RFC: vectorizer cost model

2007-02-20 Thread Devang Patel
* How do we compare the costs of if-converted vectorized code to it's scalar counterpart? o It may be convenient to calculate scalar cost during if-conversion itself. o It is possible that size of two sibling blocks (Block_A Block_B) does not match at the beginning of tree-ssa level if

Re: RFC: vectorizer cost model

2007-02-20 Thread Joern Rennecke
As a first step, to stay on conservative side, it makes sense consider the scalar cost of smaller block while calculating scalar cost. Note, smaller block may not exist. I think that this should be considwered quite common. We should base the weights of the costs of the two blocks on branch

RFC: vectorizer cost model

2007-02-16 Thread Linthicum, Tony
Hello all, Dorit Nuzman and I have been collaborating on a plan for a cost model for the vectorizer. Included below is an overview of the design for the initial implementation. We would welcome any input those of you on the list might have. Thanks in advance for your help. Dorit and Tony

Re: RFC: vectorizer cost model

2007-02-16 Thread Ian Lance Taylor
Linthicum, Tony [EMAIL PROTECTED] writes: * Would using a tree-level API like estimate_num_insns be superior to using a simple cost of 1 per statment? For this sort of calculation, I would guess not. I would imagine that on most processors the cost of a single vector instruction is

Re: RFC: vectorizer cost model

2007-02-16 Thread Zdenek Dvorak
Hello, Linthicum, Tony [EMAIL PROTECTED] writes: * Would using a tree-level API like estimate_num_insns be superior to using a simple cost of 1 per statment? For this sort of calculation, I would guess not. I would imagine that on most processors the cost of a single vector