Module Name: src
Committed By: riastradh
Date: Mon Nov 6 13:48:00 UTC 2023
Modified Files:
src/tests/lib/libm: t_fenv.c
Log Message:
t_fenv: Use volatile intermediate to force rounding to double.
See comment for details about why this is necessary.
Should fix these tests on i386 (and perhaps m68k too).
PR port-mips/57680
XXX pullup-10
To generate a diff of this commit:
cvs rdiff -u -r1.11 -r1.12 src/tests/lib/libm/t_fenv.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/tests/lib/libm/t_fenv.c
diff -u src/tests/lib/libm/t_fenv.c:1.11 src/tests/lib/libm/t_fenv.c:1.12
--- src/tests/lib/libm/t_fenv.c:1.11 Sun Nov 5 21:13:06 2023
+++ src/tests/lib/libm/t_fenv.c Mon Nov 6 13:48:00 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: t_fenv.c,v 1.11 2023/11/05 21:13:06 riastradh Exp $ */
+/* $NetBSD: t_fenv.c,v 1.12 2023/11/06 13:48:00 riastradh Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -29,7 +29,7 @@
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
-__RCSID("$NetBSD: t_fenv.c,v 1.11 2023/11/05 21:13:06 riastradh Exp $");
+__RCSID("$NetBSD: t_fenv.c,v 1.12 2023/11/06 13:48:00 riastradh Exp $");
#include <atf-c.h>
@@ -114,8 +114,19 @@ static void
checkrounding(int feround, const char *name)
{
volatile double ulp1 = DBL_EPSILON;
- double y1 = -1 + ulp1/4;
- double y2 = 1 + 3*(ulp1/2);
+
+ /*
+ * XXX These must be volatile to force rounding to double when
+ * the intermediate quantities are evaluated in long double
+ * precision, e.g. on 32-bit x86 with x87 long double. Under
+ * the C standard (C99, C11, C17, &c.), cast and assignment
+ * operators are required to remove all extra range and
+ * precision, i.e., round double to long double. But we build
+ * this code with -std=gnu99, which diverges from this
+ * requirement -- unless you add a volatile qualifier.
+ */
+ volatile double y1 = -1 + ulp1/4;
+ volatile double y2 = 1 + 3*(ulp1/2);
switch (feround) {
case FE_TONEAREST: {
