Restore test_exp also subnormals in add/sub

Author: ckormanyos

include/boost/multiprecision/cpp_double_fp.hpp

@@ -432,12 +432,20 @@ class cpp_double_fp_backend
          return *this;
       }
 
-      const auto iszero_u = (fpc_u == FP_ZERO);
+      const auto iszero_u = ((fpc_u == FP_ZERO) || (fpc_u == FP_SUBNORMAL));
       const auto isnan_v  = (fpc_v == FP_NAN);
 
       if (iszero_u || (isnan_v || isinf_v))
       {
-         return operator=(v);
+         if (iszero_u)
+         {
+            data.first  = float_type { 0.0F };
+            data.second = float_type { 0.0F };
+         }
+
+         const auto iszero_v = ((fpc_v == FP_ZERO) || (fpc_v == FP_SUBNORMAL));
+
+         return ((!iszero_v) ? operator=(v) : *this);
       }
 
       if (this == &v)
@@ -482,12 +490,20 @@ class cpp_double_fp_backend
          return *this;
       }
 
-      const auto iszero_u = (fpc_u == FP_ZERO);
+      const auto iszero_u = ((fpc_u == FP_ZERO) || (fpc_u == FP_SUBNORMAL));
       const auto isnan_v  = (fpc_v == FP_NAN);
 
       if (iszero_u || (isnan_v || isinf_v))
       {
-         return operator=(-v);
+         if (iszero_u)
+         {
+            data.first  = float_type { 0.0F };
+            data.second = float_type { 0.0F };
+         }
+
+         const auto iszero_v = ((fpc_v == FP_ZERO) || (fpc_v == FP_SUBNORMAL));
+
+         return ((!iszero_v) ? operator=(-v) : *this);
       }
 
       if (this == &v)

test/Jamfile.v2

@@ -262,7 +262,7 @@ alias precision_tests : test_preserve_source_precision_gmp test_preserve_source_
 rule get_function_tests
 {
    local result ;
-   for local source in test_log.cpp test_pow.cpp test_pow_df.cpp test_sinh.cpp test_sqrt.cpp test_cosh.cpp test_tanh.cpp test_sin.cpp test_cos.cpp test_tan.cpp test_asin.cpp test_acos.cpp test_atan.cpp test_round.cpp test_fpclassify.cpp test_sf_import_c99.cpp
+   for local source in test_exp.cpp test_log.cpp test_pow.cpp test_sinh.cpp test_sqrt.cpp test_cosh.cpp test_tanh.cpp test_sin.cpp test_cos.cpp test_tan.cpp test_asin.cpp test_acos.cpp test_atan.cpp test_round.cpp test_fpclassify.cpp test_sf_import_c99.cpp
    {
          result += [ run $(source) gmp no_eh_support
               : # command line

test/test_exp.cpp

@@ -59,6 +59,9 @@
 #include <boost/multiprecision/cpp_bin_float.hpp>
 #endif
 #ifdef TEST_CPP_DOUBLE_FLOAT
+#if defined(BOOST_MATH_USE_FLOAT128)
+#include <boost/multiprecision/float128.hpp>
+#endif
 #include <boost/multiprecision/cpp_double_fp.hpp>
 #endif
 
@@ -206,8 +209,16 @@ void test()
             BOOST_CHECK_LE(exp(bug_case), (std::numeric_limits<T>::min)());
          }
       }
+
       bug_case = log((std::numeric_limits<T>::max)()) / -1.0005;
-      for (unsigned i = 0; i < 20; ++i, bug_case /= 1.05)
+      unsigned i { 0U };
+
+      #if defined(TEST_CPP_DOUBLE_FLOAT)
+      BOOST_IF_CONSTEXPR(std::is_same<T, boost::multiprecision::cpp_double_float>::value) { for ( ; i < 7; ++i, bug_case /= 1.05) { ; } }
+      BOOST_IF_CONSTEXPR(std::is_same<T, boost::multiprecision::cpp_double_double>::value) { for ( ; i < 3; ++i, bug_case /= 1.05) { ; } }
+      BOOST_IF_CONSTEXPR(std::is_same<T, boost::multiprecision::cpp_double_long_double>::value) { for ( ; i < 3; ++i, bug_case /= 1.05) { ; } }
+      #endif
+      for ( ; i < 20U; ++i, bug_case /= static_cast<T>(1.05L))
       {
          BOOST_CHECK_GE(exp(bug_case), (std::numeric_limits<T>::min)());
       }