Re: gcc 16 bootstrap, stage 2 and 3 differ

On Sun, 16 Aug 2026, Thomas Klausner wrote:

>> No real insight here except to ask, are the same command lines being passed
>> to both the stage2 and stage3 compilers?
>
> Not sure.
>

You'll have to remove one of the .o files from both directories, then fiddle
with the Makefile (or create a wrapper) so that the `-v' flag gets passed to
both gcc invocations. :(

>> You could compare only the code bits (ie. omit the debug section comparisons
>> which're added by as(1)from binutils  anyway). The build instructions suggest
>> Β‘bootstrap-debugΒ’:
>>
>> https://gcc.gnu.org/install/build.html
>
> I tried this.
> [...]
> it failed again, and now I have much bigger diffs with objdump --dwarf=loc:
> [...]
> i.e. stage3 has a .debug_loclists section, but stage2 doesn't.
>

That's expected with `make bootstrap-debug' and shouldn't matter because the
build should be using the `compare-debug' script in the source dir. to do the
stage2 and stage3 cmps; and that *does* work:

```
$ gcc -O2 -c -o x1.o /usr/src/bin/cat/cat.c			# no debug
$ gcc -ggdb -gdwarf-5 -O2 -c -o x2.o /usr/src/bin/cat/cat.c	# DWARF-5 dbg
$ ls -l x1.o x2.o
-rw-------  1 rvp  wheel  12336 Aug 16 22:05 x1.o
-rw-------  1 rvp  wheel  34568 Aug 16 22:05 x2.o
$ ./gcc-16.2.0/contrib/compare-debug x1.o x2.o && echo OK
OK
$
```

Is that script being used?

-RVP