Merge pull request #13406 from ethereum/slot_on_reference_fix

Fix `.slot` accessing via mapping reference in assembly

Author: wechman

libsolidity/ast/Types.cpp

@@ -3789,6 +3789,11 @@ TypeResult MappingType::interfaceType(bool _inLibrary) const
 	return this;
 }
 
+std::vector<std::tuple<std::string, Type const*>> MappingType::makeStackItems() const
+{
+	return {std::make_tuple("slot", TypeProvider::uint256())};
+}
+
 string TypeType::richIdentifier() const
 {
 	return "t_type" + identifierList(actualType());

libsolidity/ast/Types.h

@@ -1528,6 +1528,8 @@ class MappingType: public CompositeType
 	bool hasSimpleZeroValueInMemory() const override { solAssert(false, ""); }
 	bool nameable() const override { return true; }
 
+	std::vector<std::tuple<std::string, Type const*>> makeStackItems() const override;
+
 	Type const* keyType() const { return m_keyType; }
 	Type const* valueType() const { return m_valueType; }
 

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -173,10 +173,9 @@ struct CopyTranslate: public yul::ASTCopier
 		{
 			solAssert(suffix == "slot" || suffix == "offset");
 			solAssert(varDecl->isLocalVariable());
+			solAssert(!varDecl->type()->isValueType());
 			if (suffix == "slot")
 				value = IRVariable{*varDecl}.part("slot").name();
-			else if (varDecl->type()->isValueType())
-				value = IRVariable{*varDecl}.part("offset").name();
 			else
 			{
 				solAssert(!IRVariable{*varDecl}.hasPart("offset"));

test/libsolidity/semanticTests/inlineAssembly/slot_access_via_mapping_pointer.sol

@@ -0,0 +1,32 @@
+contract C {
+    mapping(uint => uint) private m0;
+    mapping(uint => uint) private m1;
+    mapping(uint => uint) private m2;
+
+    function f(uint i) public returns (uint slot, uint offset) {
+        mapping(uint => uint) storage m0Ptr = m0;
+        mapping(uint => uint) storage m1Ptr = m1;
+        mapping(uint => uint) storage m2Ptr = m2;
+
+        assembly {
+            switch i
+            case 1 {
+                slot := m1Ptr.slot
+                offset := m1Ptr.offset
+            }
+            case 2 {
+                slot := m2Ptr.slot
+                offset := m2Ptr.offset
+            }
+            default {
+                slot := m0Ptr.slot
+                offset := m0Ptr.offset
+            }
+        }
+    }
+}
+
+// ----
+// f(uint256): 0 -> 0, 0
+// f(uint256): 1 -> 1, 0
+// f(uint256): 2 -> 2, 0