https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64810
--- Comment #11 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
A breakpoint on "do_option_spec" in the driver shows that the options come from
configure_default_options and option_default_specs.
configure_default_options comes from configargs.h, written out by
gcc/configure(.ac) which seems to get configure_default_options from config.gcc
(from ${t})
This would be easy to use, if only we could guarantee it was "-mKEY=VALUE", but
it isn't; doing it naively the "obvious" way:
--- a/gcc/jit/jit-playback.c
+++ b/gcc/jit/jit-playback.c
@@ -63,6 +63,7 @@ along with GCC; see the file COPYING3. If not see
#include "context.h"
#include "fold-const.h"
#include "debug.h"
+#include "configargs.h"
#include "jit-common.h"
#include "jit-logging.h"
@@ -2118,6 +2119,19 @@ make_fake_args (vec <char *> *argvec,
}
}
+ {
+ for (unsigned i = 0; i < ARRAY_SIZE (configure_default_options); i++)
+ {
+ char *arg = concat ("-m",
+ configure_default_options[i].name,
+ "=",
+ configure_default_options[i].value,
+ NULL);
+ ADD_ARG_TAKE_OWNERSHIP (arg);
+ }
+ }
+
#undef ADD_ARG
#undef ADD_ARG_TAKE_OWNERSHIP
}
fails in toplev::main:
test-empty.c.exe: error: unrecognized command line option '-mfloat=hard'
test-empty.c.exe: error: unrecognized command line option '-mtls=gnu'
(these ought to be -mfloat-abi and -mtls-dialect respectively).
option_default_specs comes from OPTION_DEFAULT_SPECS.
OPTION_DEFAULT_SPECS can be defined by the config, and is for 20 targets,
including arm (arm.h):
/* Support for a compile-time default CPU, et cetera. The rules are:
--with-arch is ignored if -march or -mcpu are specified.
--with-cpu is ignored if -march or -mcpu are specified, and is overridden
by --with-arch.
--with-tune is ignored if -mtune or -mcpu are specified (but not affected
by -march).
--with-float is ignored if -mfloat-abi is specified.
--with-fpu is ignored if -mfpu is specified.
--with-abi is ignored if -mabi is specified.
--with-tls is ignored if -mtls-dialect is specified. */
#define OPTION_DEFAULT_SPECS \
{"arch", "%{!march=*:%{!mcpu=*:-march=%(VALUE)}}" }, \
{"cpu", "%{!march=*:%{!mcpu=*:-mcpu=%(VALUE)}}" }, \
{"tune", "%{!mcpu=*:%{!mtune=*:-mtune=%(VALUE)}}" }, \
{"float", "%{!mfloat-abi=*:-mfloat-abi=%(VALUE)}" }, \
{"fpu", "%{!mfpu=*:-mfpu=%(VALUE)}"}, \
{"abi", "%{!mabi=*:-mabi=%(VALUE)}"}, \
{"mode", "%{!marm:%{!mthumb:-m%(VALUE)}}"}, \
{"tls", "%{!mtls-dialect=*:-mtls-dialect=%(VALUE)}"},
So it looks like the jit has to support whatever OPTION_DEFAULT_SPECS is set
for the target.
I'm working on a patch that expands these spec values so that they can be
injected by libgccjit into toplev::main (and maybe into its own invocation of
the driver?).
Unfortunately, this requires running the driver at build time, which would
require build==host.
