From 3bf06f344bdda4233d5cdb125b5c0caa8b6741ce Mon Sep 17 00:00:00 2001
From: Christian <c@ethdev.com>
Date: Thu, 12 Feb 2015 11:40:14 +0100
Subject: [PATCH] Added some comments.

---
 libsolidity/CompilerUtils.h        | 17 +++++++++++------
 libsolidity/ExpressionCompiler.cpp |  4 ++--
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/libsolidity/CompilerUtils.h b/libsolidity/CompilerUtils.h
index 7ac3cc295..fe28ceadf 100644
--- a/libsolidity/CompilerUtils.h
+++ b/libsolidity/CompilerUtils.h
@@ -54,6 +54,8 @@ public:
 	unsigned storeInMemory(unsigned _offset, Type const& _type = IntegerType(256), bool _padToWordBoundaries = false);
 	/// Dynamic version of @see storeInMemory, expects the memory offset below the value on the stack
 	/// and also updates that.
+	/// Stack pre: memory_offset value...
+	/// Stack post: (memory_offset+length)
 	void storeInMemoryDynamic(Type const& _type, bool _padToWordBoundaries = true);
 	/// @returns _size rounded up to the next multiple of 32 (the number of bytes occupied in the
 	///          padded calldata)
@@ -75,11 +77,13 @@ public:
 	/// @note Only works for types of fixed size.
 	void computeHashStatic(Type const& _type = IntegerType(256), bool _padToWordBoundaries = false);
 
-	/// Copies a byte array to a byte array in storage, where the target is assumed to be on the
-	/// to top of the stay. Leaves a reference to the target on the stack.
+	/// Copies a byte array to a byte array in storage.
+	/// Stack pre: [source_reference] target_reference
+	/// Stack post: target_reference
 	void copyByteArrayToStorage(ByteArrayType const& _targetType, ByteArrayType const& _sourceType) const;
 	/// Clears the length and data elements of the byte array referenced on the stack.
-	/// Removes the reference from the stack.
+	/// Stack pre: reference
+	/// Stack post:
 	void clearByteArray(ByteArrayType const& _type) const;
 
 	/// Bytes we need to the start of call data.
@@ -87,10 +91,11 @@ public:
 	static const unsigned int dataStartOffset;
 
 private:
+	/// Prepares the given type for storing in memory by shifting it if necessary.
 	unsigned prepareMemoryStore(Type const& _type, bool _padToWordBoundaries) const;
-	/// Appends a loop that clears all storage between the storage reference at the stack top
-	/// and the one below it (excluding).
-	/// Will leave the single value of the end pointer on the stack.
+	/// Appends a loop that clears a sequence of storage slots (excluding end).
+	/// Stack pre: end_ref start_ref
+	/// Stack post: end_ref
 	void clearStorageLoop() const;
 
 	CompilerContext& m_context;
diff --git a/libsolidity/ExpressionCompiler.cpp b/libsolidity/ExpressionCompiler.cpp
index b373bfbcb..63132a124 100644
--- a/libsolidity/ExpressionCompiler.cpp
+++ b/libsolidity/ExpressionCompiler.cpp
@@ -1032,7 +1032,7 @@ void ExpressionCompiler::LValue::storeValue(Expression const& _expression, Type
 		break;
 	}
 	case LValueType::Storage:
-		// stack layout: value value ... value ref
+		// stack layout: value value ... value target_ref
 		if (_expression.getType()->isValueType())
 		{
 			if (!_move) // copy values
@@ -1050,7 +1050,7 @@ void ExpressionCompiler::LValue::storeValue(Expression const& _expression, Type
 				if (i + 1 >= m_size)
 					*m_context << eth::Instruction::SSTORE;
 				else
-					// v v ... v v r+x
+					// stack here: value value ... value value (target_ref+offset)
 					*m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2
 							   << eth::Instruction::SSTORE
 							   << u256(1) << eth::Instruction::SWAP1 << eth::Instruction::SUB;