Re: print/a ... (again!)

[Andrew Cagney <ac131313 at cygnus dot com>]

Andrew Cagney wrote:
> 
> Hello,
> 
> I'm looking at a 64 bit MIPS debugging a 32 bit ISA (-mips2 -EB) and am
> seeing:
> 
>   (gdb) p/a main+4
>   $1 = 0xa0020290
>   (gdb) print main + 4
>   $5 = (int (*)()) 0xffffffffa0020290 <main+4>
> 
> notice how ``print/a'' doesn't know where main is.  Grubbing around in
> printcmd.c I find:
> 
>     case 'a':
>       {
>         /* Truncate address to the size of a target pointer, avoiding
>            shifts larger or equal than the width of a CORE_ADDR.  The
>            local variable PTR_BIT stops the compiler reporting a shift
>            overflow when it won't occure. */
>         CORE_ADDR addr = unpack_pointer (type, valaddr);
>         int ptr_bit = TARGET_PTR_BIT;
>         if (ptr_bit < (sizeof (CORE_ADDR) * HOST_CHAR_BIT))
>           addr &= ((CORE_ADDR) 1 << ptr_bit) - 1;
>         print_address (addr, stream);
>       }
>       break;
> 
> the problem is that the mask strips off a significant part of the
> address.  Commenting out that mask I get the behavour:
> 
>   (gdb) print main+4
>   $2 = (int (*)()) 0xffffffffa0020290 <main+4>
>   (gdb) print/a main+4
>   $3 = 0xffffffffa0020290 <main+4>
> 
> which is definitly an improvement.  I'm going to have to go diging
> around in the e-mail archives.  Anyone care to try to summarize the
> rationale behind the mask?

FYI,

I'm committing the attatched patch.  This is definitly more correct then
the old code while retaining the old behavour.

	enjoy,
		Andrew
Tue Jul 11 18:32:40 2000  Andrew Cagney  <cagney@b1.cygnus.com>

	* printcmd.c (print_scalar_formatted): Move masking of 'a' address
 	from here.
	(print_address_numeric): To here.
	* TODO: Update.

Index: TODO
===================================================================
RCS file: /cvs/src/src/gdb/TODO,v
retrieving revision 1.40
diff -p -r1.40 TODO
*** TODO	2000/07/09 19:11:44	1.40
--- TODO	2000/07/11 08:45:19
*************** BIG_ENDIAN and LITTLE_ENDIAN.
*** 117,122 ****
--- 117,131 ----
  
  --
  
+ printcmd.c (print_address_numeric):
+ 
+ NOTE: This assumes that the significant address information is kept in
+ the least significant bits of ADDR - the upper bits were either zero
+ or sign extended.  Should ADDRESS_TO_POINTER() or some
+ ADDRESS_TO_PRINTABLE() be used to do the conversion?
+ 
+ --
+ 
  		Code Cleanups: General
  		======================
  
Index: printcmd.c
===================================================================
RCS file: /cvs/src/src/gdb/printcmd.c,v
retrieving revision 1.9
diff -p -r1.9 printcmd.c
*** printcmd.c	2000/05/28 01:12:29	1.9
--- printcmd.c	2000/07/11 08:45:24
***************
*** 1,6 ****
  /* Print values for GNU debugger GDB.
-    Copyright 1986-1991, 1993-1995, 1998, 2000 Free Software Foundation, Inc.
  
     This file is part of GDB.
  
     This program is free software; you can redistribute it and/or modify
--- 1,8 ----
  /* Print values for GNU debugger GDB.
  
+    Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1993, 1994, 1995,
+    1998, 2000 Free Software Foundation, Inc.
+ 
     This file is part of GDB.
  
     This program is free software; you can redistribute it and/or modify
*************** print_scalar_formatted (valaddr, type, f
*** 445,458 ****
  
      case 'a':
        {
- 	/* Truncate address to the size of a target pointer, avoiding
- 	   shifts larger or equal than the width of a CORE_ADDR.  The
- 	   local variable PTR_BIT stops the compiler reporting a shift
- 	   overflow when it won't occure. */
  	CORE_ADDR addr = unpack_pointer (type, valaddr);
- 	int ptr_bit = TARGET_PTR_BIT;
- 	if (ptr_bit < (sizeof (CORE_ADDR) * HOST_CHAR_BIT))
- 	  addr &= ((CORE_ADDR) 1 << ptr_bit) - 1;
  	print_address (addr, stream);
        }
        break;
--- 447,453 ----
*************** print_address_numeric (addr, use_local, 
*** 740,747 ****
       int use_local;
       struct ui_file *stream;
  {
!   /* This assumes a CORE_ADDR can fit in a LONGEST.  Probably a safe
!      assumption.  */
    print_longest (stream, 'x', use_local, (ULONGEST) addr);
  }
  
--- 735,751 ----
       int use_local;
       struct ui_file *stream;
  {
!   /* Truncate address to the size of a target pointer, avoiding shifts
!      larger or equal than the width of a CORE_ADDR.  The local
!      variable PTR_BIT stops the compiler reporting a shift overflow
!      when it won't occure. */
!   /* NOTE: This assumes that the significant address information is
!      kept in the least significant bits of ADDR - the upper bits were
!      either zero or sign extended.  Should ADDRESS_TO_POINTER() or
!      some ADDRESS_TO_PRINTABLE() be used to do the conversion?  */
!   int ptr_bit = TARGET_PTR_BIT;
!   if (ptr_bit < (sizeof (CORE_ADDR) * HOST_CHAR_BIT))
!     addr &= ((CORE_ADDR) 1 << ptr_bit) - 1;
    print_longest (stream, 'x', use_local, (ULONGEST) addr);
  }