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

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.

Reviewed By: xazax.hun

Differential Revision: https://reviews.llvm.org/D158977

1 files changed, 7 insertions, 3 deletions

diff --git a/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp b/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
index 961a06d..e40bd3d 100644
--- a/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
@@ -458,8 +458,9 @@ void transferArrowOpCall(const Expr *UnwrapExpr, const Expr *ObjectExpr,
 void transferMakeOptionalCall(const CallExpr *E,
                               const MatchFinder::MatchResult &,
                               LatticeTransferState &State) {
-  createOptionalValue(State.Env.getResultObjectLocation(*E),
-                      State.Env.getBoolLiteralValue(true), State.Env);
+  State.Env.setValue(
+      *E, createOptionalValue(State.Env.getResultObjectLocation(*E),
+                              State.Env.getBoolLiteralValue(true), State.Env));
 }
 
 void transferOptionalHasValueCall(const CXXMemberCallExpr *CallExpr,
@@ -543,7 +544,10 @@ void transferCallReturningOptional(const CallExpr *E,
     }
   }
 
-  createOptionalValue(*Loc, State.Env.makeAtomicBoolValue(), State.Env);
+  RecordValue &Val =
+      createOptionalValue(*Loc, State.Env.makeAtomicBoolValue(), State.Env);
+  if (E->isPRValue())
+    State.Env.setValue(*E, Val);
 }
 
 void constructOptionalValue(const Expr &E, Environment &Env,