------- Comment #3 from amylaar at gcc dot gnu dot org 2006-04-12 13:46 ------- sh64 has indexed addressing, but the addition is always done as 64 bit, and there are currently no implemenmtations that allow the 64 bit logical address space to be re-mapped into a 32 physical address space - instead they trap on any access to an address that does not fit into a 32 bit address space.
This makes using indexed addressing with Pmode for -m5-32media (where Pmode is SImode) unsafe, since some optimizations can fold additions into indexed addressing and thus cause out-of-range addresses. Therefore, INDEX_REG_CLASS is NO_REGS for -m5-32media. The division code produces an address with a DImode plus of two registers - this is safe, since we exactly describe what the hardware does. However, find_reloads_address_1 sees a plus and recurses with CONTEXT set to 1, and then uses INDEX_REG_CLASS; it does not take into account that the mode is not Pmode. I think the best solution is to have an INDEX_REG_CLASS_FOR_MODE macro, which defaults to INDEX_REG_CLASS. Then this macro can be defined for the SH to return GENERAL_REGS for DImode when compiling SHmedia code. A kludgy solution would be to make reload reload the sum into a base register (to cover the general case), and make the SH LEGITIMIZE_RELOAD_ADDRESS recognize a sum with a non-pmode PLUS, and only reload pseudos inside into GENERAL_REGS. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27117
