Optimize away swizzles on single-argument constructors.
The optimizer can now turn the expression `half4(1).xyz` into
`half3(1)`, or `half4(1).w` into `1`. This is actually a somewhat common
case when inlining chains of fragment processors, as inputs are often
overridden to `half4(1)` or `half4(0)`. This optimization also applies
to more complex cases, e.g.:
`half2(anyFunc(sqrt(2))).yxyx` --> `half4(anyFunc(sqrt(2)))`
Since the interior of the constructor is always evaluated once in either
case, it does not actually matter what the constructor contains.
Change-Id: I8d5f358502eaa8e35d4968e74fbd6b0ce2ab6365
Bug: skia:10954
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/335818
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
10 files changed