This converts 2 f64 to 2 i32, then zeroes the top 2 lanes.
These 2 instructions were merged as part of #383.
This change also refactors some test cases from simd_conversions out
into a script that generates both i32x4.trunc_sati32x4{s,u} and
i32x4.trunc_satf64x2{s,u}_zero.
This converts 2 f64 to 2 i32, then zeroes the top 2 lanes.
These 2 instructions were merged as part of #383.
This change also refactors some test cases from simd_conversions out into a script that generates both i32x4.trunc_sati32x4{s,u} and i32x4.trunc_satf64x2{s,u}_zero.