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FIR CFA: properly visit subgraphs in checkers

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Interpretation: a graph A is a subgraph of B if information available at
nodes of A depends on the paths taken in B. For example, local classes
are subgraphs of a graph in which they are declared, and members of
those classes are subgraphs of the local class itself - because these
members can reference captured values.

Consequences:

 * if graph G is a subgraph of node N, then G is a subgraph of N's
   owner;
 * `ControlFlowAnalysisDiagnosticComponent` will only visit root graphs;
 * `graph.traverse` will ignore subgraph boundaries, as if all subgraphs
   are inlined into one huge root graph;
 * if a control flow checker needs information from a declaration to
   which a graph is attached, it must look at subgraphs explicitly.

For example, consider the `callsInPlace` checker. When a function
has a `callsInPlace` contract and a local declaration, the checker must
visit that local declaration to ensure it does not capture the allegedly
called-in-place argument - hence `graph.traverse` will look at the
nodes. However, the local declaration can also be a function with its
own `callsInPlace` contracts, so the checker should also run for it in
isolation. If that sounds quadratic, that's because unfortunately it is.
This commit is contained in:
pyos
2022-12-09 12:32:46 +01:00
committed by Dmitriy Novozhilov
parent 5180e1f4a4
commit aadea0e26f
35 changed files with 1191 additions and 1325 deletions
Download Patch File Download Diff File Expand all files Collapse all files
compiler/fir/analysis-tests/testData/resolve/cfg/postponedLambdaInConstructor.dot
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+11 -12
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@@ -72,19 +72,9 @@ digraph postponedLambdaInConstructor_kt {
20 -> {21};
subgraph cluster_7 {
color=red
22 [label="Enter property" style="filled" fillcolor=red];
23 [label="Access variable R|<local>/s|"];
24 [label="Exit property" style="filled" fillcolor=red];
}
22 -> {23};
23 -> {24};
24 -> {32} [color=green];
subgraph cluster_8 {
color=red
25 [label="Enter function foo" style="filled" fillcolor=red];
subgraph cluster_9 {
subgraph cluster_8 {
color=blue
26 [label="Enter block"];
27 [label="Function call: this@R|/B|.R|/B.foo|()" style="filled" fillcolor=yellow];
@@ -97,15 +87,24 @@ digraph postponedLambdaInConstructor_kt {
27 -> {28};
28 -> {29};
subgraph cluster_10 {
subgraph cluster_9 {
color=red
30 [label="Enter class B" style="filled" fillcolor=red];
31 [label="Part of class initialization"];
subgraph cluster_10 {
color=blue
22 [label="Enter property" style="filled" fillcolor=red];
23 [label="Access variable R|<local>/s|"];
24 [label="Exit property" style="filled" fillcolor=red];
}
32 [label="Exit class B" style="filled" fillcolor=red];
}
30 -> {31} [color=green];
31 -> {22} [color=green];
31 -> {32} [style=dotted];
31 -> {22} [style=dashed];
22 -> {23};
23 -> {24};
24 -> {32} [color=green];
}