On Oct 27, 2025, Richard Biener <[email protected]> wrote:
> So on x86-64-linux this is a cross configuration?
It's one of those cross-natives corner cases.
> Or is this able to bootstrap itself but then resulting in a 32bit host
> compiler?
Yeah, it can bootstrap. (It needs an additional tweak to fix multilibs
in libgnat.)
But the interesting use case for this is the non-bootstrap case.
A variant of this change that enables multilibs, and that could be more
interesting to bootstrap, can also bootstrap starting with an
x86_64-linux-gnu compiler with -m64 added to BOOT_CFLAGS, along with an
-L flag to find the 64-bit libstdc++, but you hit post-bootstrap
incompatibilities building e.g. fixincludes (and gnattools?) between the
64-bit libiberty (and other bootstrapped libraries), and the 32-bit
outputs from the bootstrapped compiler used to build the post-bootstrap
host tools.
Non-bootstrapped builds don't hit this incompatibility, because the
initial 64-bit compiler, rather than the just-built one, is used to
build these host tools.
Here's an incremental change, also by Olivier Hainque, that enables
biarch -m32-defaulting x86_64-linux-gnum32.
[PATCH] Turn x86_64-m32 configurations into biarch defaulting to m32
diff --git a/gcc/config.gcc b/gcc/config.gcc
index 8d96ef00005ad..7c85d04184b88 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -689,8 +689,7 @@ x86_64-*-*)
exit 1
esac
case ${with_multilib_list} in
- default | m32)
- with_multilib_list=m32
+ default | *m32*)
;;
*)
echo "Invalid multilib list for m32 target"
@@ -714,6 +713,7 @@ x86_64-*-*)
tm_file="i386/biarchx32.h ${tm_file}"
;;
32 | m32)
+ tm_file="i386/biarch32.h ${tm_file}"
;;
*)
echo "Unknown ABI used in --with-abi=$with_abi"
diff --git a/gcc/config/i386/biarch32.h b/gcc/config/i386/biarch32.h
new file mode 100644
index 0000000000000..116cd68acc838
--- /dev/null
+++ b/gcc/config/i386/biarch32.h
@@ -0,0 +1,29 @@
+/* Make configure files to produce biarch compiler defaulting to 64bit mode.
+ This file must be included very first, while the OS specific file later
+ to overwrite otherwise wrong defaults.
+ Copyright (C) 2001-2025 Free Software Foundation, Inc.
+ Contributed by Bo Thorsen <[email protected]>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+<http://www.gnu.org/licenses/>. */
+
+#define TARGET_64BIT_DEFAULT 0
+#define TARGET_BI_ARCH 3
diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
index dadcf7664c632..443041789555b 100644
--- a/gcc/config/i386/i386-options.cc
+++ b/gcc/config/i386/i386-options.cc
@@ -2018,22 +2018,35 @@ ix86_option_override_internal (bool main_args_p,
#ifdef TARGET_BI_ARCH
else
{
-#if TARGET_BI_ARCH == 1
- /* When TARGET_BI_ARCH == 1, by default, OPTION_MASK_ABI_64
- is on and OPTION_MASK_ABI_X32 is off. We turn off
- OPTION_MASK_ABI_64 if OPTION_MASK_ABI_X32 is turned on by
- -mx32. */
- if (TARGET_X32_P (opts->x_ix86_isa_flags))
- opts->x_ix86_isa_flags &= ~OPTION_MASK_ABI_64;
-#else
- /* When TARGET_BI_ARCH == 2, by default, OPTION_MASK_ABI_X32 is
- on and OPTION_MASK_ABI_64 is off. We turn off
- OPTION_MASK_ABI_X32 if OPTION_MASK_ABI_64 is turned on by
- -m64 or OPTION_MASK_CODE16 is turned on by -m16. */
- if (TARGET_LP64_P (opts->x_ix86_isa_flags)
- || TARGET_16BIT_P (opts->x_ix86_isa_flags))
- opts->x_ix86_isa_flags &= ~OPTION_MASK_ABI_X32;
-#endif
+ switch (TARGET_BI_ARCH)
+ {
+ case 1:
+ /* When TARGET_BI_ARCH == 1, by default, OPTION_MASK_ABI_64
+ is on and OPTION_MASK_ABI_X32 is off. We turn off
+ OPTION_MASK_ABI_64 if OPTION_MASK_ABI_X32 is turned on by
+ -mx32. */
+ if (TARGET_X32_P (opts->x_ix86_isa_flags))
+ opts->x_ix86_isa_flags &= ~OPTION_MASK_ABI_64;
+ break;
+
+ case 2:
+ /* When TARGET_BI_ARCH == 2, by default, OPTION_MASK_ABI_X32 is
+ on and OPTION_MASK_ABI_64 is off. We turn off
+ OPTION_MASK_ABI_X32 if OPTION_MASK_ABI_64 is turned on by
+ -m64 or OPTION_MASK_CODE16 is turned on by -m16. */
+ if (TARGET_LP64_P (opts->x_ix86_isa_flags)
+ || TARGET_16BIT_P (opts->x_ix86_isa_flags))
+ opts->x_ix86_isa_flags &= ~OPTION_MASK_ABI_X32;
+
+ case 3:
+ /* When TARGET_BI_ARCH == 3, by default, OPTION_MASK_ABI_X32 and
+ OPTION_MASK_ABI_64 are both off. */
+ break;
+
+ default:
+ gcc_unreachable();
+ }
+
if (TARGET_64BIT_P (opts->x_ix86_isa_flags)
&& TARGET_IAMCU_P (opts->x_target_flags))
sorry ("Intel MCU psABI isn%'t supported in %s mode",
--
Alexandre Oliva, happy hacker https://blog.lx.oliva.nom.br/
Free Software Activist FSFLA co-founder GNU Toolchain Engineer
More tolerance and less prejudice are key for inclusion and diversity.
Excluding neuro-others for not behaving ""normal"" is *not* inclusive!
