Michael Gottesman ca8179aa7c [region-isolation] Track operand info in a separate map rather than inline in a TransferringOperand data structure. ...

This is backing out an approach that I thought would be superior, but ended up
causing problems.

Originally, we mapped a region number to an immutable pointer set containing
Operand * where the region was tranferred. This worked great for a time... until
I began to need to propagate other information from the transferring code in the
analysis to the actual diagnostic emitter.

To be able to do that, my thought was to make a wrapper type around Operand
called TransferringOperand that contained the operand and the other information
I needed. This seemed to provide me what I wanted but I later found that since
the immutable pointer set was tracking TransferringOperands which were always
newly wrapped with an Operand *, we actually always created new pointer
sets. This is of course wasteful from a memory perspective, but also prevents me
from tracking transferring operand sets during the dataflow since we would never
converge.

In this commit, I fix that issue by again tracking just an Operand * in the
TransferringOperandSet and instead map each operand to a state structure which
we merge dataflow state into whenever we visit it. This provides us with
everything we need to in the next commit to including a region -> transferring
operand set equality check in our dataflow equations and always converge.

2024-04-10 10:30:10 -07:00

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