http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48220
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-03-23 20:30:53 UTC --- (In reply to comment #4) > Yes, end of the prologue. I was under the impression that, with your > alternate > scheme, the opposite situation would arise, i.e. it wouldn't be possible to > use > DW_OP_GNU_entry_value after the end of the prologue. Given how GDB works, > this > sounded far less appealing than the current scheme. Sorry if I misunderstood. If say reference to first parameter's original value is DW_OP_GNU_entry_value 1 <DW_OP_reg8> (i.e. %o0), then it will work just fine anywhere in the function. The debugger either looks up matching entry for %o0 in DW_TAG_GNU_call_site, or a debugger could put a breakpoint on the first insn in a function and remember the %o0 value there, then just use the remembered value anywhere where DW_OP_GNU_entry_value appears. And for SPARC, using %o0 is also much easier for the debugger, it doesn't have to translate anything. On IA-64 things are different because there it is mainly the call insn which moves the register window, not some insn executed somewhere in function's prologue.
