Re: /gdb/regcache.c question

[Daniel Jacobowitz <drow@false.org>]

On Sun, Apr 02, 2006 at 03:49:44PM +0200, Mark Kettenis wrote:
> No, the bug is that the code that parses your collect command is
> asking for the type of a register number that doesn't exist.  That
> typo should have been caught much earlier before register_type() was
> called.

The most useful thing to provide when you hit an abort is the
backtrace.  Then we can figure out where the real bug is.

This one's easy to reproduce.  regnum == 51, descr->nr_cooked_registers
== 50.  It turns out that the problem is "user registers", which are
implemented sort of off to the side of the regcache. 
user_reg_map_name_to_regnum returns 51 for i386's "pc".

0 <= x < NUM_REGS : raw registers
NUM_REGS <= x < NUM_REGS + NUM_PSEUDO_REGS : cooked pseudo registers
NUM_REGS + NUM_PSEUDO_REGS <= x : "user" registers

The only thing that user registers have is a value, and you can get at
their type through the value.  The user-regs and std-regs
infrastructure isn't much used; I don't know what the plan was for it. 
I don't think we can collect user registers without changing the
interface.

It is only used for $pc, $sp, $fp, and $ps.  For $sp and $ps it either
returns a normal register or an error.  For $fp and $pc it's a bit more
complicated.

Anyway, for now the easiest thing to do would be to refuse to collect
registers >= NUM_REGS + NUM_PSEUDO_REGS.

-- 
Daniel Jacobowitz
CodeSourcery