[binutils-gdb] gdb/csky: remove nullptr return from csky_pseudo_register_name

[binutils-gdb] gdb/csky: remove nullptr return from csky_pseudo_register_name

[Andrew Burgess]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7ac20d65a8d0c9cdb329d49e8d9e58e38c39fec4

commit 7ac20d65a8d0c9cdb329d49e8d9e58e38c39fec4
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Thu Sep 1 15:39:59 2022 +0100

    gdb/csky: remove nullptr return from csky_pseudo_register_name
    
    Building on the previous commits, in this commit I remove two
    instances of 'return NULL' from csky_pseudo_register_name, and replace
    them with a return of the empty string.
    
    These two are particularly interesting, and worth pulling into their
    own commit, because these returns of NULL appear to be depended on
    within other parts of the csky code.
    
    In csky-linux-tdep.c in the register collect/supply code, GDB checks
    for the register name being nullptr in order to decide if a target
    supports a particular feature or not.  I've updated the code to check
    for the empty string.
    
    I have no way of testing this change.

Diff:
---
 gdb/csky-linux-tdep.c | 14 +++++++-------
 gdb/csky-tdep.c       | 17 ++++-------------
 2 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/gdb/csky-linux-tdep.c b/gdb/csky-linux-tdep.c
index 7bcc1712180..ea306cded09 100644
--- a/gdb/csky-linux-tdep.c
+++ b/gdb/csky-linux-tdep.c
@@ -155,7 +155,7 @@ csky_supply_fregset (const struct regset *regset,
       /* Supply vr0~vr15.  */
       for (i = 0; i < 16; i ++)
 	{
-	  if (gdbarch_register_name (gdbarch, (CSKY_VR0_REGNUM + i)))
+	  if (*gdbarch_register_name (gdbarch, (CSKY_VR0_REGNUM + i)) != '\0')
 	    {
 	      offset = 16 * i;
 	      regcache->raw_supply (CSKY_VR0_REGNUM + i, fregs + offset);
@@ -164,7 +164,7 @@ csky_supply_fregset (const struct regset *regset,
       /* Supply fr0~fr15.  */
       for (i = 0; i < 16; i ++)
 	{
-	  if (gdbarch_register_name (gdbarch, (CSKY_FR0_REGNUM + i)))
+	  if (*gdbarch_register_name (gdbarch, (CSKY_FR0_REGNUM + i)) != '\0')
 	    {
 	      offset = 16 * i;
 	      regcache->raw_supply (CSKY_FR0_REGNUM + i, fregs + offset);
@@ -173,7 +173,7 @@ csky_supply_fregset (const struct regset *regset,
       /* Supply fr16~fr31.  */
       for (i = 0; i < 16; i ++)
 	{
-	  if (gdbarch_register_name (gdbarch, (CSKY_FR16_REGNUM + i)))
+	  if (*gdbarch_register_name (gdbarch, (CSKY_FR16_REGNUM + i)) != '\0')
 	    {
 	      offset = (16 * 16) + (8 * i);
 	      regcache->raw_supply (CSKY_FR16_REGNUM + i, fregs + offset);
@@ -182,7 +182,7 @@ csky_supply_fregset (const struct regset *regset,
      /* Supply fcr, fesr, fid.  */
       for (i = 0; i < 3; i ++)
 	{
-	  if (gdbarch_register_name (gdbarch, fcr_regno[i]))
+	  if (*gdbarch_register_name (gdbarch, fcr_regno[i]) != '\0')
 	    {
 	      offset = (16 * 16) + (16 * 8) + (4 * i);
 	      regcache->raw_supply (fcr_regno[i], fregs + offset);
@@ -245,7 +245,7 @@ csky_collect_fregset (const struct regset *regset,
       /* Supply vr0~vr15.  */
       for (i = 0; i < 16; i ++)
 	{
-	  if (gdbarch_register_name (gdbarch, (CSKY_VR0_REGNUM + i)))
+	  if (*gdbarch_register_name (gdbarch, (CSKY_VR0_REGNUM + i)) != '\0')
 	    {
 	      offset = 16 * i;
 	      regcache ->raw_collect (CSKY_VR0_REGNUM + i, fregs + offset);
@@ -254,7 +254,7 @@ csky_collect_fregset (const struct regset *regset,
       /* Supply fr16~fr31.  */
       for (i = 0; i < 16; i ++)
 	{
-	  if (gdbarch_register_name (gdbarch, (CSKY_FR16_REGNUM + i)))
+	  if (*gdbarch_register_name (gdbarch, (CSKY_FR16_REGNUM + i)) != '\0')
 	    {
 	      offset = (16 * 16) + (8 * i);
 	      regcache ->raw_collect (CSKY_FR16_REGNUM + i, fregs + offset);
@@ -263,7 +263,7 @@ csky_collect_fregset (const struct regset *regset,
       /* Supply fcr, fesr, fid.  */
       for (i = 0; i < 3; i ++)
 	{
-	  if (gdbarch_register_name (gdbarch, fcr_regno[i]))
+	  if (*gdbarch_register_name (gdbarch, fcr_regno[i]) != '\0')
 	    {
 	      offset = (16 * 16) + (16 * 8) + (4 * i);
 	      regcache ->raw_collect (fcr_regno[i], fregs + offset);
diff --git a/gdb/csky-tdep.c b/gdb/csky-tdep.c
index cbf12c18063..17820aab6eb 100644
--- a/gdb/csky-tdep.c
+++ b/gdb/csky-tdep.c
@@ -660,21 +660,12 @@ static const char * const csky_register_names[] =
 static const char *
 csky_register_name (struct gdbarch *gdbarch, int reg_nr)
 {
-  int num_regs = gdbarch_num_regs (gdbarch);
-  int num_pseudo_regs =  gdbarch_num_pseudo_regs (gdbarch);
-
-  if ((reg_nr >= num_regs) && (reg_nr < (num_regs + num_pseudo_regs)))
+  if (reg_nr >= gdbarch_num_regs (gdbarch))
     return csky_pseudo_register_name (gdbarch, reg_nr);
 
   if (tdesc_has_registers (gdbarch_target_desc (gdbarch)))
     return tdesc_register_name (gdbarch, reg_nr);
 
-  if (reg_nr < 0)
-    return NULL;
-
-  if (reg_nr >= gdbarch_num_regs (gdbarch))
-    return NULL;
-
   return csky_register_names[reg_nr];
 }
 
@@ -2543,15 +2534,15 @@ csky_pseudo_register_name (struct gdbarch *gdbarch, int regno)
       if (regno < tdep->fv_pseudo_registers_count)
         {
           if ((regno < 64) && ((regno % 4) >= 2) && !tdep->has_vr0)
-            return NULL;
+            return "";
           else if ((regno >= 64) && ((regno % 4) >= 2))
-            return NULL;
+            return "";
           else
             return fv_pseudo_names[regno];
         }
     }
 
-  return NULL;
+  return "";
 }
 
 /* Read for csky pseudo regs.  */