Hi!
As reported in the PR, GCC 10 (and also 9.3.1 but not 9.3.0) fails to build
when using older binutils which lack LSE support, because those instructions
are used in libgcc.
Thanks to Kyrylo's hint, the following patches (hopefully) allow it to build
even with older binutils by using .inst directive if LSE support isn't
available in the assembler.
There are two versions of the patch, one is using .macro to ignore the
operands when emitting .inst, the other moves the operands for the
HAVE_AS_LSE case into the macro. My slight preference is the latter,
because for maintanance it makes it clear that if one wants to use different
operands, one needs to use a different macro and different .inst
constant(s).
I've been testing this in distro scratch builds, so I don't really have
there the old assembler, but bootstrapped/regtested 5 times, for each of the
two patches once as is and once with s/cas/caszz/ in the configure{.ac,} to
simulate missing support of LSE (and verified that as is the build logs
contain checking...supports LSE yes and with the tweaked ...supports LSE no)
and once vanilla trunk, and aarch64-linux-gnu-objdump -dr libgcc.a is
identical from all 5 builds.
Ok for trunk (which version), or do we want to instead document a newer
binutils requirement? Yet another option is to go with the patch for a
while and later bump the requirement and revert the patch.
Jakub
2020-04-15 Jakub Jelinek <ja...@redhat.com>
PR target/93053
* configure.ac (LIBGCC_CHECK_AS_LSE): Add HAVE_AS_LSE checking.
* config/aarch64/lse.S: Include auto-target.h, if HAVE_AS_LSE
is not defined, use just .arch armv8-a.
(B, M, N, OPN): Define.
(COMMENT): New .macro.
(CAS, CASP, SWP, LDOP): Use .inst directive if HAVE_AS_LSE is not
defined.
* configure: Regenerated.
* config.in: Regenerated.
--- libgcc/configure.ac.jj 2020-01-24 22:34:36.301641823 +0100
+++ libgcc/configure.ac 2020-04-14 13:48:48.771866654 +0200
@@ -599,6 +599,25 @@ i[[34567]]86-*-* | x86_64-*-*)
esac])
LIBGCC_CHECK_AS_AVX
+dnl Check if as supports LSE instructions.
+AC_DEFUN([LIBGCC_CHECK_AS_LSE], [
+case "${target}" in
+aarch64*-*-*)
+ AC_CACHE_CHECK([if the assembler supports LSE], libgcc_cv_as_lse, [
+ AC_TRY_COMPILE([],
+changequote(,)dnl
+ asm(".arch armv8-a+lse\n\tcas w0, w1, [x2]");
+changequote([,])dnl
+ ,
+ [libgcc_cv_as_lse=yes], [libgcc_cv_as_lse=no])
+ ])
+ if test x$libgcc_cv_as_lse = xyes; then
+ AC_DEFINE(HAVE_AS_LSE, 1, [Define to 1 if the assembler supports LSE.])
+ fi
+ ;;
+esac])
+LIBGCC_CHECK_AS_LSE
+
dnl Check if as supports RTM instructions.
AC_CACHE_CHECK(for init priority support, libgcc_cv_init_priority, [
AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,
--- libgcc/config/aarch64/lse.S.jj 2020-01-12 11:54:38.610380262 +0100
+++ libgcc/config/aarch64/lse.S 2020-04-14 13:44:57.403253956 +0200
@@ -48,8 +48,14 @@ see the files COPYING3 and COPYING.RUNTI
* separately to minimize code size.
*/
+#include "auto-target.h"
+
/* Tell the assembler to accept LSE instructions. */
+#ifdef HAVE_AS_LSE
.arch armv8-a+lse
+#else
+ .arch armv8-a
+#endif
/* Declare the symbol gating the LSE implementations. */
.hidden __aarch64_have_lse_atomics
@@ -58,12 +64,19 @@ see the files COPYING3 and COPYING.RUNTI
#if SIZE == 1
# define S b
# define UXT uxtb
+# define B 0x00000000
#elif SIZE == 2
# define S h
# define UXT uxth
+# define B 0x40000000
#elif SIZE == 4 || SIZE == 8 || SIZE == 16
# define S
# define UXT mov
+# if SIZE == 4
+# define B 0x80000000
+# elif SIZE == 8
+# define B 0xc0000000
+# endif
#else
# error
#endif
@@ -72,18 +85,26 @@ see the files COPYING3 and COPYING.RUNTI
# define SUFF _relax
# define A
# define L
+# define M 0x000000
+# define N 0x000000
#elif MODEL == 2
# define SUFF _acq
# define A a
# define L
+# define M 0x400000
+# define N 0x800000
#elif MODEL == 3
# define SUFF _rel
# define A
# define L l
+# define M 0x008000
+# define N 0x400000
#elif MODEL == 4
# define SUFF _acq_rel
# define A a
# define L l
+# define M 0x408000
+# define N 0xc00000
#else
# error
#endif
@@ -138,13 +159,23 @@ see the files COPYING3 and COPYING.RUNTI
cbz w(tmp0), \label
.endm
+#ifndef HAVE_AS_LSE
+/* Throw away all arguments. */
+.macro COMMENT args:vararg
+.endm
+#endif
+
#ifdef L_cas
STARTFN NAME(cas)
JUMP_IF_NOT_LSE 8f
#if SIZE < 16
-#define CAS glue4(cas, A, L, S)
+#ifdef HAVE_AS_LSE
+# define CAS glue4(cas, A, L, S)
+#else
+# define CAS .inst 0x08a07c41 + B + M; COMMENT
+#endif
CAS s(0), s(1), [x2]
ret
@@ -160,7 +191,11 @@ STARTFN NAME(cas)
#else
#define LDXP glue3(ld, A, xp)
#define STXP glue3(st, L, xp)
-#define CASP glue3(casp, A, L)
+#ifdef HAVE_AS_LSE
+# define CASP glue3(casp, A, L)
+#else
+# define CASP .inst 0x48207c82 + M; COMMENT
+#endif
CASP x0, x1, x2, x3, [x4]
ret
@@ -181,7 +216,11 @@ ENDFN NAME(cas)
#endif
#ifdef L_swp
-#define SWP glue4(swp, A, L, S)
+#ifdef HAVE_AS_LSE
+# define SWP glue4(swp, A, L, S)
+#else
+# define SWP .inst 0x38208020 + B + N; COMMENT
+#endif
STARTFN NAME(swp)
JUMP_IF_NOT_LSE 8f
@@ -204,19 +243,27 @@ ENDFN NAME(swp)
#ifdef L_ldadd
#define LDNM ldadd
#define OP add
+#define OPN 0x0000
#elif defined(L_ldclr)
#define LDNM ldclr
#define OP bic
+#define OPN 0x1000
#elif defined(L_ldeor)
#define LDNM ldeor
#define OP eor
+#define OPN 0x2000
#elif defined(L_ldset)
#define LDNM ldset
#define OP orr
+#define OPN 0x3000
#else
#error
#endif
-#define LDOP glue4(LDNM, A, L, S)
+#ifdef HAVE_AS_LSE
+# define LDOP glue4(LDNM, A, L, S)
+#else
+# define LDOP .inst 0x38200020 + OPN + B + N; COMMENT
+#endif
STARTFN NAME(LDNM)
JUMP_IF_NOT_LSE 8f
--- libgcc/configure.jj 2020-02-12 23:17:24.866303077 +0100
+++ libgcc/configure 2020-04-14 13:48:52.627810203 +0200
@@ -5530,6 +5530,46 @@ $as_echo "#define HAVE_AS_AVX 1" >>confd
;;
esac
+
+
+case "${target}" in
+aarch64*-*-*)
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking if the assembler supports
LSE" >&5
+$as_echo_n "checking if the assembler supports LSE... " >&6; }
+if ${libgcc_cv_as_lse+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+int
+main ()
+{
+ asm(".arch armv8-a+lse\n\tcas w0, w1, [x2]");
+
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+ libgcc_cv_as_lse=yes
+else
+ libgcc_cv_as_lse=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libgcc_cv_as_lse" >&5
+$as_echo "$libgcc_cv_as_lse" >&6; }
+ if test x$libgcc_cv_as_lse = xyes; then
+
+$as_echo "#define HAVE_AS_LSE 1" >>confdefs.h
+
+ fi
+ ;;
+esac
+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for init priority support"
>&5
$as_echo_n "checking for init priority support... " >&6; }
if ${libgcc_cv_init_priority+:} false; then :
--- libgcc/config.in.jj 2020-01-12 11:54:38.610380262 +0100
+++ libgcc/config.in 2020-04-14 13:53:19.037908554 +0200
@@ -10,6 +10,9 @@
*/
#undef HAVE_AS_CFI_SECTIONS
+/* Define to 1 if the assembler supports LSE. */
+#undef HAVE_AS_LSE
+
/* Define to 1 if the target assembler supports thread-local storage. */
#undef HAVE_CC_TLS
2020-04-15 Jakub Jelinek <ja...@redhat.com>
PR target/93053
* configure.ac (LIBGCC_CHECK_AS_LSE): Add HAVE_AS_LSE checking.
* config/aarch64/lse.S: Include auto-target.h, if HAVE_AS_LSE
is not defined, use just .arch armv8-a.
(B, M, N, OPN): Define.
(COMMENT): New .macro.
(CAS, CASP, SWP, LDOP): Use .inst directive if HAVE_AS_LSE is not
defined. Otherwise, move the operands right after the glue? and
comment out operands where the macros are used.
* configure: Regenerated.
* config.in: Regenerated.
--- libgcc/configure.ac.jj 2020-01-24 22:34:36.301641823 +0100
+++ libgcc/configure.ac 2020-04-14 13:48:48.771866654 +0200
@@ -599,6 +599,25 @@ i[[34567]]86-*-* | x86_64-*-*)
esac])
LIBGCC_CHECK_AS_AVX
+dnl Check if as supports LSE instructions.
+AC_DEFUN([LIBGCC_CHECK_AS_LSE], [
+case "${target}" in
+aarch64*-*-*)
+ AC_CACHE_CHECK([if the assembler supports LSE], libgcc_cv_as_lse, [
+ AC_TRY_COMPILE([],
+changequote(,)dnl
+ asm(".arch armv8-a+lse\n\tcas w0, w1, [x2]");
+changequote([,])dnl
+ ,
+ [libgcc_cv_as_lse=yes], [libgcc_cv_as_lse=no])
+ ])
+ if test x$libgcc_cv_as_lse = xyes; then
+ AC_DEFINE(HAVE_AS_LSE, 1, [Define to 1 if the assembler supports LSE.])
+ fi
+ ;;
+esac])
+LIBGCC_CHECK_AS_LSE
+
dnl Check if as supports RTM instructions.
AC_CACHE_CHECK(for init priority support, libgcc_cv_init_priority, [
AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,
--- libgcc/config/aarch64/lse.S.jj 2020-01-12 11:54:38.610380262 +0100
+++ libgcc/config/aarch64/lse.S 2020-04-14 19:34:19.641346299 +0200
@@ -48,8 +48,14 @@ see the files COPYING3 and COPYING.RUNTI
* separately to minimize code size.
*/
+#include "auto-target.h"
+
/* Tell the assembler to accept LSE instructions. */
+#ifdef HAVE_AS_LSE
.arch armv8-a+lse
+#else
+ .arch armv8-a
+#endif
/* Declare the symbol gating the LSE implementations. */
.hidden __aarch64_have_lse_atomics
@@ -58,12 +64,19 @@ see the files COPYING3 and COPYING.RUNTI
#if SIZE == 1
# define S b
# define UXT uxtb
+# define B 0x00000000
#elif SIZE == 2
# define S h
# define UXT uxth
+# define B 0x40000000
#elif SIZE == 4 || SIZE == 8 || SIZE == 16
# define S
# define UXT mov
+# if SIZE == 4
+# define B 0x80000000
+# elif SIZE == 8
+# define B 0xc0000000
+# endif
#else
# error
#endif
@@ -72,18 +85,26 @@ see the files COPYING3 and COPYING.RUNTI
# define SUFF _relax
# define A
# define L
+# define M 0x000000
+# define N 0x000000
#elif MODEL == 2
# define SUFF _acq
# define A a
# define L
+# define M 0x400000
+# define N 0x800000
#elif MODEL == 3
# define SUFF _rel
# define A
# define L l
+# define M 0x008000
+# define N 0x400000
#elif MODEL == 4
# define SUFF _acq_rel
# define A a
# define L l
+# define M 0x408000
+# define N 0xc00000
#else
# error
#endif
@@ -144,9 +165,13 @@ STARTFN NAME(cas)
JUMP_IF_NOT_LSE 8f
#if SIZE < 16
-#define CAS glue4(cas, A, L, S)
+#ifdef HAVE_AS_LSE
+# define CAS glue4(cas, A, L, S) s(0), s(1), [x2]
+#else
+# define CAS .inst 0x08a07c41 + B + M
+#endif
- CAS s(0), s(1), [x2]
+ CAS /* s(0), s(1), [x2] */
ret
8: UXT s(tmp0), s(0)
@@ -160,9 +185,13 @@ STARTFN NAME(cas)
#else
#define LDXP glue3(ld, A, xp)
#define STXP glue3(st, L, xp)
-#define CASP glue3(casp, A, L)
+#ifdef HAVE_AS_LSE
+# define CASP glue3(casp, A, L) x0, x1, x2, x3, [x4]
+#else
+# define CASP .inst 0x48207c82 + M
+#endif
- CASP x0, x1, x2, x3, [x4]
+ CASP /* x0, x1, x2, x3, [x4] */
ret
8: mov x(tmp0), x0
@@ -181,12 +210,16 @@ ENDFN NAME(cas)
#endif
#ifdef L_swp
-#define SWP glue4(swp, A, L, S)
+#ifdef HAVE_AS_LSE
+# define SWP glue4(swp, A, L, S) s(0), s(0), [x1]
+#else
+# define SWP .inst 0x38208020 + B + N
+#endif
STARTFN NAME(swp)
JUMP_IF_NOT_LSE 8f
- SWP s(0), s(0), [x1]
+ SWP /* s(0), s(0), [x1] */
ret
8: mov s(tmp0), s(0)
@@ -204,24 +237,32 @@ ENDFN NAME(swp)
#ifdef L_ldadd
#define LDNM ldadd
#define OP add
+#define OPN 0x0000
#elif defined(L_ldclr)
#define LDNM ldclr
#define OP bic
+#define OPN 0x1000
#elif defined(L_ldeor)
#define LDNM ldeor
#define OP eor
+#define OPN 0x2000
#elif defined(L_ldset)
#define LDNM ldset
#define OP orr
+#define OPN 0x3000
#else
#error
#endif
-#define LDOP glue4(LDNM, A, L, S)
+#ifdef HAVE_AS_LSE
+# define LDOP glue4(LDNM, A, L, S) s(0), s(0), [x1]
+#else
+# define LDOP .inst 0x38200020 + OPN + B + N
+#endif
STARTFN NAME(LDNM)
JUMP_IF_NOT_LSE 8f
- LDOP s(0), s(0), [x1]
+ LDOP /* s(0), s(0), [x1] */
ret
8: mov s(tmp0), s(0)
--- libgcc/configure.jj 2020-02-12 23:17:24.866303077 +0100
+++ libgcc/configure 2020-04-14 13:48:52.627810203 +0200
@@ -5530,6 +5530,46 @@ $as_echo "#define HAVE_AS_AVX 1" >>confd
;;
esac
+
+
+case "${target}" in
+aarch64*-*-*)
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking if the assembler supports
LSE" >&5
+$as_echo_n "checking if the assembler supports LSE... " >&6; }
+if ${libgcc_cv_as_lse+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+int
+main ()
+{
+ asm(".arch armv8-a+lse\n\tcas w0, w1, [x2]");
+
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+ libgcc_cv_as_lse=yes
+else
+ libgcc_cv_as_lse=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libgcc_cv_as_lse" >&5
+$as_echo "$libgcc_cv_as_lse" >&6; }
+ if test x$libgcc_cv_as_lse = xyes; then
+
+$as_echo "#define HAVE_AS_LSE 1" >>confdefs.h
+
+ fi
+ ;;
+esac
+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for init priority support"
>&5
$as_echo_n "checking for init priority support... " >&6; }
if ${libgcc_cv_init_priority+:} false; then :
--- libgcc/config.in.jj 2020-01-12 11:54:38.610380262 +0100
+++ libgcc/config.in 2020-04-14 13:53:19.037908554 +0200
@@ -10,6 +10,9 @@
*/
#undef HAVE_AS_CFI_SECTIONS
+/* Define to 1 if the assembler supports LSE. */
+#undef HAVE_AS_LSE
+
/* Define to 1 if the target assembler supports thread-local storage. */
#undef HAVE_CC_TLS
