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Fix lgamma implementations for -Wuninitialized [committed]
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Thu, 21 May 2015 23:45:24 +0000
- Subject: Fix lgamma implementations for -Wuninitialized [committed]
- Authentication-results: sourceware.org; auth=none
If you remove the "override CFLAGS += -Wno-uninitialized" in
math/Makefile, you get errors from lgamma implementations of the form:
../sysdeps/ieee754/dbl-64/e_lgamma_r.c: In function '__ieee754_lgamma_r':
../sysdeps/ieee754/dbl-64/e_lgamma_r.c:297:13: error: 'nadj' may be used uninitialized in this function [-Werror=maybe-uninitialized]
if(hx<0) r = nadj - r;
This is one of the standard kinds of false positive uninitialized
warnings: nadj is set under a certain condition, and then later used
under the same condition. This patch uses DIAG_* macros to suppress
the warning on the use of nadj. The ldbl-128 / ldbl-128ibm
implementation has a substantially different structure that avoids
this issue.
Tested for x86_64. (In fact this patch eliminates the need for that
-Wno-uninitialized on x86_64, but I want to test on more architectures
before removing it.) Committed.
2015-05-21 Joseph Myers <joseph@codesourcery.com>
* sysdeps/ieee754/dbl-64/e_lgamma_r.c: Include <libc-internal.h>.
(__ieee754_lgamma_r): Ignore uninitialized warnings around use of
NADJ.
* sysdeps/ieee754/flt-32/e_lgammaf_r.c: Include <libc-internal.h>.
(__ieee754_lgammaf_r): Ignore uninitialized warnings around use of
NADJ.
* sysdeps/ieee754/ldbl-96/e_lgammal_r.c: Include <libc-internal.h>.
(__ieee754_lgammal_r): Ignore uninitialized warnings around use of
NADJ.
diff --git a/sysdeps/ieee754/dbl-64/e_lgamma_r.c b/sysdeps/ieee754/dbl-64/e_lgamma_r.c
index af7d06c..fc6f594 100644
--- a/sysdeps/ieee754/dbl-64/e_lgamma_r.c
+++ b/sysdeps/ieee754/dbl-64/e_lgamma_r.c
@@ -77,6 +77,7 @@
*
*/
+#include <libc-internal.h>
#include <math.h>
#include <math_private.h>
@@ -294,7 +295,18 @@ __ieee754_lgamma_r(double x, int *signgamp)
} else
/* 2**58 <= x <= inf */
r = x*(__ieee754_log(x)-one);
+ /* NADJ is set for negative arguments but not otherwise,
+ resulting in warnings that it may be used uninitialized
+ although in the cases where it is used it has always been
+ set. */
+ DIAG_PUSH_NEEDS_COMMENT;
+#if __GNUC_PREREQ (4, 7)
+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wmaybe-uninitialized");
+#else
+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wuninitialized");
+#endif
if(hx<0) r = nadj - r;
+ DIAG_POP_NEEDS_COMMENT;
return r;
}
strong_alias (__ieee754_lgamma_r, __lgamma_r_finite)
diff --git a/sysdeps/ieee754/flt-32/e_lgammaf_r.c b/sysdeps/ieee754/flt-32/e_lgammaf_r.c
index 4743bee..c0bf415 100644
--- a/sysdeps/ieee754/flt-32/e_lgammaf_r.c
+++ b/sysdeps/ieee754/flt-32/e_lgammaf_r.c
@@ -13,6 +13,7 @@
* ====================================================
*/
+#include <libc-internal.h>
#include <math.h>
#include <math_private.h>
@@ -229,7 +230,18 @@ __ieee754_lgammaf_r(float x, int *signgamp)
} else
/* 2**26 <= x <= inf */
r = x*(__ieee754_logf(x)-one);
+ /* NADJ is set for negative arguments but not otherwise,
+ resulting in warnings that it may be used uninitialized
+ although in the cases where it is used it has always been
+ set. */
+ DIAG_PUSH_NEEDS_COMMENT;
+#if __GNUC_PREREQ (4, 7)
+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wmaybe-uninitialized");
+#else
+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wuninitialized");
+#endif
if(hx<0) r = nadj - r;
+ DIAG_POP_NEEDS_COMMENT;
return r;
}
strong_alias (__ieee754_lgammaf_r, __lgammaf_r_finite)
diff --git a/sysdeps/ieee754/ldbl-96/e_lgammal_r.c b/sysdeps/ieee754/ldbl-96/e_lgammal_r.c
index 1a95f84..0cc35f9 100644
--- a/sysdeps/ieee754/ldbl-96/e_lgammal_r.c
+++ b/sysdeps/ieee754/ldbl-96/e_lgammal_r.c
@@ -91,6 +91,7 @@
*
*/
+#include <libc-internal.h>
#include <math.h>
#include <math_private.h>
@@ -423,8 +424,18 @@ __ieee754_lgammal_r (long double x, int *signgamp)
else
/* 2**66 <= x <= inf */
r = x * (__ieee754_logl (x) - one);
+ /* NADJ is set for negative arguments but not otherwise, resulting
+ in warnings that it may be used uninitialized although in the
+ cases where it is used it has always been set. */
+ DIAG_PUSH_NEEDS_COMMENT;
+#if __GNUC_PREREQ (4, 7)
+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wmaybe-uninitialized");
+#else
+ DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wuninitialized");
+#endif
if (se & 0x8000)
r = nadj - r;
+ DIAG_POP_NEEDS_COMMENT;
return r;
}
strong_alias (__ieee754_lgammal_r, __lgammal_r_finite)
--
Joseph S. Myers
joseph@codesourcery.com