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Fuzz tuple lowering against interpreter
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‎de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/LuaBackendAuditTests.java‎

Lines changed: 113 additions & 0 deletions
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@@ -121,6 +121,119 @@ public void randomizedTupleValueSemanticsStayScalar() throws IOException {
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assertFalse(compiled.contains("tupleEquals"));
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}
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@Test
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public void randomizedTupleEvaluationMatchesInterpreterAndLua() throws IOException {
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Random random = new Random(0x0D1FF3A7L);
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List<String> source = new ArrayList<>();
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source.add("package Test");
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source.add("native testSuccess()");
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source.add("tuple pair(int x, int y)");
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source.add("tuple nested(pair left, pair right)");
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source.add("int trace");
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source.add("int calls");
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source.add("class Holder");
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source.add(" pair value");
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source.add("Holder current");
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source.add("Holder replacement");
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source.add("int currentIndex");
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source.add("pair array values");
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source.add("function mark(int value) returns int");
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source.add(" trace = trace * 37 + value");
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source.add(" return value");
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source.add("@noinline function produce(int seed) returns pair");
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source.add(" calls++");
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source.add(" return pair(mark(seed), mark(seed + 1))");
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source.add("@noinline function recursive(int seed) returns pair");
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source.add(" if seed == 0");
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source.add(" return pair(mark(7), recursive(1).x)");
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source.add(" return pair(mark(seed), mark(seed + 10))");
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source.add("function retarget(int x, int y) returns pair");
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source.add(" current = replacement");
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source.add(" currentIndex = 2");
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source.add(" return pair(mark(x), mark(y))");
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source.add("init");
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source.add(" int checksum = 0");
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int expected = 0;
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for (int i = 0; i < 96; i++) {
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int a = random.nextInt(9) + 1;
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int b = random.nextInt(9) + 1;
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int c = random.nextInt(9) + 1;
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int d = random.nextInt(9) + 1;
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switch (random.nextInt(6)) {
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case 0 -> {
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boolean selectFirst = random.nextBoolean();
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source.add(" trace = 0");
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source.add(" let selected" + i + " = pair(mark(" + a + "), mark(" + b + "))."
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+ (selectFirst ? "x" : "y"));
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source.add(" checksum += trace + selected" + i + " * 13");
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expected += a * 37 + b + (selectFirst ? a : b) * 13;
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}
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case 1 -> {
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int selection = random.nextInt(4);
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String[] paths = {"left.x", "left.y", "right.x", "right.y"};
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int[] values = {a, b, c, d};
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source.add(" trace = 0");
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source.add(" let selected" + i + " = nested(pair(mark(" + a + "), mark(" + b
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+ ")), pair(mark(" + c + "), mark(" + d + ")))." + paths[selection]);
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source.add(" checksum += trace + selected" + i + " * 17");
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expected += (((a * 37 + b) * 37 + c) * 37 + d) + values[selection] * 17;
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}
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case 2 -> {
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source.add(" trace = 0");
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source.add(" calls = 0");
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source.add(" let selected" + i + " = produce(" + a + ").y");
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source.add(" checksum += trace + selected" + i + " * 19 + calls * 23");
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expected += a * 37 + (a + 1) + (a + 1) * 19 + 23;
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}
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case 3 -> {
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source.add(" trace = 0");
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source.add(" calls = 0");
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source.add(" if produce(" + a + ") != produce(" + b + ")");
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source.add(" checksum += " + (a == b ? 29 : 31));
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source.add(" else");
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source.add(" checksum += " + (a == b ? 31 : 29));
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source.add(" checksum += trace + calls * 37");
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expected += 31
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+ (((a * 37 + (a + 1)) * 37 + b) * 37 + (b + 1)) + 2 * 37;
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}
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case 4 -> {
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source.add(" let original" + i + " = new Holder()");
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source.add(" replacement = new Holder()");
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source.add(" current = original" + i);
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source.add(" trace = 0");
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source.add(" current.value = retarget(" + a + ", " + b + ")");
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source.add(" checksum += original" + i + ".value.x * 41 + original" + i
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+ ".value.y * 43 + replacement.value.x + trace");
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expected += a * 41 + b * 43 + a * 37 + b;
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}
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case 5 -> {
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source.add(" values[1] = pair(0, 0)");
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source.add(" values[2] = pair(0, 0)");
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source.add(" replacement = new Holder()");
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source.add(" currentIndex = 1");
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source.add(" trace = 0");
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source.add(" values[currentIndex] = retarget(" + a + ", " + b + ")");
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source.add(" checksum += values[1].x * 47 + values[1].y * 53 + values[2].x + trace");
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expected += a * 47 + b * 53 + a * 37 + b;
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}
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}
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}
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source.add(" trace = 0");
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source.add(" let recursiveResult = recursive(0)");
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source.add(" checksum += recursiveResult.x * 59 + recursiveResult.y * 61 + trace");
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expected += 7 * 59 + 61 + ((7 * 37 + 1) * 37 + 11);
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source.add(" if checksum == " + expected);
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source.add(" testSuccess()");
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// executeProg validates the source-level IM interpreter; testLua additionally runs the
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// scalarized output in Lua 5.3, making the generated program a deterministic differential test.
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test().testLua(true).executeProg().lines(source.toArray(new String[0]));
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String compiled = compiledLua("randomizedTupleEvaluationMatchesInterpreterAndLua");
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assertFalse(compiled.contains("tupleCopy"));
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assertFalse(compiled.contains("tupleEquals"));
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}
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@Test
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public void tupleReturnSlotsAreSharedAcrossMultipleInterfaceRoots() throws IOException {
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test().testLua(true).executeProg().lines(

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