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| -rw-r--r-- | clang/docs/LTOVisibility.rst | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/clang/docs/LTOVisibility.rst b/clang/docs/LTOVisibility.rst index 67367f3d635..e1372d667a1 100644 --- a/clang/docs/LTOVisibility.rst +++ b/clang/docs/LTOVisibility.rst @@ -10,15 +10,16 @@ using link-time optimization; in the case where LTO is not being used, the linkage unit's LTO unit is empty. Each linkage unit has only a single LTO unit. The LTO visibility of a class is used by the compiler to determine which -classes the virtual function call optimization and control flow integrity -features apply to. These features use whole-program information, so they -require the entire class hierarchy to be visible in order to work correctly. - -If any translation unit in the program uses either of the virtual function -call optimization or control flow integrity features, it is effectively an -ODR violation to define a class with hidden LTO visibility in multiple linkage +classes the whole-program devirtualization (``-fwhole-program-vtables``) and +control flow integrity (``-fsanitize=cfi-vcall``) features apply to. These +features use whole-program information, so they require the entire class +hierarchy to be visible in order to work correctly. + +If any translation unit in the program uses either of the whole-program +devirtualization or control flow integrity features, it is effectively an ODR +violation to define a class with hidden LTO visibility in multiple linkage units. A class with public LTO visibility may be defined in multiple linkage -units, but the tradeoff is that the virtual function call optimization and +units, but the tradeoff is that the whole-program devirtualization and control flow integrity features can only be applied to classes with hidden LTO visibility. A class's LTO visibility is treated as an ODR-relevant property of its definition, so it must be consistent between translation units. |
