Re: RFA: dwarf2read.c patch

["J. Johnston" <jjohnstn@redhat.com>]

Patch checked in.  Thanks.

-- Jeff J.

Jim Blandy wrote:
> 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:
>