[PATCH] pseudo-register un-optimization

[PATCH] pseudo-register un-optimization

[Michael Snyder]

 
2001-08-10  Michael Snyder  <msnyder@redhat.com>

	* regcache.c (legacy_write_register_gen): Don't 'optimize out'
	a write_register to a pseudo-reg.  Target_store_pseudo_register
	needs to get called, because these regs may be computed and may
	have side-effects.

Index: regcache.c
===================================================================
RCS file: /cvs/src/src/gdb/regcache.c,v
retrieving revision 1.24
diff -c -3 -p -r1.24 regcache.c
*** regcache.c	2001/06/15 23:50:46	1.24
--- regcache.c	2001/08/10 21:49:23
*************** legacy_write_register_gen (int regnum, c
*** 334,348 ****
  
    size = REGISTER_RAW_SIZE (regnum);
  
-   /* If we have a valid copy of the register, and new value == old value,
-      then don't bother doing the actual store. */
- 
-   if (register_cached (regnum)
-       && memcmp (register_buffer (regnum), myaddr, size) == 0)
-     return;
- 
    if (real_register (regnum))
!     target_prepare_to_store ();
  
    memcpy (register_buffer (regnum), myaddr, size);
  
--- 334,349 ----
  
    size = REGISTER_RAW_SIZE (regnum);
  
    if (real_register (regnum))
!     {
!       /* If we have a valid copy of the register, and new value == old
! 	 value, then don't bother doing the actual store. */
!       if (register_cached (regnum)
! 	  && memcmp (register_buffer (regnum), myaddr, size) == 0)
! 	return;
!       else
! 	target_prepare_to_store ();
!     }
  
    memcpy (register_buffer (regnum), myaddr, size);
  
From hjl@lucon.org Fri Aug 10 15:31:00 2001
From: "H . J . Lu" <hjl@lucon.org>
To: gdb@sources.redhat.com, gdb-patches@sources.redhat.com
Subject: Re: [rfa] Re: The problem with stabs and sign extension
Date: Fri, 10 Aug 2001 15:31:00 -0000
Message-id: <20010810153149.A15186@lucon.org>
References: <20010808141207.A31287@nevyn.them.org> <20010808161421.A3360@lucon.org> <20010808165359.A3964@lucon.org> <20010808170326.A4132@lucon.org> <20010808171616.A7610@nevyn.them.org>
X-SW-Source: 2001-08/msg00115.html
Content-length: 2370

On Wed, Aug 08, 2001 at 05:16:16PM -0700, Daniel Jacobowitz wrote:
> 
> There's actually a clear bug here, once you know where to look.  A
> CORE_ADDR is assigned to a long int in partial-stab.h.  There's a
> warning flag in GCC for this, isn't there?
> 

You miised one CORE_ADDR in partial-stab.h. This patch seems to fix
my problem. Any comments?

Thanks.


H.J.
-----
2001-08-10  Daniel Jacobowitz  <drow@mvista.com>
	    H.J. Lu  (hjl@gnu.org)

	* partial-stab.h: valu should be a CORE_ADDR.

2001-08-08  H.J. Lu  (hjl@gnu.org)

	* dbxread.c (SWAP_SYMBOL): Removed.
	(INTERNALIZE_SYMBOL): Check sign extended vma.

--- gdb/dbxread.c.vma	Fri Jul 13 12:12:34 2001
+++ gdb/dbxread.c	Wed Aug  8 21:02:29 2001
@@ -946,22 +946,15 @@ fill_symbuf (bfd *sym_bfd)
   symbuf_read += nbytes;
 }
 
-#define SWAP_SYMBOL(symp, abfd) \
-  { \
-    (symp)->n_strx = bfd_h_get_32(abfd,			\
-				(unsigned char *)&(symp)->n_strx);	\
-    (symp)->n_desc = bfd_h_get_16 (abfd,			\
-				(unsigned char *)&(symp)->n_desc);  	\
-    (symp)->n_value = bfd_h_get_32 (abfd,			\
-				(unsigned char *)&(symp)->n_value); 	\
-  }
-
 #define INTERNALIZE_SYMBOL(intern, extern, abfd)			\
   {									\
     (intern).n_type = bfd_h_get_8 (abfd, (extern)->e_type);		\
     (intern).n_strx = bfd_h_get_32 (abfd, (extern)->e_strx);		\
     (intern).n_desc = bfd_h_get_16 (abfd, (extern)->e_desc);  		\
-    (intern).n_value = bfd_h_get_32 (abfd, (extern)->e_value);		\
+    if (bfd_get_sign_extend_vma (abfd))					\
+      (intern).n_value = bfd_h_get_signed_32 (abfd, (extern)->e_value);	\
+    else								\
+      (intern).n_value = bfd_h_get_32 (abfd, (extern)->e_value);	\
   }
 
 /* Invariant: The symbol pointed to by symbuf_idx is the first one
--- gdb/partial-stab.h.vma	Fri Jul 13 12:12:54 2001
+++ gdb/partial-stab.h	Fri Aug 10 15:25:10 2001
@@ -201,7 +201,7 @@ switch (CUR_SYMBOL_TYPE)
 
   case N_SO:
     {
-      unsigned long valu;
+      CORE_ADDR valu;
       static int prev_so_symnum = -10;
       static int first_so_symnum;
       char *p;
@@ -399,7 +399,7 @@ switch (CUR_SYMBOL_TYPE)
     /* See if this is an end of function stab.  */
     if (pst && CUR_SYMBOL_TYPE == N_FUN && *namestring == '\000')
       {
-	unsigned long valu;
+	CORE_ADDR valu;
 
 	/* It's value is the size (in bytes) of the function for
 	   function relative stabs, or the address of the function's

Re: [PATCH] pseudo-register un-optimization

[Andrew Cagney]

> 
> 
> 2001-08-10  Michael Snyder  <msnyder@redhat.com>
> 
> * regcache.c (legacy_write_register_gen): Don't 'optimize out'
> 	a write_register to a pseudo-reg.  Target_store_pseudo_register
> 	needs to get called, because these regs may be computed and may
> 	have side-effects.


Michael, can you expand a little?  This is legacy code, so as long as 
this change is to keep an old target working, I'm not too fussed.

However, if this is for a new target then it should really be looking at 
gdbarch_register_{read,write} and bypassing the legacy mess entirely.

	Andrew


> Index: regcache.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/regcache.c,v
> retrieving revision 1.24
> diff -c -3 -p -r1.24 regcache.c
> *** regcache.c	2001/06/15 23:50:46	1.24
> --- regcache.c	2001/08/10 21:49:23
> *************** legacy_write_register_gen (int regnum, c
> *** 334,348 ****
>   
>     size = REGISTER_RAW_SIZE (regnum);
>   
> -   /* If we have a valid copy of the register, and new value == old value,
> -      then don't bother doing the actual store. */
> - 
> -   if (register_cached (regnum)
> -       && memcmp (register_buffer (regnum), myaddr, size) == 0)
> -     return;
> - 
>     if (real_register (regnum))
> !     target_prepare_to_store ();
>   
>     memcpy (register_buffer (regnum), myaddr, size);
>   
> --- 334,349 ----
>   
>     size = REGISTER_RAW_SIZE (regnum);
>   
>     if (real_register (regnum))
> !     {
> !       /* If we have a valid copy of the register, and new value == old
> ! 	 value, then don't bother doing the actual store. */
> !       if (register_cached (regnum)
> ! 	  && memcmp (register_buffer (regnum), myaddr, size) == 0)
> ! 	return;
> !       else
> ! 	target_prepare_to_store ();
> !     }
>   
>     memcpy (register_buffer (regnum), myaddr, size);
>   
> 

Re: [PATCH] pseudo-register un-optimization

[Michael Snyder]

Andrew Cagney wrote:
> 
> >
> >
> > 2001-08-10  Michael Snyder  <msnyder@redhat.com>
> >
> > * regcache.c (legacy_write_register_gen): Don't 'optimize out'
> >       a write_register to a pseudo-reg.  Target_store_pseudo_register
> >       needs to get called, because these regs may be computed and may
> >       have side-effects.
> 
> Michael, can you expand a little?  This is legacy code, so as long as
> this change is to keep an old target working, I'm not too fussed.
> 
> However, if this is for a new target then it should really be looking at
> gdbarch_register_{read,write} and bypassing the legacy mess entirely.

This is fixing an earlier change that broke part of the intended
functionality of pseudo-registers.  The pseudo-register store method
should be called any time that the pseudo-register is modified, even
if the pseudo-register is an alias for a real register.  This is so
that modifying a pseudo-register can have enforced side-effects such
as re-computing other pseudo-registers.


> 
>         Andrew
> 
> > Index: regcache.c
> > ===================================================================
> > RCS file: /cvs/src/src/gdb/regcache.c,v
> > retrieving revision 1.24
> > diff -c -3 -p -r1.24 regcache.c
> > *** regcache.c        2001/06/15 23:50:46     1.24
> > --- regcache.c        2001/08/10 21:49:23
> > *************** legacy_write_register_gen (int regnum, c
> > *** 334,348 ****
> >
> >     size = REGISTER_RAW_SIZE (regnum);
> >
> > -   /* If we have a valid copy of the register, and new value == old value,
> > -      then don't bother doing the actual store. */
> > -
> > -   if (register_cached (regnum)
> > -       && memcmp (register_buffer (regnum), myaddr, size) == 0)
> > -     return;
> > -
> >     if (real_register (regnum))
> > !     target_prepare_to_store ();
> >
> >     memcpy (register_buffer (regnum), myaddr, size);
> >
> > --- 334,349 ----
> >
> >     size = REGISTER_RAW_SIZE (regnum);
> >
> >     if (real_register (regnum))
> > !     {
> > !       /* If we have a valid copy of the register, and new value == old
> > !      value, then don't bother doing the actual store. */
> > !       if (register_cached (regnum)
> > !       && memcmp (register_buffer (regnum), myaddr, size) == 0)
> > !     return;
> > !       else
> > !     target_prepare_to_store ();
> > !     }
> >
> >     memcpy (register_buffer (regnum), myaddr, size);
> >
> >