[PATCH] gdbserver: extract code out of regcache's registers_to_string

[PATCH] gdbserver: extract code out of regcache's registers_to_string

[Tankut Baris Aktemur]

Extract out code from regcache's registers_to_string to dump a single
register value to a string.  Reuse the new method in
'collect_register_as_string' so that unavailable registers are dumped
as 'xx...x' instead of arbitrary values.
---
 gdbserver/regcache.cc | 34 +++++++++++++++++++---------------
 gdbserver/regcache.h  |  5 +++++
 2 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/gdbserver/regcache.cc b/gdbserver/regcache.cc
index 0b1141662ac..82accdb89fc 100644
--- a/gdbserver/regcache.cc
+++ b/gdbserver/regcache.cc
@@ -205,29 +205,34 @@ find_register_by_number (const struct target_desc *tdesc, int n)
   return tdesc->reg_defs[n];
 }
 
+static unsigned char *register_data (const regcache *regcache, int n);
+
 #ifndef IN_PROCESS_AGENT
 
+void
+register_to_string (struct regcache *regcache, int n, char *buf)
+{
+  int reg_size = register_size (regcache->tdesc, n);
+
+  if (regcache->register_status[n] == REG_VALID)
+    bin2hex (register_data (regcache, n), buf, reg_size);
+  else
+    memset (buf, 'x', reg_size * 2);
+
+  buf += reg_size * 2;
+  *buf = '\0';
+}
+
 void
 registers_to_string (struct regcache *regcache, char *buf)
 {
-  unsigned char *registers = regcache->registers;
   const struct target_desc *tdesc = regcache->tdesc;
 
   for (int i = 0; i < tdesc->reg_defs.size (); ++i)
     {
-      if (regcache->register_status[i] == REG_VALID)
-	{
-	  bin2hex (registers, buf, register_size (tdesc, i));
-	  buf += register_size (tdesc, i) * 2;
-	}
-      else
-	{
-	  memset (buf, 'x', register_size (tdesc, i) * 2);
-	  buf += register_size (tdesc, i) * 2;
-	}
-      registers += register_size (tdesc, i);
+      register_to_string (regcache, i, buf);
+      buf += register_size (tdesc, i) * 2;
     }
-  *buf = '\0';
 }
 
 void
@@ -472,8 +477,7 @@ regcache_raw_get_unsigned_by_name (struct regcache *regcache,
 void
 collect_register_as_string (struct regcache *regcache, int n, char *buf)
 {
-  bin2hex (register_data (regcache, n), buf,
-	   register_size (regcache->tdesc, n));
+  register_to_string (regcache, n, buf);
 }
 
 void
diff --git a/gdbserver/regcache.h b/gdbserver/regcache.h
index 7248bcf5808..fba9498712a 100644
--- a/gdbserver/regcache.h
+++ b/gdbserver/regcache.h
@@ -93,6 +93,11 @@ void regcache_invalidate (void);
 
 void regcache_release (void);
 
+/* Convert the register N's value to a string in the currently
+   specified remote format.  */
+
+void register_to_string (regcache *regcache, int n, char *buf);
+
 /* Convert all registers to a string in the currently specified remote
    format.  */
 
-- 
2.25.1

Intel Deutschland GmbH
Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de>
Managing Directors: Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva  
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928

Re: [PATCH] gdbserver: extract code out of regcache's registers_to_string

[Tom Tromey]

>>>>> "Tankut" == Tankut Baris Aktemur via Gdb-patches <gdb-patches@sourceware.org> writes:

Tankut> Extract out code from regcache's registers_to_string to dump a single
Tankut> register value to a string.  Reuse the new method in
Tankut> 'collect_register_as_string' so that unavailable registers are dumped
Tankut> as 'xx...x' instead of arbitrary values.

Seems like a good idea.

Tankut>  void
Tankut>  collect_register_as_string (struct regcache *regcache, int n, char *buf)
Tankut>  {
Tankut> -  bin2hex (register_data (regcache, n), buf,
Tankut> -	   register_size (regcache->tdesc, n));
Tankut> +  register_to_string (regcache, n, buf);


This is just a wrapper now, so I wonder if it could just be removed; or
if register_to_string should be renamed to collect_register_as_string.

Tom

RE: [PATCH] gdbserver: extract code out of regcache's registers_to_string

[Aktemur, Tankut Baris]

On Tuesday, June 20, 2023 4:23 PM, Tom Tromey wrote:
> >>>>> "Tankut" == Tankut Baris Aktemur via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> Tankut> Extract out code from regcache's registers_to_string to dump a single
> Tankut> register value to a string.  Reuse the new method in
> Tankut> 'collect_register_as_string' so that unavailable registers are dumped
> Tankut> as 'xx...x' instead of arbitrary values.
> 
> Seems like a good idea.
> 
> Tankut>  void
> Tankut>  collect_register_as_string (struct regcache *regcache, int n, char *buf)
> Tankut>  {
> Tankut> -  bin2hex (register_data (regcache, n), buf,
> Tankut> -	   register_size (regcache->tdesc, n));
> Tankut> +  register_to_string (regcache, n, buf);
> 
> 
> This is just a wrapper now, so I wonder if it could just be removed; or
> if register_to_string should be renamed to collect_register_as_string.

Thanks for the comment.  I followed the latter suggestion and revised the 
patch in V2 accordingly:
https://sourceware.org/pipermail/gdb-patches/2023-June/200377.html

-Baris


Intel Deutschland GmbH
Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de>
Managing Directors: Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva  
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928