Re: RFA: dwarf2read.c patch

[Jim Blandy <jimb at redhat dot com>]

Looks good to me --- please commit this.

"J. Johnston" <jjohnstn@redhat.com> writes:

> The following patch fixes a problem on ia64.  In dwarf2read.c,
> dwarf_decode_lines(), the function check_cu_functions() is called
> to check for a specific scenario caused by gcc.
> 
> The function takes an address and returns an address.  In some
> cases, it will return the lowpc value of the function rather than
> the address that was input.
> 
> On the ia64, this causes problems because the line table info spit
> out by the compiler is often specified with relative addresses.
> As well, ia64 addresses are special as they encode a slot number which goes
> 0, 1, 2, then skips to the next quadword boundary.  For example,
> 
> 0x00, 0x01, 0x02, 0x10, 0x11, 0x12, 0x20, 0x21, 0x22, ...
> 
> Addresses such as 0x0e or 0x0f are invalid and cause an error to
> occur if, say, a breakpoint was attempted to be inserted there.
> 
> Now, in dwarf_decode_lines(), if we update the address counter when we call
> check_cu_functions(), adding relative offsets in subsequent entries often results in
> invalid addresses.
> 
> This patch makes it so the check_cu_functions() call is only used to
> alter the address passed to record_line(); the calculated address is left untouched
> so subsequent relative operations result in valid results.
> 
> Tested on ia64 and x86.
> 
> Ok to commit?
> 
> -- Jeff J.
> 
> 2003-05-05  Jeff Johnston  <jjohnstn@redhat.com>
> 
> 	* dwarf2read.c (dwarf_decode_lines): Only use output of check_cu_functions()
> 	when calling record_line().  Do not update the current address.
> Index: dwarf2read.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/dwarf2read.c,v
> retrieving revision 1.90
> diff -u -p -r1.90 dwarf2read.c
> --- dwarf2read.c	15 Apr 2003 23:07:11 -0000	1.90
> +++ dwarf2read.c	5 May 2003 21:55:26 -0000
> @@ -4878,8 +4878,8 @@ dwarf_decode_lines (struct line_header *
>  		* lh->minimum_instruction_length;
>  	      line += lh->line_base + (adj_opcode % lh->line_range);
>  	      /* append row to matrix using current values */
> -	      address = check_cu_functions (address);
> -	      record_line (current_subfile, line, address);
> +	      record_line (current_subfile, line, 
> +	                   check_cu_functions (address));
>  	      basic_block = 1;
>  	    }
>  	  else switch (op_code)
> @@ -4925,8 +4925,8 @@ dwarf_decode_lines (struct line_header *
>  		}
>  	      break;
>  	    case DW_LNS_copy:
> -	      address = check_cu_functions (address);
> -	      record_line (current_subfile, line, address);
> +	      record_line (current_subfile, line, 
> +	                   check_cu_functions (address));
>  	      basic_block = 0;
>  	      break;
>  	    case DW_LNS_advance_pc: