swift234

IRGen: Coerce parameters using the larger of the from and to types.

Upstream clang got better about preserving the type of lowered vector parameters, so float_vec3 lowers to a <3 x float> parameter rather than a generic <2 x double>. We still represent the opaque blob as an aligned i128, since we don't understand padding in imported structs, so we need to generalize coerceValue to deal with size mismatches in both directions. Fixes rdar://problem/20011424.

Swift SVN r25701