Re: [PATCH 0/5] cp-namespace.c cleanup pass

[Doug Evans <xdje42@gmail.com>]

Doug Evans <xdje42@gmail.com> writes:
> Hi.
>
> This patch set is a cleanup pass over cp-namespace.c.
>
> There are two things I wish to achieve here:
>
> 1a) Remove redundancy to make the code more readable.
>     There are several redundant lookups here, and it's hard to reason
>     about the code because one has to ask if there's something one is
>     missing or whether the lookup really is redundant.  Plus it's more
>     code to have to follow while studying the flow of any particular
>     function.
>
> 1b) Performance.
>     While redundant lookups don't always hurt performance if a symbol is
>     found, efficient handling of the null case (symbol not found) is at
>     least as important.
>
> 2)  Lay the groundwork so that I can finish this patch, that adds support
>     for looking up primitive types as symbols:
>     https://sourceware.org/ml/gdb-patches/2014-12/msg00169.html
>
> 1/5: whitespace
> 2/5: simplify cp_lookup_symbol_in_namespace
> 3/5: introduce cp_lookup_nested_symbol_1
> 4/5: remove redundant calls to cp_lookup_symbol_in_namespace
> 5/5: remove redundancies in cp_lookup_symbol_nonlocal
>
> Appended is a patch I wrote to log symbol lookup calls while
> running the testsuite, and here are the before/after numbers:
>
> [dje@seba gdb]$ sed -e "s/ *(.*$//" </tmp/gdb-call.log >before.tmp
> [dje@seba gdb]$ sort before.tmp | uniq -c
>   40230 basic_lookup_symbol_nonlocal
>   74647 lookup_global_symbol
>   18834 lookup_language_this
>   73063 lookup_local_symbol
>   30849 lookup_static_symbol
>   73063 lookup_symbol_aux
>   59411 lookup_symbol_in_block
>  656240 lookup_symbol_in_objfile
>      23 lookup_symbol_in_objfile_from_linkage_name
>  656298 lookup_symbol_in_objfile_symtabs
>   74075 lookup_symbol_in_static_block
>  614899 lookup_symbol_via_quick_fns
>
> [dje@seba gdb]$ sed -e "s/ *(.*$//" </tmp/gdb-call.log >after.tmp
> [dje@seba gdb]$ sort after.tmp | uniq -c
>   39019 basic_lookup_symbol_nonlocal
>   61959 lookup_global_symbol
>    9614 lookup_language_this
>   71826 lookup_local_symbol
>   29565 lookup_static_symbol
>   71826 lookup_symbol_aux
>   55214 lookup_symbol_in_block
>  504688 lookup_symbol_in_objfile
>      23 lookup_symbol_in_objfile_from_linkage_name
>  504746 lookup_symbol_in_objfile_symtabs
>   63217 lookup_symbol_in_static_block
>  463884 lookup_symbol_via_quick_fns
>
> There's a clear reduction in the number of symbol looks being done here.
> A later patch will augment our performance testsuite, but my main focus
> at the moment is getting to the "use the index better" speedup patch.
> [And along the way cleaning things up so that I understand the code
> better, and *hopefully* making it so that others will too.]

Hi.  fyi,
I committed this series.