Merge pull request #6646 from ethereum/storageAccess

[Yul] Storage access for sol -> yul

test/libsolidity/SolidityExecutionFramework.h

@@ -92,7 +92,9 @@ public:
 			yul::AssemblyStack asmStack(
 				m_evmVersion,
 				yul::AssemblyStack::Language::StrictAssembly,
-				m_optimiserSettings
+				// Ignore optimiser settings here because we need Yul optimisation to
+				// get code that does not exhaust the stack.
+				OptimiserSettings::full()
 			);
 			if (!asmStack.parseAndAnalyze("", m_compiler.yulIROptimized(
 				_contractName.empty() ? m_compiler.lastContractName() : _contractName

test/libsolidity/semanticTests/viaYul/storage/packed_storage.sol

@@ -0,0 +1,16 @@
+contract C {
+    uint16 x;
+    byte y;
+    uint16 z;
+    function f(uint8 a) public returns (uint _x) {
+        x = a;
+        y = byte(uint8(x) + 1);
+        z = uint8(y) + 1;
+        x = z + 1;
+        _x = x;
+    }
+}
+// ====
+// compileViaYul: true
+// ----
+// f(uint8): 6 -> 9

test/libsolidity/semanticTests/viaYul/storage/simple_storage.sol

@@ -0,0 +1,17 @@
+contract C {
+    uint x;
+    uint y;
+    function setX(uint a) public returns (uint _x) {
+        x = a;
+        _x = x;
+    }
+    function setY(uint a) public returns (uint _y) {
+        y = a;
+        _y = y;
+    }
+}
+// ====
+// compileViaYul: true
+// ----
+// setX(uint256): 6 -> 6
+// setY(uint256): 2 -> 2