tree 4d923ff7b9e104455717b8bea1ee5a338a82017b
parent a2fd4865af600f2c3d79ef260328c4b5f5e5afb3
author Jinseong Jeon <jsjeon@google.com> 1543446607 -0800
committer Jinseong Jeon <jsjeon@google.com> 1543446607 -0800

Redesign array type lattice element.

Previously, array type lattice has DexType as array type, and join was
using that to compute the least upper bound of base types. However, if
participated base type is interface and class, we lose the accuracy.

To use pair-wise class/interface join, array type lattice should have
either array or element type as type lattice, not DexType.
In this CL, we chose a nested structure: ArrayTypeLatticeElement is
composed of element type lattice, which could be array type lattice in
a recursive way.

One caveat is to distinguish int[] v.s. (boolean|byte|short|char)[]
because those smaller types were merged to IntTypeLatticeElement.
This CL introduces smaller type lattice elements only for array
element type, and ensure that they are never assigned to SSA value.

Bug: 119181813, 119042956, 72693244, 117414337
Change-Id: I4c67db06485c0d0e3fc5245c8525370141587936