Support appendAssemblySize() in AbstractAssembly

3 files changed, 22 insertions, 0 deletions

diff --git a/libjulia/backends/evm/AbstractAssembly.h b/libjulia/backends/evm/AbstractAssembly.h
index f667c1a7..cfc9b8a5 100644
--- a/libjulia/backends/evm/AbstractAssembly.h
+++ b/libjulia/backends/evm/AbstractAssembly.h
@@ -89,6 +89,9 @@ public:
 	/// Return from a subroutine.
 	/// @param _stackDiffAfter the stack adjustment after this instruction.
 	virtual void appendReturnsub(int _returns, int _stackDiffAfter = 0) = 0;
+
+	/// Append the assembled size as a constant.
+	virtual void appendAssemblySize() = 0;
 };
 
 enum class IdentifierContext { LValue, RValue };
diff --git a/libjulia/backends/evm/EVMAssembly.cpp b/libjulia/backends/evm/EVMAssembly.cpp
index 7ec26957..8ebebda1 100644
--- a/libjulia/backends/evm/EVMAssembly.cpp
+++ b/libjulia/backends/evm/EVMAssembly.cpp
@@ -32,6 +32,8 @@ namespace
 {
 /// Size of labels in bytes. Four-byte labels are required by some EVM1.5 instructions.
 size_t constexpr labelReferenceSize = 4;
+
+size_t constexpr assemblySizeReferenceSize = 4;
 }
 
 
@@ -145,6 +147,12 @@ void EVMAssembly::appendReturnsub(int _returns, int _stackDiffAfter)
 
 eth::LinkerObject EVMAssembly::finalize()
 {
+	size_t bytecodeSize = m_bytecode.size();
+	solAssert(uint64_t(bytecodeSize) < (uint64_t(1) << (8 * assemblySizeReferenceSize)), "Bytecode too big.");
+	for (auto const& ref: m_assemblySizePositions)
+		for (size_t i = 0; i < assemblySizeReferenceSize; i++)
+			m_bytecode[ref + i] = byte((bytecodeSize >> (8 * (assemblySizeReferenceSize - i - 1))) & 0xff);
+
 	for (auto const& ref: m_labelReferences)
 	{
 		size_t referencePos = ref.first;
@@ -156,6 +164,7 @@ eth::LinkerObject EVMAssembly::finalize()
 		for (size_t i = 0; i < labelReferenceSize; i++)
 			m_bytecode[referencePos + i] = byte((labelPos >> (8 * (labelReferenceSize - i - 1))) & 0xff);
 	}
+
 	eth::LinkerObject obj;
 	obj.bytecode = m_bytecode;
 	return obj;
@@ -173,3 +182,10 @@ void EVMAssembly::appendLabelReferenceInternal(LabelID _labelId)
 	m_labelReferences[m_bytecode.size()] = _labelId;
 	m_bytecode += bytes(labelReferenceSize);
 }
+
+void EVMAssembly::appendAssemblySize()
+{
+	appendInstruction(solidity::pushInstruction(assemblySizeReferenceSize));
+	m_assemblySizePositions.push_back(m_bytecode.size());
+	m_bytecode += bytes(assemblySizeReferenceSize);
+}
diff --git a/libjulia/backends/evm/EVMAssembly.h b/libjulia/backends/evm/EVMAssembly.h
index a2df0cdc..d6d667b0 100644
--- a/libjulia/backends/evm/EVMAssembly.h
+++ b/libjulia/backends/evm/EVMAssembly.h
@@ -70,6 +70,8 @@ public:
 	/// Return from a subroutine.
 	virtual void appendReturnsub(int _returns, int _stackDiffAfter) override;
 
+	/// Append the assembled size as a constant.
+	virtual void appendAssemblySize() override;
 
 	/// Resolves references inside the bytecode and returns the linker object.
 	eth::LinkerObject finalize();
@@ -84,6 +86,7 @@ private:
 	bytes m_bytecode;
 	std::map<LabelID, size_t> m_labelPositions;
 	std::map<size_t, LabelID> m_labelReferences;
+	std::vector<size_t> m_assemblySizePositions;
 };
 
 }