[Patch ARM] Add cpu_defines.h for ARM

[Patch ARM] Add cpu_defines.h for ARM

[Ramana Radhakrishnan]

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Hardware Integer divide instructions do not trap. Define this to be so 
for the ARM port.

Applied to trunk after a build and test across architecture ranges and a 
bootstrap and regression run on a Cortex-A15 - a v7ve core that has 
hardware divide instructions.

A patch for AArch64 follows.

regards
Ramana

2015-05-17  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>

         * configure.host: Define cpu_defines_dir for ARM.
         * config/cpu/arm/cpu_defines.h: New file.


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Index: ChangeLog
===================================================================
--- ChangeLog	(revision 223359)
+++ ChangeLog	(working copy)
@@ -1,3 +1,8 @@
+2015-05-17  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
+
+	* configure.host: Define cpu_defines_dir for ARM.
+	* config/cpu/arm/cpu_defines.h: New file.
+
 2015-05-17  François Dumont  <fdumont@gcc.gnu.org>
 
 	* include/bits/unordered_map.h (unordered_map, unordered_multimap): Add
Index: config/cpu/arm/cpu_defines.h
===================================================================
--- config/cpu/arm/cpu_defines.h	(revision 0)
+++ config/cpu/arm/cpu_defines.h	(working copy)
@@ -0,0 +1,40 @@
+// Specific definitions for generic platforms  -*- C++ -*-
+
+// Copyright (C) 2015 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This 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 General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file bits/cpu_defines.h
+ *  This is an internal header file, included by other library headers.
+ *  Do not attempt to use it directly. @headername{iosfwd}
+ */
+
+#ifndef _GLIBCXX_CPU_DEFINES
+#define _GLIBCXX_CPU_DEFINES 1
+
+// Integer divide instructions don't trap on ARM.
+#ifdef __ARM_ARCH_EXT_IDIV__
+#define __glibcxx_integral_traps false
+#else
+#define __glibcxx_integral_traps true
+#endif
+
+#endif
Index: configure.host
===================================================================
--- configure.host	(revision 223359)
+++ configure.host	(working copy)
@@ -143,6 +143,9 @@
 # Set specific CPU overrides for cpu_defines_dir. Most can just use generic.
 # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
 case "${host_cpu}" in
+  arm*)
+    cpu_defines_dir=cpu/arm
+    ;;
   powerpc* | rs6000)
     cpu_defines_dir=cpu/powerpc
     ;;

Re: [Patch ARM] Add cpu_defines.h for ARM

[Richard Earnshaw]

On 19/05/15 13:48, Ramana Radhakrishnan wrote:
> Hardware Integer divide instructions do not trap. Define this to be so
> for the ARM port.
> 
> Applied to trunk after a build and test across architecture ranges and a
> bootstrap and regression run on a Cortex-A15 - a v7ve core that has
> hardware divide instructions.
> 
> A patch for AArch64 follows.
> 
> regards
> Ramana
> 
> 2015-05-17  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
> 
>         * configure.host: Define cpu_defines_dir for ARM.
>         * config/cpu/arm/cpu_defines.h: New file.
> 

+#ifdef __ARM_ARCH_EXT_IDIV__
+#define __glibcxx_integral_traps false
+#else
+#define __glibcxx_integral_traps true
+#endif

Hmm, I wonder if we should always define this to false.  If we're
building on an architecture that doesn't have division, we'll call a
library function; but if that is picked at link time, and the link time
options suggest that hw division is available, we could end up with a
library function that doesn't trap.

R.