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

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

[Mark Kettenis]

Using alloca() here is pretty obvious.  I discussed the other fix with
Michael Ludvig.

Checked in.

Mark

Index: ChangeLog
from  Mark Kettenis  <kettenis@gnu.org>

	* dwarf2cfi.c (cfi_pop_frame): Use alloca() for regbuf.
	Don't call get_current_frame().

Index: dwarf2cfi.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2cfi.c,v
retrieving revision 1.11
diff -u -p -r1.11 dwarf2cfi.c
--- dwarf2cfi.c 21 Jun 2002 13:53:24 -0000 1.11
+++ dwarf2cfi.c 4 Jul 2002 14:40:22 -0000
@@ -1757,10 +1757,8 @@ cfi_write_fp (CORE_ADDR val)
 void
 cfi_pop_frame (struct frame_info *fi)
 {
-  char regbuf[MAX_REGISTER_RAW_SIZE];
+  char *regbuf = alloca (MAX_REGISTER_RAW_SIZE);
   int regnum;
-
-  fi = get_current_frame ();
 
   for (regnum = 0; regnum < NUM_REGS; regnum++)
     {

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

[Andrew Cagney]

> Using alloca() here is pretty obvious.  I discussed the other fix with
> Michael Ludvig.
> 
> Checked in.
> 
> 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

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

[Richard Earnshaw]

> > Using alloca() here is pretty obvious.  I discussed the other fix with
> > Michael Ludvig.
> > 
> > Checked in.
> > 
> > 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.

R.

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

[Andrew Cagney]

> 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''.