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 0bfe5f56a49f19e0cbf21d115c53411116b7bae5..1ceae346df1f92155564e0e05b4133b850ce33c5 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 352e468603b8732dbd99aeeff3247eee8a2b9b6d..5c239f3988f9404fe98ca631f6dabfae784b87dd 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 39f95adc216e7a3f4d6968d8d460fcb067761ad8..d004594bc2571c85dd967769a5be3dfdf616da25 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