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authorGabriel F. T. Gomes <gabriel@inconstante.eti.br>2017-09-20 15:10:26 -0300
committerGabriel F. T. Gomes <gabriel@inconstante.eti.br>2017-09-22 14:47:16 -0300
commitc5c4a626098ec884b8527356abdf2a4bb7b6bf27 (patch)
tree0f8f63a5117bb8df4972968ebccc3b9dc9547628 /math
parent23947846658fd41875381c0bcc05b319c3c7bde4 (diff)
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Let fpclassify use the builtin when optimizing for size in C++ mode (bug 22146)
When optimization for size is on (-Os), fpclassify does not use the type-generic __builtin_fpclassify builtin, instead it uses __MATH_TG. However, when library support for float128 is available, __MATH_TG uses __builtin_types_compatible_p, which is not available in C++ mode. On the other hand, libstdc++ undefines (in cmath) many macros from math.h, including fpclassify, so that it can provide its own functions. However, during its configure tests, libstdc++ just tests for the availability of the macros (it does not undefine them, nor does it provide its own functions). Finally, when libstdc++ is configured with optimization for size enabled, its configure tests include math.h and get the definition of fpclassify that uses __MATH_TG (and __builtin_types_compatible_p). Since libstdc++ does not undefine the macros during its configure tests, they fail. This patch lets fpclassify use the builtin in C++ mode, even when optimization for size is on. This allows the configure test in libstdc++ to work. Tested for powerpc64le and x86_64. [BZ #22146] math/math.h: Let fpclassify use the builtin in C++ mode, even when optimazing for size.
Diffstat (limited to 'math')
-rw-r--r--math/math.h8
1 files changed, 7 insertions, 1 deletions
diff --git a/math/math.h b/math/math.h
index 6c2ad97fb8..c6c289d5d2 100644
--- a/math/math.h
+++ b/math/math.h
@@ -432,7 +432,13 @@ enum
/* Return number of classification appropriate for X. */
# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__ \
- && !defined __OPTIMIZE_SIZE__
+ && (!defined __OPTIMIZE_SIZE__ || defined __cplusplus)
+ /* The check for __cplusplus allows the use of the builtin, even
+ when optimization for size is on. This is provided for
+ libstdc++, only to let its configure test work when it is built
+ with -Os. No further use of this definition of fpclassify is
+ expected in C++ mode, since libstdc++ provides its own version
+ of fpclassify in cmath (which undefines fpclassify). */
# define fpclassify(x) __builtin_fpclassify (FP_NAN, FP_INFINITE, \
FP_NORMAL, FP_SUBNORMAL, FP_ZERO, x)
# else