Code generation for creating arrays.

3 files changed, 67 insertions, 9 deletions

diff --git a/libsolidity/codegen/CompilerUtils.cpp b/libsolidity/codegen/CompilerUtils.cpp
index 2ebf5b64..357013e6 100644
--- a/libsolidity/codegen/CompilerUtils.cpp
+++ b/libsolidity/codegen/CompilerUtils.cpp
@@ -266,6 +266,19 @@ void CompilerUtils::encodeToMemory(
 	popStackSlots(argSize + dynPointers + 1);
 }
 
+void CompilerUtils::zeroInitialiseMemoryArray(ArrayType const& _type)
+{
+	auto repeat = m_context.newTag();
+	m_context << repeat;
+	pushZeroValue(*_type.baseType());
+	storeInMemoryDynamic(*_type.baseType());
+	m_context << eth::Instruction::SWAP1 << u256(1) << eth::Instruction::SWAP1;
+	m_context << eth::Instruction::SUB << eth::Instruction::SWAP1;
+	m_context << eth::Instruction::DUP2;
+	m_context.appendConditionalJumpTo(repeat);
+	m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
+}
+
 void CompilerUtils::memoryCopy()
 {
 	// Stack here: size target source
@@ -646,15 +659,8 @@ void CompilerUtils::pushZeroValue(Type const& _type)
 		{
 			m_context << arrayType->length() << eth::Instruction::SWAP1;
 			// stack: items_to_do memory_pos
-			auto repeat = m_context.newTag();
-			m_context << repeat;
-			pushZeroValue(*arrayType->baseType());
-			storeInMemoryDynamic(*arrayType->baseType());
-			m_context << eth::Instruction::SWAP1 << u256(1) << eth::Instruction::SWAP1;
-			m_context << eth::Instruction::SUB << eth::Instruction::SWAP1;
-			m_context << eth::Instruction::DUP2;
-			m_context.appendConditionalJumpTo(repeat);
-			m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
+			zeroInitialiseMemoryArray(*arrayType);
+			// stack: updated_memory_pos
 		}
 	}
 	else
diff --git a/libsolidity/codegen/CompilerUtils.h b/libsolidity/codegen/CompilerUtils.h
index 6292e5c7..134afd78 100644
--- a/libsolidity/codegen/CompilerUtils.h
+++ b/libsolidity/codegen/CompilerUtils.h
@@ -103,6 +103,11 @@ public:
 		bool _encodeAsLibraryTypes = false
 	);
 
+	/// Zero-initialises (the data part of) an already allocated memory array.
+	/// Stack pre: <length> <memptr>
+	/// Stack post: <updated_memptr>
+	void zeroInitialiseMemoryArray(ArrayType const& _type);
+
 	/// Uses a CALL to the identity contract to perform a memory-to-memory copy.
 	/// Stack pre: <size> <target> <source>
 	/// Stack post:
diff --git a/libsolidity/codegen/ExpressionCompiler.cpp b/libsolidity/codegen/ExpressionCompiler.cpp
index 1a089d63..c94c988b 100644
--- a/libsolidity/codegen/ExpressionCompiler.cpp
+++ b/libsolidity/codegen/ExpressionCompiler.cpp
@@ -703,6 +703,53 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 				StorageByteArrayElement(m_context).storeValue(*type, _functionCall.location(), true);
 			break;
 		}
+		case Location::ObjectCreation:
+		{
+			// Will allocate at the end of memory (MSIZE) and not write at all unless the base
+			// type is dynamically sized.
+			ArrayType const& arrayType = dynamic_cast<ArrayType const&>(*_functionCall.annotation().type);
+			_functionCall.expression().accept(*this);
+			solAssert(arguments.size() == 1, "");
+
+			// Fetch requested length.
+			arguments[0]->accept(*this);
+			utils().convertType(*arguments[0]->annotation().type, IntegerType(256));
+
+			// Stack: requested_length
+			// Allocate at max(MSIZE, freeMemoryPointer)
+			utils().fetchFreeMemoryPointer();
+			m_context << eth::Instruction::DUP1 << eth::Instruction::MSIZE;
+			m_context << eth::Instruction::LT;
+			auto initialise = m_context.appendConditionalJump();
+			// Free memory pointer does not point to empty memory, use MSIZE.
+			m_context << eth::Instruction::POP;
+			m_context << eth::Instruction::MSIZE;
+			m_context << initialise;
+
+			// Stack: requested_length memptr
+			m_context << eth::Instruction::SWAP1;
+			// Stack: memptr requested_length
+			// store length
+			m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3 << eth::Instruction::MSTORE;
+			// Stack: memptr requested_length
+			// update free memory pointer
+			m_context << eth::Instruction::DUP1 << arrayType.baseType()->memoryHeadSize();
+			m_context << eth::Instruction::MUL << u256(32) << eth::Instruction::ADD;
+			m_context << eth::Instruction::DUP3 << eth::Instruction::ADD;
+			utils().storeFreeMemoryPointer();
+			// Stack: memptr requested_length
+
+			// We only have to initialise if the base type is a not a value type.
+			if (dynamic_cast<ReferenceType const*>(arrayType.baseType().get()))
+			{
+				m_context << eth::Instruction::DUP2 << u256(32) << eth::Instruction::ADD;
+				utils().zeroInitialiseMemoryArray(arrayType);
+				m_context << eth::Instruction::POP;
+			}
+			else
+				m_context << eth::Instruction::POP;
+			break;
+		}
 		default:
 			BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Invalid function type."));
 		}