From: "Daniel Berlin" <dberlin@dberlin.org>
Date: August 9, 2007 2:31:08 AM CEDT
To: "Cupertino Miranda" <cupertinomiranda@gmail.com>
Subject: Re: Fixed function compilation order
On 8/8/07, Cupertino Miranda <cupertinomiranda@gmail.com> wrote:
On Aug 9, 2007, at 2:03 AM, Daniel Berlin wrote:
On 8/8/07, Cupertino Miranda <cupertinomiranda@gmail.com> wrote:
Hello everyone,
I am currently trying to enable GCC to perform compilation without
having to respect any compilation order, i.e. execute some pass to
any function at any time (it is not only pass reordering).
As what I have seen from (trunk version of) GCC, it doesn't seem an
easy task to be achieved and it might traduce in many complications
later in development.
In that sense I would like to have some opinions and suggestions
from
you all:
For tree level optimization, this is really not difficult.
For RTL, this is probably going to be really hard.
- Imagining I am able to change the function context by updating
cfun, etc. Will passes (all_passes) execute without
missing/wrong data, i.e. is all shared data between passes
accessed/
updated thought pointers such as cfun, etc. ?
What do you mean "missing/wrong" data.
Just as an example, imagine you just executed the pass for the
creation of the CFG and after that, you decided to change context to
another function to perform the same pass.
Let me be clear. We create CFG/SSA for *all* functions at once right
now, run a bunch of SSA passes, and then run a bunch of passes
per-function. If you try to do something before this happens, yes,
you will have issues. The simple answer is "don't do that".
:)
So basically, you can throw your pass in the list of passes and expect
changing functions to work like it does in an IPA pass.
The one datastructure you cannot have stored on multiple functions at
once right now are those related to tree level aliasing.
We are fixing this, but it is not done yet.