Force eval for fma implementations

5 files changed, 33 insertions, 20 deletions

diff --git a/ChangeLog b/ChangeLog
index 5aaea43891..c3006f57e7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2014-08-01  Richard Henderon  <rth@redhat.com>
+
+	* sysdeps/ieee754/dbl-64/s_fma.c (__fma): Use math_force_eval before
+	feclearexcept; use math_opt_barrier instead of open-coded asm; fix
+	typo in exact zero test.
+	* sysdeps/ieee754/ldbl-128/s_fmal.c (__fmal): Likewise.
+	* sysdeps/ieee754/ldbl-96/s_fma.c (__fma): Likewise.
+	* sysdeps/ieee754/ldbl-96/s_fmal.c (__fmal): Likewise.
+
 2014-08-01  Roland McGrath  <roland@hack.frob.com>
 
 	* sysdeps/unix/sysv/linux/arm/sysdep.h (PTR_MANGLE_LOAD, PTR_MANGLE)
diff --git a/sysdeps/ieee754/dbl-64/s_fma.c b/sysdeps/ieee754/dbl-64/s_fma.c
index 389acd4cde..77065aaba1 100644
--- a/sysdeps/ieee754/dbl-64/s_fma.c
+++ b/sysdeps/ieee754/dbl-64/s_fma.c
@@ -198,16 +198,17 @@ __fma (double x, double y, double z)
   t1 = m1 - t1;
   t2 = z - t2;
   double a2 = t1 + t2;
+  /* Ensure the arithmetic is not scheduled after feclearexcept call.  */
+  math_force_eval (m2);
+  math_force_eval (a2);
   feclearexcept (FE_INEXACT);
 
-  /* If the result is an exact zero, ensure it has the correct
-     sign.  */
+  /* If the result is an exact zero, ensure it has the correct sign.  */
   if (a1 == 0 && m2 == 0)
     {
       libc_feupdateenv (&env);
-      /* Ensure that round-to-nearest value of z + m1 is not
-	 reused.  */
-      asm volatile ("" : "=m" (z) : "m" (z));
+      /* Ensure that round-to-nearest value of z + m1 is not reused.  */
+      z = math_opt_barrier (z);
       return z + m1;
     }
 
diff --git a/sysdeps/ieee754/ldbl-128/s_fmal.c b/sysdeps/ieee754/ldbl-128/s_fmal.c
index 1d5f27b7b6..814709482b 100644
--- a/sysdeps/ieee754/ldbl-128/s_fmal.c
+++ b/sysdeps/ieee754/ldbl-128/s_fmal.c
@@ -203,16 +203,17 @@ __fmal (long double x, long double y, long double z)
   t1 = m1 - t1;
   t2 = z - t2;
   long double a2 = t1 + t2;
+  /* Ensure the arithmetic is not scheduled after feclearexcept call.  */
+  math_force_eval (m2);
+  math_force_eval (a2);
   feclearexcept (FE_INEXACT);
 
-  /* If the result is an exact zero, ensure it has the correct
-     sign.  */
+  /* If the result is an exact zero, ensure it has the correct sign.  */
   if (a1 == 0 && m2 == 0)
     {
       feupdateenv (&env);
-      /* Ensure that round-to-nearest value of z + m1 is not
-	 reused.  */
-      asm volatile ("" : "=m" (z) : "m" (z));
+      /* Ensure that round-to-nearest value of z + m1 is not reused.  */
+      z = math_opt_barrier (z);
       return z + m1;
     }
 
diff --git a/sysdeps/ieee754/ldbl-96/s_fma.c b/sysdeps/ieee754/ldbl-96/s_fma.c
index 354be4eae9..a27102eff1 100644
--- a/sysdeps/ieee754/ldbl-96/s_fma.c
+++ b/sysdeps/ieee754/ldbl-96/s_fma.c
@@ -64,16 +64,17 @@ __fma (double x, double y, double z)
   t1 = m1 - t1;
   t2 = z - t2;
   long double a2 = t1 + t2;
+  /* Ensure the arithmetic is not scheduled after feclearexcept call.  */
+  math_force_eval (m2);
+  math_force_eval (a2);
   feclearexcept (FE_INEXACT);
 
-  /* If the result is an exact zero, ensure it has the correct
-     sign.  */
+  /* If the result is an exact zero, ensure it has the correct sign.  */
   if (a1 == 0 && m2 == 0)
     {
       feupdateenv (&env);
-      /* Ensure that round-to-nearest value of z + m1 is not
-	 reused.  */
-      asm volatile ("" : "=m" (z) : "m" (z));
+      /* Ensure that round-to-nearest value of z + m1 is not reused.  */
+      z = math_opt_barrier (z);
       return z + m1;
     }
 
diff --git a/sysdeps/ieee754/ldbl-96/s_fmal.c b/sysdeps/ieee754/ldbl-96/s_fmal.c
index 4983eda9c6..0f299da7c1 100644
--- a/sysdeps/ieee754/ldbl-96/s_fmal.c
+++ b/sysdeps/ieee754/ldbl-96/s_fmal.c
@@ -201,16 +201,17 @@ __fmal (long double x, long double y, long double z)
   t1 = m1 - t1;
   t2 = z - t2;
   long double a2 = t1 + t2;
+  /* Ensure the arithmetic is not scheduled after feclearexcept call.  */
+  math_force_eval (m2);
+  math_force_eval (a2);
   feclearexcept (FE_INEXACT);
 
-  /* If the result is an exact zero, ensure it has the correct
-     sign.  */
+  /* If the result is an exact zero, ensure it has the correct sign.  */
   if (a1 == 0 && m2 == 0)
     {
       feupdateenv (&env);
-      /* Ensure that round-to-nearest value of z + m1 is not
-	 reused.  */
-      asm volatile ("" : "=m" (z) : "m" (z));
+      /* Ensure that round-to-nearest value of z + m1 is not reused.  */
+      z = math_opt_barrier (z);
       return z + m1;
     }