Extracted some test cases from SolidityEndToEnd.cpp

test/libsolidity/semanticTests/strings/constant_string_literal.sol

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+contract Test {
+    bytes32 constant public b = "abcdefghijklmnopq";
+    string constant public x = "abefghijklmnopqabcdefghijklmnopqabcdefghijklmnopqabca";
+
+    constructor() {
+        string memory xx = x;
+        bytes32 bb = b;
+    }
+    function getB() public returns (bytes32) { return b; }
+    function getX() public returns (string memory) { return x; }
+    function getX2() public returns (string memory r) { r = x; }
+    function unused() public returns (uint) {
+        "unusedunusedunusedunusedunusedunusedunusedunusedunusedunusedunusedunused";
+        return 2;
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// b() -> 0x6162636465666768696a6b6c6d6e6f7071000000000000000000000000000000
+// x() -> 0x20, 0x35, 0x616265666768696a6b6c6d6e6f70716162636465666768696a6b6c6d6e6f7071, 44048183304486788312148433451363384677562177293131179093971701692629931524096
+// getB() -> 0x6162636465666768696a6b6c6d6e6f7071000000000000000000000000000000
+// getX() -> 0x20, 0x35, 0x616265666768696a6b6c6d6e6f70716162636465666768696a6b6c6d6e6f7071, 44048183304486788312148433451363384677562177293131179093971701692629931524096
+// getX2() -> 0x20, 0x35, 0x616265666768696a6b6c6d6e6f70716162636465666768696a6b6c6d6e6f7071, 44048183304486788312148433451363384677562177293131179093971701692629931524096
+// unused() -> 2

test/libsolidity/semanticTests/strings/return_string.sol

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+contract Main {
+    string public s;
+    function set(string calldata _s) external {
+        s = _s;
+    }
+    function get1() public returns (string memory r) {
+        return s;
+    }
+    function get2() public returns (string memory r) {
+        r = s;
+    }
+}
+// ====
+// compileToEwasm: also
+// compileViaYul: also
+// ----
+// set(string): 0x20, 5, "Julia" ->
+// get1() -> 0x20, 5, "Julia"
+// get2() -> 0x20, 5, "Julia"
+// s() -> 0x20, 5, "Julia"