[PATCH, i386]: Use mxcsr register to set SFP rounding mode for 64bit targets

[Uros Bizjak]

Hello!

For 64bit targets, we can use mxcsr register to set soft-FP rounding mode.

2012-10-10  Uros Bizjak  <ubiz...@gmail.com>

        * config/i386/sfp-machine.h (FP_RND_NEAREST, FP_RND_ZERO, FP_RND_PINF,
        FP_RND_MINF, FP_RND_MASK, FP_INIT_ROUNDMODE, _FP_DECL_EX): Move to ...
        * config/i386/32/sfp-machine.h: ... here.
        * config/i386/64/sfp-machine.h (FP_RND_NEAREST, FP_RND_ZERO,
        FP_RND_PINF, FP_RND_MINF, FP_RND_MASK, FP_INIT_ROUNDMODE, _FP_DECL_EX):
        New defines.

Bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32},
committed to mainline SVN.

Uros.

Index: config/i386/32/sfp-machine.h
===================================================================
--- config/i386/32/sfp-machine.h        (revision 192323)
+++ config/i386/32/sfp-machine.h        (working copy)
@@ -76,3 +76,18 @@
    16byte since soft-fp emulation is done in 16byte.  */
 #define _FP_NANFRAC_E          _FP_QNANBIT_E, 0, 0, 0
 #define _FP_NANFRAC_Q          _FP_QNANBIT_Q, 0, 0, 0
+
+#define FP_RND_NEAREST         0
+#define FP_RND_ZERO            0xc00
+#define FP_RND_PINF            0x800
+#define FP_RND_MINF            0x400
+
+#define FP_RND_MASK            0xc00
+
+#define _FP_DECL_EX \
+  unsigned short _fcw __attribute__ ((unused)) = FP_RND_NEAREST;
+
+#define FP_INIT_ROUNDMODE                              \
+  do {                                                 \
+    __asm__ __volatile__ ("fnstcw\t%0" : "=m" (_fcw)); \
+  } while (0)
Index: config/i386/64/sfp-machine.h
===================================================================
--- config/i386/64/sfp-machine.h        (revision 192323)
+++ config/i386/64/sfp-machine.h        (working copy)
@@ -17,3 +17,18 @@
 #define _FP_NANFRAC_D          _FP_QNANBIT_D
 #define _FP_NANFRAC_E          _FP_QNANBIT_E, 0
 #define _FP_NANFRAC_Q          _FP_QNANBIT_Q, 0
+
+#define FP_RND_NEAREST         0
+#define FP_RND_ZERO            0x6000
+#define FP_RND_PINF            0x4000
+#define FP_RND_MINF            0x2000
+
+#define FP_RND_MASK            0x6000
+
+#define _FP_DECL_EX \
+  unsigned int _fcw __attribute__ ((unused)) = FP_RND_NEAREST;
+
+#define FP_INIT_ROUNDMODE                                      \
+  do {                                                         \
+    __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (_fcw));      \
+  } while (0)
Index: config/i386/sfp-machine.h
===================================================================
--- config/i386/sfp-machine.h   (revision 192323)
+++ config/i386/sfp-machine.h   (working copy)
@@ -55,21 +55,6 @@
       __sfp_handle_exceptions (_fex);          \
   } while (0);
 
-#define FP_RND_NEAREST         0
-#define FP_RND_ZERO            0xc00
-#define FP_RND_PINF            0x800
-#define FP_RND_MINF            0x400
-
-#define FP_RND_MASK            0xc00
-
-#define _FP_DECL_EX \
-  unsigned short _fcw __attribute__ ((unused)) = FP_RND_NEAREST
-
-#define FP_INIT_ROUNDMODE                              \
-  do {                                                 \
-    __asm__ __volatile__ ("fnstcw\t%0" : "=m" (_fcw)); \
-  } while (0)
-
 #define FP_ROUNDMODE           (_fcw & FP_RND_MASK)
 
 #define        __LITTLE_ENDIAN 1234