fix: improve switch out search in loop (#2246)

jadx-core/src/main/java/jadx/core/dex/visitors/regions/RegionMaker.java

@@ -864,6 +864,10 @@ public class RegionMaker {
 		// works if no fallthrough cases and no returns inside switch
 		BitSet outs = BlockUtils.newBlocksBitSet(mth);
 		for (BlockNode s : block.getCleanSuccessors()) {
+			if (s.contains(AFlag.LOOP_END)) {
+				// loop end dom frontier is loop start, ignore it
+				continue;
+			}
 			outs.or(s.getDomFrontier());
 		}
 		outs.clear(block.getId());

jadx-core/src/test/java/jadx/tests/integration/switches/TestSwitchInLoop3.java

@@ -0,0 +1,44 @@
+package jadx.tests.integration.switches;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.tests.api.IntegrationTest;
+
+import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
+
+public class TestSwitchInLoop3 extends IntegrationTest {
+
+	@SuppressWarnings("SwitchStatementWithTooFewBranches")
+	public static class TestCls {
+		public int test(int k) {
+			int a = 0;
+			while (true) {
+				int x = 0; // keep this: force to generate the necessary CFG
+				switch (k) {
+					case 0:
+						return a;
+					default:
+						a++;
+						k >>= 1;
+				}
+			}
+		}
+
+		public void check() {
+			assertThat(test(1)).isEqualTo(1);
+		}
+	}
+
+	@Test
+	public void test() {
+		assertThat(getClassNode(TestCls.class))
+				.code()
+				.containsLines(3,
+						"switch (k) {",
+						indent() + "case 0:",
+						indent(2) + "return a;",
+						indent() + "default:",
+						indent(2) + "a++;",
+						indent(2) + "k >>= 1;");
+	}
+}