Implement the watermarker using operands swapping method

src/kyut/watermarker/OperandSwappingWatermarker.cpp

@@ -423,13 +423,25 @@ namespace kyut::watermarker {
                 return (std::max)(embedExpression(expr.left, stream), embedExpression(expr.right, stream));
             }
 
-            // TODO: implement watermarking
-            const auto leftSideEffect = embedExpression(expr.left, stream);
-            const auto rightSideEffect = embedExpression(expr.right, stream);
+            // Sort both of the operands
+            auto [lo, hi] = std::minmax(expr.left, expr.right, [](auto a, auto b) { return *a < *b; });
 
-            (void)swapOperands;
+            const auto loEffect = embedExpression(lo, stream);
+            const auto hiEffect = embedExpression(hi, stream);
 
-            return (std::max)(leftSideEffect, rightSideEffect);
+            if (static_cast<std::uint32_t>(loEffect) + static_cast<std::uint32_t>(hiEffect) >= 3) {
+                // The operands have side effect and cannot be swapped
+                return (std::max)(loEffect, hiEffect);
+            }
+
+            // Embed watermarks by swapping operands
+            const bool bit = stream.readBit();
+
+            if (bit == (expr.left == lo)) {
+                swapOperands(expr);
+            }
+
+            return (std::max)(loEffect, hiEffect);
         }
 
         SideEffect embedSelect(wasm::Select &expr, CircularBitStreamReader &stream) {

test/kyut/watermarker/test_OperandSwappingWatermarker.cpp

@@ -14,7 +14,7 @@
 BOOST_AUTO_TEST_SUITE(kyut)
 BOOST_AUTO_TEST_SUITE(watermarker)
 
-BOOST_AUTO_TEST_CASE(embed_operand_swapping) {
+BOOST_AUTO_TEST_CASE(embed_operand_swapping_000000) {
     wasm::Module module;
     wasm::ModuleReader{}.read(KYUT_TEST_SOURCE_DIR "/example/test2.wast", module);
 
@@ -24,7 +24,6 @@ BOOST_AUTO_TEST_CASE(embed_operand_swapping) {
     BOOST_REQUIRE_EQUAL(module.functions[2]->name, "f3");
 
     // Embed 0b0000'00
-    {
     CircularBitStreamReader s{{0b0000'0000}};
     const auto numBitsEmbedded = embedOperandSwapping(module, s);
 
@@ -36,12 +35,106 @@ BOOST_AUTO_TEST_CASE(embed_operand_swapping) {
 
     // f1
     {
-            const auto bin = module.functions[0]->body->cast<wasm::Binary>();
+        const auto body = module.functions[0]->body->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(body->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(body->left->cast<wasm::Const>()->value.geti32(), 1);
+        BOOST_REQUIRE_EQUAL(body->right->cast<wasm::Const>()->value.geti32(), 2);
+    }
+    // f2
+    {
+        const auto body = module.functions[1]->body->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(body->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(body->left->cast<wasm::Const>()->value.geti32(), 3);
+
+        const auto r = body->right->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(r->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(r->left->cast<wasm::Const>()->value.geti32(), 1);
+        BOOST_REQUIRE_EQUAL(r->right->cast<wasm::Const>()->value.geti32(), 2);
+    }
+    // f3
+    {
+        const auto body = module.functions[2]->body->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(body->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(body->left->is<wasm::Binary>(), true);
+        BOOST_REQUIRE_EQUAL(body->right->is<wasm::Binary>(), true);
+
+        const auto l = body->left->cast<wasm::Binary>();
+        const auto r = body->right->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(l->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(l->left->cast<wasm::Const>()->value.geti32(), 1);
+        BOOST_REQUIRE_EQUAL(l->right->cast<wasm::Const>()->value.geti32(), 2);
+
+        BOOST_REQUIRE_EQUAL(r->op, wasm::GtSInt32);
+        BOOST_REQUIRE_EQUAL(r->left->cast<wasm::Const>()->value.geti32(), 3);
+        BOOST_REQUIRE_EQUAL(r->right->cast<wasm::Const>()->value.geti32(), 4);
+    }
+}
+
+BOOST_AUTO_TEST_CASE(embed_operand_swapping_110111) {
+    wasm::Module module;
+    wasm::ModuleReader{}.read(KYUT_TEST_SOURCE_DIR "/example/test2.wast", module);
+
+    BOOST_REQUIRE_EQUAL(module.functions.size(), std::size_t{3});
+    BOOST_REQUIRE_EQUAL(module.functions[0]->name, "f1");
+    BOOST_REQUIRE_EQUAL(module.functions[1]->name, "f2");
+    BOOST_REQUIRE_EQUAL(module.functions[2]->name, "f3");
+
+    // Embed 0b1101'11
+    CircularBitStreamReader s{{0b1101'1100}};
+    const auto numBitsEmbedded = embedOperandSwapping(module, s);
+
+    BOOST_REQUIRE_EQUAL(numBitsEmbedded, std::size_t{6});
+    BOOST_REQUIRE_EQUAL(module.functions.size(), std::size_t{3});
+    BOOST_REQUIRE_EQUAL(module.functions[0]->name, "f1");
+    BOOST_REQUIRE_EQUAL(module.functions[1]->name, "f2");
+    BOOST_REQUIRE_EQUAL(module.functions[2]->name, "f3");
+
+    // f1
+    {
+        const auto body = module.functions[0]->body->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(body->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(body->left->cast<wasm::Const>()->value.geti32(), 2);
+        BOOST_REQUIRE_EQUAL(body->right->cast<wasm::Const>()->value.geti32(), 1);
+    }
+    // f2
+    {
+        const auto body = module.functions[1]->body->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(body->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(body->left->cast<wasm::Const>()->value.geti32(), 3);
+
+        const auto r = body->right->cast<wasm::Binary>();
 
-            BOOST_REQUIRE_EQUAL(bin->left->cast<wasm::Const>()->value.geti32(), 1);
-            BOOST_REQUIRE_EQUAL(bin->right->cast<wasm::Const>()->value.geti32(), 2);
+        BOOST_REQUIRE_EQUAL(r->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(r->left->cast<wasm::Const>()->value.geti32(), 2);
+        BOOST_REQUIRE_EQUAL(r->right->cast<wasm::Const>()->value.geti32(), 1);
     }
+    // f3
+    {
+        const auto body = module.functions[2]->body->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(body->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(body->left->is<wasm::Binary>(), true);
+        BOOST_REQUIRE_EQUAL(body->right->is<wasm::Binary>(), true);
+
+        const auto l = body->left->cast<wasm::Binary>();
+        const auto r = body->right->cast<wasm::Binary>();
+
+        BOOST_REQUIRE_EQUAL(l->op, wasm::LtSInt32);
+        BOOST_REQUIRE_EQUAL(l->left->cast<wasm::Const>()->value.geti32(), 4);
+        BOOST_REQUIRE_EQUAL(l->right->cast<wasm::Const>()->value.geti32(), 3);
+
+        BOOST_REQUIRE_EQUAL(r->op, wasm::AddInt32);
+        BOOST_REQUIRE_EQUAL(r->left->cast<wasm::Const>()->value.geti32(), 2);
+        BOOST_REQUIRE_EQUAL(r->right->cast<wasm::Const>()->value.geti32(), 1);
     }
 }
 
-BOOST_AUTO_TEST_SUITE_END() BOOST_AUTO_TEST_SUITE_END()
+BOOST_AUTO_TEST_SUITE_END()
+BOOST_AUTO_TEST_SUITE_END()