Add assembly if regression test source

test/sources/assembly/if.sol

@@ -0,0 +1,43 @@
+pragma solidity ^0.5.0;
+
+contract Test {
+
+  /// @notice Checks if a given address is whitelisted
+  /// @return true if address is whitelisted, false if not
+  function isWhitelisted
+  (
+    address _address
+  )
+    public
+    view
+    returns (bool _isWhitelisted)
+  {
+    bytes4 _signature = bytes4(keccak256("whitelisted(address)"));
+    address _whitelistContract = getContractAddress("Whitelist");
+
+    assembly {
+      let _pointer := mload(0x40)  // Set _pointer to free memory pointer
+      mstore(_pointer, _signature) // Store _signature at _pointer
+      mstore(add(_pointer, 0x04), _address) // Store _address at _pointer. Offset by 4 bytes for previously stored _signature
+
+      // staticcall(g, a, in, insize, out, outsize) => returns 0 on error, 1 on success
+      let result := staticcall(
+        gas,                // g = gas: whatever was passed already
+        _whitelistContract, // a = address: _whitelist address assigned from getContractAddress()
+        _pointer,           // in = mem in  mem[in..(in+insize): set to _pointer pointer
+        0x24,               // insize = mem insize  mem[in..(in+insize): size of signature (bytes4) + bytes32 = 0x24
+        _pointer,           // out = mem out  mem[out..(out+outsize): output assigned to this storage address
+        0x20                // outsize = mem outsize  mem[out..(out+outsize): output should be 32byte slot (bool size = 0x01 < slot size 0x20)
+      )
+
+      // Revert if not successful
+      if iszero(result) {
+        revert(0, 0)
+      }
+
+      _isWhitelisted := mload(_pointer) // Assign result to returned value
+      mstore(0x40, add(_pointer, 0x24)) // Advance free memory pointer by largest _pointer size
+    }
+  }
+}
+