Fix dbl-64 lrint for 64-bit long (bug 19095).

The dbl-64 implementation of lrint produces incorrect results for some
arguments with 64-bit long because a 32-bit (unsigned) low part of the
mantissa is shifted left, losing high bits in the process.  This patch
fixes this by casting to long int before shifting, as in lround (as
this case only applies for 64-bit long, there are no issues with
sign-extension).

Tested for mips64 (n64).

	[BZ #19095]
	* sysdeps/ieee754/dbl-64/s_lrint.c (__lrint): Cast low part of
	mantissa to long int before shifting left.

diff --git a/ChangeLog b/ChangeLog
index 0bfe5f5..1ceae34 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2015-10-09  Joseph Myers  <joseph@codesourcery.com>
+
+       [BZ #19095]
+       * sysdeps/ieee754/dbl-64/s_lrint.c (__lrint): Cast low part of
+       mantissa to long int before shifting left.
+
 2015-10-08  Joseph Myers  <joseph@codesourcery.com>
 
        [BZ #19094]

diff --git a/NEWS b/NEWS
index 352e468..5c239f3 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -19,7 +19,7 @@ Version 2.23
   18875, 18887, 18921, 18951, 18952, 18956, 18961, 18966, 18967, 18969,
   18970, 18977, 18980, 18981, 18985, 19003, 19012, 19016, 19018, 19032,
   19046, 19049, 19050, 19059, 19071, 19076, 19077, 19078, 19079, 19085,
-  19086, 19088, 19094.
+  19086, 19088, 19094, 19095.
 
 * The obsolete header <regexp.h> has been removed.  Programs that require
   this header must be updated to use <regex.h> instead.

diff --git a/sysdeps/ieee754/dbl-64/s_lrint.c b/sysdeps/ieee754/dbl-64/s_lrint.c
index 39f95ad..d004594 100644 (file)
--- a/sysdeps/ieee754/dbl-64/s_lrint.c
+++ b/sysdeps/ieee754/dbl-64/s_lrint.c
@@ -61,7 +61,7 @@ __lrint (double x)
   else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
     {
       if (j0 >= 52)
-       result = ((long int) i0 << (j0 - 20)) | (i1 << (j0 - 52));
+       result = ((long int) i0 << (j0 - 20)) | ((long int) i1 << (j0 - 52));
       else
        {
 #if defined FE_INVALID || defined FE_INEXACT