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 --git a/libatomic/acinclude.m4 b/libatomic/acinclude.m4
index 6d2e0b1c355c470e4417696412864d20a6c1c62c..f35ab5b60a509b3c7324dcc4acf73b82a6cc3894 100644 (file)
--- 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 7c78933b07d10d971f3f41b84d66ba11392979dc..ab3424a759eae8c5fba17957baeac2ed8397de44 100644 (file)
--- 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 b63e97ac5a22849c05bdb989f74f5dcb9131cf07..d6e71ba6e167184a7fba7c099b9362154897996f 100644 (file)
--- 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 32cb3ecac262b4815cfe56788d2347b98ecfa0fe..d579bab96f86ce863882d4dc04e59af399b0b9c5 100755 (executable)
--- 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 85824fa7614c3030d248e2026c94b800bee9538e..32a2cdb13aee40adac3c0f97180d7ca71835e7b8 100644 (file)
--- 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(