Question on arithmetic overflow detection support in C2

Rémi Forax forax at
Wed Jun 27 06:52:23 PDT 2012

On 06/27/2012 03:37 PM, Krystal Mok wrote:
> Hi all,
> Just FYI, I've posted an updated version of the patch here:
> It pretty much implements what John suggested in a previous email 
> (quoted below).
> This version still suffers from a couple of problem mentioned before:
> 1. It's emitting a jmpConU instead of a jmpCon during instruction 
> selection. Is there a way to force it use jmpCon here?

I'm may be wrong but the idea is to put 0 (or a very small value) to the 
frequency of the basic block
that follow the jump on overflow.

> 2. I had to use a fixed register for the sum projection of 
> CheckedAddI, otherwise I couldn't find a way to specify this 
> projection should use the same register as "dst".
> - Kris


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