[llvm-commits] [llvm] r166865 - /llvm/trunk/lib/Transforms/Vectorize/BBVectorize.cpp

[Nadav Rotem]

On Oct 26, 2012, at 10:08 PM, Hal Finkel <hfinkel at anl.gov> wrote:

> To be fair, I think we expected this. I see two general solutions:
> 1. Cover all such cases with target hooks

This is possible. 

> 2. When the cost of some operation is requested, actually compile it (make a small selection DAG and run instruction selection), and then use the result (we could just count the number of machine instructions, for example). We'd need to cache the results for this to be practical.

I don't think that this is a good approach. The compile time for this kind of mechanism would be very high. 

We can build an off-line tool that would compile IR to assembly. We can use this (off-line) tool to generate cost-tables. 

> 
> What do you think?
> 
> -Hal



Thanks,
Nadav
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