On Fri, Dec 07, 2012 at 12:23:03PM +0100, Richard Biener wrote:
> > That would still mean we can fail bootstrap with -O2 -g1, if there is a
> > DEBUG_IMPLICIT_PTR created during RTL expansion to some unused var, then
> > that var's varpool node is varpool_remove_node removed and initializer
> > cleared, and dwarf2out_finish would want to make_decl_rtl_for_debug again.
>
> "fail"? Well, dwarf2out_finish definitely has to care for no initializer
> being in-place. Does it somehow record that it was present somewhen
> early and is confused later when it got dropped? If so, why not always
> decide late if there is an initializer?
How? During expansion to create DEBUG_IMPLICIT_PTR argument, we need some
RTL for the vars (and can't make it using make_decl_rtl, as that would
affect code generation). So, we use make_decl_rtl_for_debug that doesn't
remember the RTL, but still it does all the processing make_decl_rtl
normally does. bss_initializer_p is called deeply from that somewhere.
As I said in the PR/initial mail, the other option would be to come up with
some other special value for this DECL_INITIAL has been forgotten, but
it wasn't bss_initializer_p. But that seems to be lots of work for very
little gain (rarely used -g1).
Jakub
