Re: Diagnostic advice for "Internal compiler error in ?" ?

Hi!

On Sat, Jun 13, 2026 at 06:05:41PM -0400, Ross Patterson via Gcc-help wrote:
> I've got a thorny problem, and I could use some advice about how to
> diagnose it.  I've got an ancient version of GCC (3.2.3), built for a
> platform GCC hasn't supported in years (IBM System/370), and using a
> back-end that was removed from GCC 20 years ago (i370).  Upgrading isn't an
> option - this is the newest there is.  Switching to another compiler isn't
> either - this is all there is.
> 
> The error message is literally:
> 
> rxvmvars.h: In function `extract_double_decimal':
> rxvmvars.h:1547: Internal compiler error in ?, at <stdin>:902
> Please submit a full bug report,
> with preprocessed source if appropriate.
> See <URL:http://gcc.gnu.org/bugs.html> for instructions.
> 
> I'm not asking anyone to chase this bug, but other that just randomly
> cutting code out of my program over and over until it goes away, are there
> hints I can follow for this?  I'm a very experienced OS-level programmer,
> so I've got the background to dig into this.  But "Internal compiler error
> in ?" isn't much of a pointer to follow :-)

Try one (or more!) of the following:

-Q
-ftime-report

or the extremely heavy hammer, the tool I always recommend for
precision surgery:

-dap

(it will dump a fuckload of dump files in your cwd, enough to figure
out what was going on pretty much always, that's the -da part; the -dp
thing adds (hopefully ;-)) helpful commentary to the resulting asm
output.

The -da thing alone should be enough for you to tell what thing in your
program is too much for your ancient GCC's feeble mind, and hopefully
will let you avoid the problem :-)

Good luck, and have fun!


Segher