Matt Turner <matts...@gmail.com> writes: > When I implemented these built-ins couple of years ago, I thought there > must be a neat way to optimize them. I tried a couple of things with the > different vector immediates i965 provides, but the V/UV types are too > small to represent the appropriate shift values, and shift instructions > can't shift by a floating-point source (if using the vector float imm). > > Curro pointed out that I could actually load the integer shift values > with VF immediate just by doing a type converting move. How simple. > > So anyway, these optimizations are of pretty negligible value, except > for maybe demonstrating that VF works. I've had them sitting on a branch > for months, so time for them to live somewhere else. At least we can > disassemble VF immediates now. > > I hope to have some more uses of VF immediates soon too.
Hi Matt, a different approach I had in mind was to write an optimization pass that would vectorize immediate moves by using VF where the original arguments can be represented exactly as an 8-bit float. That would probably help in many more cases than hand-optimizing a couple of built-in operations -- That said, I guess it doesn't hurt to do this for the time being until we have such an optimization pass.
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