llvm dev - Jan 2009 - [LLVMdev] if-conversion

Hello everyone,

I'd like to know if there is an optimization in llvm doing something
like an if-conversion on the IR. I only found IfConversion.cpp which
appears to only provide the desired functionality on machine code during
code-generation.

I want to transform branches into serial code with select-instructions
as a pre-processing step for further transformations.

If there is no such pass, I will possibly write one and share it
(although I have no idea how to do so yet), so please let me know :).

Cheers,
Ralf

On Tue, Jan 20, 2009 at 2:29 AM, Ralf Karrenberg <Chareos at gmx.de>
wrote:
> I want to transform branches into serial code with select-instructions
> as a pre-processing step for further transformations.
SimplifyCFG should be doing this transform in very simple cases.
Depending on what you're doing, though, its might not be aggressive
enough.

-Eli

On Jan 20, 2009, at 2:29 AM, Ralf Karrenberg wrote:
> Hello everyone,
>
> I'd like to know if there is an optimization in llvm doing something
> like an if-conversion on the IR. I only found IfConversion.cpp which
> appears to only provide the desired functionality on machine code  
> during
> code-generation.
>
> I want to transform branches into serial code with select-instructions
> as a pre-processing step for further transformations.
>
> If there is no such pass, I will possibly write one and share it
> (although I have no idea how to do so yet), so please let me know :).
There is not any pass that can transform branches into serial code  
with select-instructions. Simplify CFG can handle simple cases of  
selecting one value based on a condition, but its goal is to simplify  
cfg. This may not be enough for your needs.

If you write a separate pass, we'd like to integrate it in mainline  
llvm sources.

-
Devang

> If you write a separate pass, we'd like to integrate it in mainline
> llvm sources.
Thank you for your answers. I will do my best to develop something which 
could be useful for more people :).

Cheers,
Ralf