Add volatiles for x86-64 bits/mathinline.h

[BZ #14053]
GCC 4.7 might remove consecutive calls to e.g. lrintf since
the assembler instructions are the same and GCC does not know
that the result is different depending on the rounding mode.  For
SSE instructions, the control register is not available so there
is no way to inform GCC about this. Therefore the asms are marked
as volatile.

1 files changed, 40 insertions, 8 deletions

diff --git a/sysdeps/x86_64/fpu/bits/mathinline.h b/sysdeps/x86_64/fpu/bits/mathinline.h
index c072f16a21..49a199b60b 100644
--- a/sysdeps/x86_64/fpu/bits/mathinline.h
+++ b/sysdeps/x86_64/fpu/bits/mathinline.h
@@ -79,7 +79,11 @@ __MATH_INLINE long int
 __NTH (lrintf (float __x))
 {
   long int __res;
-  __asm ("cvtss2si %1, %0" : "=r" (__res) : "xm" (__x));
+  /* Mark as volatile since the result is dependend on the state of
+     the SSE control register (the rounding mode). Otherwise GCC might
+     remove these assembler instructions since it does not know about
+     the rounding mode change and cannot currently be told.  */
+  __asm __volatile__ ("cvtss2si %1, %0" : "=r" (__res) : "xm" (__x));
   return __res;
 }
 #  endif
@@ -88,7 +92,11 @@ __MATH_INLINE long int
 __NTH (lrint (double __x))
 {
   long int __res;
-  __asm ("cvtsd2si %1, %0" : "=r" (__res) : "xm" (__x));
+  /* Mark as volatile since the result is dependend on the state of
+     the SSE control register (the rounding mode). Otherwise GCC might
+     remove these assembler instructions since it does not know about
+     the rounding mode change and cannot currently be told.  */
+  __asm __volatile__ ("cvtsd2si %1, %0" : "=r" (__res) : "xm" (__x));
   return __res;
 }
 #  endif
@@ -97,14 +105,22 @@ __MATH_INLINE long long int
 __NTH (llrintf (float __x))
 {
   long long int __res;
-  __asm ("cvtss2si %1, %0" : "=r" (__res) : "xm" (__x));
+  /* Mark as volatile since the result is dependend on the state of
+     the SSE control register (the rounding mode). Otherwise GCC might
+     remove these assembler instructions since it does not know about
+     the rounding mode change and cannot currently be told.  */
+  __asm __volatile__ ("cvtss2si %1, %0" : "=r" (__res) : "xm" (__x));
   return __res;
 }
 __MATH_INLINE long long int
 __NTH (llrint (double __x))
 {
   long long int __res;
-  __asm ("cvtsd2si %1, %0" : "=r" (__res) : "xm" (__x));
+  /* Mark as volatile since the result is dependend on the state of
+     the SSE control register (the rounding mode). Otherwise GCC might
+     remove these assembler instructions since it does not know about
+     the rounding mode change and cannot currently be told.  */
+  __asm __volatile__ ("cvtsd2si %1, %0" : "=r" (__res) : "xm" (__x));
   return __res;
 }
 #  endif
@@ -176,14 +192,22 @@ __MATH_INLINE double
 __NTH (rint (double __x))
 {
   double __res;
-  __asm ("roundsd $4, %1, %0" : "=x" (__res) : "xm" (__x));
+  /* Mark as volatile since the result is dependend on the state of
+     the SSE control register (the rounding mode). Otherwise GCC might
+     remove these assembler instructions since it does not know about
+     the rounding mode change and cannot currently be told.  */
+  __asm __volatile__ ("roundsd $4, %1, %0" : "=x" (__res) : "xm" (__x));
   return __res;
 }
 __MATH_INLINE float
 __NTH (rintf (float __x))
 {
   float __res;
-  __asm ("roundss $4, %1, %0" : "=x" (__res) : "xm" (__x));
+  /* Mark as volatile since the result is dependend on the state of
+     the SSE control register (the rounding mode). Otherwise GCC might
+     remove these assembler instructions since it does not know about
+     the rounding mode change and cannot currently be told.  */
+  __asm __volatile__ ("roundss $4, %1, %0" : "=x" (__res) : "xm" (__x));
   return __res;
 }
 
@@ -193,14 +217,22 @@ __MATH_INLINE double
 __NTH (nearbyint (double __x))
 {
   double __res;
-  __asm ("roundsd $0xc, %1, %0" : "=x" (__res) : "xm" (__x));
+  /* Mark as volatile since the result is dependend on the state of
+     the SSE control register (the rounding mode). Otherwise GCC might
+     remove these assembler instructions since it does not know about
+     the rounding mode change and cannot currently be told.  */
+  __asm __volatile__ ("roundsd $0xc, %1, %0" : "=x" (__res) : "xm" (__x));
   return __res;
 }
 __MATH_INLINE float
 __NTH (nearbyintf (float __x))
 {
   float __res;
-  __asm ("roundss $0xc, %1, %0" : "=x" (__res) : "xm" (__x));
+  /* Mark as volatile since the result is dependend on the state of
+     the SSE control register (the rounding mode). Otherwise GCC might
+     remove these assembler instructions since it does not know about
+     the rounding mode change and cannot currently be told.  */
+  __asm __volatile__ ("roundss $0xc, %1, %0" : "=x" (__res) : "xm" (__x));
   return __res;
 }
 #   endif