[PATCH] fix for PR 59691

[Iyer, Balaji V]

Hello Everyone,
        Attached, please find a patch that will fix the issue in PR 59691. The 
main issue was that the Cilk library (libcilkrts) was not checking if the 
target has SSE support before emitting SSE instruction. This patch should fix 
that.

Here is the ChangeLog entries:
libcilkrts/ChangeLog
2014-02-06  Balaji V. Iyer  <balaji.v.i...@intel.com>

        * runtime/config/x86/os-unix-sysdep.c (__builtin_cpu_supports): New
        function.
        (restore_x86_fp_state): Added a check if the cpu supports the
        instruction before emitting it.
        (sysdep_save_fp_ctrl_state): Likewise.



Is this Ok to install?

Thanks,

Balaji V. Iyer.

diff --git a/libcilkrts/runtime/config/x86/os-unix-sysdep.c 
b/libcilkrts/runtime/config/x86/os-unix-sysdep.c
index 881bc3f..b505ddf 100644
--- a/libcilkrts/runtime/config/x86/os-unix-sysdep.c
+++ b/libcilkrts/runtime/config/x86/os-unix-sysdep.c
@@ -2,11 +2,9 @@
  *
  *************************************************************************
  *
- *  @copyright
- *  Copyright (C) 2009-2013, Intel Corporation
+ *  Copyright (C) 2009-2014, Intel Corporation
  *  All rights reserved.
  *  
- *  @copyright
  *  Redistribution and use in source and binary forms, with or without
  *  modification, are permitted provided that the following conditions
  *  are met:
@@ -21,7 +19,6 @@
  *      contributors may be used to endorse or promote products derived
  *      from this software without specific prior written permission.
  *  
- *  @copyright
  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
@@ -91,6 +88,20 @@ COMMON_SYSDEP int __cilkrts_xchg(volatile int *ptr, int x)
     return x;
 }
 
+/*
+ * The Intel compiler distribution assumes newer CPUs and doesn't yet support
+ * the __builtin_cpu_supports intrinsic added by GCC 4.8, so just return 1 in
+ * that environment.
+ *
+ * This declaration should generate an error when the Intel compiler adds
+ * supprt for the intrinsic.
+ */
+#ifdef __INTEL_COMPILER
+static inline int __builtin_cpu_supports(const char *feature)
+{
+    return 1;
+}
+#endif
 
 /*
  * Restore the floating point state that is stored in a stack frame at each
@@ -100,11 +111,16 @@ COMMON_SYSDEP int __cilkrts_xchg(volatile int *ptr, int x)
  */
 void restore_x86_fp_state (__cilkrts_stack_frame *sf) {
 #ifdef RESTORE_X86_FP_STATE
-    __asm__ ( "ldmxcsr %0\n\t"
-              "fnclex\n\t"
-              "fldcw %1"
-              :
-              : "m" (sf->mxcsr), "m" (sf->fpcsr));
+    if (__builtin_cpu_supports("sse"))
+    {
+        __asm__ ("ldmxcsr %0"
+                 :
+                 : "m" (sf->mxcsr));
+    }
+    __asm__ ("fnclex\n\t"
+             "fldcw %0"
+             :
+             : "m" (sf->fpcsr));
 #endif
 }
 
@@ -115,7 +131,10 @@ void sysdep_save_fp_ctrl_state(__cilkrts_stack_frame *sf)
 #ifdef RESTORE_X86_FP_STATE
     if (CILK_FRAME_VERSION_VALUE(sf->flags) >= 1)
     {
-        __asm__ ("stmxcsr %0" : "=m" (sf->mxcsr));
+        if (__builtin_cpu_supports("sse"))
+        {
+            __asm__ ("stmxcsr %0" : "=m" (sf->mxcsr));
+        }
         __asm__ ("fnstsw %0" : "=m" (sf->fpcsr));
     }
 #endif