https://gcc.gnu.org/g:f6b9a064a295f5371901e2fac380d20e77cf7131
commit r15-1202-gf6b9a064a295f5371901e2fac380d20e77cf7131
Author: Victor Do Nascimento <victor.donascime...@arm.com>
Date: Fri May 31 14:25:11 2024 +0100
Libatomic: AArch64: Convert all lse128 assembly to .insn directives
Given the lack of support for the LSE128 instructions in all but the
the most up-to-date version of Binutils (2.42), having the build-time
test for assembler support for these instructions often leads to the
building of Libatomic without support for LSE128-dependent atomic
function implementations. This ultimately leads to different people
having different versions of Libatomic on their machines, depending on
which assembler was available at compilation time.
Furthermore, the conditional inclusion of these atomic function
implementations predicated on assembler support leads to a series of
`#if HAVE_FEAT_LSE128' guards scattered throughout the codebase and
the need for a series of aliases when the feature flag evaluates
to false. The preprocessor macro guards, together with the
conditional aliasing leads to code that is cumbersome to understand
and maintain.
Both of the issues highlighted above will only get worse with the
coming support for LRCPC3 atomics which under the current scheme will
also require build-time checks.
Consequently, a better option for both consistency across builds and
code cleanness is to make recourse to the `.inst' directive. By
replacing all novel assembly instructions for their hexadecimal
representation within `.inst's, we ensure that the Libatomic code is
both considerably cleaner and all machines build the same binary,
irrespective of binutils version available at compile time.
This patch therefore removes all configure checks for LSE128-support
in the assembler and all the guards and aliases that were associated
with `HAVE_FEAT_LSE128'
libatomic/ChangeLog:
* acinclude.m4 (LIBAT_TEST_FEAT_AARCH64_LSE128): Delete.
* auto-config.h.in (HAVE_FEAT_LSE128): Likewise
* config/linux/aarch64/atomic_16.S: Replace all LSE128
instructions with equivalent `.inst' directives.
(HAVE_FEAT_LSE128): Remove all references.
* configure: Regenerate.
* configure.ac: Remove call to LIBAT_TEST_FEAT_AARCH64_LSE128.
Diff:
---
libatomic/acinclude.m4 | 18 -------
libatomic/auto-config.h.in | 3 --
libatomic/config/linux/aarch64/atomic_16.S | 76 +++++++++++++-----------------
libatomic/configure | 43 -----------------
libatomic/configure.ac | 3 --
5 files changed, 32 insertions(+), 111 deletions(-)
diff --git a/libatomic/acinclude.m4 b/libatomic/acinclude.m4
index 6d2e0b1c355c..f35ab5b60a50 100644
--- a/libatomic/acinclude.m4
+++ b/libatomic/acinclude.m4
@@ -83,24 +83,6 @@ AC_DEFUN([LIBAT_TEST_ATOMIC_BUILTIN],[
])
])
-dnl
-dnl Test if the host assembler supports armv9.4-a LSE128 isns.
-dnl
-AC_DEFUN([LIBAT_TEST_FEAT_AARCH64_LSE128],[
- AC_CACHE_CHECK([for armv9.4-a LSE128 insn support],
- [libat_cv_have_feat_lse128],[
- AC_LANG_CONFTEST([AC_LANG_PROGRAM([],[asm(".arch armv9-a+lse128")])])
- if AC_TRY_EVAL(ac_compile); then
- eval libat_cv_have_feat_lse128=yes
- else
- eval libat_cv_have_feat_lse128=no
- fi
- rm -f conftest*
- ])
- LIBAT_DEFINE_YESNO([HAVE_FEAT_LSE128], [$libat_cv_have_feat_lse128],
- [Have LSE128 support for 16 byte integers.])
-])
-
dnl
dnl Test if we have __atomic_load and __atomic_store for mode $1, size $2
dnl
diff --git a/libatomic/auto-config.h.in b/libatomic/auto-config.h.in
index 7c78933b07d1..ab3424a759ea 100644
--- a/libatomic/auto-config.h.in
+++ b/libatomic/auto-config.h.in
@@ -105,9 +105,6 @@
/* Define to 1 if you have the <dlfcn.h> header file. */
#undef HAVE_DLFCN_H
-/* Have LSE128 support for 16 byte integers. */
-#undef HAVE_FEAT_LSE128
-
/* Define to 1 if you have the <fenv.h> header file. */
#undef HAVE_FENV_H
diff --git a/libatomic/config/linux/aarch64/atomic_16.S
b/libatomic/config/linux/aarch64/atomic_16.S
index b63e97ac5a22..d6e71ba6e167 100644
--- a/libatomic/config/linux/aarch64/atomic_16.S
+++ b/libatomic/config/linux/aarch64/atomic_16.S
@@ -40,18 +40,9 @@
#include "auto-config.h"
-#if !HAVE_IFUNC
-# undef HAVE_FEAT_LSE128
-# define HAVE_FEAT_LSE128 0
-#endif
-
#define HAVE_FEAT_LSE2 HAVE_IFUNC
-#if HAVE_FEAT_LSE128
- .arch armv9-a+lse128
-#else
.arch armv8-a+lse
-#endif
#define LSE128(NAME) libat_##NAME##_i1
#define LSE2(NAME) libat_##NAME##_i2
@@ -226,7 +217,6 @@ ENTRY (exchange_16)
END (exchange_16)
-#if HAVE_FEAT_LSE128
ENTRY_FEAT (exchange_16, LSE128)
mov tmp0, x0
mov res0, in0
@@ -234,21 +224,23 @@ ENTRY_FEAT (exchange_16, LSE128)
cbnz w4, 1f
/* RELAXED. */
- swpp res0, res1, [tmp0]
+ /* swpp res0, res1, [tmp0] */
+ .inst 0x192180c0
ret
1:
cmp w4, ACQUIRE
b.hi 2f
/* ACQUIRE/CONSUME. */
- swppa res0, res1, [tmp0]
+ /* swppa res0, res1, [tmp0] */
+ .inst 0x19a180c0
ret
/* RELEASE/ACQ_REL/SEQ_CST. */
-2: swppal res0, res1, [tmp0]
+2: /* swppal res0, res1, [tmp0] */
+ .inst 0x19e180c0
ret
END_FEAT (exchange_16, LSE128)
-#endif
ENTRY (compare_exchange_16)
@@ -446,7 +438,6 @@ ENTRY (fetch_or_16)
END (fetch_or_16)
-#if HAVE_FEAT_LSE128
ENTRY_FEAT (fetch_or_16, LSE128)
mov tmp0, x0
mov res0, in0
@@ -454,21 +445,23 @@ ENTRY_FEAT (fetch_or_16, LSE128)
cbnz w4, 1f
/* RELAXED. */
- ldsetp res0, res1, [tmp0]
+ /* ldsetp res0, res1, [tmp0] */
+ .inst 0x192130c0
ret
1:
cmp w4, ACQUIRE
b.hi 2f
/* ACQUIRE/CONSUME. */
- ldsetpa res0, res1, [tmp0]
+ /* ldsetpa res0, res1, [tmp0] */
+ .inst 0x19a130c0
ret
/* RELEASE/ACQ_REL/SEQ_CST. */
-2: ldsetpal res0, res1, [tmp0]
+2: /* ldsetpal res0, res1, [tmp0] */
+ .inst 0x19e130c0
ret
END_FEAT (fetch_or_16, LSE128)
-#endif
ENTRY (or_fetch_16)
@@ -493,14 +486,14 @@ ENTRY (or_fetch_16)
END (or_fetch_16)
-#if HAVE_FEAT_LSE128
ENTRY_FEAT (or_fetch_16, LSE128)
cbnz w4, 1f
mov tmp0, in0
mov tmp1, in1
/* RELAXED. */
- ldsetp in0, in1, [x0]
+ /* ldsetp in0, in1, [x0] */
+ .inst 0x19233002
orr res0, in0, tmp0
orr res1, in1, tmp1
ret
@@ -509,18 +502,19 @@ ENTRY_FEAT (or_fetch_16, LSE128)
b.hi 2f
/* ACQUIRE/CONSUME. */
- ldsetpa in0, in1, [x0]
+ /* ldsetpa in0, in1, [x0] */
+ .inst 0x19a33002
orr res0, in0, tmp0
orr res1, in1, tmp1
ret
/* RELEASE/ACQ_REL/SEQ_CST. */
-2: ldsetpal in0, in1, [x0]
+2: /* ldsetpal in0, in1, [x0] */
+ .inst 0x19e33002
orr res0, in0, tmp0
orr res1, in1, tmp1
ret
END_FEAT (or_fetch_16, LSE128)
-#endif
ENTRY (fetch_and_16)
@@ -545,7 +539,6 @@ ENTRY (fetch_and_16)
END (fetch_and_16)
-#if HAVE_FEAT_LSE128
ENTRY_FEAT (fetch_and_16, LSE128)
mov tmp0, x0
mvn res0, in0
@@ -553,7 +546,8 @@ ENTRY_FEAT (fetch_and_16, LSE128)
cbnz w4, 1f
/* RELAXED. */
- ldclrp res0, res1, [tmp0]
+ /* ldclrp res0, res1, [tmp0] */
+ .inst 0x192110c0
ret
1:
@@ -561,14 +555,15 @@ ENTRY_FEAT (fetch_and_16, LSE128)
b.hi 2f
/* ACQUIRE/CONSUME. */
- ldclrpa res0, res1, [tmp0]
+ /* ldclrpa res0, res1, [tmp0] */
+ .inst 0x19a110c0
ret
/* RELEASE/ACQ_REL/SEQ_CST. */
-2: ldclrpal res0, res1, [tmp0]
+2: /* ldclrpal res0, res1, [tmp0] */
+ .inst 0x19e110c0
ret
END_FEAT (fetch_and_16, LSE128)
-#endif
ENTRY (and_fetch_16)
@@ -593,14 +588,14 @@ ENTRY (and_fetch_16)
END (and_fetch_16)
-#if HAVE_FEAT_LSE128
ENTRY_FEAT (and_fetch_16, LSE128)
mvn tmp0, in0
mvn tmp0, in1
cbnz w4, 1f
/* RELAXED. */
- ldclrp tmp0, tmp1, [x0]
+ /* ldclrp tmp0, tmp1, [x0] */
+ .inst 0x19271006
and res0, tmp0, in0
and res1, tmp1, in1
ret
@@ -610,18 +605,19 @@ ENTRY_FEAT (and_fetch_16, LSE128)
b.hi 2f
/* ACQUIRE/CONSUME. */
- ldclrpa tmp0, tmp1, [x0]
+ /* ldclrpa tmp0, tmp1, [x0] */
+ .inst 0x19a71006
and res0, tmp0, in0
and res1, tmp1, in1
ret
/* RELEASE/ACQ_REL/SEQ_CST. */
-2: ldclrpal tmp0, tmp1, [x5]
+2: /* ldclrpal tmp0, tmp1, [x5] */
+ .inst 0x19e710a6
and res0, tmp0, in0
and res1, tmp1, in1
ret
END_FEAT (and_fetch_16, LSE128)
-#endif
ENTRY (fetch_xor_16)
@@ -729,16 +725,9 @@ ENTRY (test_and_set_16)
END (test_and_set_16)
-/* Alias entry points which are the same in LSE2 and LSE128. */
-
#if HAVE_IFUNC
-# if !HAVE_FEAT_LSE128
-ALIAS (exchange_16, LSE128, LSE2)
-ALIAS (fetch_or_16, LSE128, LSE2)
-ALIAS (fetch_and_16, LSE128, LSE2)
-ALIAS (or_fetch_16, LSE128, LSE2)
-ALIAS (and_fetch_16, LSE128, LSE2)
-# endif
+
+/* Alias entry points which are the same in LSE2 and LSE128. */
ALIAS (load_16, LSE128, LSE2)
ALIAS (store_16, LSE128, LSE2)
ALIAS (compare_exchange_16, LSE128, LSE2)
@@ -753,7 +742,6 @@ ALIAS (nand_fetch_16, LSE128, LSE2)
ALIAS (test_and_set_16, LSE128, LSE2)
/* Alias entry points which are the same in baseline and LSE2. */
-
ALIAS (exchange_16, LSE2, CORE)
ALIAS (fetch_add_16, LSE2, CORE)
ALIAS (add_fetch_16, LSE2, CORE)
diff --git a/libatomic/configure b/libatomic/configure
index 32cb3ecac262..d579bab96f86 100755
--- a/libatomic/configure
+++ b/libatomic/configure
@@ -14697,49 +14697,6 @@ _ACEOF
-# Check for target-specific assembly-level support for atomic operations.
-
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking for armv9.4-a LSE128 insn
support" >&5
-$as_echo_n "checking for armv9.4-a LSE128 insn support... " >&6; }
-if ${libat_cv_have_feat_lse128+:} false; then :
- $as_echo_n "(cached) " >&6
-else
-
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h. */
-
-int
-main ()
-{
-asm(".arch armv9-a+lse128")
- ;
- return 0;
-}
-_ACEOF
- if { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_compile\""; } >&5
- (eval $ac_compile) 2>&5
- ac_status=$?
- $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
- test $ac_status = 0; }; then
- eval libat_cv_have_feat_lse128=yes
- else
- eval libat_cv_have_feat_lse128=no
- fi
- rm -f conftest*
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libat_cv_have_feat_lse128"
>&5
-$as_echo "$libat_cv_have_feat_lse128" >&6; }
-
- yesno=`echo $libat_cv_have_feat_lse128 | tr 'yesno' '1 0 '`
-
-cat >>confdefs.h <<_ACEOF
-#define HAVE_FEAT_LSE128 $yesno
-_ACEOF
-
-
-
-
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether byte ordering is
bigendian" >&5
$as_echo_n "checking whether byte ordering is bigendian... " >&6; }
if ${ac_cv_c_bigendian+:} false; then :
diff --git a/libatomic/configure.ac b/libatomic/configure.ac
index 85824fa7614c..32a2cdb13aee 100644
--- a/libatomic/configure.ac
+++ b/libatomic/configure.ac
@@ -206,9 +206,6 @@ LIBAT_FORALL_MODES([LIBAT_HAVE_ATOMIC_CAS])
LIBAT_FORALL_MODES([LIBAT_HAVE_ATOMIC_FETCH_ADD])
LIBAT_FORALL_MODES([LIBAT_HAVE_ATOMIC_FETCH_OP])
-# Check for target-specific assembly-level support for atomic operations.
-LIBAT_TEST_FEAT_AARCH64_LSE128()
-
AC_C_BIGENDIAN
# I don't like the default behaviour of WORDS_BIGENDIAN undefined for LE.
AH_BOTTOM(
