infcmd.c: Output user registers correctly

["Maciej W. Rozycki" <macro@mips.com>]

Hello,

 We have a problem, seen at least for the MIPS target, with user 
registers.  If one is requested with "info registers", an assertion 
failure happens.  For example (with GNU sim):

(gdb) info registers
          zero       at       v0       v1       a0       a1       a2       a3
 R0   00000000 00000000 ffffffff ffffffff 00000000 807fffe0 807fffe8 00000000
            t0       t1       t2       t3       t4       t5       t6       t7
 R8   800287a4 80000000 aaaa5555 00000000 ff0055aa 00000000 00000000 00000000
            s0       s1       s2       s3       s4       s5       s6       s7
 R16  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
            t8       t9       k0       k1       gp       sp       s8       ra
 R24  00000000 00000000 00000000 00000000 80030e80 807fffa0 807fffa0 80020164
            sr       lo       hi      bad    cause       pc
      20000000 00000000 00000000 00000000 00000000 80020284
           fsr      fir
      00000000 00000000
(gdb) info registers $ta0
/n/bank/raid/macro/src7-mdi/combined/gdb/regcache.c:164: internal-error: register_type: Assertion `regnum >= 0 && regnum < descr->nr_cooked_registers' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) n

/n/bank/raid/macro/src7-mdi/combined/gdb/regcache.c:164: internal-error: register_type: Assertion `regnum >= 0 && regnum < descr->nr_cooked_registers' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Create a core file of GDB? (y or n) n
(gdb)

The "ta0" register is an alias for the "t4" register.  With the fix below 
I get:

(gdb) info registers $ta0
ta0: 0xff0055aa
(gdb)

 Tested using the mipsisa32-sde-elf target, with the mips-sim-sde32/-EB
and mips-sim-sde32/-EL boards with no regressions.

2007-10-24  David Ung  <davidu@mips.com>
            Maciej W. Rozycki  <macro@mips.com>

	* infcmd.c (registers_info): Check for a user register before
	calling target's gdbarch_print_registers_info().  If found to be
	so, extract the implicit value of user register and call
	print_scalar_formatted().
	* value.h (value_of_user_reg): Add prototype.

 OK to apply?

  Maciej

12659.diff
Index: binutils-quilt/src/gdb/infcmd.c
===================================================================
--- binutils-quilt.orig/src/gdb/infcmd.c	2007-10-24 14:20:01.000000000 +0100
+++ binutils-quilt/src/gdb/infcmd.c	2007-10-24 16:16:09.000000000 +0100
@@ -1705,21 +1705,35 @@
       while ((*addr_exp) != '\0' && !isspace ((*addr_exp)))
 	addr_exp++;
       end = addr_exp;
-      
+
       /* Figure out what we've found and display it.  */
 
       /* A register name?  */
       {
-	int regnum = frame_map_name_to_regnum (frame,
-					       start, end - start);
+	int regnum = frame_map_name_to_regnum (frame, start, end - start);
 	if (regnum >= 0)
 	  {
-	    gdbarch_print_registers_info (gdbarch, gdb_stdout,
-					  frame, regnum, fpregs);
+	    /* User registers lie completely outside of the range of
+	       normal registers.  Catch them early so that the target
+	       never sees them.  */
+	    if (regnum >= gdbarch_num_regs (gdbarch)
+			  + gdbarch_num_pseudo_regs (gdbarch))
+	      {
+		struct value *val = value_of_user_reg (regnum, frame);
+
+		printf_filtered ("%s: ", start);
+		print_scalar_formatted (value_contents (val),
+					check_typedef (value_type (val)),
+					'x', 0, gdb_stdout);
+		printf_filtered ("\n");
+	      }
+	    else
+	      gdbarch_print_registers_info (gdbarch, gdb_stdout,
+					    frame, regnum, fpregs);
 	    continue;
 	  }
       }
-	
+
       /* A register number?  (how portable is this one?).  */
       {
 	char *endptr;
Index: binutils-quilt/src/gdb/value.h
===================================================================
--- binutils-quilt.orig/src/gdb/value.h	2007-10-24 14:20:01.000000000 +0100
+++ binutils-quilt/src/gdb/value.h	2007-10-24 16:16:54.000000000 +0100
@@ -299,6 +299,8 @@
 
 extern struct value *value_of_register (int regnum, struct frame_info *frame);
 
+extern struct value *value_of_user_reg (int regnum, struct frame_info *frame);
+
 extern int symbol_read_needs_frame (struct symbol *);
 
 extern struct value *read_var_value (struct symbol *var,