Andrew Pinski <pins...@gmail.com> 于2024年5月21日周二 20:23写道：
>
> On Tue, May 21, 2024 at 5:12 AM YunQiang Su <s...@gcc.gnu.org> wrote:
> >
> > If `find_a_program` cannot find `as/ld` and we are a cross toolchain,
> > the final fallback is `as/ld` of system. In fact, we can have a try
> > with <triple>-as/ld before fallback to native as/ld.
> >
> > This patch is derivatived from Debian's patch:
> > gcc-search-prefixed-as-ld.diff
> >
> > gcc
> > * gcc.cc(execute): Looks for <triple>-as/ld before fallback
> > to native as/ld.
> > ---
> > gcc/gcc.cc | 21 +++++++++++++++++++++
> > 1 file changed, 21 insertions(+)
> >
> > diff --git a/gcc/gcc.cc b/gcc/gcc.cc
> > index 830a4700a87..8a1bdb5e3e2 100644
> > --- a/gcc/gcc.cc
> > +++ b/gcc/gcc.cc
> > @@ -3293,6 +3293,27 @@ execute (void)
> > string = find_a_program(commands[0].prog);
> > if (string)
> > commands[0].argv[0] = string;
> > + else if (*cross_compile != '0'
> > + && (!strcmp (commands[0].argv[0], "as")
> > + || !strcmp (commands[0].argv[0], "ld")))
> > + {
> > + string = XNEWVEC (char, strlen (commands[0].argv[0]) + 2
> > + + strlen (DEFAULT_REAL_TARGET_MACHINE));
> > + strcpy (string, DEFAULT_REAL_TARGET_MACHINE);
> > + strcat (string, "-");
> > + strcat (string, commands[0].argv[0]);
> > + const char *string_args[] = {string, "--version", NULL};
> > + int exit_status = 0;
> > + int err = 0;
> > + const char *errmsg = pex_one (PEX_SEARCH, string,
> > + CONST_CAST (char **, string_args), string,
> > + NULL, NULL, &exit_status, &err);
>
> I think this should be handled under find_a_program instead of
> execute. That should simplify things slightly.
Maybe. But it seems that they are two different problems.
`find_a_program` won't try to find any as/ld from user path dirs,
such as /usr/bin
My patch tries to resolve the problem: if `find_a_program` fails to find
any usable ld/as, then let's fallback to /usr/bin/<triple>-as
instead of /usr/bin/as.
Yes, we should also make `find_a_program` look for <triple>-as
from its search path, while I guess it should be done by another patch.
> You should also most likely use concat here instead of
> XNEWVEC/strcpy/strcat which will also simplify the code.
> Like string = concat (DEFAULT_REAL_TARGET_MACHINE, "-", commands[0].prog);
>
> I think this should be done for more than just as/ld but also objcopy
> (which is used for gsplit-dwarf).
> Is there a reason why you are needing to try to execute with
> "--version" as an argument here?
>
I try to make it possible to fallback to system's ld/as, if
<triple>-as/ld doesn't exist.
With `--version` args, I have a test to <triple>-as/ld.
> Thanks,
> Andrew Pinski
>
> > + if (errmsg == NULL && exit_status == 0 && err == 0)
> > + {
> > + commands[0].argv[0] = string;
> > + commands[0].prog = string;
> > + }
> > + }
> > }
> >
> > for (n_commands = 1, i = 0; argbuf.iterate (i, &arg); i++)
> > --
> > 2.39.2
> >
