lvaFloatVars is set using varTypeIsFloating(), which doesn't include SIMD register types. The count of these registers is used in Compiler::optIsProfitableToHoistTree() to determine hoisting profitability of a tree, also using varTypeIsFloating(). The effect is probably that SIMD type trees are treated as using integer registers for hoisting profitability calculations.

varTypeUsesFloatReg() should probably be used instead.