Re: [BUG] print_address_numeric

[Andrew Cagney <ac131313 at cygnus dot com>]

David Taylor wrote:
> 
> In printcmd.c (print_address_numeric), we find the lines:
> 
>       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);

You forgot the lines:

  /* 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?  */

:-)

> This code has a bug, namely it assumes that addresses and pointers are
> the same size.
> 
> [address == gdb representation; pointer == target representation]

	CORE_ADDR - GDB's internal representation of an address
		it is large enough to fit target address information.

	pointer - targets pointer representation

	??? - minimum number of bits needed to represent an address on the
target.

When printing a symbolic address, should it be displayed using GDB's
internal format (for MIPS definitly not) or target pointer format.

> For some processors they are different.  For the d10v and at least one
> other processor, the size of a pointer is 2 bytes, but the size of an
> address is 4 bytes.
> 
> I propose the creation of a new macro TARGET_ADDR_BIT, the addition of
> the lines:
> 
>     #if !defined(TARGET_ADDR_BIT)
>     #define TARGET_ADDR_BIT     TARGET_PTR_BIT
>     #endif
> 
> to defs.h, and that the above lines of print_address_numeric be changed to:
> 
>     int addr_bit = TARGET_ADDR_BIT
>     if (addr_bit < (sizeof (CORE_ADDR) * HOST_CHAR_BIT))
>       addr & ((CORE_ADDR) 1 << ptr_bit) - 1;
>     print_longest (stream, 'x', use_local, (ULONGEST) addr);
> 
> Comments?

I think it should be a method (function) rather than a macro.  The
default function using TARGET_PTR_BIT.  It would give your target
complete freedom over how the numeric address is printed.

	Andrew