GCC 4.1.0 doesn't generate DWARF 2 output for function arguments?

[Nick Roberts]

I've just upgraded to Fedora Core 5 (kernel 2.6.15-1.2054_FC5) and with the
program below I get results which didn't occur before (Fedora Core 3).  I
posted them to gdb@sources.redhat.com but I think something is up with GCC
4.1.0.  I no longer have Core 3 so I've compared output with Mandrake.  These
results are with DWARF 2.  GCC 4.1.0 with stabs worked as expected


Nick                                           http://www.inet.net.nz/~nickrob


/* -*- compile-command: "cc -g -o simple simple.c"; -*- */

main(int argc, char **argv) {
  int i;
  i = 1;
}

After starting execution and breaking at main:

With gcc --version
gcc (GCC) 3.2 (Mandrake Linux 9.0 3.2-1mdk)

  (gdb) info args
  argc = 1
  argv = (char **) 0xbffff7a4

With gcc --version
gcc (GCC) 4.1.0 20060304 (Red Hat 4.1.0-3)

  (gdb) info args
  No arguments.


readelf -wi simple (for GCC 3.2) gives (about 1200 lines of output):

 ...
 <2><c6d>: Abbrev Number: 3 (DW_TAG_formal_parameter)
   DW_AT_name        : (indirect string, offset: 0x98e): argc 
     DW_AT_decl_file   : 1      
     DW_AT_decl_line   : 3      
     DW_AT_type        : <c96>  
     DW_AT_location    : 2 byte block: 91 8     (DW_OP_fbreg: 8; )
 <2><c7b>: Abbrev Number: 3 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0x993): argv 
     DW_AT_decl_file   : 1      
     DW_AT_decl_line   : 3      
     DW_AT_type        : <c9d>  
     DW_AT_location    : 2 byte block: 91 c     (DW_OP_fbreg: 12; )
 <2><c89>: Abbrev Number: 4 (DW_TAG_variable)
     DW_AT_name        : i      
     DW_AT_decl_file   : 1      
     DW_AT_decl_line   : 4      
     DW_AT_type        : <c96>  
     DW_AT_location    : 2 byte block: 91 7c    (DW_OP_fbreg: -4; )
     ...

readelf -wi simple (for GCC 4.1.0) gives (about 60 lines of output):

 ...
 <2><75>: Abbrev Number: 3 (DW_TAG_formal_parameter)
     DW_AT_name        : argc	
     DW_AT_decl_file   : 1	
     DW_AT_decl_line   : 3	
     DW_AT_type        : <9a>	
 <2><81>: Abbrev Number: 3 (DW_TAG_formal_parameter)
     DW_AT_name        : argv	
     DW_AT_decl_file   : 1	
     DW_AT_decl_line   : 3	
     DW_AT_type        : <a1>	
 <2><8d>: Abbrev Number: 4 (DW_TAG_variable)
     DW_AT_name        : i	
     DW_AT_decl_file   : 1	
     DW_AT_decl_line   : 4	
     DW_AT_type        : <9a>	
     DW_AT_location    : 2 byte block: 91 70 	(DW_OP_fbreg: -16)
     ...