2005-08-14 H.J. Lu <hongjiu.lu@intel.com>

[pf3gnuchains/gcc-fork.git] / gcc / config / i386 / crtfastmath.c

diff --git a/gcc/config/i386/crtfastmath.c b/gcc/config/i386/crtfastmath.c
index 3412d6c..fdff247 100644 (file)
--- a/gcc/config/i386/crtfastmath.c
+++ b/gcc/config/i386/crtfastmath.c
@@ -34,11 +34,15 @@
 #define MXCSR_DAZ (1 << 6)     /* Enable denormals are zero mode */
 #define MXCSR_FTZ (1 << 15)    /* Enable flush to zero mode */
 
+#define FXSAVE (1 << 24)
+#define SSE    (1 << 25)
+
 static void __attribute__((constructor))
 set_fast_math (void)
 {
 #ifndef __x86_64__
-  /* SSE is the part of 64bit. Only need to check it for 32bit.  */
+  /* All 64-bit targets have SSE and DAZ; only check them explicitly
+     for 32-bit ones. */
   unsigned int eax, ebx, ecx, edx;
 
   /* See if we can use cpuid.  */
@@ -62,11 +66,45 @@ set_fast_math (void)
                : "=a" (eax), "=r" (ebx), "=c" (ecx), "=d" (edx)
                : "0" (1));
 
-  if (edx & (1 << 25))
-#endif
+  if (edx & SSE)
     {
       unsigned int mxcsr = __builtin_ia32_stmxcsr ();
-      mxcsr |= MXCSR_DAZ | MXCSR_FTZ;
+  
+      mxcsr |= MXCSR_FTZ;
+
+      if (edx & FXSAVE)
+       {
+         /* Check if DAZ is available.  */
+         struct
+           {
+             unsigned short int cwd;
+             unsigned short int swd;
+             unsigned short int twd;
+             unsigned short int fop;
+             long int fip;
+             long int fcs;
+             long int foo;
+             long int fos;
+             long int mxcsr;
+             long int mxcsr_mask;
+             long int st_space[32];
+             long int xmm_space[32];
+             long int padding[56];
+           } __attribute__ ((aligned (16))) fxsave;
+
+         __builtin_memset (&fxsave, 0, sizeof (fxsave));
+
+         asm volatile ("fxsave %0" : : "m" (fxsave));
+
+         if (fxsave.mxcsr_mask & MXCSR_DAZ)
+           mxcsr |= MXCSR_DAZ;
+       }
+
       __builtin_ia32_ldmxcsr (mxcsr);
     }
+#else
+  unsigned int mxcsr = __builtin_ia32_stmxcsr ();
+  mxcsr |= MXCSR_DAZ | MXCSR_FTZ;
+  __builtin_ia32_ldmxcsr (mxcsr);
+#endif
 }