[PATCH] D82598: [analyzer][Liveness][NFC] Get rid of statement liveness, because such a thing doesn't exist

[Gábor Horváth via Phabricator via cfe-commits]

xazax.hun added inline comments.


================
Comment at: clang/lib/Analysis/LiveVariables.cpp:317-320
   for (Stmt *Child : S->children()) {
-    if (Child)
-      AddLiveStmt(val.liveStmts, LV.SSetFact, Child);
+    if (const auto *E = dyn_cast_or_null<Expr>(Child))
+      AddLiveExpr(val.liveExprs, LV.SSetFact, E);
   }
----------------
Szelethus wrote:
> ..this part of the code caused the issue. Looking at the related CFG,
> ```lang=c++
> void test_lambda_refcapture()
>  [B2 (ENTRY)]
>    Succs (1): B1
> 
>  [B1]
>    1: 6
>    2: int a = 6;
>    3: operator()
>    4: [B1.3] (ImplicitCastExpr, FunctionToPointerDecay, void (*)(int &) const)
>    5: [&](int &a) {
>     a = 42;
> }
>    6: [B1.5]
>    7: [B1.6] (ImplicitCastExpr, NoOp, const class (lambda at /home/szelethus/Documents/llvm-project/clang/test/Analysis/live-stmts.cpp:183:3))
>    8: a
>    9: [B1.7]([B1.8]) (OperatorCall)
>   10: clang_analyzer_eval
>   11: [B1.10] (ImplicitCastExpr, FunctionToPointerDecay, void (*)(_Bool))
>   12: a
>   13: [B1.12] (ImplicitCastExpr, LValueToRValue, int)
>   14: 42
>   15: [B1.13] == [B1.14]
>   16: [B1.11]([B1.15])
>    Preds (1): B2
>    Succs (1): B0
> 
>  [B0 (EXIT)]
>    Preds (1): B1
> ```
> its clear that element 5 added the live statement, and I think that that this entire CFG just simply isn't right. Shouldn't we have a distinct element for the assignment?
> 
>  Shouldn't we have a distinct element for the assignment?

Strictly speaking, we have CFGs for a function. The assignment is **not** in this function, it is in the `operator()` of the class representing this lambda expression. 

So basically, we do have a `LambdaExpr` to represent the expression, but the body of the lambda is in a separate entity.


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  https://reviews.llvm.org/D82598/new/

https://reviews.llvm.org/D82598