[PATCH, libgfortran]: Improve get_fpu_trap_exceptions

[PATCH, libgfortran]: Improve get_fpu_trap_exceptions

[Uros Bizjak]

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Following patch substantially improves generated code for
get_fpu_trap_exceptions, reducing insn count from 31 to 9.

2015-08-04  Uros Bizjak  <ubizjak@gmail.com>

    * config/fpu-387.h (get_fpu_trap_exceptions): Add temporary variable
    to improve generated code.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Committed to mainline SVN.

Uros.

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Index: config/fpu-387.h
===================================================================
--- config/fpu-387.h	(revision 226547)
+++ config/fpu-387.h	(working copy)
@@ -215,12 +215,13 @@ set_fpu (void)
 int
 get_fpu_trap_exceptions (void)
 {
+  unsigned short cw;
+  int mask;
   int res = 0;
-  unsigned short cw;
 
   __asm__ __volatile__ ("fstcw\t%0" : "=m" (cw));
-  cw &= _FPU_MASK_ALL;
-
+  mask = cw;
+  
   if (has_sse())
     {
       unsigned int cw_sse;
@@ -228,16 +229,18 @@ get_fpu_trap_exceptions (void)
       __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (cw_sse));
 
       /* The SSE exception masks are shifted by 7 bits.  */
-      cw = cw | ((cw_sse >> 7) & _FPU_MASK_ALL);
+      mask |= (cw_sse >> 7);
     }
 
-  if (~cw & _FPU_MASK_IM) res |= GFC_FPE_INVALID;
-  if (~cw & _FPU_MASK_DM) res |= GFC_FPE_DENORMAL;
-  if (~cw & _FPU_MASK_ZM) res |= GFC_FPE_ZERO;
-  if (~cw & _FPU_MASK_OM) res |= GFC_FPE_OVERFLOW;
-  if (~cw & _FPU_MASK_UM) res |= GFC_FPE_UNDERFLOW;
-  if (~cw & _FPU_MASK_PM) res |= GFC_FPE_INEXACT;
+  mask = ~mask & _FPU_MASK_ALL;
 
+  if (mask & _FPU_MASK_IM) res |= GFC_FPE_INVALID;
+  if (mask & _FPU_MASK_DM) res |= GFC_FPE_DENORMAL;
+  if (mask & _FPU_MASK_ZM) res |= GFC_FPE_ZERO;
+  if (mask & _FPU_MASK_OM) res |= GFC_FPE_OVERFLOW;
+  if (mask & _FPU_MASK_UM) res |= GFC_FPE_UNDERFLOW;
+  if (mask & _FPU_MASK_PM) res |= GFC_FPE_INEXACT;
+
   return res;
 }