Re: Thoughts on LLVM and LTO

[Devang Patel <devang dot patel at gmail dot com>]

> >
> > With our limited resources, we cannot really afford to go off on a
> > multi-year tangent nurturing and growing a new technology just to add
> > a
> > new feature.
> >
> What makes you think implementing LTO from scratch is different here?

I read entire thread (last msg, I read is from Mike Stump) but I did not
see any discussion about productivity of GCC developers.

If one approach provides tools that make developer very very productive
then it may blew initial work estimates out of water.

Here are the questions for LLVM as well as LTO folks. (To be fair,
Chris gave us some hints on few of this, but it is OK if people ask him
for clarifications :) And I have not read anything about this in LTO
proposal, so I take that this may need extra work not considered in
LTO time estimates).

1) Documentation

How well is the documentation so that _new_ compiler engineer can
become productive sooner ?

2) Testability of optimization passes

How much precision one can get while testing particular feature,
optimization pass?

3) Integrated tools to investigate/debug/fix optimizer bugs

4) Basic APIs needed to implement various optimization techniques

-
Devang