From f6ed29b88b0a721984173df04f04ad4c48d8711d Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 4 Dec 2018 18:57:07 +0100
Subject: [PATCH] Extend abstract assembly to be able to handle sub-objects.

---
 libsolidity/codegen/AsmCodeGen.cpp     | 36 ++++++++++++++++++++++++++
 libsolidity/codegen/AsmCodeGen.h       |  6 +++++
 libyul/backends/evm/AbstractAssembly.h | 10 +++++++
 libyul/backends/evm/EVMAssembly.cpp    | 21 +++++++++++++++
 libyul/backends/evm/EVMAssembly.h      |  4 +++
 5 files changed, 77 insertions(+)

diff --git a/libsolidity/codegen/AsmCodeGen.cpp b/libsolidity/codegen/AsmCodeGen.cpp
index 4ca0c4e22..dfcc900b3 100644
--- a/libsolidity/codegen/AsmCodeGen.cpp
+++ b/libsolidity/codegen/AsmCodeGen.cpp
@@ -27,10 +27,13 @@
 #include <libyul/backends/evm/EVMCodeTransform.h>
 
 #include <libevmasm/Assembly.h>
+#include <libevmasm/AssemblyItem.h>
 #include <libevmasm/Instruction.h>
 
 #include <liblangutil/SourceLocation.h>
 
+#include <libdevcore/FixedHash.h>
+
 #include <memory>
 #include <functional>
 
@@ -131,6 +134,39 @@ void EthAssemblyAdapter::appendAssemblySize()
 	m_assembly.appendProgramSize();
 }
 
+pair<shared_ptr<AbstractAssembly>, AbstractAssembly::SubID> EthAssemblyAdapter::createSubAssembly()
+{
+	shared_ptr<eth::Assembly> assembly{make_shared<eth::Assembly>()};
+	auto sub = m_assembly.newSub(assembly);
+	return {make_shared<EthAssemblyAdapter>(*assembly), size_t(sub.data())};
+}
+
+void EthAssemblyAdapter::appendDataOffset(AbstractAssembly::SubID _sub)
+{
+	auto it = m_dataHashBySubId.find(_sub);
+	if (it == m_dataHashBySubId.end())
+		m_assembly.pushSubroutineOffset(size_t(_sub));
+	else
+		m_assembly << eth::AssemblyItem(eth::PushData, it->second);
+}
+
+void EthAssemblyAdapter::appendDataSize(AbstractAssembly::SubID _sub)
+{
+	auto it = m_dataHashBySubId.find(_sub);
+	if (it == m_dataHashBySubId.end())
+		m_assembly.pushSubroutineSize(size_t(_sub));
+	else
+		m_assembly << u256(m_assembly.data(h256(it->second)).size());
+}
+
+AbstractAssembly::SubID EthAssemblyAdapter::appendData(bytes const& _data)
+{
+	eth::AssemblyItem pushData = m_assembly.newData(_data);
+	SubID subID = m_nextDataCounter++;
+	m_dataHashBySubId[subID] = pushData.data();
+	return subID;
+}
+
 EthAssemblyAdapter::LabelID EthAssemblyAdapter::assemblyTagToIdentifier(eth::AssemblyItem const& _tag)
 {
 	u256 id = _tag.data();
diff --git a/libsolidity/codegen/AsmCodeGen.h b/libsolidity/codegen/AsmCodeGen.h
index b5bd33d55..4c6d97f48 100644
--- a/libsolidity/codegen/AsmCodeGen.h
+++ b/libsolidity/codegen/AsmCodeGen.h
@@ -63,11 +63,17 @@ public:
 	void appendJumpsub(LabelID, int, int) override;
 	void appendReturnsub(int, int) override;
 	void appendAssemblySize() override;
+	std::pair<std::shared_ptr<AbstractAssembly>, SubID> createSubAssembly() override;
+	void appendDataOffset(SubID _sub) override;
+	void appendDataSize(SubID _sub) override;
+	SubID appendData(dev::bytes const& _data) override;
 
 private:
 	static LabelID assemblyTagToIdentifier(eth::AssemblyItem const& _tag);
 
 	eth::Assembly& m_assembly;
+	std::map<SubID, dev::u256> m_dataHashBySubId;
+	size_t m_nextDataCounter = std::numeric_limits<size_t>::max() / 2;
 };
 
 class CodeGenerator
diff --git a/libyul/backends/evm/AbstractAssembly.h b/libyul/backends/evm/AbstractAssembly.h
index 97b1d3052..1f224dedf 100644
--- a/libyul/backends/evm/AbstractAssembly.h
+++ b/libyul/backends/evm/AbstractAssembly.h
@@ -26,6 +26,7 @@
 #include <libdevcore/CommonData.h>
 
 #include <functional>
+#include <memory>
 
 namespace langutil
 {
@@ -52,6 +53,7 @@ class AbstractAssembly
 {
 public:
 	using LabelID = size_t;
+	using SubID = size_t;
 
 	virtual ~AbstractAssembly() {}
 
@@ -98,6 +100,14 @@ public:
 
 	/// Append the assembled size as a constant.
 	virtual void appendAssemblySize() = 0;
+	/// Creates a new sub-assembly, which can be referenced using dataSize and dataOffset.
+	virtual std::pair<std::shared_ptr<AbstractAssembly>, SubID> createSubAssembly() = 0;
+	/// Appends the offset of the given sub-assembly or data.
+	virtual void appendDataOffset(SubID _sub) = 0;
+	/// Appends the size of the given sub-assembly or data.
+	virtual void appendDataSize(SubID _sub) = 0;
+	/// Appends the given data to the assembly and returns its ID.
+	virtual SubID appendData(dev::bytes const& _data) = 0;
 };
 
 enum class IdentifierContext { LValue, RValue };
diff --git a/libyul/backends/evm/EVMAssembly.cpp b/libyul/backends/evm/EVMAssembly.cpp
index 99506317a..2cf9f0011 100644
--- a/libyul/backends/evm/EVMAssembly.cpp
+++ b/libyul/backends/evm/EVMAssembly.cpp
@@ -194,6 +194,27 @@ void EVMAssembly::appendAssemblySize()
 	m_bytecode += bytes(assemblySizeReferenceSize);
 }
 
+pair<shared_ptr<AbstractAssembly>, AbstractAssembly::SubID> EVMAssembly::createSubAssembly()
+{
+	solAssert(false, "Sub assemblies not implemented.");
+	return {};
+}
+
+void EVMAssembly::appendDataOffset(AbstractAssembly::SubID)
+{
+	solAssert(false, "Data not implemented.");
+}
+
+void EVMAssembly::appendDataSize(AbstractAssembly::SubID)
+{
+	solAssert(false, "Data not implemented.");
+}
+
+AbstractAssembly::SubID EVMAssembly::appendData(bytes const&)
+{
+	solAssert(false, "Data not implemented.");
+}
+
 void EVMAssembly::updateReference(size_t pos, size_t size, u256 value)
 {
 	solAssert(m_bytecode.size() >= size && pos <= m_bytecode.size() - size, "");
diff --git a/libyul/backends/evm/EVMAssembly.h b/libyul/backends/evm/EVMAssembly.h
index d0a437ccd..cef9c19ac 100644
--- a/libyul/backends/evm/EVMAssembly.h
+++ b/libyul/backends/evm/EVMAssembly.h
@@ -77,6 +77,10 @@ public:
 
 	/// Append the assembled size as a constant.
 	void appendAssemblySize() override;
+	std::pair<std::shared_ptr<AbstractAssembly>, SubID> createSubAssembly() override;
+	void appendDataOffset(SubID _sub) override;
+	void appendDataSize(SubID _sub) override;
+	SubID appendData(dev::bytes const& _data) override;
 
 	/// Resolves references inside the bytecode and returns the linker object.
 	dev::eth::LinkerObject finalize();