Re: gdb patch for 64-bit enum values on 64-bit hosts (ia64-linux)

[Michael Snyder <msnyder at cygnus dot com>]

Hi Jim, 

Jim Blandy, our Dwarf maintainer, is occupied right now.
I think your change looks good -- I only worry that we have
no guarantee that even a long will be 64-bits.  I suppose a
long is more likely to be correct than an int...

Elena, this is your call.

				Michael

Jim Wilson wrote:
> 
> This fixes two bugs in the handling of 64-bit values on 64-bit LP64 hosts.
> We need to use long instead of int in several places, so that we don't
> accidentally truncate values to 32-bits when longs are 64-bits.
> 
> The specific problems fixed are unsigned 64-bit enum values, and signed 64-bit
> enum values.
> 
> This testcase is extracted from emacs.
> 
> enum gdb_lisp_params
> {
>   gdb_data_seg_bits = 0x8000000000000000UL,
> };
> 
> main()
> {
>   printf ("0x%lx\n", gdb_data_seg_bits);
> }
> 
> Without this patch, "print (long) gdb_data_seg_bits" gives 0.
> 
> #include <limits.h>
> 
> enum foo
> {
>   bar = LONG_MIN
> };
> 
> main()
> {
>   printf ("0x%lx\n", bar);
> }
> 
> Without this patch, "print (long) bar" gives 0.
> 
> In order for these testcases to work, you also need the gcc patches I checked
> in today, as gcc also got it wrong until today.
> 
> This was tested on ia64-linux with make check in the gdb directory.
> 
> 2000-06-08  James E. Wilson  <wilson@bletchleypark.cygnus.com>
> 
>         * dwarf2read.c (struct attribute): Change unsnd and snd field types
>         to long.
>         (read_8_bytes): Change return type to long.
>         (read_unsigned_leb128): Change return type to long.  Change type of
>         local result to long.  Cast argument of left shift to long.
>         (read_signed_leb128): Likewise.
> 
> *** orig-devo/gdb/dwarf2read.c  Fri Jun  2 14:22:37 2000
> --- devo/gdb/dwarf2read.c       Thu Jun  8 15:37:41 2000
> *************** struct attribute
> *** 227,234 ****
>         {
>         char *str;
>         struct dwarf_block *blk;
> !       unsigned int unsnd;
> !       int snd;
>         CORE_ADDR addr;
>         }
>       u;
> --- 227,234 ----
>         {
>         char *str;
>         struct dwarf_block *blk;
> !       unsigned long unsnd;
> !       long int snd;
>         CORE_ADDR addr;
>         }
>       u;
> *************** static unsigned int read_2_bytes (bfd *,
> *** 591,597 ****
> 
>   static unsigned int read_4_bytes (bfd *, char *);
> 
> ! static unsigned int read_8_bytes (bfd *, char *);
> 
>   static CORE_ADDR read_address (bfd *, char *);
> 
> --- 591,597 ----
> 
>   static unsigned int read_4_bytes (bfd *, char *);
> 
> ! static unsigned long read_8_bytes (bfd *, char *);
> 
>   static CORE_ADDR read_address (bfd *, char *);
> 
> *************** static char *read_n_bytes (bfd *, char *
> *** 599,607 ****
> 
>   static char *read_string (bfd *, char *, unsigned int *);
> 
> ! static unsigned int read_unsigned_leb128 (bfd *, char *, unsigned int *);
> 
> ! static int read_signed_leb128 (bfd *, char *, unsigned int *);
> 
>   static void set_cu_language (unsigned int);
> 
> --- 599,607 ----
> 
>   static char *read_string (bfd *, char *, unsigned int *);
> 
> ! static unsigned long read_unsigned_leb128 (bfd *, char *, unsigned int *);
> 
> ! static long read_signed_leb128 (bfd *, char *, unsigned int *);
> 
>   static void set_cu_language (unsigned int);
> 
> *************** read_4_signed_bytes (abfd, buf)
> *** 3446,3452 ****
>     return bfd_get_signed_32 (abfd, (bfd_byte *) buf);
>   }
> 
> ! static unsigned int
>   read_8_bytes (abfd, buf)
>        bfd *abfd;
>        char *buf;
> --- 3446,3452 ----
>     return bfd_get_signed_32 (abfd, (bfd_byte *) buf);
>   }
> 
> ! static unsigned long
>   read_8_bytes (abfd, buf)
>        bfd *abfd;
>        char *buf;
> *************** read_string (abfd, buf, bytes_read_ptr)
> *** 3543,3555 ****
>   #endif
>   }
> 
> ! static unsigned int
>   read_unsigned_leb128 (abfd, buf, bytes_read_ptr)
>        bfd *abfd;
>        char *buf;
>        unsigned int *bytes_read_ptr;
>   {
> !   unsigned int result, num_read;
>     int i, shift;
>     unsigned char byte;
> 
> --- 3543,3556 ----
>   #endif
>   }
> 
> ! static unsigned long
>   read_unsigned_leb128 (abfd, buf, bytes_read_ptr)
>        bfd *abfd;
>        char *buf;
>        unsigned int *bytes_read_ptr;
>   {
> !   unsigned long result;
> !   unsigned int num_read;
>     int i, shift;
>     unsigned char byte;
> 
> *************** read_unsigned_leb128 (abfd, buf, bytes_r
> *** 3562,3568 ****
>         byte = bfd_get_8 (abfd, (bfd_byte *) buf);
>         buf++;
>         num_read++;
> !       result |= ((byte & 127) << shift);
>         if ((byte & 128) == 0)
>         {
>           break;
> --- 3563,3569 ----
>         byte = bfd_get_8 (abfd, (bfd_byte *) buf);
>         buf++;
>         num_read++;
> !       result |= ((unsigned long)(byte & 127) << shift);
>         if ((byte & 128) == 0)
>         {
>           break;
> *************** read_unsigned_leb128 (abfd, buf, bytes_r
> *** 3573,3585 ****
>     return result;
>   }
> 
> ! static int
>   read_signed_leb128 (abfd, buf, bytes_read_ptr)
>        bfd *abfd;
>        char *buf;
>        unsigned int *bytes_read_ptr;
>   {
> !   int result;
>     int i, shift, size, num_read;
>     unsigned char byte;
> 
> --- 3574,3586 ----
>     return result;
>   }
> 
> ! static long
>   read_signed_leb128 (abfd, buf, bytes_read_ptr)
>        bfd *abfd;
>        char *buf;
>        unsigned int *bytes_read_ptr;
>   {
> !   long result;
>     int i, shift, size, num_read;
>     unsigned char byte;
> 
> *************** read_signed_leb128 (abfd, buf, bytes_rea
> *** 3593,3599 ****
>         byte = bfd_get_8 (abfd, (bfd_byte *) buf);
>         buf++;
>         num_read++;
> !       result |= ((byte & 127) << shift);
>         shift += 7;
>         if ((byte & 128) == 0)
>         {
> --- 3594,3600 ----
>         byte = bfd_get_8 (abfd, (bfd_byte *) buf);
>         buf++;
>         num_read++;
> !       result |= ((long)(byte & 127) << shift);
>         shift += 7;
>         if ((byte & 128) == 0)
>         {