[LLVMdev] Undoing DAG Combiner patterns

Martin Filteau martin.filteau at octasic.com
Wed May 15 19:03:14 PDT 2013

Hi all,

It's the first LLVM backend we do for our asynchronous DSP. So, I apologize if this is a trivial question!

The target-independent DAG combiner performs the following transformation:

sub  n, c                ->  add n, -c

For our target, negative constants are more costly to encode.  What is the best place to revert to a sub instruction?

Kind regards,

-- Martin


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130516/ea2e8929/attachment.html>

More information about the llvm-dev mailing list