[Core] Grab-bag of improvements for Scalar.
It was noted on the list that this method is unused. So, this patch
Fix Scalar::Promote for most integer types
This fixes promotion of most integer types (128- and 256-bit types are
handled in a subsequent patch) to floating-point types. Previously
promotion was done bitwise, where value preservation is correct.
Fix Scalar::Promote for 128- and 256-bit integer types
This patch fixes the behavior of Scalar::Promote when trying to
perform a binary operation involving a 128- or 256-bit integer type
and a floating-point type. Now, the integer is cast to the floating
point type for the operation.
Patch by Tom Tromey!
Differential Revision: https://reviews.llvm.org/D44907