[SMTChecker] Fix ICE compound bitwise op inside branch

test/libsolidity/smtCheckerTests/operators/compound_bitwise_and_1.sol

@@ -0,0 +1,13 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f(bool b) public pure {
+		uint v = 1;
+		if (b)
+			v &= 1;
+		assert(v == 1);
+	}
+}
+// ----
+// Warning: (106-112): Assertion checker does not yet implement this assignment operator.
+// Warning: (116-130): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/compound_bitwise_or_1.sol

@@ -0,0 +1,13 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f(bool b) public pure {
+		uint v = 0;
+		if (b)
+			v |= 1;
+		assert(v == 1);
+	}
+}
+// ----
+// Warning: (106-112): Assertion checker does not yet implement this assignment operator.
+// Warning: (116-130): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/compound_bitwise_xor_1.sol

@@ -0,0 +1,13 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f(bool b) public pure {
+		uint v = 0;
+		if (b)
+			v ^= 1;
+		assert(v == 1);
+	}
+}
+// ----
+// Warning: (106-112): Assertion checker does not yet implement this assignment operator.
+// Warning: (116-130): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/compound_shl_1.sol

@@ -0,0 +1,13 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f(bool b) public pure {
+		uint v = 1000000;
+		if (b)
+			v <<= 2;
+		assert(v > 0);
+	}
+}
+// ----
+// Warning: (112-119): Assertion checker does not yet implement this assignment operator.
+// Warning: (123-136): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/compound_shr_1.sol

@@ -0,0 +1,13 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f(bool b) public pure {
+		uint v = 1;
+		if (b)
+			v >>= 2;
+		assert(v > 0);
+	}
+}
+// ----
+// Warning: (106-113): Assertion checker does not yet implement this assignment operator.
+// Warning: (117-130): Assertion violation happens here