Don't use dbl-64/wordsize-64 lround based on llround for ILP32 (bug 19079).

The implementation of lround in dbl-64/wordsize-64 as an alias or
wrapper for llround is always incorrect when long is not 64-bit,
because it misses required exceptions in overflow cases, as shown by
my recently added tests.  This patch removes that alias / wrapper in
the non-LP64 case, together with the REGISTER_CAST_INT32_TO_INT64
macro, restoring the previous version of lround for dbl-64/wordsize-64
(newly conditioned on !_LP64).

Tested for x86_64, and for mips64 with use of dbl-64/wordsize-64
enabled.

	[BZ #19079]
	* sysdeps/ieee754/dbl-64/wordsize-64/s_lround.c: Restore previous
	file, conditioned on [!_LP64].
	* sysdeps/ieee754/dbl-64/wordsize-64/s_llround.c
	[!_LP64] (__lround): Do not define as function or alias.
	[!_LP64] (lround): Likewise.
	[!_LP64] (__lroundl): Likewise.
	[!_LP64] (lroundl): Likewise.
	* sysdeps/tile/sysdep.h (REGISTER_CAST_INT32_TO_INT64): Remove
	macro.
	* sysdeps/x86_64/x32/sysdep.h (REGISTER_CAST_INT32_TO_INT64):
	Likewise.

6 files changed, 87 insertions, 25 deletions

diff --git a/ChangeLog b/ChangeLog
index b49f35d..8df2817 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2015-10-07  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #19079]
+	* sysdeps/ieee754/dbl-64/wordsize-64/s_lround.c: Restore previous
+	file, conditioned on [!_LP64].
+	* sysdeps/ieee754/dbl-64/wordsize-64/s_llround.c
+	[!_LP64] (__lround): Do not define as function or alias.
+	[!_LP64] (lround): Likewise.
+	[!_LP64] (__lroundl): Likewise.
+	[!_LP64] (lroundl): Likewise.
+	* sysdeps/tile/sysdep.h (REGISTER_CAST_INT32_TO_INT64): Remove
+	macro.
+	* sysdeps/x86_64/x32/sysdep.h (REGISTER_CAST_INT32_TO_INT64):
+	Likewise.
+
 2015-10-06  Joseph Myers  <joseph@codesourcery.com>
 
 	* math/libm-test.inc (lrint_test_data): Add more tests.
diff --git a/NEWS b/NEWS
index 5ad75a3..a0a91b5 100644
--- a/NEWS
+++ b/NEWS
@@ -18,7 +18,7 @@ Version 2.23
   18820, 18823, 18824, 18825, 18857, 18863, 18870, 18872, 18873, 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.
+  19049, 19050, 19059, 19071, 19076, 19077, 19078, 19079.
 
 * 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/wordsize-64/s_llround.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_llround.c
index 8bb5252..483d4a0 100644
--- a/sysdeps/ieee754/dbl-64/wordsize-64/s_llround.c
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_llround.c
@@ -69,23 +69,10 @@ strong_alias (__llround, __llroundl)
 weak_alias (__llround, llroundl)
 #endif
 
-/* long has the same width as long long on LP64 machines, so use an alias.
-   If building for ILP32 on a machine with 64-bit registers, however,
-   use a cast if necessary.  */
+/* long has the same width as long long on LP64 machines, so use an alias.  */
 #undef lround
 #undef __lround
-#if !defined (_LP64) && REGISTER_CAST_INT32_TO_INT64
-long int
-__lround (double x)
-{
-  return __llround (x);
-}
-weak_alias (__lround, lround)
-# ifdef NO_LONG_DOUBLE
-strong_alias (__lround, __lroundl)
-weak_alias (__lround, lroundl)
-# endif
-#else
+#ifdef _LP64
 strong_alias (__llround, __lround)
 weak_alias (__llround, lround)
 # ifdef NO_LONG_DOUBLE
diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_lround.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_lround.c
index 1e06fcb..390e733 100644
--- a/sysdeps/ieee754/dbl-64/wordsize-64/s_lround.c
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_lround.c
@@ -1 +1,69 @@
-/* The code is the same as llround.  Use an alias, see s_llround.c.  */
+/* Round double value to long int.
+   Copyright (C) 1997-2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+
+#include <math_private.h>
+
+/* For LP64, lround is an alias for llround.  */
+#ifndef _LP64
+
+long int
+__lround (double x)
+{
+  int32_t j0;
+  int64_t i0;
+  long int result;
+  int sign;
+
+  EXTRACT_WORDS64 (i0, x);
+  j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
+  sign = i0 < 0 ? -1 : 1;
+  i0 &= UINT64_C(0xfffffffffffff);
+  i0 |= UINT64_C(0x10000000000000);
+
+  if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
+    {
+      if (j0 < 0)
+	return j0 < -1 ? 0 : sign;
+      else if (j0 >= 52)
+	result = i0 << (j0 - 52);
+      else
+	{
+	  i0 += UINT64_C(0x8000000000000) >> j0;
+
+	  result = i0 >> (52 - j0);
+	}
+    }
+  else
+    {
+      /* The number is too large.  It is left implementation defined
+	 what happens.  */
+      return (long int) x;
+    }
+
+  return sign * result;
+}
+
+weak_alias (__lround, lround)
+# ifdef NO_LONG_DOUBLE
+strong_alias (__lround, __lroundl)
+weak_alias (__lround, lroundl)
+# endif
+
+#endif
diff --git a/sysdeps/tile/sysdep.h b/sysdeps/tile/sysdep.h
index 7b3d873..ead9dba 100644
--- a/sysdeps/tile/sysdep.h
+++ b/sysdeps/tile/sysdep.h
@@ -108,7 +108,3 @@
 #endif
 
 #endif /* __ASSEMBLER__ */
-
-/* On tilegx, 32-bit values must have their high 32 bits sign extended;
-   random values are not allowed.  */
-#define REGISTER_CAST_INT32_TO_INT64 1
diff --git a/sysdeps/x86_64/x32/sysdep.h b/sysdeps/x86_64/x32/sysdep.h
index 0cbc1a0..9b87005 100644
--- a/sysdeps/x86_64/x32/sysdep.h
+++ b/sysdeps/x86_64/x32/sysdep.h
@@ -90,7 +90,3 @@
 # define R15_LP	"r15d"
 
 #endif	/* __ASSEMBLER__ */
-
-/* On x32, it is not required to normalize a 64-bit value before using
-   it as a 32-bit value.  */
-#define REGISTER_CAST_INT32_TO_INT64 0