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Hi Nadav, I'm interested in knowing how you'll work up the ARM cost model and how easy it'd be to split the work. As far as I can see, LoopVectorizationCostModel is the class that does all the work, with assistance from the target transform info. Do you think that updating ARMTTI would be the best course of action now, and inspect the differences in the CostModel later? I also haven't seen anything related to context switches and pipeline decisions on the cost model, another issue that will be quite different between targets and sub-targets (especially in ARM world). B...

...to check if the types are legal and how many times large vectors need to be split. Different targets need to implement the cases that the BasicTTI does not catch. For example, the cost of zext <8xi8> to <8 x i32> which is custom lowered on some targets. > Do you think that updating ARMTTI would be the best course of action now, and inspect the differences in the CostModel later? > We should update TTI and inspect the cost model as we go. > I also haven't seen anything related to context switches and pipeline decisions on the cost model, another issue that will be quite d...

Hi Renato, I think that we need to improve ::isTruncateFree, ::isZextFree, etc to include all of the free conversions. Vector and Scalar. Non-free conversions are marked with setOperationAction so the generic parts of TTI should be able to give a reasonable cost estimation. The cost tables should contain cases that are not handled by TTI. So, if we have a clever DAGCombine optimization (that

Hi all, I'm looking for a place where to put the costs of vector (and scalar) cast operations for ARM, but I noticed the TargetTransform methods call the TargetLowering ones when unsure. Now, I'm not sure... Many casts on ARM are free, and I could build a list of cases where it is true, but should I put this on the lowering or the transform? My main motivation is to get the costs right

...assume this is the case by type, but I wanted to limit to the arithmetic operations, not loads and stores, that have their own halving and doubling that are, sometimes, free. But since TT already lost the information on the operations (passing only the type), I can't reach that info. And since ARMTTI is supposed to only apply the exceptions, I didn't want to override it on that. Am I making any sense? cheers, --renato -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130125/363135e2/attachment.html&gt...

...I don't think it'll be a hard engineering problem to know where to put the code, but it won't be easy to get some things right without badly breaking others. Let's be conservative for now... ;) We can use the Subtarget when we implement the hooks. This is an example > from the ARMTTI Yes, this direct access is very convenient. For now, I'll focus on A9 and later we can add the subtleties of each sub-target. cheers, --renato -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130110/a73...