This is the mail archive of the glibc-cvs@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

GNU C Library master sources branch master updated. glibc-2.26-412-gf124cb3


This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".

The branch, master has been updated
       via  f124cb381116b5809de198327690ad0bd8d1478e (commit)
      from  7edd06916d0f18714f323b180b890f1fea39e1ff (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=f124cb381116b5809de198327690ad0bd8d1478e

commit f124cb381116b5809de198327690ad0bd8d1478e
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Thu Sep 28 01:59:02 2017 +0000

    Fix nearbyint arithmetic moved before feholdexcept (bug 22225).
    
    In <https://sourceware.org/ml/libc-alpha/2013-05/msg00722.html> I
    remarked on the possibility of arithmetic in various nearbyint
    implementations being scheduled before feholdexcept calls, resulting
    in spurious "inexact" exceptions.
    
    I'm now actually observing this occurring in glibc built for ARM with
    GCC 7 (in fact, both copies of the same addition/subtraction sequence
    being combined and moved out before the conditionals and
    feholdexcept/fesetenv pairs), resulting in test failures.
    
    This patch makes the nearbyint implementations with this particular
    feholdexcept / arithmetic / fesetenv pattern consistently use
    math_opt_barrier on the function argument when first used in
    arithmetic, and also consistently use math_force_eval before fesetenv
    (the latter was generally already done, but the dbl-64/wordsize-64
    implementation used math_opt_barrier instead, and as
    math_opt_barrier's intended effect is through its output value being
    used, such a use that doesn't use the return value is suspect).
    
    Tested for x86_64 (--disable-multi-arch so more of these
    implementations get used), and for ARM in a configuration where I saw
    the problem scheduling.
    
    	[BZ #22225]
    	* sysdeps/ieee754/dbl-64/s_nearbyint.c (__nearbyint): Use
    	math_opt_barrier on argument when doing arithmetic on it.
    	* sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c (__nearbyint):
    	Likewise.  Use math_force_eval not math_opt_barrier after
    	arithmetic.
    	* sysdeps/ieee754/flt-32/s_nearbyintf.c (__nearbyintf): Use
    	math_opt_barrier on argument when doing arithmetic on it.
    	* sysdeps/ieee754/ldbl-128/s_nearbyintl.c (__nearbyintl):
    	Likewise.

diff --git a/ChangeLog b/ChangeLog
index 2e29752..60c9521 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2017-09-28  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #22225]
+	* sysdeps/ieee754/dbl-64/s_nearbyint.c (__nearbyint): Use
+	math_opt_barrier on argument when doing arithmetic on it.
+	* sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c (__nearbyint):
+	Likewise.  Use math_force_eval not math_opt_barrier after
+	arithmetic.
+	* sysdeps/ieee754/flt-32/s_nearbyintf.c (__nearbyintf): Use
+	math_opt_barrier on argument when doing arithmetic on it.
+	* sysdeps/ieee754/ldbl-128/s_nearbyintl.c (__nearbyintl):
+	Likewise.
+
 2017-09-27  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* sysdeps/unix/sysv/linux/ifaddrs.c (__getifaddrs): Add
diff --git a/sysdeps/ieee754/dbl-64/s_nearbyint.c b/sysdeps/ieee754/dbl-64/s_nearbyint.c
index dec0c5d..6e3f831 100644
--- a/sysdeps/ieee754/dbl-64/s_nearbyint.c
+++ b/sysdeps/ieee754/dbl-64/s_nearbyint.c
@@ -48,7 +48,7 @@ __nearbyint (double x)
       if (j0 < 0)
 	{
 	  libc_feholdexcept (&env);
-	  w = TWO52[sx] + x;
+	  w = TWO52[sx] + math_opt_barrier (x);
 	  t = w - TWO52[sx];
 	  math_force_eval (t);
 	  libc_fesetenv (&env);
@@ -65,7 +65,7 @@ __nearbyint (double x)
 	return x;                       /* x is integral */
     }
   libc_feholdexcept (&env);
-  w = TWO52[sx] + x;
+  w = TWO52[sx] + math_opt_barrier (x);
   t = w - TWO52[sx];
   math_force_eval (t);
   libc_fesetenv (&env);
diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c
index 8293819..7d135b5 100644
--- a/sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c
@@ -42,9 +42,9 @@ __nearbyint(double x)
 	if(__builtin_expect(j0<52, 1)) {
 	    if(j0<0) {
 		libc_feholdexcept (&env);
-		double w = TWO52[sx]+x;
+		double w = TWO52[sx] + math_opt_barrier (x);
 		double t =  w-TWO52[sx];
-		math_opt_barrier(t);
+		math_force_eval (t);
 		libc_fesetenv (&env);
 		return __copysign (t, x);
 	    }
@@ -53,9 +53,9 @@ __nearbyint(double x)
 	    else return x;		/* x is integral */
 	}
 	libc_feholdexcept (&env);
-	double w = TWO52[sx]+x;
+	double w = TWO52[sx] + math_opt_barrier (x);
 	double t = w-TWO52[sx];
-	math_opt_barrier (t);
+	math_force_eval (t);
 	libc_fesetenv (&env);
 	return t;
 }
diff --git a/sysdeps/ieee754/flt-32/s_nearbyintf.c b/sysdeps/ieee754/flt-32/s_nearbyintf.c
index afacdef..a8af894 100644
--- a/sysdeps/ieee754/flt-32/s_nearbyintf.c
+++ b/sysdeps/ieee754/flt-32/s_nearbyintf.c
@@ -38,7 +38,7 @@ __nearbyintf(float x)
 	if(j0<23) {
 	    if(j0<0) {
 		libc_feholdexceptf (&env);
-		w = TWO23[sx]+x;
+		w = TWO23[sx] + math_opt_barrier (x);
 		t =  w-TWO23[sx];
 		math_force_eval (t);
 		libc_fesetenvf (&env);
@@ -51,7 +51,7 @@ __nearbyintf(float x)
 	    else return x;		/* x is integral */
 	}
 	libc_feholdexceptf (&env);
-	w = TWO23[sx]+x;
+	w = TWO23[sx] + math_opt_barrier (x);
 	t = w-TWO23[sx];
 	math_force_eval (t);
 	libc_fesetenvf (&env);
diff --git a/sysdeps/ieee754/ldbl-128/s_nearbyintl.c b/sysdeps/ieee754/ldbl-128/s_nearbyintl.c
index 631b0e0..c1ee68b 100644
--- a/sysdeps/ieee754/ldbl-128/s_nearbyintl.c
+++ b/sysdeps/ieee754/ldbl-128/s_nearbyintl.c
@@ -45,7 +45,7 @@ _Float128 __nearbyintl(_Float128 x)
 	if(j0<112) {
 	    if(j0<0) {
 		feholdexcept (&env);
-	        w = TWO112[sx]+x;
+	        w = TWO112[sx] + math_opt_barrier (x);
 	        t = w-TWO112[sx];
 		math_force_eval (t);
 	        fesetenv (&env);
@@ -58,7 +58,7 @@ _Float128 __nearbyintl(_Float128 x)
 	    else return x;		/* x is integral */
 	}
 	feholdexcept (&env);
-	w = TWO112[sx]+x;
+	w = TWO112[sx] + math_opt_barrier (x);
 	t = w-TWO112[sx];
 	math_force_eval (t);
 	fesetenv (&env);

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                                        |   13 +++++++++++++
 sysdeps/ieee754/dbl-64/s_nearbyint.c             |    4 ++--
 sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c |    8 ++++----
 sysdeps/ieee754/flt-32/s_nearbyintf.c            |    4 ++--
 sysdeps/ieee754/ldbl-128/s_nearbyintl.c          |    4 ++--
 5 files changed, 23 insertions(+), 10 deletions(-)


hooks/post-receive
-- 
GNU C Library master sources


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]