From 14c92d83974e801f849d2ed69473d9e2bdacb2fb Mon Sep 17 00:00:00 2001
From: Gav Wood <i@gavwood.com>
Date: Mon, 26 May 2014 20:09:15 +0200
Subject: [PATCH] Convenience fixups.

---
 liblll/Assembly.cpp     | 4 ++++
 liblll/Assembly.h       | 1 +
 liblll/CodeFragment.cpp | 9 ++++++---
 liblll/CodeFragment.h   | 4 ++--
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/liblll/Assembly.cpp b/liblll/Assembly.cpp
index 1f53cfb5f..3614bfc48 100644
--- a/liblll/Assembly.cpp
+++ b/liblll/Assembly.cpp
@@ -142,6 +142,10 @@ AssemblyItem const& Assembly::append(AssemblyItem const& _i)
 	return back();
 }
 
+void Assembly::optimise()
+{
+}
+
 bytes Assembly::assemble() const
 {
 	bytes ret;
diff --git a/liblll/Assembly.h b/liblll/Assembly.h
index 86b37622e..26392d141 100644
--- a/liblll/Assembly.h
+++ b/liblll/Assembly.h
@@ -92,6 +92,7 @@ public:
 	std::string out() const { std::stringstream ret; streamOut(ret); return ret.str(); }
 	int deposit() const { return m_deposit; }
 	bytes assemble() const;
+	void optimise();
 	std::ostream& streamOut(std::ostream& _out) const;
 
 private:
diff --git a/liblll/CodeFragment.cpp b/liblll/CodeFragment.cpp
index 59ff729e7..299cda5f6 100644
--- a/liblll/CodeFragment.cpp
+++ b/liblll/CodeFragment.cpp
@@ -102,7 +102,7 @@ CodeFragment::CodeFragment(sp::utree const& _t, CompilerState& _s, bool _allowAS
 
 void CodeFragment::constructOperation(sp::utree const& _t, CompilerState& _s)
 {
-	if (_t.empty())
+	if (_t.tag() == 0 && _t.empty())
 		error<EmptyList>();
 	else if (_t.tag() == 0 && _t.front().which() != sp::utree_type::symbol_type)
 		error<DataNotExecutable>();
@@ -361,14 +361,17 @@ void CodeFragment::constructOperation(sp::utree const& _t, CompilerState& _s)
 		{
 			requireSize(3);
 			requireDeposit(0, 1);
+			int minDep = min(code[1].m_asm.deposit(), code[2].m_asm.deposit());
 
 			m_asm.append(code[0].m_asm);
 			auto pos = m_asm.appendJumpI();
 			m_asm.onePath();
-			m_asm << code[2].m_asm;
+			m_asm.append(code[2].m_asm, minDep);
 			auto end = m_asm.appendJump();
 			m_asm.otherPath();
-			m_asm << pos.tag() << code[1].m_asm << end.tag();
+			m_asm << pos.tag();
+			m_asm.append(code[1].m_asm, minDep);
+			m_asm << end.tag();
 			m_asm.donePaths();
 		}
 		else if (us == "WHEN" || us == "UNLESS")
diff --git a/liblll/CodeFragment.h b/liblll/CodeFragment.h
index 647604849..6935a111c 100644
--- a/liblll/CodeFragment.h
+++ b/liblll/CodeFragment.h
@@ -43,10 +43,10 @@ public:
 	static CodeFragment compile(std::string const& _src, CompilerState& _s);
 
 	/// Consolidates data and compiles code.
-	bytes code() const { return m_asm.assemble(); }
+	bytes code() { m_asm.optimise(); return m_asm.assemble(); }
 
 	/// Consolidates data and compiles code.
-	std::string assembly() const { return m_asm.out(); }
+	std::string assembly() { m_asm.optimise(); return m_asm.out(); }
 
 private:
 	template <class T> void error() const { throw T(); }