Re: dwarf name canonicalization

[Keith Seitz <keiths at redhat dot com>]

On 02/23/2010 12:52 PM, Tom Tromey wrote:
> Keith, do you happen to know offhand what things in gdb rely on
> canonicalizing C++ names in the dwarf reader?

I have a pretty good idea. :-)

> I was discussing this canonicalization with a user who prefers to remain
> anonymous.  His experience is that this canonicalization greatly slows
> down gdb startup (he said 15%), and in his experience isn't needed for
> his use case, which is running gdb as part of an IDE.

[OT: I would love a test case. I *pleaded* for specific test cases.]

Anonymous obviously has evidence that his IDE can work around the 
problems of generic input which we must deal with in the console. I see 
no reason why anonymous shouldn't submit a patch to disable 
canonicalization (and related). He'll probably want to also disable 
dwarf2_physname and bring back DW_AT_MIPS_linkage_name (assuming that 
doesn't disappear altogether).

> I'm wondering whether it would make sense to somehow disable this, maybe
> via some special mode for IDEs to use.  I thought maybe you'd know what
> would break...

Unless the IDE provided a console that accepted generic input (like 
"normal" gdb), I don't think that much would break, if anything. IDEs 
really rather rely on linespecs for the most part, no? As long as you're 
not sending input to gdb that looks like a function name, you should be 
safe. But I cannot guarantee. I have no first-hand experience with IDEs 
(in many years).

I would much rather address (fix?) the speed problem first. The idea of 
multiple paths through the code for the "same" task would seem a high 
bit rot risk.

Keith