Merge pull request #8777 from ethereum/sol_yul_simplefunctions

[Sol - Yul] Add some built-in functions.

test/libsolidity/semanticTests/arithmetics/addmod_mulmod_zero.sol

@@ -18,6 +18,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint256): 0 -> FAILURE
 // g(uint256): 0 -> FAILURE

test/libsolidity/semanticTests/builtinFunctions/blockhash.sol

@@ -0,0 +1,17 @@
+contract C {
+    function f() public returns(bytes32) {
+        return blockhash(1);
+    }
+    function g() public returns(bytes32) {
+        return blockhash(2);
+    }
+    function h() public returns(bytes32) {
+        return blockhash(3);
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f() -> 0x3737373737373737373737373737373737373737373737373737373737373738
+// g() -> 0x3737373737373737373737373737373737373737373737373737373737373739
+// h() -> 0x373737373737373737373737373737373737373737373737373737373737373a