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| author | Jonathan Wakely <jwakely@redhat.com> | 2021-08-23 13:12:24 +0100 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2021-08-23 14:45:00 +0100 |
| commit | da6ce351069bda74d814b723934008d75bd4e8b0 (patch) | |
| tree | 2d9a2c128877375521ca94a0582099f9b6e18323 | |
| parent | bc97e736a5597ac1545b7f9069472117b6caa867 (diff) | |
| download | gcc-da6ce351069bda74d814b723934008d75bd4e8b0.zip gcc-da6ce351069bda74d814b723934008d75bd4e8b0.tar.gz gcc-da6ce351069bda74d814b723934008d75bd4e8b0.tar.bz2 | |
libstdc++: Use __builtin_expect in __dynamic_cast
The null pointer check is never needed for correct code, only to
gracefully handle undefined cases. Add __builtin_expect to be sure that
we don't pessimize the valid uses.
libstdc++-v3/ChangeLog:
* libsupc++/dyncast.cc (__dynamic_cast): Add __builtin_expect to
precondition check.
| -rw-r--r-- | libstdc++-v3/libsupc++/dyncast.cc | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/libstdc++-v3/libsupc++/dyncast.cc b/libstdc++-v3/libsupc++/dyncast.cc index f8f707e..a1138d0 100644 --- a/libstdc++-v3/libsupc++/dyncast.cc +++ b/libstdc++-v3/libsupc++/dyncast.cc @@ -47,9 +47,9 @@ __dynamic_cast (const void *src_ptr, // object started from const __class_type_info *dst_type, // desired target type ptrdiff_t src2dst) // how src and dst are related { - if (!src_ptr) - /* Handle precondition violations gracefully. */ - return NULL; + if (__builtin_expect(!src_ptr, 0)) + return NULL; // Handle precondition violations gracefully. + const void *vtable = *static_cast <const void *const *> (src_ptr); const vtable_prefix *prefix = (adjust_pointer <vtable_prefix> @@ -70,7 +70,7 @@ __dynamic_cast (const void *src_ptr, // object started from (whole_vtable, -ptrdiff_t (offsetof (vtable_prefix, origin)))); if (whole_prefix->whole_type != whole_type) return NULL; - + whole_type->__do_dyncast (src2dst, __class_type_info::__contained_public, dst_type, whole_ptr, src_type, src_ptr, result); if (!result.dst_ptr) |