On Tue, 9 Oct 2018, Richard Biener wrote: > It was repeatedly suggested that we _could_ derive alignment info from > function parameter types since we rely on precise typing there for example > for points-to analysis (albeit only for restrict qualification processing and > for DECL_BY_REFERENCE "pointers"). That would fix the simple testcase > that was presented here.
Even in that case you mustn't assume alignment for pointer comparisons, only for dereferences. Assuming it for comparisons breaks e.g. glibc's # define LC_GLOBAL_LOCALE ((locale_t) -1L) (locale_t is a pointer-to-pointer-aligned-struct) and other similar constructs involving magic constants (not dereferenced) of pointer type; comparisons of a locale_t value against LC_GLOBAL_LOCALE need to work. -- Joseph S. Myers jos...@codesourcery.com
