https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96952
Bug ID: 96952
Summary: __builtin_thread_pointer support cannot be probed
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
Assignee: unassigned at gcc dot gnu.org
Reporter: sorear at fastmail dot com
Target Milestone: ---
I would like to use __builtin_thread_pointer instead of inline asm to access
the thread pointer (concretely, in kernel or libc code for risc-v), but it's
only supported by extremely recent versions of gcc and clang. So, I would like
to detect it at compile time, but this does not work:
#if __has_builtin(__builtin_thread_pointer)
void *get_tp() { return __builtin_thread_pointer(); }
#else
/* inline asm fallback */
#endif
x.c: In function 'get_tp':
x.c:2:25: error: '__builtin_thread_pointer' is not supported on this target
2 | void *get_tp() { return __builtin_thread_pointer(); }
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
__has_builtin seems to be falsely returning true?
