API for getting lane width of x86 SIMD operands

Created by: khuey

I have an application that tracks the flow of data through instructions. It would be useful for this to know the lane width of SIMD operands. This data already exists in source form in DynamoRIO (e.g. Xvd vs Xvs entries for operand size in the decoder table) but gets compiled out (because Xvd and Xvs are #defined to the same thing). It's not obvious where to put this: adding variations of the operand size (e.g. OPSZ_16_vex32_ps and OPSZ_16_vex32_pd) would be kind of disruptive. Any thoughts?