http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48220
--- Comment #4 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-03-23 17:33:54 UTC --- > The aim of the extension is to allow correct debug info, not almost correct, > so I think defining "upon entering of the current subprogram" as anything but > before the first insn in it is wrong and would make it not possible to use > DW_OP_GNU_entry_value before the point (end of prologue or what?). 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. > As for teaching var-tracking about save/restore on SPARC, it would be a matter > of adding probably two target hooks, one that would be run e.g. at the end of > adjust_insn and would be supposed to change it using validate_change (..., > true); in whatever way var-tracking should understand the insn. > So e.g. for save you'd add into the parallel things like: > (set (reg:P 24) (reg:P 8)) > (clobber (reg:P 8)) > and similarly for all the other param regs. Perhaps even make it explicit > what exactly is subtracted from %sp. > And the second target hook would return a different rtx for DECL_INCOMING_RTL, > with registers adjusted back. Because for -O0 if we don't do var-tracking we > probably want DECL_INCOMING_RTL to still refer to %i0 etc., even when it is > not correct before the save. I see, thanks for the explanation.
