================
@@ -311,7 +318,10 @@ computeBlockInputState(const CFGBlock &Block,
AnalysisContext &AC) {
}
}
- JoinedStateBuilder Builder(AC);
+ // When performing the join, only retain state for those expressions that are
+ // consumed by this block. This avoids performing joins and potentially
+ // extending the flow condition for expressions that we won't need anyway.
+ JoinedStateBuilder Builder(AC, AC.CFCtx.getExprConsumedByBlock(&Block));
----------------
martinboehme wrote:
> We have getStableStorageLocation that will first look up an expression in
> ExprToLoc and it will try to reuse the some location. In case we clear
> ExprToLoc along the back edge, in the second iteration through processing B2
> we would create new locations for the expressions.
Confusingly, there are two different maps called `ExprToLoc`:
*
[`Environment::ExprToLoc`](https://github.com/llvm/llvm-project/blob/03f05a4e72891237264ab48adf62034aaac8bd46/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h#L661)
This is the one from which this PR (and the simpler version in #72985)
removes entries.
*
[`DataflowAnalysisContext::ExprToLoc`](https://github.com/llvm/llvm-project/blob/03f05a4e72891237264ab48adf62034aaac8bd46/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h#L218)
This is the one used by
[`DataflowAnalysisContext::getStableStorageLocation()`](https://github.com/llvm/llvm-project/blob/03f05a4e72891237264ab48adf62034aaac8bd46/clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp#L86).
This PR does not remove any entries from this map.
So the answer is that stable storage locations are not affected by this PR. If
we have a storage location that is cleared from `Environment::ExprToLoc` as a
result of this PR, then if we call `Environment::createStorageLocation(const
Expr&)` on the next iteration, that will call through to
`DataflowAnalysisContext::getStableStorageLocation()`, which will return the
same storage location as it did on the previous iteration.
In the PR description, I merely used `ExprToLoc` as shorthand for
`Environment::ExprToLoc` since that is the one that I'm concerned with most
often -- but I realize this is potentially confusing.
https://github.com/llvm/llvm-project/pull/72850
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