[LLVMdev] [RFC] Replacing EVT:s with MVT:s (when possible)
david.chisnall at cl.cam.ac.uk
Wed Dec 5 04:51:13 PST 2012
On 3 Dec 2012, at 23:45, Chris Lattner wrote:
> Please do. MVT is cheaper than EVT and conceptually cleaner when dealing with physical machine types. EVT should only be used in parts of the code generator that are "pre-legalization" because they can represent arbitrary IR types. Anything that takes a legal machine type should take an MVT.
A side issue of this is that it is currently relatively hard to add new machine-specific register types. The only way of doing this involves extending MVT, which requires tweaking three files in the (nominally) target-independent parts of the compiler. It would be great if we could simply reserve a (small?) number of MVTs for target-specific legal values.
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