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.
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Is there a better way to fix this? If not I plan to push this
to master in a few days.
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.
---
gcc/diagnostic.c | 45 +++++++++++++++++++++++++++++++++++++++------
1 file changed, 39 insertions(+), 6 deletions(-)
diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
index 4250bf96c8b..3be7748eb39 100644
--- a/gcc/diagnostic.c
+++ b/gcc/diagnostic.c
@@ -431,6 +431,13 @@ 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. */
@@ -438,12 +445,6 @@ 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]);
@@ -1832,6 +1833,38 @@ 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);
}
--
2.26.2
