diff options
Diffstat (limited to 'gcc/builtins.c')
| -rw-r--r-- | gcc/builtins.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/gcc/builtins.c b/gcc/builtins.c index 4df0e95..2e8189d 100644 --- a/gcc/builtins.c +++ b/gcc/builtins.c @@ -5949,16 +5949,21 @@ fold_builtin_logarithm (tree exp, const REAL_VALUE_TYPE *value) tree type = TREE_TYPE (TREE_TYPE (fndecl)); tree arg = TREE_VALUE (arglist); const enum built_in_function fcode = builtin_mathfn_code (arg); - const REAL_VALUE_TYPE value_mode = - real_value_truncate (TYPE_MODE (type), *value); /* Optimize log*(1.0) = 0.0. */ if (real_onep (arg)) return build_real (type, dconst0); - /* Optimize logN(N) = 1.0. */ - if (real_dconstp (arg, &value_mode)) - return build_real (type, dconst1); + /* Optimize logN(N) = 1.0. If N can't be truncated to MODE + exactly, then only do this if flag_unsafe_math_optimizations. */ + if (exact_real_truncate (TYPE_MODE (type), value) + || flag_unsafe_math_optimizations) + { + const REAL_VALUE_TYPE value_truncate = + real_value_truncate (TYPE_MODE (type), *value); + if (real_dconstp (arg, &value_truncate)) + return build_real (type, dconst1); + } /* Special case, optimize logN(expN(x)) = x. */ if (flag_unsafe_math_optimizations |