[PATCH] D158977: [clang][dataflow] Don't associate prvalue expressions with storage locations.

[Martin Böhme via Phabricator via cfe-commits]

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Instead, map prvalue expressions directly to values in a newly introduced map
`Environment::ExprToVal`.

This change introduces an additional member variable in `Environment` but is
an overall win:

- It is more conceptually correctly, since prvalues don't have storage locations.

- It eliminates complexity from `Environment::setValue(const Expr &E, Value &Val)`.

- It reduces the amount of data stored in `Environment`: A prvalue now has a single entry in `ExprToVal` instead of one in `ExprToLoc` and one in `LocToVal`.

- Not allocating `StorageLocation`s for prvalues additionally reduces memory usage.

This patch is the last step in the migration to strict handling of value
categories (see https://discourse.llvm.org/t/70086 for details). The changes
here are almost entirely internal to `Environment`.

The only externally observable change is that when associating a `RecordValue`
with the location returned by `Environment::getResultObjectLocation()` for a
given expression, callers additionally need to associate the `RecordValue` with
the expression themselves.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158977

Files:
  clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h
  clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
  clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
  clang/lib/Analysis/FlowSensitive/Transfer.cpp

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