Re: [GIT PULL] llvm fixes

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

On Sun, Nov 05, 2017 at 04:49:37PM +0800, Christopher Li wrote:
> >commit 5674da2d1af2467605fcc9b798fb54ee2d28efc7
> >Author: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
> >Date:   Mon Mar 20 15:18:53 2017 +0100
> >
> >    canonicalize compare instructions
> >
> >    Currently only commutative instructions are canonicalized
> >    (the "simpler" operands, often a constant, is forced, if present
> >    to be in the second operand). This improve CSE (more cases are
> >    considered as equivalent) and help to reduce the number of "pattern"
> >    to be handled at simplification.
> >
> 
> 
> Notice that LT and GT and equivalent instructions after swapping the src.
> Another way to do it we might just remove one kind of instruction from the
> sparse IR. From the linearization point just map GT into LT and swap the source.
> 
> So the IR does not allow those duplicated equilateral instructions. There is
> less canonization to be done.

The principal and most important action done during canonicalization is
insuring that constants are on the RHS.

-- Luc