Merge pull request #6940 from ethereum/sol-yul-storage-array-index

[Sol->Yul] Implement index access for storage arrays

libsolidity/codegen/YulUtilFunctions.cpp

@@ -724,6 +724,36 @@ string YulUtilFunctions::arrayDataAreaFunction(ArrayType const& _type)
 	});
 }
 
+string YulUtilFunctions::storageArrayIndexAccessFunction(ArrayType const& _type)
+{
+	solUnimplementedAssert(_type.baseType()->storageBytes() > 16, "");
+
+	string functionName = "storage_array_index_access_" + _type.identifier();
+	return m_functionCollector->createFunction(functionName, [&]() {
+		return Whiskers(R"(
+			function <functionName>(array, index) -> slot, offset {
+				if iszero(lt(index, <arrayLen>(array))) {
+					invalid()
+				}
+
+				let data := <dataAreaFunc>(array)
+				<?multipleItemsPerSlot>
+
+				<!multipleItemsPerSlot>
+					slot := add(data, mul(index, <storageSize>))
+					offset := 0
+				</multipleItemsPerSlot>
+			}
+		)")
+		("functionName", functionName)
+		("arrayLen", arrayLengthFunction(_type))
+		("dataAreaFunc", arrayDataAreaFunction(_type))
+		("multipleItemsPerSlot", _type.baseType()->storageBytes() <= 16)
+		("storageSize", _type.baseType()->storageSize().str())
+		.render();
+	});
+}
+
 string YulUtilFunctions::nextArrayElementFunction(ArrayType const& _type)
 {
 	solAssert(!_type.isByteArray(), "");

libsolidity/codegen/YulUtilFunctions.h

@@ -140,6 +140,12 @@ public:
 	/// a memory pointer or a calldata pointer to the slot number / memory pointer / calldata pointer
 	/// for the data position of an array which is stored in that slot / memory area / calldata area.
 	std::string arrayDataAreaFunction(ArrayType const& _type);
+
+	/// @returns the name of a function that returns the slot and offset for the
+	/// given array and index
+	/// signature: (array, index) -> slot, offset
+	std::string storageArrayIndexAccessFunction(ArrayType const& _type);
+
 	/// @returns the name of a function that advances an array data pointer to the next element.
 	/// Only works for memory arrays, calldata arrays and storage arrays that every item occupies one or multiple full slots.
 	std::string nextArrayElementFunction(ArrayType const& _type);

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -56,6 +56,35 @@ struct CopyTranslate: public yul::ASTCopier
 
 	using ASTCopier::operator();
 
+	yul::Expression operator()(yul::Identifier const& _identifier) override
+	{
+		if (m_references.count(&_identifier))
+		{
+			auto const& reference = m_references.at(&_identifier);
+			auto const varDecl = dynamic_cast<VariableDeclaration const*>(reference.declaration);
+			solUnimplementedAssert(varDecl, "");
+
+			if (reference.isOffset || reference.isSlot)
+			{
+				solAssert(reference.isOffset != reference.isSlot, "");
+
+				pair<u256, unsigned> slot_offset = m_context.storageLocationOfVariable(*varDecl);
+
+				string const value = reference.isSlot ?
+					slot_offset.first.str() :
+					to_string(slot_offset.second);
+
+				return yul::Literal{
+					_identifier.location,
+						yul::LiteralKind::Number,
+						yul::YulString{value},
+						yul::YulString{"uint256"}
+				};
+			}
+		}
+		return ASTCopier::operator()(_identifier);
+	}
+
 	yul::YulString translateIdentifier(yul::YulString _name) override
 	{
 		// Strictly, the dialect used by inline assembly (m_dialect) could be different
@@ -76,9 +105,10 @@ struct CopyTranslate: public yul::ASTCopier
 		auto const& reference = m_references.at(&_identifier);
 		auto const varDecl = dynamic_cast<VariableDeclaration const*>(reference.declaration);
 		solUnimplementedAssert(varDecl, "");
-		solUnimplementedAssert(
+
+		solAssert(
 			reference.isOffset == false && reference.isSlot == false,
-			""
+			"Should not be called for offset/slot"
 		);
 
 		return yul::Identifier{
@@ -790,7 +820,45 @@ void IRGeneratorForStatements::endVisit(IndexAccess const& _indexAccess)
 		));
 	}
 	else if (baseType.category() == Type::Category::Array)
-		solUnimplementedAssert(false, "");
+	{
+		ArrayType const& arrayType = dynamic_cast<ArrayType const&>(baseType);
+		solAssert(_indexAccess.indexExpression(), "Index expression expected.");
+
+		switch (arrayType.location())
+		{
+			case DataLocation::Storage:
+			{
+				string slot = m_context.newYulVariable();
+				string offset = m_context.newYulVariable();
+
+				m_code << Whiskers(R"(
+					let <slot>, <offset> := <indexFunc>(<array>, <index>)
+				)")
+				("slot", slot)
+				("offset", offset)
+				("indexFunc", m_utils.storageArrayIndexAccessFunction(arrayType))
+				("array", m_context.variable(_indexAccess.baseExpression()))
+				("index", m_context.variable(*_indexAccess.indexExpression()))
+				.render();
+
+				setLValue(_indexAccess, make_unique<IRStorageItem>(
+					m_context,
+					slot,
+					offset,
+					*_indexAccess.annotation().type
+				));
+
+				break;
+			}
+			case DataLocation::Memory:
+				solUnimplementedAssert(false, "");
+				break;
+			case DataLocation::CallData:
+				solUnimplementedAssert(false, "");
+				break;
+		}
+
+	}
 	else if (baseType.category() == Type::Category::FixedBytes)
 		solUnimplementedAssert(false, "");
 	else if (baseType.category() == Type::Category::TypeType)

libsolidity/codegen/ir/IRLValue.cpp

@@ -135,7 +135,8 @@ string IRStorageItem::storeValue(string const& _value, Type const& _sourceType)
 
 string IRStorageItem::setToZero() const
 {
-	solUnimplemented("Delete for storage location not yet implemented");
+	solUnimplementedAssert(m_type->isValueType(), "");
+	return storeValue(m_context.utils().zeroValueFunction(*m_type) + "()", *m_type);
 }
 
 IRStorageArrayLength::IRStorageArrayLength(IRGenerationContext& _context, string _slot, Type const& _type, ArrayType const& _arrayType):

test/libsolidity/semanticTests/viaYul/array_storage_index_access.sol

@@ -0,0 +1,26 @@
+contract C {
+	uint[] storageArray;
+	function test_indicies(uint256 len) public
+	{
+		storageArray.length = len;
+
+		for (uint i = 0; i < len; i++)
+			storageArray[i] = i + 1;
+
+		for (uint i = 0; i < len; i++)
+			require(storageArray[i] == i + 1);
+	}
+}
+// ====
+// compileViaYul: true
+// ----
+// test_indicies(uint256): 1 ->
+// test_indicies(uint256): 129 ->
+// test_indicies(uint256): 5 ->
+// test_indicies(uint256): 10 ->
+// test_indicies(uint256): 15 ->
+// test_indicies(uint256): 0xFF ->
+// test_indicies(uint256): 1000 ->
+// test_indicies(uint256): 129 ->
+// test_indicies(uint256): 128 ->
+// test_indicies(uint256): 1 ->

test/libsolidity/semanticTests/viaYul/array_storage_index_boundery_test.sol

@@ -0,0 +1,21 @@
+contract C {
+	uint[] storageArray;
+	function test_boundery_check(uint256 len, uint256 access) public returns
+(uint256)
+	{
+		storageArray.length = len;
+		return storageArray[access];
+	}
+}
+// ====
+// compileViaYul: true
+// ----
+// test_boundery_check(uint256, uint256): 10, 11 -> FAILURE
+// test_boundery_check(uint256, uint256): 10, 9 -> 0
+// test_boundery_check(uint256, uint256): 1, 9 -> FAILURE
+// test_boundery_check(uint256, uint256): 1, 1 -> FAILURE
+// test_boundery_check(uint256, uint256): 10, 10 -> FAILURE
+// test_boundery_check(uint256, uint256): 256, 256 -> FAILURE
+// test_boundery_check(uint256, uint256): 256, 255 -> 0
+// test_boundery_check(uint256, uint256): 256, 0xFFFF -> FAILURE
+// test_boundery_check(uint256, uint256): 256, 2 -> 0

test/libsolidity/semanticTests/viaYul/array_storage_index_zeroed_test.sol

@@ -0,0 +1,51 @@
+contract C {
+	uint[] storageArray;
+	function test_zeroed_indicies(uint256 len) public
+	{
+		storageArray.length = len;
+
+		for (uint i = 0; i < len; i++)
+			storageArray[i] = i + 1;
+
+		if (len > 3)
+		{
+			storageArray.length = 3;
+
+			for (uint i = 3; i < len; i++)
+			{
+				assembly {
+					mstore(0, storageArray_slot)
+					let pos := add(keccak256(0, 0x20), i)
+
+					if iszero(eq(sload(pos), 0)) {
+						revert(0, 0)
+					}
+				}
+			}
+
+		}
+
+		storageArray.length = 0;
+		storageArray.length = len;
+
+		for (uint i = 0; i < len; i++)
+		{
+			require(storageArray[i] == 0);
+
+			uint256 val = storageArray[i];
+			uint256 check;
+
+			assembly { check := iszero(val) }
+
+			require(check == 1);
+		}
+	}
+}
+// ====
+// compileViaYul: true
+// ----
+// test_zeroed_indicies(uint256): 1 ->
+// test_zeroed_indicies(uint256): 5 ->
+// test_zeroed_indicies(uint256): 10 ->
+// test_zeroed_indicies(uint256): 15 ->
+// test_zeroed_indicies(uint256): 0xFF ->