[Yul] Directly jump over a series of function definitions

Implement a AbstractAssembly::setStackHeight function
Update the tests
Update Changelog

Changelog.md

@@ -85,6 +85,7 @@ Compiler Features:
  * Yul: Adds break and continue keywords to for-loop syntax.
  * Yul: Support ``.`` as part of identifiers.
  * Yul Optimizer: Adds steps for detecting and removing of dead code.
+ * Yul Code Generator: Directly jump over a series of function definitions (instead of jumping over each one)
 
 
 Bugfixes:

libyul/backends/evm/AbstractAssembly.h

@@ -62,6 +62,7 @@ public:
 	/// Retrieve the current height of the stack. This does not have to be zero
 	/// at the beginning.
 	virtual int stackHeight() const = 0;
+	virtual void setStackHeight(int height) = 0;
 	/// Append an EVM instruction.
 	virtual void appendInstruction(dev::eth::Instruction _instruction) = 0;
 	/// Append a constant.

libyul/backends/evm/AsmCodeGen.cpp

@@ -57,6 +57,11 @@ int EthAssemblyAdapter::stackHeight() const
 	return m_assembly.deposit();
 }
 
+void EthAssemblyAdapter::setStackHeight(int height)
+{
+	m_assembly.setDeposit(height);
+}
+
 void EthAssemblyAdapter::appendInstruction(dev::eth::Instruction _instruction)
 {
 	m_assembly.append(_instruction);

libyul/backends/evm/AsmCodeGen.h

@@ -44,6 +44,7 @@ public:
 	explicit EthAssemblyAdapter(dev::eth::Assembly& _assembly);
 	void setSourceLocation(langutil::SourceLocation const& _location) override;
 	int stackHeight() const override;
+	void setStackHeight(int height) override;
 	void appendInstruction(dev::eth::Instruction _instruction) override;
 	void appendConstant(dev::u256 const& _constant) override;
 	void appendLabel(LabelID _labelId) override;

libyul/backends/evm/EVMAssembly.h

@@ -45,6 +45,7 @@ public:
 	/// Retrieve the current height of the stack. This does not have to be zero
 	/// at the beginning.
 	int stackHeight() const override { return m_stackHeight; }
+	void setStackHeight(int height) override { m_stackHeight = height; }
 	/// Append an EVM instruction.
 	void appendInstruction(dev::eth::Instruction _instruction) override;
 	/// Append a constant.

libyul/backends/evm/EVMCodeTransform.cpp

@@ -490,19 +490,15 @@ void CodeTransform::operator()(FunctionDefinition const& _function)
 	}
 
 	m_assembly.setSourceLocation(_function.location);
-	int stackHeightBefore = m_assembly.stackHeight();
+	int const stackHeightBefore = m_assembly.stackHeight();
-	AbstractAssembly::LabelID afterFunction = m_assembly.newLabelId();
 
 	if (m_evm15)
-	{
-		m_assembly.appendJumpTo(afterFunction, -stackHeightBefore);
 		m_assembly.appendBeginsub(functionEntryID(_function.name, function), _function.parameters.size());
-	}
 	else
-	{
-		m_assembly.appendJumpTo(afterFunction, -stackHeightBefore + height);
 		m_assembly.appendLabel(functionEntryID(_function.name, function));
-	}
+
+	m_assembly.setStackHeight(height);
+
 	m_stackAdjustment += localStackAdjustment;
 
 	for (auto const& v: _function.returnVariables)
@@ -592,8 +588,8 @@ void CodeTransform::operator()(FunctionDefinition const& _function)
 	else
 		m_assembly.appendJump(stackHeightBefore - _function.returnVariables.size());
 	m_stackAdjustment -= localStackAdjustment;
-	m_assembly.appendLabel(afterFunction);
 	checkStackHeight(&_function);
+	m_assembly.setStackHeight(stackHeightBefore);
 }
 
 void CodeTransform::operator()(ForLoop const& _forLoop)
@@ -727,11 +723,32 @@ void CodeTransform::visitExpression(Expression const& _expression)
 
 void CodeTransform::visitStatements(vector<Statement> const& _statements)
 {
+	// Workaround boost bug:
+	// https://www.boost.org/doc/libs/1_63_0/libs/optional/doc/html/boost_optional/tutorial/gotchas/false_positive_with__wmaybe_uninitialized.html
+	boost::optional<AbstractAssembly::LabelID> jumpTarget = boost::make_optional(false, AbstractAssembly::LabelID());
+
 	for (auto const& statement: _statements)
 	{
 		freeUnusedVariables();
+		auto const* functionDefinition = boost::get<FunctionDefinition>(&statement);
+		if (functionDefinition && !jumpTarget)
+		{
+			m_assembly.setSourceLocation(locationOf(statement));
+			jumpTarget = m_assembly.newLabelId();
+			m_assembly.appendJumpTo(*jumpTarget, 0);
+		}
+		else if (!functionDefinition && jumpTarget)
+		{
+			m_assembly.appendLabel(*jumpTarget);
+			jumpTarget = boost::none;
+		}
+
 		boost::apply_visitor(*this, statement);
 	}
+	// we may have a leftover jumpTarget
+	if (jumpTarget)
+		m_assembly.appendLabel(*jumpTarget);
+
 	freeUnusedVariables();
 }
 

libyul/backends/evm/NoOutputAssembly.h

@@ -49,6 +49,7 @@ public:
 
 	void setSourceLocation(langutil::SourceLocation const&) override {}
 	int stackHeight() const override { return m_stackHeight; }
+	void setStackHeight(int height) override { m_stackHeight = height; }
 	void appendInstruction(dev::eth::Instruction _instruction) override;
 	void appendConstant(dev::u256 const& _constant) override;
 	void appendLabel(LabelID _labelId) override;

test/libyul/StackReuseCodegen.cpp

@@ -277,16 +277,15 @@ BOOST_AUTO_TEST_CASE(functions_multi_return)
 		let unused := 7
 	})";
 	BOOST_CHECK_EQUAL(assemble(in),
-		"PUSH1 0xB JUMP "
+		"PUSH1 0x13 JUMP "
 		"JUMPDEST PUSH1 0x0 SWAP3 SWAP2 POP POP JUMP " // f
-		"JUMPDEST PUSH1 0x17 JUMP "
 		"JUMPDEST PUSH1 0x0 PUSH1 0x0 SWAP1 SWAP2 JUMP " // g
-		"JUMPDEST PUSH1 0x21 PUSH1 0x2 PUSH1 0x1 PUSH1 0x3 JUMP " // f(1, 2)
+		"JUMPDEST PUSH1 0x1D PUSH1 0x2 PUSH1 0x1 PUSH1 0x3 JUMP " // f(1, 2)
-		"JUMPDEST PUSH1 0x2B PUSH1 0x4 PUSH1 0x3 PUSH1 0x3 JUMP " // f(3, 4)
+		"JUMPDEST PUSH1 0x27 PUSH1 0x4 PUSH1 0x3 PUSH1 0x3 JUMP " // f(3, 4)
 		"JUMPDEST SWAP1 POP " // assignment to x
 		"POP " // remove x
-		"PUSH1 0x34 PUSH1 0xF JUMP " // g()
+		"PUSH1 0x30 PUSH1 0xB JUMP " // g()
-		"JUMPDEST PUSH1 0x3A PUSH1 0xF JUMP " // g()
+		"JUMPDEST PUSH1 0x36 PUSH1 0xB JUMP " // g()
 		"JUMPDEST SWAP2 POP SWAP2 POP " // assignments
 		"POP POP " // removal of y and z
 		"PUSH1 0x7 POP "

test/libyul/objectCompiler/function_series.yul

@@ -0,0 +1,28 @@
+object "Contract" {
+  code {
+    function f() {}
+    function g() {}
+    sstore(0, 1)
+  }
+}
+
+// ----
+// Assembly:
+//     /* "source":33:48   */
+//   jump(tag_1)
+// tag_2:
+//     /* "source":46:48   */
+//   jump
+//     /* "source":53:68   */
+// tag_3:
+//     /* "source":66:68   */
+//   jump
+// tag_1:
+//     /* "source":83:84   */
+//   0x01
+//     /* "source":80:81   */
+//   0x00
+//     /* "source":73:85   */
+//   sstore
+// Bytecode: 6007565b565b565b6001600055
+// Opcodes: PUSH1 0x7 JUMP JUMPDEST JUMP JUMPDEST JUMP JUMPDEST PUSH1 0x1 PUSH1 0x0 SSTORE