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authorJoseph Myers <joseph@codesourcery.com>2015-05-21 23:44:33 +0000
committerJoseph Myers <joseph@codesourcery.com>2015-05-21 23:44:33 +0000
commit9124ccf76abc5a2ffe4603e6424b1dc2b5a5db44 (patch)
treedf43bd150365d7da6bee80df86d59f7bb57c7da3 /sysdeps/ieee754/ldbl-96/e_lgammal_r.c
parent89f3b6e18c6e7833438789746fcfc2e7189f7cac (diff)
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Fix lgamma implementations for -Wuninitialized.
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.)

	* 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.
Diffstat (limited to 'sysdeps/ieee754/ldbl-96/e_lgammal_r.c')
-rw-r--r--sysdeps/ieee754/ldbl-96/e_lgammal_r.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-96/e_lgammal_r.c b/sysdeps/ieee754/ldbl-96/e_lgammal_r.c
index 1a95f846ae..0cc35f9252 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)