proposal for compilation unil wide alias analyis

[Kenneth Zadeck]

Diego Novillo wrote:

>On Fri, 2004-06-25 at 18:08, Jan Hubicka wrote:
>
>  
>
>>However the mainline might be good as well as we already do have
>>functions gimplified at the time cgraph_analize is called (ie when you
>>would like to do the analysis).
>>
>>    
>>
>Really?  Then why do we call the gimplifier as one of the tree
>optimization passes?  That makes things easier then.  But the bodies are
>still in high GIMPLE, are they not?  Meaning that they still have
>nesting and scopes.
>
>What would be Really Cool, though, is to have all the function bodies in
>the call graph already in SSA form.
>
>Now, when exactly is cgraph_analyze called?  After we called t_r_o_c on
>each function body?  That'd be too late.  We want to do this analysis
>before we optimize the first body in the call graph.
>
>  
>
I will need someone's help to do this.  I was not going to try to 
restructure the compiler on my first programming assignment, only insert 
small changes here and there to get the info I needed.

>>Also I was under impression that doing basic IPA alias analysis should
>>be just question of hooking Daniel's points to analyzers into
>>cgraph code
>>
>>    
>>
>This would fix some of the low hanging fruit wrt IPA analysis.  I don't
>think the idea is to do a full context-sensitive analysis at first.
>
>
>Diego.
>
>  
>
This is not the goal of this first hack.  My initial hack is remove the 
needlessly bad assumptions we are making about file level statics.  For 
this I need to look the entire file at one time and gather some simple 
information.  Diego felt that this should be done at the gimplified 
level because it is quite likely that we will eventually want to do 
something more aggressive and if we start to high, we will have to start 
from scratch.