feat: respect return in cfg construction

Author: EagleoutIce

src/control-flow/cfg-dead-code.ts

@@ -127,10 +127,6 @@ class CfgConditionalDeadCodeRemoval extends SemanticCfgGuidedVisitor {
 		this.handleWithCondition(data);
 	}
 
-	protected onReturnCall(data: { call: DataflowGraphVertexFunctionCall }): void {
-		this.cachedStatements.set(data.call.id, true);
-	}
-
 	protected onStopCall(data: { call: DataflowGraphVertexFunctionCall }): void {
 		this.cachedStatements.set(data.call.id, true);
 	}

src/control-flow/extract-cfg.ts

@@ -415,6 +415,11 @@ function cfgFunctionCall(call: RFunctionCall<ParentInformation>, name: ControlFl
 		graph.addEdge(callId + '-exit', exit, { label: CfgEdgeType.Fd });
 	}
 
+	if(call.named && call.functionName.content === 'return') {
+		info.returns.push(callId + '-exit');
+		info.exitPoints.length = 0;
+	}
+
 	// should not contain any breaks, nexts, or returns, (except for the body if something like 'break()')
 	return info;
 }

test/functionality/control-flow/control-flow-graph.test.ts

@@ -114,6 +114,17 @@ describe('Control Flow Graph', withTreeSitter(parser => {
 					.addEdge('7-exit', '6-exit', { label: CfgEdgeType.Fd })
 					.addEdge('8-exit', '7-exit', { label: CfgEdgeType.Fd })
 			});
+
+			assertCfg(parser, 'f <- function() if (u) return(42) else return(1)', {
+				entryPoints: [ '4' ],
+				exitPoints:  [ '4-exit' ],
+				graph:       new ControlFlowGraph()
+					.addVertex({ id: 5, type: CfgVertexType.Statement, end: ['5-exit'] }, false)
+					.addVertex({ id: 10, type: CfgVertexType.Statement, end: ['10-exit'] }, false)
+					.addEdge('14-exit', '5-exit', { label: CfgEdgeType.Fd })
+					.addEdge('14-exit', '10-exit', { label: CfgEdgeType.Fd })
+			}, { simplificationPasses: ['analyze-dead-code'], expectIsSubgraph: true });
+
 		});
 
 		describe('loops', () => {

test/functionality/control-flow/dead-code/cfg-dead-code.test.ts

@@ -21,7 +21,7 @@ describe('Control Flow Graph', withTreeSitter(parser => {
 			expectIsSubgraph:     true,
 			simplificationPasses: ['analyze-dead-code'],
 			/** we break unreachable edges for this test, the whole point is for not all of them being reachable */
-			excludeProperties:    ['entry-reaches-all', 'exit-reaches-all'],
+			excludeProperties:    ['entry-reaches-all', 'exit-reaches-all', 'single-entry-and-exit'],
 			testIds:              ids,
 			additionalAsserts:    (cfg, ast) => {
 				for(const [n, i] of [...reachableFromStart.map(n => [n, false] as const), ...unreachableFromStart.map(n => [n, true] as const)]) {