LoongArch: adjust the default of -mexplicit-relocs by checking gas feature
Commit Message
> > Maybe we can add a check in gcc/configure.ac to see if gcc_cv_ld
> > supports %got_pc_hi20 and adjust the default for -m[no]-explicit-relocs?
> I think this is a good way, I'll look at adding a check.
The following should work. I've tested it locally by building GCC with
both old (2.38 with patch) and new (trunk) Binutils. Ok for trunk?
I simply checked as instead of ld. If as supports explicitly
relocations, the produced .o file won't be supported by an old ld even
if we use -mno-explicit-relocs (because as will generate new relocation
types for la.local etc). So such a mismatch between as and ld can be
considered "completely broken" and we don't need to support it. And,
the Alpha port also check the assembler for the default of -mexplicit-
relocs.
This should be documented in invoke.texi, but currently it does not
mention -mexplicit-relocs for LoongArch at all. So I'll submit the
doclater in another patch.
-- >8 --
The assembly produced with -mexplicit-relocs is not supported by gas <=
2.39. Check if the assembler supports explicit relocations and set the
default accordingly.
gcc/ChangeLog:
* configure.ac (HAVE_AS_EXPLICIT_RELOCS): Define to 1 if the
assembler supports explicit relocation for LoongArch.
* configure: Regenerate.
* config/loongarch/loongarch-opts.h (HAVE_AS_EXPLICIT_RELOCS):
Define to 0 if not defined.
* config/loongarch/genopts/loongarch.opt.in
(TARGET_EXPLICIT_RELOCS): Default to HAVE_AS_EXPLICIT_RELOCS.
* config/loongarch/loongarch.opt: Regenerate.
---
gcc/config/loongarch/genopts/loongarch.opt.in | 2 +-
gcc/config/loongarch/loongarch-opts.h | 4 ++
gcc/config/loongarch/loongarch.opt | 2 +-
gcc/configure | 37 +++++++++++++++++--
gcc/configure.ac | 7 +++-
5 files changed, 46 insertions(+), 6 deletions(-)
Comments
在 2022/7/26 下午10:15, Xi Ruoyao 写道:
>
> The following should work. I've tested it locally by building GCC with
> both old (2.38 with patch) and new (trunk) Binutils. Ok for trunk?
>
> I simply checked as instead of ld. If as supports explicitly
> relocations, the produced .o file won't be supported by an old ld even
> if we use -mno-explicit-relocs (because as will generate new relocation
> types for la.local etc). So such a mismatch between as and ld can be
> considered "completely broken" and we don't need to support it. And,
> the Alpha port also check the assembler for the default of -mexplicit-
> relocs.
>
> This should be documented in invoke.texi, but currently it does not
> mention -mexplicit-relocs for LoongArch at all. So I'll submit the
> doclater in another patch.
>
> -- >8 --
>
> The assembly produced with -mexplicit-relocs is not supported by gas <=
> 2.39. Check if the assembler supports explicit relocations and set the
> default accordingly.
Looks good to me.
On Wed, 2022-07-27 at 09:34 +0800, Lulu Cheng wrote:
> > -- >8 --
> >
> > The assembly produced with -mexplicit-relocs is not supported by gas
> > <=
> > 2.39. Check if the assembler supports explicit relocations and set
> > the
> > default accordingly.
> Looks good to me.
Pushed r13-1851.
@@ -155,7 +155,7 @@ Target Joined RejectNegative UInteger Var(loongarch_max_inline_memcpy_size) Init
-mmax-inline-memcpy-size=SIZE Set the max size of memcpy to inline, default is 1024.
mexplicit-relocs
-Target Var(TARGET_EXPLICIT_RELOCS) Init(1)
+Target Var(TARGET_EXPLICIT_RELOCS) Init(HAVE_AS_EXPLICIT_RELOCS)
Use %reloc() assembly operators.
; The code model option names for -mcmodel.
@@ -87,4 +87,8 @@ loongarch_config_target (struct loongarch_target *target,
while -m[no]-memcpy imposes a global constraint. */
#define TARGET_DO_OPTIMIZE_BLOCK_MOVE_P loongarch_do_optimize_block_move_p()
+#ifndef HAVE_AS_EXPLICIT_RELOCS
+#define HAVE_AS_EXPLICIT_RELOCS 0
+#endif
+
#endif /* LOONGARCH_OPTS_H */
@@ -162,7 +162,7 @@ Target Joined RejectNegative UInteger Var(loongarch_max_inline_memcpy_size) Init
-mmax-inline-memcpy-size=SIZE Set the max size of memcpy to inline, default is 1024.
mexplicit-relocs
-Target Var(TARGET_EXPLICIT_RELOCS) Init(1)
+Target Var(TARGET_EXPLICIT_RELOCS) Init(HAVE_AS_EXPLICIT_RELOCS)
Use %reloc() assembly operators.
; The code model option names for -mcmodel.
@@ -19674,7 +19674,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 19679 "configure"
+#line 19677 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -19780,7 +19780,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 19785 "configure"
+#line 19783 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -28771,7 +28771,7 @@ $as_echo "#define HAVE_AS_MARCH_ZIFENCEI 1" >>confdefs.h
fi
;;
- loongarch*-*-*)
+ loongarch*-*-*)
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for .dtprelword support" >&5
$as_echo_n "checking assembler for .dtprelword support... " >&6; }
if ${gcc_cv_as_loongarch_dtprelword+:} false; then :
@@ -28807,6 +28807,37 @@ if test $gcc_cv_as_loongarch_dtprelword != yes; then
$as_echo "#define HAVE_AS_DTPRELWORD 1" >>confdefs.h
fi
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for explicit relocation support" >&5
+$as_echo_n "checking assembler for explicit relocation support... " >&6; }
+if ${gcc_cv_as_loongarch_explicit_relocs+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ gcc_cv_as_loongarch_explicit_relocs=no
+ if test x$gcc_cv_as != x; then
+ $as_echo 'a:pcalau12i $t0,%pc_hi20(a)' > conftest.s
+ if { ac_try='$gcc_cv_as $gcc_cv_as_flags -o conftest.o conftest.s >&5'
+ { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+ test $ac_status = 0; }; }
+ then
+ gcc_cv_as_loongarch_explicit_relocs=yes
+ else
+ echo "configure: failed program was" >&5
+ cat conftest.s >&5
+ fi
+ rm -f conftest.o conftest.s
+ fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_loongarch_explicit_relocs" >&5
+$as_echo "$gcc_cv_as_loongarch_explicit_relocs" >&6; }
+if test $gcc_cv_as_loongarch_explicit_relocs = yes; then
+
+$as_echo "#define HAVE_AS_EXPLICIT_RELOCS 1" >>confdefs.h
+
+fi
+
;;
s390*-*-*)
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for .gnu_attribute support" >&5
@@ -5287,7 +5287,7 @@ configured with --enable-newlib-nano-formatted-io.])
[AC_DEFINE(HAVE_AS_MARCH_ZIFENCEI, 1,
[Define if the assembler understands -march=rv*_zifencei.])])
;;
- loongarch*-*-*)
+ loongarch*-*-*)
gcc_GAS_CHECK_FEATURE([.dtprelword support],
gcc_cv_as_loongarch_dtprelword, [2,18,0],,
[.section .tdata,"awT",@progbits
@@ -5297,6 +5297,11 @@ x:
.dtprelword x+0x8000],,
[AC_DEFINE(HAVE_AS_DTPRELWORD, 1,
[Define if your assembler supports .dtprelword.])])
+ gcc_GAS_CHECK_FEATURE([explicit relocation support],
+ gcc_cv_as_loongarch_explicit_relocs,,
+ [a:pcalau12i $t0,%pc_hi20(a)],,
+ [AC_DEFINE(HAVE_AS_EXPLICIT_RELOCS, 1,
+ [Define if your assembler supports explicit relocation.])])
;;
s390*-*-*)
gcc_GAS_CHECK_FEATURE([.gnu_attribute support],