Re: debugging gcc/cc1

[Mike Stump <mrs at apple dot com>]

On Wednesday, May 26, 2004, at 01:29 PM, Johnny Huynh wrote:
> This must have been asked before, but my google and mailing list 
> searches
> havent gotten me anything too useful...

http://gcc.gnu.org/ml/gcc/2000-09/msg00705.html

> I have written an extra pass that is causes a seg fault in my gcc
> cross-compiler, but no core file is generated (presumably from the sig
> handler) and I don't know how to attach gdb to my cross-compiler.

gcc -v t.c -c
gcc -E t.c >t.i

and the mostly likely command under gdb:

	run -quiet t.i

Some platforms might have flags you might have to add, -fPIC and the 
testcase might be dependent upon optimization (-O2), but 90% of 
testcases run this simply.

> I've tried using the output provided by "gcc -v -save-temps ..." and 
> then
> invoke cc1 from inside gdb, but thats not immediately working

Then you probably did it wrong.  Run with -v again, and see what other 
flags are being passed to cc1, and pass more of them until you find the 
one you need.

> and its a pain to have to copy and paste huge chunks of text everytime 
> I want to
> trace my new changes.

?  You're doing something wrong.  90% of the time, in gdb, you just say:

	run

that's one word, no pasting.  If you have a program that needs input, 
you do

	run ... <file

to test, and just run thereafter, again, one word.

> tips on how to disable the sig handler (to get a core file) or trace my
> new changes (preferred) would be appreciated.

On my platform, I see:

$ gcc -c -v t.cc
Reading specs from /usr/libexec/gcc/darwin/ppc/3.3/specs
Thread model: posix
gcc version 3.3 20030304 (Apple Computer, Inc. build 1490)
 /usr/libexec/gcc/darwin/ppc/3.3/cc1plus -quiet -v -D__GNUC__=3 
-D__GNUC_MINOR__=3 -D__GNUC_PATCHLEVEL__=0 -D__APPLE_CC__=1490 
-D__DYNAMIC__ t.cc -D__GNUG__=3 -fPIC -quiet -dumpbase t.cc -auxbase t 
-version -D__private_extern__=extern -o /var/tmp//cccKpmT6.s

technically, I might need to pass all of these, 98% of the time, -fPIC 
-quiet and the filename is enough.