[patch] Set FPU defaults for -ffast-math on MIPS. (Take 2)

[kazu at codesourcery dot com (Kazu Hirata)]

Hi,

Attached is a revised patch to set FPU defaults for -ffast-math on
MIPS.

The previous version was posted at:

  http://gcc.gnu.org/ml/gcc-patches/2010-06/msg00961.html

In this iteration, I have removed changes to gcc/config/mips/linux64.h
as they were duplicates of ones to gcc/config/mips/linux.h.

The revised patch does not introduce gcc/config/mips/t-crtfm.

We do still need to set extra_parts because libgcc/Makefile.in checks
to see if EXTRA_PARTS from gcc and EXTRA_PARTS from libgcc are
identical.  I have moved the definition of EXTRA_PARTS to config.gcc
(and lower-cased it).

Tested on mips-linux-gnu.  OK to apply?

Kazu Hirata

gcc/
2010-06-12  Kazu Hirata  <kazu@codesourcery.com>

	* config.gcc (mips64*-*-linux*, mipsisa64*-*-linux*,
	mips*-*-linux*): Add crtfastmath.o to extra_parts.
	* config/mips/crtfastmath.c: New.
	* config/mips/linux.h (ENDFILE_SPEC): New.

libgcc/
2010-06-12  Kazu Hirata  <kazu@codesourcery.com>

	* config.host (mips64*-*-linux*, mips*-*-linux*): Add mips/t-crtfm
	to tmake_file.  Add crtfastmath.o to extra_parts.
	* config/mips/t-crtfm: New.

Index: gcc/config.gcc
===================================================================
--- gcc/config.gcc	(revision 160484)
+++ gcc/config.gcc	(working copy)
@@ -1750,6 +1750,7 @@ mips64*-*-linux* | mipsisa64*-*-linux*)
 			tm_defines="${tm_defines} MIPS_ISA_DEFAULT=65"
 			;;
 	esac
+	extra_parts="$extra_parts crtfastmath.o"
 	gnu_ld=yes
 	gas=yes
 	test x$with_llsc != x || with_llsc=yes
@@ -1764,6 +1765,7 @@ mips*-*-linux*)				# Linux MIPS, either 
         mipsisa32*)
 		tm_defines="${tm_defines} MIPS_ISA_DEFAULT=32"
         esac
+	extra_parts="$extra_parts crtfastmath.o"
 	test x$with_llsc != x || with_llsc=yes
 	;;
 mips*-*-openbsd*)
Index: gcc/config/mips/crtfastmath.c
===================================================================
--- gcc/config/mips/crtfastmath.c	(revision 0)
+++ gcc/config/mips/crtfastmath.c	(revision 0)
@@ -0,0 +1,53 @@
+/* Copyright (C) 2010 Free Software Foundation, Inc. 
+
+   This file is part of GCC.
+
+   GCC 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.
+
+   GCC 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/>.  */
+
+#ifdef __mips_hard_float
+
+/* Flush denormalized numbers to zero.  */
+#define _FPU_FLUSH_TZ   0x1000000
+
+/* Rounding control.  */
+#define _FPU_RC_NEAREST 0x0     /* RECOMMENDED */
+#define _FPU_RC_ZERO    0x1
+#define _FPU_RC_UP      0x2
+#define _FPU_RC_DOWN    0x3
+
+/* Enable interrupts for IEEE exceptions.  */
+#define _FPU_IEEE     0x00000F80
+
+/* Macros for accessing the hardware control word.  */
+#define _FPU_GETCW(cw) __asm__ ("cfc1 %0,$31" : "=r" (cw))
+#define _FPU_SETCW(cw) __asm__ ("ctc1 %0,$31" : : "r" (cw))
+
+static void __attribute__((constructor))
+set_fast_math (void)
+{
+  unsigned int fcr;
+
+  /* Flush to zero, round to nearest, IEEE exceptions disabled.  */
+  fcr = _FPU_FLUSH_TZ | _FPU_RC_NEAREST;
+
+  _FPU_SETCW(fcr);
+}
+
+#endif /* __mips_hard_float */
Index: gcc/config/mips/linux.h
===================================================================
--- gcc/config/mips/linux.h	(revision 160484)
+++ gcc/config/mips/linux.h	(working copy)
@@ -147,3 +147,9 @@ extern const char *host_detect_local_cpu
 #define DRIVER_SELF_SPECS \
   BASE_DRIVER_SELF_SPECS, \
   LINUX_DRIVER_SELF_SPECS
+
+/* Similar to standard Linux, but adding -ffast-math support.  */
+#undef  ENDFILE_SPEC
+#define ENDFILE_SPEC \
+  "%{ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
+   %{shared|pie:crtendS.o%s;:crtend.o%s} crtn.o%s"
Index: libgcc/config.host
===================================================================
--- libgcc/config.host	(revision 160631)
+++ libgcc/config.host	(working copy)
@@ -400,8 +400,12 @@ mips-sgi-irix[56]*)
 mips*-*-netbsd*)			# NetBSD/mips, either endian.
 	;;
 mips64*-*-linux*)
+	extra_parts="$extra_parts crtfastmath.o"
+	tmake_file="{$tmake_file} mips/t-crtfm"
 	;;
 mips*-*-linux*)				# Linux MIPS, either endian.
+	extra_parts="$extra_parts crtfastmath.o"
+	tmake_file="{$tmake_file} mips/t-crtfm"
 	;;
 mips*-*-openbsd*)
 	;;
Index: libgcc/config/mips/t-crtfm
===================================================================
--- libgcc/config/mips/t-crtfm	(revision 0)
+++ libgcc/config/mips/t-crtfm	(revision 0)
@@ -0,0 +1,3 @@
+crtfastmath.o: $(gcc_srcdir)/config/mips/crtfastmath.c
+	$(gcc_compile) -c $(gcc_srcdir)/config/mips/crtfastmath.c
+