provided __asm version of assembly code for atomic atomic operations

for better compatibility. (this is a temporary resolution so that this one won't block other tests. we'll revisit this change when we figure out performance implication of the __asm version.)
2025-08-30 14:07:59 +00:00 · 2005-06-16 21:58:00 +00:00
parent 2f3f555262
commit c528bd6986
5 changed files with 155 additions and 17 deletions
--- a/configure.in
+++ b/configure.in
@@ -18,7 +18,7 @@ AC_DIVERT_PUSH(1)dnl
 esyscmd([sed "s/^/# /" COPYRIGHT])dnl
 AC_DIVERT_POP()dnl

-AC_REVISION($Revision: 1.378 $)
+AC_REVISION($Revision: 1.379 $)

 AC_INIT(lib/dns/name.c)
 AC_PREREQ(2.13)
@@ -1867,7 +1867,6 @@ if test "$use_atomic" = "yes"; then
 	AC_MSG_CHECKING([architecture type for atomic operations])
 	case "$host" in
 	[i[3456]86-*]|x86_64-*)
-		# XXX: also need to check portability of the "asm" keyword?
 		# XXX: some old x86 architectures actualy do not support
 		#      (some of) these operations.  Do we need stricter checks?
 		# Note: We currently use the same code for both the x86_32 and
@@ -1879,15 +1878,6 @@ if test "$use_atomic" = "yes"; then
 	alpha*-*)
 		have_atomic=yes
 		arch=alpha
-		if test "X$GCC" != "Xyes"; then
-			case "$host" in
-			*-dec-osf*)
-			# Tru64 compiler has its own syntax for inline
-			# assembly.
-			ISC_PLATFORM_USEOSFASM="#define ISC_PLATFORM_USEOSFASM 1"
-			;;
-			esac
-		fi
 	;;
 	*)
 		have_atomic=no
@@ -1897,6 +1887,52 @@ if test "$use_atomic" = "yes"; then
 	AC_MSG_RESULT($arch)
 fi

+if test "$have_atomic" = "yes"; then
+	AC_MSG_CHECKING([compiler support for inline assembly code])
+
+	compiler=generic
+	# Check whehter the compiler supports the assembly syntax we provide.
+	if test "X$GCC" = "Xyes"; then
+		# GCC's ASM extension always works
+		compiler=gcc
+	else
+		case "$host" in
+		alpha*-dec-osf*)
+			# Tru64 compiler has its own syntax for inline 
+			# assembly.
+			AC_TRY_COMPILE(, [
+#ifndef __DECC
+#error "unexpected compiler"
+#endif
+				return (0);],
+				[compiler=osf],)
+		;;
+		esac
+	fi
+	case "$compiler" in
+	gcc)
+		ISC_PLATFORM_USEGCCASM="#define ISC_PLATFORM_USEGCCASM 1"
+		;;
+	osf)
+		ISC_PLATFORM_USEOSFASM="#define ISC_PLATFORM_USEOSFASM 1"
+		;;
+	*)
+		# See if the generic __asm function works.  If not,
+		# we need to disable the atomic operations.
+		AC_TRY_LINK(, [
+					__asm("nop")
+				],
+		[compiler="standard"
+		ISC_PLATFORM_USESTDASM="#define ISC_PLATFORM_USESTDASM 1"],
+		[compiler="not supported (atomic operations disabled)"
+		have_atomic=no
+		arch=noatomic ]);
+		;;
+	esac
+
+	AC_MSG_RESULT($compiler)
+fi
+
 if test "$have_atomic" = "yes"; then
 	ISC_PLATFORM_HAVEXADD="#define ISC_PLATFORM_HAVEXADD 1"
 	ISC_PLATFORM_HAVECMPXCHG="#define ISC_PLATFORM_HAVECMPXCHG 1"
@@ -1910,7 +1946,10 @@ fi
 AC_SUBST(ISC_PLATFORM_HAVEXADD)
 AC_SUBST(ISC_PLATFORM_HAVECMPXCHG)
 AC_SUBST(ISC_PLATFORM_HAVEATOMICSTORE)
+
+AC_SUBST(ISC_PLATFORM_USEGCCASM)
 AC_SUBST(ISC_PLATFORM_USEOSFASM)
+AC_SUBST(ISC_PLATFORM_USESTDASM)

 ISC_ARCH_DIR=$arch
 AC_SUBST(ISC_ARCH_DIR)
--- a/lib/isc/alpha/include/isc/atomic.h
+++ b/lib/isc/alpha/include/isc/atomic.h
@@ -14,7 +14,7 @@
 * PERFORMANCE OF THIS SOFTWARE.
 */

-/* $Id: atomic.h,v 1.2 2005/06/04 05:32:48 jinmei Exp $ */
+/* $Id: atomic.h,v 1.3 2005/06/16 21:57:59 jinmei Exp $ */

 /*
 * This code was written based on FreeBSD's kernel source whose copyright
@@ -107,7 +107,7 @@ isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
 		   "2:",
 		   p, cmpval, val));
 }
-#else  /* ISC_PLATFORM_USEOSFASM */
+#elif defined (ISC_PLATFORM_USEGCCASM)
 static inline isc_int32_t 
 isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) {
 	isc_int32_t temp, prev;
@@ -161,6 +161,10 @@ isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {

 	return (prev);
 }
-#endif /* ISC_PLATFORM_USEOSFASM */
+#else
+
+#error "unsupported compiler.  disable atomic ops by --disable-atomic"
+
+#endif

 #endif /* ISC_ATOMIC_H */
--- a/lib/isc/include/isc/platform.h.in
+++ b/lib/isc/include/isc/platform.h.in
@@ -15,7 +15,7 @@
 * PERFORMANCE OF THIS SOFTWARE.
 */

-/* $Id: platform.h.in,v 1.38 2005/06/04 05:32:48 jinmei Exp $ */
+/* $Id: platform.h.in,v 1.39 2005/06/16 21:57:59 jinmei Exp $ */

 #ifndef ISC_PLATFORM_H
 #define ISC_PLATFORM_H 1
@@ -235,11 +235,21 @@
 */
@ISC_PLATFORM_HAVECMPXCHG@

+/*
+ * Define if gcc ASM extension is available
+ */
+@ISC_PLATFORM_USEGCCASM@
+
 /*
 * Define if Tru64 style ASM syntax must be used.
 */
@ISC_PLATFORM_USEOSFASM@

+/*
+ * Define if the standard __asm function must be used.
+ */
+@ISC_PLATFORM_USESTDASM@
+
 #ifndef ISC_PLATFORM_USEDECLSPEC
 #define LIBISC_EXTERNAL_DATA
 #define LIBDNS_EXTERNAL_DATA
--- a/lib/isc/sparc64/include/isc/atomic.h
+++ b/lib/isc/sparc64/include/isc/atomic.h
@@ -14,7 +14,7 @@
 * PERFORMANCE OF THIS SOFTWARE.
 */

-/* $Id: atomic.h,v 1.2 2005/06/04 05:32:49 jinmei Exp $ */
+/* $Id: atomic.h,v 1.3 2005/06/16 21:58:00 jinmei Exp $ */

 /*
 * This code was written based on FreeBSD's kernel source whose copyright
@@ -59,6 +59,8 @@

 #define	ASI_P	0x80		/* Primary Address Space Identifier */

+#ifdef ISC_PLATFORM_USEGCCASM
+
 /*
 * This routine atomically increments the value stored in 'p' by 'val', and
 * returns the previous value.
@@ -116,4 +118,10 @@ isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
 	return (temp);
 }

+#else  /* ISC_PLATFORM_USEGCCASM */
+
+#error "unsupported compiler.  disable atomic ops by --disable-atomic"
+
+#endif /* ISC_PLATFORM_USEGCCASM */
+
 #endif /* ISC_ATOMIC_H */
--- a/lib/isc/x86_32/include/isc/atomic.h
+++ b/lib/isc/x86_32/include/isc/atomic.h
@@ -14,7 +14,7 @@
 * PERFORMANCE OF THIS SOFTWARE.
 */

-/* $Id: atomic.h,v 1.2 2005/06/04 05:32:50 jinmei Exp $ */
+/* $Id: atomic.h,v 1.3 2005/06/16 21:58:00 jinmei Exp $ */

 #ifndef ISC_ATOMIC_H
 #define ISC_ATOMIC_H 1
@@ -22,6 +22,7 @@
 #include <isc/platform.h>
 #include <isc/types.h>

+#ifdef ISC_PLATFORM_USEGCCASM
 /*
 * This routine atomically increments the value stored in 'p' by 'val', and
 * returns the previous value.
@@ -55,6 +56,7 @@ isc_atomic_store(isc_int32_t *p, isc_int32_t val) {
 		 */
 		"lock;"		
 #endif
+
 		"xchgl %1, %0"
 		:
 		: "r"(val), "m"(*p)
@@ -80,4 +82,79 @@ isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
 	return (cmpval);
 }

+#elif defined(ISC_PLATFORM_USESTDASM)
+/*
+ * The followings are "generic" assembly code which implements the same
+ * functionality in case the gcc extension cannot be used.  It should be
+ * better to avoid inlining below, since we directly refer to specific
+ * positions of the stack frame, which would not actually point to the
+ * intended address in the embedded mnemonic.
+ *
+ * XXX: this code may also not work on a 64-bit (w/o gcc) machine.
+ */
+#include <isc/util.h>		/* for 'UNUSED' macro */
+
+static isc_int32_t
+isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) {
+	UNUSED(p);
+	UNUSED(val);
+
+	__asm (
+		"movl 8(%ebp), %ecx\n"
+		"movl 12(%ebp), %edx\n"
+#ifdef ISC_PLATFORM_USETHREADS
+		"lock;"
+#endif
+		"xadd %edx, (%ecx)\n"
+
+		/*
+		 * set the return value directly in the register so that we
+		 * can avoid guessing the correct position in the stack for a
+		 * local variable.
+		 */
+		"movl %edx, %eax"
+		);
+}
+
+static void
+isc_atomic_store(isc_int32_t *p, isc_int32_t val) {
+	UNUSED(p);
+	UNUSED(val);
+
+	__asm (
+		"movl 8(%ebp), %ecx\n"
+		"movl 12(%ebp), %edx\n"
+#ifdef ISC_PLATFORM_USETHREADS
+		"lock;"
+#endif
+		"xchgl (%ecx), %edx\n"
+		);
+}
+
+static isc_int32_t
+isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
+	UNUSED(p);
+	UNUSED(cmpval);
+	UNUSED(val);
+
+	__asm (
+		"movl 8(%ebp), %ecx\n"
+		"movl 12(%ebp), %eax\n"	/* must be %eax for cmpxchgl */
+		"movl 16(%ebp), %edx\n"
+#ifdef ISC_PLATFORM_USETHREADS
+		"lock;"
+#endif
+
+		/*
+		 * If (%ecx) == %eax then (%ecx) := %edx.
+		 % %eax is set to old (%ecx), which will be the return value.
+		 */
+		"cmpxchgl %edx, (%ecx)"
+		);
+}
+#else /* !ISC_PLATFORM_USEGCCASM && !ISC_PLATFORM_USESTDASM */
+
+#error "unsupported compiler.  disable atomic ops by --disable-atomic"
+
+#endif
 #endif /* ISC_ATOMIC_H */