Re: [ANNOUNCE] pahole and other DWARF2 utilities

On Mon, Oct 30, 2006 at 08:33:34PM -0800, Andrew Morton wrote:
On Mon, 30 Oct 2006 18:33:19 -0300
Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxx> wrote:

I've been working on some DWARF2 utilities and thought that it
is about time I announce it to the community, so that what is already
available can be used by people interested in reducing structure sizes
and otherwise taking advantage of the information available in the elf
sections of files compiled with 'gcc -g' or in the case of the kernel
with CONFIG_DEBUG_INFO enabled, so here it goes the description of said
tools:

pahole: Poke-a-Hole is a tool to find out holes in structures, holes
being defined as the space between members of functions due to alignemnt
rules that could be used for new struct entries or to reorganize
existing structures to reduce its size, without more ado lets see what
that means:

...

Further ideas on how to use the DWARF2 information include tools
that will show where inlines are being used, how much code is added by
inline functions,

It would be quite useful to be able to identify inlined functions which are
good candidates for uninlining.

I'm working on making good use of this information:

--------------- 8< --------------

3.3.8.2 Concrete Inlined Instances

Each inline expansion of an inlinable subroutine is represented by a
debugging information entry with the tag DW_TAG_inlined_subroutine.
Each such entry should be a direct child of the entry that represents
the scope with in which the inlining occurs.

--------------- 8< --------------

To write this tool:

<Ralf> So imagine a tool which says function x was inlined y times
bloating the code by z bytes :)

:-)

- Arnaldo
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