[LLVMdev] Detecting reduction operations

[David Greene]

On Tuesday 13 October 2009 00:36, Chris Lattner wrote:

> If you want to detect simple reductions like this, just walk the SSA
> graph starting from the PHIs in the loop header.  The code should look
> very similar to how LoopInfo identifies the canonical induction
> variable for a loop, it should not be difficult to write.

ScalarEvolution is another place to look for examples.  It discovers add 
recurrences today and altering the analysis slightly to detect in-register
reductions shouldn't be hard to do.

                               -Dave