Re: [rtlopt] "variable tracking" pass

[Daniel Berlin <dberlin at dberlin dot org>]

On Tuesday, January 14, 2003, at 04:59  PM, Josef Zlomek wrote:

> > > The file which fails is from libstdc++-v3/libsupc++/
> > > (it is being compiled after the final compiler is built).
> > > I think it is eh_globals.cc but I'm not sure.
> > Yeah, i reproduced it.
> > Thanks.
> > It's a fun bug exposed by the interaction of -ffunction-sections and
> > global variables.
> >
> > Simple fix, however:
> > change
> >
> > +         if (separate_line_info_table_in_use == 0)
> > +           endname = text_end_label;
> > +         else
> > to
> >
> > +         if (separate_line_info_table_in_use == 0 ||
> > !current_function_decl)
> > +           endname = text_end_label;
> > +         else
> >
> > in the patch.
> >
> > I'm bootstrapping now to see if there are any further problems.
> It should at least avoid the segfault :-)
> I was not sure what does the code mean so I did not want to write such
> a fix myself.
It's actually buggy, but the goal is was to determine the label for the 
end of the code for this function (so we can say where the last part of 
the range is valid to).

I actually meant to write something like

if (!current_function_decl)
	endname = text_end_label;
else
	...

That way, we say ranges for globals are valid during all code, and 
otherwise, it's valid to the end of the function (which is what the 
other arm of the if is doing).

There's also a reversed strcmp test i swear i fixed:
if (strcmp (curr->section, ".text") == 0)
    {
      /* dw2_asm_output_data will mask off any extra bits in the ~0.  */
      dw2_asm_output_data (DWARF2_ADDR_SIZE, ~(unsigned HOST_WIDE_INT) 
0,
                           "Location list base address specifier fake 
entry");
      dw2_asm_output_offset (DWARF2_ADDR_SIZE, curr->section,
                             "Location list base address specifier 
base");
    }
should be
if (strcmp (curr->section, ".text") != 0)
    {
      /* dw2_asm_output_data will mask off any extra bits in the ~0.  */
      dw2_asm_output_data (DWARF2_ADDR_SIZE, ~(unsigned HOST_WIDE_INT) 
0,
                           "Location list base address specifier fake 
entry");
      dw2_asm_output_offset (DWARF2_ADDR_SIZE, curr->section,
                             "Location list base address specifier 
base");
    }


I wrote the debug output code over the course of about 30 minutes 
(seriously, i didn't spend more than 30 minutes writing it originally) 
while half paying attention to a CS class, so it's not very cleanly 
written.

I'll rewrite it so it's understandable, and not so ugly.


> Thank you!
>
> Josef