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Handle fancy_abort before diagnostic initialization [PR98586]

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If fancy_abort is called before the diagnostic subsystem is initialized,
internal_error will crash internally in a way that prevents a useful
message reaching the user.

This can happen with libgccjit in the case of gcc_assert failures
that occur outside of the libgccjit mutex that guards the rest of
gcc's state, including global_dc (when global_dc may not be
initialized yet, or might be in use by another thread).

I tried a few approaches to fixing this as noted in PR jit/98586
e.g. using a temporary diagnostic_context and initializing it for
the call to internal_error, however the more code that runs, the
more chance there is for other errors to occur.

The best fix appears to be to simply fall back to a minimal abort
implementation that only relies on i18n, as implemented by this
patch.

gcc/ChangeLog:
	PR jit/98586
	* diagnostic.c (diagnostic_kind_text): Break out this array
	from...
	(diagnostic_build_prefix): ...here.
	(fancy_abort): Detect when diagnostic_initialize has not yet been
	called and fall back to a minimal implementation of printing the
	ICE, rather than segfaulting in internal_error.
This commit is contained in:
David Malcolm 2021-01-14 17:02:28 -05:00
parent 02e7af1122
commit 387f6c15d3
1 changed files with 39 additions and 6 deletions
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45
gcc/diagnostic.c
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@ -449,6 +449,13 @@ diagnostic_get_location_text (diagnostic_context *context,
line_col, locus_ce);
}
static const char *const diagnostic_kind_text[] = {
#define DEFINE_DIAGNOSTIC_KIND(K, T, C) (T),
#include "diagnostic.def"
#undef DEFINE_DIAGNOSTIC_KIND
"must-not-happen"
};
/* Return a malloc'd string describing a location and the severity of the
diagnostic, e.g. "foo.c:42:10: error: ". The caller is responsible for
freeing the memory. */
@ -456,12 +463,6 @@ char *
diagnostic_build_prefix (diagnostic_context *context,
const diagnostic_info *diagnostic)
{
static const char *const diagnostic_kind_text[] = {
#define DEFINE_DIAGNOSTIC_KIND(K, T, C) (T),
#include "diagnostic.def"
#undef DEFINE_DIAGNOSTIC_KIND
"must-not-happen"
};
gcc_assert (diagnostic->kind < DK_LAST_DIAGNOSTIC_KIND);
const char *text = _(diagnostic_kind_text[diagnostic->kind]);
@ -1871,6 +1872,38 @@ error_recursion (diagnostic_context *context)
void
fancy_abort (const char *file, int line, const char *function)
{
/* If fancy_abort is called before the diagnostic subsystem is initialized,
internal_error will crash internally in a way that prevents a
useful message reaching the user.
This can happen with libgccjit in the case of gcc_assert failures
that occur outside of the libgccjit mutex that guards the rest of
gcc's state, including global_dc (when global_dc may not be
initialized yet, or might be in use by another thread).
Handle such cases as gracefully as possible by falling back to a
minimal abort handler that only relies on i18n. */
if (global_dc->printer == NULL)
{
/* Print the error message. */
fnotice (stderr, diagnostic_kind_text[DK_ICE]);
fnotice (stderr, "in %s, at %s:%d", function, trim_filename (file), line);
fputc ('\n', stderr);
/* Attempt to print a backtrace. */
struct backtrace_state *state
= backtrace_create_state (NULL, 0, bt_err_callback, NULL);
int count = 0;
if (state != NULL)
backtrace_full (state, 2, bt_callback, bt_err_callback,
(void *) &count);
/* We can't call warn_if_plugins or emergency_dump_function as these
rely on GCC state that might not be initialized, or might be in
use by another thread. */
/* Abort the process. */
real_abort ();
}
internal_error ("in %s, at %s:%d", function, trim_filename (file), line);
}