just figured I'd mention it as a heads 
up. It would affect users writing code.
>
> void breakpoint() {
> __asm__ volatile ("int3);
> }