[PATCH roland/arm-atomic] ARM: split generic and Linux-specific bits/atomic.h

[PATCH roland/arm-atomic] ARM: split generic and Linux-specific bits/atomic.h

[Roland McGrath]

The branch has two commits.  The second is this trivial renaming,
because there is nothing in the file that is at all specific to
anything about the nptl add-on:

ports/ChangeLog.arm
	* sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h: Renamed to ...
	* sysdeps/unix/sysv/linux/arm/bits/atomic.h: ... this.

diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h b/ports/sysdeps/unix/sysv/linux/arm/bits/atomic.h
similarity index 100%
rename from ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h
rename to ports/sysdeps/unix/sysv/linux/arm/bits/atomic.h


The first commit is as follows, separating the pure ARM-specific bits from
the Linux-specific bits that are only needed if you don't have GCC support
for __sync_* builtins.

I did only the basic compile test on arm-linux-gnueabi.

Ok?


Thanks,
Roland


ports/ChangeLog.arm
2012-08-14  Roland McGrath  <roland@hack.frob.com>

	* sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h
	[!__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4]
	(atomic_full_barrier): Renamed to ...
	(__arm_assisted_full_barrier): ... this.
	(__arch_compare_and_exchange_val_32_acq): Renamed to ...
	(__arm_assisted_compare_and_exchange_val_32_acq): ... this.
	(atomic8_t, uatomic8_t, atomic_fast8_t, uatomic_fast8_t,
	atomic32_t, uatomic32_t, atomic_fast32_t, uatomic_fast32_t,
	atomicptr_t, uatomicptr_t, atomic_max_t, uatomic_max_t,
	atomic_full_barrier, __arch_compare_and_exchange_val_32_acq,
	__arch_compare_and_exchange_val_8_acq,
	__arch_compare_and_exchange_val_16_acq,
	__arch_compare_and_exchange_val_64_acq): Types and macros moved to ...
	* sysdeps/arm/bits/atomic.h: ... this new file.


diff --git a/ports/sysdeps/arm/bits/atomic.h b/ports/sysdeps/arm/bits/atomic.h
new file mode 100644
index 0000000..9984210
--- /dev/null
+++ b/ports/sysdeps/arm/bits/atomic.h
@@ -0,0 +1,81 @@
+/* Atomic operations.  Pure ARM version.
+   Copyright (C) 2002-2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdint.h>
+
+typedef int8_t atomic8_t;
+typedef uint8_t uatomic8_t;
+typedef int_fast8_t atomic_fast8_t;
+typedef uint_fast8_t uatomic_fast8_t;
+
+typedef int32_t atomic32_t;
+typedef uint32_t uatomic32_t;
+typedef int_fast32_t atomic_fast32_t;
+typedef uint_fast32_t uatomic_fast32_t;
+
+typedef intptr_t atomicptr_t;
+typedef uintptr_t uatomicptr_t;
+typedef intmax_t atomic_max_t;
+typedef uintmax_t uatomic_max_t;
+
+void __arm_link_error (void);
+
+/* Use the atomic builtins provided by GCC in case the backend provides
+   a pattern to do this efficiently.  */
+
+#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
+# define atomic_full_barrier() __sync_synchronize ()
+#else
+# define atomic_full_barrier() __arm_assisted_full_barrier ()
+#endif
+
+/* An OS-specific bits/atomic.h file will define this macro if
+   the OS can provide something.  If not, we'll fail to build
+   with a compiler that doesn't supply the operation.  */
+#ifndef __arm_assisted_full_barrier
+# define __arm_assisted_full_barrier()  __arm_link_error()
+#endif
+
+/* Atomic compare and exchange.  */
+
+#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
+# define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
+  __sync_val_compare_and_swap ((mem), (oldval), (newval))
+#else
+# define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
+  __arm_assisted_compare_and_exchange_val_32_acq ((mem), (oldval), (newval))
+#endif
+
+/* We don't support atomic operations on any non-word types.
+   So make them link errors.  */
+#define __arch_compare_and_exchange_val_8_acq(mem, newval, oldval) \
+  ({ __arm_link_error (); oldval; })
+
+#define __arch_compare_and_exchange_val_16_acq(mem, newval, oldval) \
+  ({ __arm_link_error (); oldval; })
+
+#define __arch_compare_and_exchange_val_64_acq(mem, newval, oldval) \
+  ({ __arm_link_error (); oldval; })
+
+/* An OS-specific bits/atomic.h file will define this macro if
+   the OS can provide something.  If not, we'll fail to build
+   with a compiler that doesn't supply the operation.  */
+#ifndef __arm_assisted_compare_and_exchange_val_32_acq
+# define __arm_assisted_compare_and_exchange_val_32_acq(mem, newval, oldval) \
+  ({ __arm_link_error (); oldval; })
+#endif
diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h b/ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h
index c9ad50d..3374153 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h
+++ b/ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 2002-2012 Free Software Foundation, Inc.
+/* Atomic operations.  ARM/Linux version.
+   Copyright (C) 2002-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -15,41 +16,17 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <stdint.h>
-#include <sysdep.h>
-
-
-typedef int8_t atomic8_t;
-typedef uint8_t uatomic8_t;
-typedef int_fast8_t atomic_fast8_t;
-typedef uint_fast8_t uatomic_fast8_t;
-
-typedef int32_t atomic32_t;
-typedef uint32_t uatomic32_t;
-typedef int_fast32_t atomic_fast32_t;
-typedef uint_fast32_t uatomic_fast32_t;
-
-typedef intptr_t atomicptr_t;
-typedef uintptr_t uatomicptr_t;
-typedef intmax_t atomic_max_t;
-typedef uintmax_t uatomic_max_t;
-
-void __arm_link_error (void);
-
-/* Use the atomic builtins provided by GCC in case the backend provides
-   a pattern to do this efficiently.  */
-
-#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
-#define atomic_full_barrier() __sync_synchronize ()
-#elif defined __thumb2__
-#define atomic_full_barrier() \
+/* If the compiler doesn't provide a primitive, we'll use this macro
+   to get assistance from the kernel.  */
+#ifdef __thumb2__
+# define __arm_assisted_full_barrier() \
      __asm__ __volatile__						      \
 	     ("movw\tip, #0x0fa0\n\t"					      \
 	      "movt\tip, #0xffff\n\t"					      \
 	      "blx\tip"							      \
 	      : : : "ip", "lr", "cc", "memory");
 #else
-#define atomic_full_barrier() \
+# define __arm_assisted_full_barrier() \
      __asm__ __volatile__						      \
 	     ("mov\tip, #0xffff0fff\n\t"				      \
 	      "mov\tlr, pc\n\t"						      \
@@ -60,19 +37,9 @@ void __arm_link_error (void);
 /* Atomic compare and exchange.  This sequence relies on the kernel to
    provide a compare and exchange operation which is atomic on the
    current architecture, either via cleverness on pre-ARMv6 or via
-   ldrex / strex on ARMv6.  */
-
-#define __arch_compare_and_exchange_val_8_acq(mem, newval, oldval) \
-  ({ __arm_link_error (); oldval; })
-
-#define __arch_compare_and_exchange_val_16_acq(mem, newval, oldval) \
-  ({ __arm_link_error (); oldval; })
-
-#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
-#define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
-  __sync_val_compare_and_swap ((mem), (oldval), (newval))
+   ldrex / strex on ARMv6.
 
-/* It doesn't matter what register is used for a_oldval2, but we must
+   It doesn't matter what register is used for a_oldval2, but we must
    specify one to work around GCC PR rtl-optimization/21223.  Otherwise
    it may cause a_oldval or a_tmp to be moved to a different register.
 
@@ -81,10 +48,10 @@ void __arm_link_error (void);
    form *PTR and PTR has a 'volatile ... *' type, then __typeof (*PTR) has
    a 'volatile ...' type and this triggers -Wvolatile-register-var to
    complain about 'register volatile ... asm ("reg")'.  */
-#elif defined __thumb2__
+#ifdef __thumb2__
 /* Thumb-2 has ldrex/strex.  However it does not have barrier instructions,
    so we still need to use the kernel helper.  */
-#define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
+# define __arm_assisted_compare_and_exchange_val_32_acq(mem, newval, oldval) \
   ({ union { __typeof (oldval) a; uint32_t v; } oldval_arg = { .a = (oldval) };\
      union { __typeof (newval) a; uint32_t v; } newval_arg = { .a = (newval) };\
      register uint32_t a_oldval asm ("r0");				      \
@@ -109,7 +76,7 @@ void __arm_link_error (void);
 	      : "ip", "lr", "cc", "memory");				      \
      (__typeof (oldval)) a_tmp; })
 #else
-#define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval)	      \
+# define __arm_assisted_compare_and_exchange_val_32_acq(mem, newval, oldval) \
   ({ union { __typeof (oldval) a; uint32_t v; } oldval_arg = { .a = (oldval) };\
      union { __typeof (newval) a; uint32_t v; } newval_arg = { .a = (newval) };\
      register uint32_t a_oldval asm ("r0");				      \
@@ -135,5 +102,4 @@ void __arm_link_error (void);
      (__typeof (oldval)) a_tmp; })
 #endif
 
-#define __arch_compare_and_exchange_val_64_acq(mem, newval, oldval) \
-  ({ __arm_link_error (); oldval; })
+#include <sysdeps/arm/bits/atomic.h>

Re: [PATCH roland/arm-atomic] ARM: split generic and Linux-specific bits/atomic.h

[Joseph S. Myers]

On Tue, 14 Aug 2012, Roland McGrath wrote:

> The branch has two commits.  The second is this trivial renaming,
> because there is nothing in the file that is at all specific to
> anything about the nptl add-on:
> 
> ports/ChangeLog.arm
> 	* sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h: Renamed to ...
> 	* sysdeps/unix/sysv/linux/arm/bits/atomic.h: ... this.
> 
> diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h b/ports/sysdeps/unix/sysv/linux/arm/bits/atomic.h
> similarity index 100%
> rename from ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h
> rename to ports/sysdeps/unix/sysv/linux/arm/bits/atomic.h
> 
> 
> The first commit is as follows, separating the pure ARM-specific bits from
> the Linux-specific bits that are only needed if you don't have GCC support
> for __sync_* builtins.
> 
> I did only the basic compile test on arm-linux-gnueabi.
> 
> Ok?

OK.

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: [PATCH roland/arm-atomic] ARM: split generic and Linux-specific bits/atomic.h

[Roland McGrath]

Committed.

Thanks,
Roland

Re: [PATCH roland/arm-atomic] ARM: split generic and Linux-specific bits/atomic.h

[Joseph S. Myers]

This patch <http://sourceware.org/ml/libc-ports/2012-08/msg00122.html>
caused around 150 test failures for pre-v6/v7 ARM systems using the
kernel helpers, because the arguments in a call to
__arm_assisted_compare_and_exchange_val_32_acq were the wrong way
round.  I've applied this patch to fix this.

2012-09-21  Joseph Myers  <joseph@codesourcery.com>

	* sysdeps/arm/bits/atomic.h [!__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4]
	(__arch_compare_and_exchange_val_32_acq): Correct order of
	arguments of __arm_assisted_compare_and_exchange_val_32_acq.

diff --git a/ports/sysdeps/arm/bits/atomic.h b/ports/sysdeps/arm/bits/atomic.h
index 9984210..39e276f 100644
--- a/ports/sysdeps/arm/bits/atomic.h
+++ b/ports/sysdeps/arm/bits/atomic.h
@@ -58,7 +58,7 @@ void __arm_link_error (void);
   __sync_val_compare_and_swap ((mem), (oldval), (newval))
 #else
 # define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
-  __arm_assisted_compare_and_exchange_val_32_acq ((mem), (oldval), (newval))
+  __arm_assisted_compare_and_exchange_val_32_acq ((mem), (newval), (oldval))
 #endif
 
 /* We don't support atomic operations on any non-word types.

-- 
Joseph S. Myers
joseph@codesourcery.com