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Re: [PATCH] Remove bogosities from dwarf2cfi.c:cfi_pop_frame()


Mark
> > Index: ChangeLog
> from Mark Kettenis <kettenis@gnu.org>
> > * dwarf2cfi.c (cfi_pop_frame): Use alloca() for regbuf.
> Don't call get_current_frame().
>


Heads up,

I think the write_register_bytes() call should be replaced by regcache_register_write(current_regcache, ). This is new code so it doesn't need to go through any of that nasty write_register_bytes() stuff.

Andrew



Why is this code trying to poke directly into the regcache at all? AFAICT it should be operating on the pseudo registers not the cache.
[cooked]

Hmm, yes, good point. It should at least use regcache_cpy() so that it is ``bug compatible'' with generic_pop_dummy_frame()(1).

At present GDB saves/restores registers in a confused sort of way. Firstly, the save/restore operation (see regcache_cpy):

- for old targets it iterates over 0..NUM_REGS (the full raw register space) using write_register_bytes() to restore the registers.

- for new targets it iterates over 0..NUM_REGS (the full raw register space) using regcache_write() to directly transfer the raw registers.

It then uses this single mechanism(2) to handle two orthogonal situtations, and that is the problem:

- saving / restoring a raw register cache before / after an inferior function call. Here, a select list of raw registers should be transfered.

- unwinding a stack frame, storing those unwound register values, and hence having the effect of poping one or more frames. Here, a select list of cooked registers should be stored.


Andrew

(1) I also suspect that some cleanups would let the function in question be eliminated from dwarf2cfi but that is another story.

(2) I believe the regcache changes were ``bug compatible''.



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