On Sun, Mar 6, 2011 at 9:18 AM, H.J. Lu <hongjiu...@intel.com> wrote:
> We shouldn't save call frame hard registers as "void *". This patch > changes the unwind library to save call frame hard registers as > _Unwind_Word. OK for 4.7? > + PR other/48007 > + * unwind-dw2.c (_Unwind_Context): Save call frame hard registers > + as _Unwind_Word. > + (_Unwind_GetGR): Get GR value as _Unwind_Word. > + (_Unwind_SetGR): Set GR value as _Unwind_Word. > + (_Unwind_SetGRValue): Likewise. > + (_Unwind_GetGRPtr): Cast return to "void *". > + (_Unwind_SetGRPtr): Cast pointer to _Unwind_Word. > + (uw_install_context_1): Cast pointer to "void *". The approach you are using here looks wrong to me. When looking at the DWARF2 _Unwind_Context, you have to look at the by_value field for the register. If by_value is true, then the reg field for that register holds an _Unwind_Word which is the value of the register. If by_value is false, then the reg field holds a pointer to the place where the actual value is stored. The size of the actual value is determined by dwarf_reg_size_table. In other words, the reg field is a really a union of _Unwind_Word and void*. You have correctly observed that the current code fails for the case where sizeof(_Unwind_Word) > sizeof(void*). However, the answer is not to change the type from void* to _Unwind_Word. That will fail when sizeof(void*) > sizeof(_Unwind_Word). I think you have to make the reg field a union. By the way, don't use intptr_t in the unwind code. Use _Unwind_Internal_Ptr. But I think if you make the field a union, you won't need to use either type. Ian
