c888a0ce88
Rewrite and document multi-buffering properly: 1. Use IndexingUtils / StaticValueUtils instead of duplicating functionality 2. Properly plumb RewriterBase through. 3. Add support 4. Better debug messages. This revision is otherwise almost NFC, if it weren't for the extra DeallocOp support that would previoulsy make multi-buffering fail. Depends on: D145036 Differential Revision: https://reviews.llvm.org/D145055