Reland https://github.com/llvm/llvm-project/pull/115229 which was
reverted by https://github.com/llvm/llvm-project/pull/115388 because it
was hitting an assertion in IREE. From the original change: If the
`DenseIntElementsAttr` is a splat value, there is no need to loop over
the entire attr. Instead, just update with the splat value.
The problem with the original implementation is that `SplatElementsAttr`
might be an attr of non `APInt` (e.g. float) elements. Instead, check if
`DenseIntElementsAttr` is splat and use the splat value. Added a test to
ensure there's no crash when handling float attrs.
PR #112292 added support for vectors to the integer range inference
interface and analysis, but didn't update the getDestWidth() method.
This caused crashes when trying to infer the ranges of `arith.extsi`
with vector inputs, as the code would try to sign-extend a N-bit value
to a 0-bit one, which would assert and crash.
This commit fixes the issue by adding a getElementTypeOrSelf().
Treat integer range for vector type as union of ranges of individual
elements. With this semantics, most arith ops on vectors will work out
of the box, the only special handling needed for constants and vector
elements manipulation ops.
The end goal of these changes is to be able to optimize vectorized index
calculations.
