Re: [patch rfc] Add NUM_REGS pseudo regs to MIPS

[Andrew Cagney <ac131313 at redhat dot com>]

> OK...  cvs as of about 9:30PDT 21 July.  Confirmed that the GDB build
> was only -O -g, though some other things (newlib, mostly) got -O2.
>
> That was quite a tail-call optimization -- looks like 3 frames
> vanished.  I'm a little worried about a warning I got in this
> backtrace from top-gdb:
> During symbol reading, debug info mismatch between compiler and debugger.
>
> The top gdb and gcc came from RedHat 7.1.  I suppose I could build a
> new host gcc and gdb, but that seems like a fair amount of pain.
>
> Anyway, here's the trace, along with a bunch of "up; list" to make sure
> everything's sane looking:

Yep!


> (top-gdb) info stack
> #0  internal_error (file=0x824e580 "../../combined/gdb/mips-tdep.c", line=5671, 
>     string=0x824e555 "%s: Assertion `%s' failed.") at ../../combined/gdb/utils.c:807
> #1  0x080dd45c in mips_register_sim_regno (regnum=90)
>     at ../../combined/gdb/mips-tdep.c:5671
> #2  0x080cb037 in gdbarch_register_sim_regno (gdbarch=0x83179d8, reg_nr=90)
>     at ../../combined/gdb/gdbarch.c:3983
> #3  0x08127e0f in gdbsim_fetch_register (regno=90) at ../../combined/gdb/remote-sim.c:299
> #4  0x08094450 in legacy_read_register_gen (regnum=90, 
>     myaddr=0xbffff0f0 "Ððÿ¿Øy1\b\030ñÿ¿\020\227\f\bØy1\bZ")
>     at ../../combined/gdb/regcache.c:730
> #5  0x0809453e in regcache_raw_read (regcache=0x8323000, regnum=90, buf=0xbffff0f0)
>     at ../../combined/gdb/regcache.c:748
> #6  0x0809499a in regcache_cooked_read (regcache=0x8323000, regnum=90, buf=0xbffff0f0)
>     at ../../combined/gdb/regcache.c:838

It went wrong here.  It tests (regnum < ->nr_raw_registers), but for 
legacy targets NR_RAW_REGISTERS == NUM_REGS + NUM_PSEUDO_REGS :-(

The correct fix is to just delete a heap of code, however ...

From regcache.c:

>   if ((!gdbarch_pseudo_register_read_p (gdbarch)
>        && !gdbarch_pseudo_register_write_p (gdbarch)
>        && !gdbarch_register_type_p (gdbarch))
>       || REGISTER_BYTE_P () || REGISTER_RAW_SIZE_P ())
>     {
>       descr->legacy_p = 1;
>       init_legacy_regcache_descr (gdbarch, descr);
>       return descr;
>     }

can you try removing the two || ... clauses I added 2003-07-03?

I think my change may have fixed some legacy code but broke others :-(

Andrew