Re: [RFA 2/4] dwarf2_physname

André Pönitz
2009-11-23T07:31:20Z

On Friday 20 November 2009 22:19:35 Keith Seitz wrote:
> [...] Some warnings are in order. First, this is probably going to really slow
> down large C++ applications, because we no longer use
> DW_AT_MIPS_linkage_name as generated from the compiler. We essentially
> build this name during DIE reading. [...]
> With those caveats out of the way, I will say that I understand there
> are some controversial changes in here: it is a pretty big paradigm
> shift for the dwarf reader. Nonetheless, the benefits outweigh the
> performance degradation (for C++ ONLY) and the minor java regression.
> IMO, the elimination of single-quoting for C++ expressions alone is
> worth it.
>
> Questions/comments/concerns?

I am really worried about the performance degradation you expect.

How bad will that be?

Medium to large sized C++ applications is basically "all I have", and speed
is already by now the biggest issue I have with gdb. [1]

If the deal is "correct but slow" vs "flaky but faster" I surely prefer the
"flaky but fast" side. I have encountered quite a few issues with C++ in
gdb, so yes, that's not nice. But usually one can work around somehow on
the user side. Raw speed on the other hand is nothing the user can improve.

Andre'

[1] Actually "the biggest issue that is left": Python scripting turned out
to be a panacea for basically everything else. Thanks to everybody involved.