[SMTChecker] Support addmod and mulmod.

test/libsolidity/smtCheckerTests/math/addmod_1.sol

@@ -0,0 +1,21 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f() public pure {
+		assert(addmod(2**256 - 1, 10, 9) == 7);
+		uint y = 0;
+		uint x = addmod(2**256 - 1, 10, y);
+		assert(x == 1);
+	}
+	function g(uint x, uint y, uint k) public pure returns (uint) {
+		return addmod(x, y, k);
+	}
+}
+// ----
+// Warning 1218: (83-108): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (141-166): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (76-114): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (170-184): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (263-278): CHC: Error trying to invoke SMT solver.
+// Warning 3046: (141-166): BMC: Division by zero happens here.
+// Warning 3046: (263-278): BMC: Division by zero happens here.

test/libsolidity/smtCheckerTests/math/addmod_mulmod.sol

@@ -0,0 +1,16 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function test() public pure {
+		uint x;
+		if ((2**255 + 2**255) % 7 != addmod(2**255, 2**255, 7)) x = 1;
+		if ((2**255 + 2**255) % 7 != addmod(2**255, 2**255, 7)) x = 2;
+		assert(x == 0);
+	}
+}
+// ----
+// Warning 1218: (118-143): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (183-208): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (219-233): CHC: Error trying to invoke SMT solver.
+// Warning 6838: (93-143): BMC: Condition is always false.
+// Warning 6838: (158-208): BMC: Condition is always false.

test/libsolidity/smtCheckerTests/math/addmod_mulmod_zero.sol

@@ -0,0 +1,35 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f(uint256 d) public pure {
+		uint x = addmod(1, 2, d);
+		assert(x < d);
+	}
+
+	function g(uint256 d) public pure {
+		uint x = mulmod(1, 2, d);
+		assert(x < d);
+	}
+
+	function h() public pure returns (uint256) {
+		uint x = mulmod(0, 1, 2);
+		uint y = mulmod(1, 0, 2);
+		assert(x == y);
+		uint z = addmod(0, 1, 2);
+		uint t = addmod(1, 0, 2);
+		assert(z == t);
+	}
+}
+// ----
+// Warning 1218: (94-109): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (113-126): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (180-195): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (199-212): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (275-290): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (303-318): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (349-364): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (377-392): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (322-336): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (396-410): CHC: Error trying to invoke SMT solver.
+// Warning 3046: (94-109): BMC: Division by zero happens here.
+// Warning 3046: (180-195): BMC: Division by zero happens here.

test/libsolidity/smtCheckerTests/math/addmulmod.sol

@@ -0,0 +1,24 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function test_addmod(uint x, uint y) public pure {
+		require(x % 13 == 0);
+		require(y % 13 == 0);
+
+		uint z = addmod(x, y, 13);
+		assert(z == 0);
+	}
+	function test_mulmod(uint x, uint y) public pure {
+		require(x % 13 == 0);
+		require(y % 13 == 0);
+
+		uint z = mulmod(x, y, 13);
+		assert(z == 0);
+	}
+}
+// ----
+// Warning 1218: (158-174): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (178-192): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (309-325): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (329-343): CHC: Error trying to invoke SMT solver.
+// Warning 7812: (329-343): BMC: Assertion violation might happen here.

test/libsolidity/smtCheckerTests/math/mulmod_1.sol

@@ -0,0 +1,21 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f() public pure {
+		assert(mulmod(2**256 - 1, 2, 14) == 2);
+		uint y = 0;
+		uint x = mulmod(2**256 - 1, 10, y);
+		assert(x == 1);
+	}
+	function g(uint x, uint y, uint k) public pure returns (uint) {
+		return mulmod(x, y, k);
+	}
+}
+// ----
+// Warning 1218: (83-108): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (141-166): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (76-114): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (170-184): CHC: Error trying to invoke SMT solver.
+// Warning 1218: (263-278): CHC: Error trying to invoke SMT solver.
+// Warning 3046: (141-166): BMC: Division by zero happens here.
+// Warning 3046: (263-278): BMC: Division by zero happens here.