[Bug target/55672] [4.8 Regression] -fstack-check=generic ICEs in print_reg, at config/i386/i386.c:13868

[vmakarov at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55672



--- Comment #4 from Vladimir Makarov <vmakarov at gcc dot gnu.org> 2012-12-17 
21:39:28 UTC ---

If stack_realign_p is true, frame_pointer_needed is also true.   So we can use

fp to eliminate frame but i386.c::x86_can_eliminate prohibits it.  The code

looks strange:





 if (stack_realign_fp)

    return ((from == ARG_POINTER_REGNUM

             && to == HARD_FRAME_POINTER_REGNUM)

            || (from == FRAME_POINTER_REGNUM

                && to == STACK_POINTER_REGNUM));



So we permit to change argument pointer but not frame pointer to FP which again

is strange IMHO.   Changing the code to



 if (stack_realign_fp)

    return ((from == ARG_POINTER_REGNUM

             && to == HARD_FRAME_POINTER_REGNUM)

            || (from == FRAME_POINTER_REGNUM

                && to == STACK_POINTER_REGNUM)

            || (from == FRAME_POINTER_REGNUM

                && to == HARD_FRAME_POINTER_REGNUM));



solves the problem.