Given the following code from gdb's funcargs test:
typedef struct s
{
short s;
int i;
long l;
} SVAL;
void recurse (SVAL a, int depth)
{
a.s = a.i = a.l = --depth;
if (depth == 0)
hitbottom ();
else
recurse (a, depth);
}
compiled with -g
gcc-4.0 does not emit a dwarf location for the 'a' argument:
$ readelf -wi funcargs
[....]
<2><1921>: Abbrev Number: 11 (DW_TAG_formal_parameter)
DW_AT_name : a
DW_AT_decl_file : 1
DW_AT_decl_line : 612
DW_AT_type : <18e0>
in gcc-3.x, you will get one more dwarf attribute:
DW_AT_location : 3 byte block: 91 18 6 (DW_OP_fbreg: 24; DW_OP_deref)
The difference is that in gcc 3.x, the first argument is first copied from the
incoming argument register to the stack. In gcc-4.x the generated code does not
do this stack save and uses the incoming register directly (actually it first
copies it to a scratch register).
--
Summary: gcc generates code that does not allow retrieval of
struct arguments with debugger
Product: gcc
Version: 4.0.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tausq at debian dot org
GCC build triplet: hppa-unknown-linux
GCC host triplet: hppa-unknown-linux
GCC target triplet: hppa-unknown-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26330
