Enable DA by Default

[sjoerdmeijer]

We would like to enable LoopInterchange by default (RFC), but are blocked on DependenceAnalysis correctness issues.

This is a bucket ticket that lists all DA correctness issues that we need to fix before reenabling interchange.

• [DA] Does not account for wrapping accesses #149501
• [DA] SIV test expected at least one AddRec #148435
• [DA] strongSIV produces incorrect results #149977
• [DA] Aliasing checks in DA are incorrect #41488
• [DA] Assume coefficient of subscript is non-zero #149991
• [DA] Incorrect DA results likely due to mishandling of signed/unsigned comparisons #159846
• LoopUnrollAndJam miscompiles loop with vector load/store #84796

[sjoerdmeijer]

@sebpop , @kasuga-fj , @nikic : because we have collected quite a few DA issues, it is difficult to see where we are with this.
I was thinking that this bucket ticket can provide this overview and this enablement ticket is "blocked by" all DA is I could quickly find. And maybe we can use this as our work and todo list that we agree on that needs fixing before enablement, so feel free to add things.