llvm dev - Jul 2007 - [LLVMdev] not to break 'for' statement into basic blocks

Thank you so much but could you tell me a little bit more in detail about that
you suggested?
Sorry, I'm just a greenhorn.

Thanks,
Seung J. Lee

---- Original message ----
>Date: Sat, 14 Jul 2007 21:26:14 -0500
>From: "David A. Greene" <greened at obbligato.org>  
>Subject: Re: [LLVMdev] not to break 'for' statement into basic
blocks
>To: llvmdev at cs.uiuc.edu
>
>On Saturday 14 July 2007 17:23, Anton Korobeynikov wrote:
>
>> > 1) First, I tried to re-unite basic blocks which llvm-gcc spits
out to
>> > make 'for' again. But this is quite tricky. Generalizing
it for the
>> > optimzed llvm bytecode is not easy.
>>
>> I'd say 'is not possible at all'.
>
>No, it certainly is possible.  One does this, for example, when constructing
>a control dependence graph.  It can't be represented in llvm, so one
needs
>a higher-level abstraction.  A control dependence graph is one such 
>abstraction.
>
>Even llvm has a notion of "loops" that it extracts from the
control flow
>graph.  Now, these are very low-level abstractions and probably won't
work
>for the purposes of this ISA.
>
>And when you get difficult control behavior...
>

On Monday 16 July 2007 03:20, Seung Jae Lee wrote:
> Thank you so much but could you tell me a little bit more in detail about
> that you suggested? Sorry, I'm just a greenhorn.
There's far too much to cover on an e-mail list.  Use Google, Citeseer, the
ACM digital library, etc. and search for "control dependence graph." 
I
provided the reference for an algorithm to remove unstructured gotos.

Everyone starts out as a greenhorn.  Compilers are complicated beasts,
as evidenced by the number of Ph.D.s still centered on "solved"
problems
like register allocation.  :)

It takes a lot of reading and doing to become fluent.  I'm very happy to try
and answer specific questions.  Here are some specific references:

Compilers: Principles, Techniques and Tools (a.k.a. The Purple Dragon
Book) by Aho, Lam, Sethi and Ullman.  This is a good, if at times dense,
introductory text.

Advanced Compiler Design & Implementation by Muchnick.  A somewhat more
advanced treatment, better as a reference than a learning book.

I strongly suggest that if you're at a University, that you investigate the 
compiler course offerings.  You'll only get so far just reading.  Doing is
really important.

                                              -Dave