On Thu, 7 Nov 2019, Alexandre Oliva wrote:
> On Nov 7, 2019, Richard Biener <rguent...@suse.de> wrote:
>
> > (also raises the question why we have both -dumpbase and -auxbase ...)
>
> https://gcc.gnu.org/ml/gcc-patches/2002-08/msg00294.html
>
> This was before -dumpdir, however.
>
> Here's the current logic for aux_base_name:
>
> -c or -S with -o [odir/]obase.oext: [odir/]obase
> otherwise, given input [idir/]ibase.iext: ibase
>
> Whereas the current logic for dump_base_name, once aux_base_name has
> been determined as [auxdir/]auxbase, is:
>
> given -dumpbase ddir/dbase: ddir/dbase
> otherwise, given -dumpdir ddir and -dumpbase dbase: ddir/dbase
> otherwise, given -dumpbase dbase: [auxdir/]dbase
> otherwise, given -dumpdir ddir: ddir/ibase.iext
> otherwise: [auxdir/]ibase.iext
>
> Relevant cases to consider: (aux, dump) for each compilation with
> CC='gcc -fstack-usage -fdump-tree-original'
>
> compiling without -o: (ibase, ibase.iext)
> ex $CC -c srcdir/foo.c srcdir/x/bar.c
> -> foo.o foo.su foo.c.#t.original
> + bar.o bar.su bar.c.#t.original
>
> compiling with -o: ([odir/]obase, [odir/]ibase.iext)
> ex $CC -c srcdir/foo.c -o objdir/foobaz.o -Dfoobaz
> -> objdir/foobaz.o objdir/foobaz.su objdir/foo.c.#t.original
>
> compiling multiple sources with -dumpbase: (ibase, [ddir/]dbase)
> ex $CC -dumpbase outdir/runme.dump -c srcdir/foo.c srcdir/x/bar.c
> -> foo.o foo.su outdir/runme.dump.#t.original
> + bar.o bar.su outdir/runme.dump.#t.original (dupe)
>
> compiling and linking with -o: (ibase, ibase.iext)
> ex $CC -o outdir/runme srcdir/foo.c srcdir/x/bar.c
> -> /tmp/temp().o foo.su foo.c.#t.original
> + /tmp/temp().o bar.su bar.c.#t.original
> + outdir/runme
>
> lto-recompiling and linking with -o: (/tmp/obase.temp().ltrans#.ltrans,
> odir/obase.ltrans#)
> ex $CC -o outdir/runme ltobjdir/foo.o ltobjdir/bar.o -fdump-rtl-expand
> -> /tmp/runme.temp().ltrans0.ltrans.o /tmp/runme.temp().ltrans0.ltrans.su
> + outdir/runme.ltrans0.#r.expand
> + outdir/runme
>
> lto-recompiling and linking without -o: (/tmp/temp().ltrans#.ltrans,
> /tmp/temp().ltrans#.o)
> ex $CC ltobjdir/foo.o ltobjdir/bar.o -fdump-rtl-expand
> -> /tmp/temp().ltrans0.ltrans.o /tmp/temp().ltrans0.ltrans.su
> + /tmp/temp().ltrans0.#r.expand
> + a.out
>
>
> If we were to unify auxbase and dumpbase, I'd take the opportunity to
> fix the -o objdir/foobaz.o compilation to output dumps named after
> objdir/foobaz or objdir/foobaz-foo.c rather than ./foo.c; for
> outdir/runme.dump to be used as a prefix for aux and dump names, so that
> we wouldn't create and then overwrite outdir/runme.dump, and so that
> other compilations of foo.c and bar.c wouldn't overwrite the .su files,
> but rather create outdir/runme.dump-{foo,bar}.* dumps and aux files; and
> likewise use outdir/runme.ltrans0 or a.out.ltrans0 for the .su and
> .expand files.
>
>
> The logic I suggest is involves combining some of the -auxbase and some
> of the -dumpbase logic, namely:
>
> In the driver:
>
> compiling a single source idir/ibase.iext:
>
> -o odir/obase.oext specified: default -dumpdir odir -dumpbase obase.iext
> -o obase.oext specified: default -dumpbase obase.iext
> -o ibase.oext implied: default -dumpbase ibase.iext
>
> compiling multiple sources named as ibase.iext for linking:
>
> -dumpbase [ddir/]dbase specified: make it -dumpbase [ddir/]dbase-ibase.iext
> -o odir/output specified: default -dumpdir odir -dumpbase output-ibase.iext
> -o output specified: default -dumpbase output-ibase.iext
> -o a.out implied: default -dumpbase a.out-ibase.iext
>
> LTO recompiling:
>
> same as above, with each ibase.iext set to ltrans#
>
>
> In the compiler, set dump_base_name to:
>
> Given -dumpbase ddir/dbase: ddir/dbase
> otherwise, given -dumpdir ddir and -dumpbase dbase: ddir/dbase
> otherwise, given -dumpbase dbase: dbase
>
> and copy aux_base_name from dump_base_name, but if it ends in .iext,
> drop the extension.
>
> The resulting behavior (aux_base_name, dump_base_name)
>
> compiling without -o: (ibase, ibase.iext) unchanged
> ex $CC -c srcdir/foo.c srcdir/x/bar.c
> -> foo.o foo.su foo.c.#t.original
> + bar.o bar.su bar.c.#t.original
>
> compiling with -o: ([odir/]obase, [odir/]obase.iext)
> ex $CC -c srcdir/foo.c -o objdir/foobaz.o -Dfoobaz
> -> objdir/foobaz.o objdir/foobaz.su objdir/foobaz.c.#t.original
>
> compiling multiple sources with -dumpbase: ([ddir]/dbase, [ddir/]dbase)
> ex $CC -dumpbase outdir/runme.dump -c srcdir/foo.c srcdir/x/bar.c
> -> foo.o outdir/runme.dump-foo.su outdir/runme.dump-foo.c.#t.original
> + bar.o outdir/runme.dump-bar.su outdir/runme.dump-bar.c.#t.original
>
> compiling and linking with -o: (outdir/runme-ibase, outdir/runme-ibase.iext)
> ex $CC -o outdir/runme srcdir/foo.c srcdir/x/bar.c
> -> /tmp/temp().o outdir/runme-foo.su outdir/runme-foo.c.#t.original
> + /tmp/temp().o outdir/runme-bar.su outdir/runme-bar.c.#t.original
> + outdir/runme
>
> lto-recompiling and linking with -o: (outdir/runme.ltrans#,
> outdir/runme.ltrans#)
> ex $CC -o outdir/runme ltobjdir/foo.o ltobjdir/bar.o -fdump-rtl-expand
> -> /tmp/runme.temp().ltrans0.ltrans.o outdir/runme.ltrans0.su
> + outdir/runme.ltrans0.#r.expand
> + outdir/runme
>
> lto-recompiling and linking without -o: (a.out.ltrans#, a.out.ltrans#)
> ex $CC ltobjdir/foo.o ltobjdir/bar.o -fdump-rtl-expand
> -> /tmp/temp().ltrans0.ltrans.o a.out.ltrans0.su
> + a.out.ltrans0.#r.expand
> + a.out
Wow, thanks for the elaborate write-up! I wonder if we can
cut&paste this into documentation somewhere appropriate, maybe
there's already a section for "auxiliary compiler outputs".
> I'm a little hesitant, this amounts to quite significant behavior
> changes. Do these seem acceptable and desirable nevertheless?
I think the current state is somewhat of a mess and in some
cases confusing and your suggestion sounds like an overall
improvement to me (you didn't actually suggest to remove
either of the -dump{base,dir} -auxbase{-strip} options?)
Of course, others please feel free to comment (but let's not start
bikeshedding too much...).
Thanks a lot!
Richard.
