Merge pull request #2499 from ethereum/shift-helper

Add shift helper to CompilerUtils

4 files changed, 39 insertions, 19 deletions

diff --git a/libsolidity/codegen/CompilerUtils.cpp b/libsolidity/codegen/CompilerUtils.cpp
index a105036f..7067ddd5 100644
--- a/libsolidity/codegen/CompilerUtils.cpp
+++ b/libsolidity/codegen/CompilerUtils.cpp
@@ -353,13 +353,16 @@ void CompilerUtils::splitExternalFunctionType(bool _leftAligned)
 	// address (right aligned), function identifier (right aligned)
 	if (_leftAligned)
 	{
-		m_context << Instruction::DUP1 << (u256(1) << (64 + 32)) << Instruction::SWAP1 << Instruction::DIV;
+		m_context << Instruction::DUP1;
+		rightShiftNumberOnStack(64 + 32, false);
 		// <input> <address>
-		m_context << Instruction::SWAP1 << (u256(1) << 64) << Instruction::SWAP1 << Instruction::DIV;
+		m_context << Instruction::SWAP1;
+		rightShiftNumberOnStack(64, false);
 	}
 	else
 	{
-		m_context << Instruction::DUP1 << (u256(1) << 32) << Instruction::SWAP1 << Instruction::DIV;
+		m_context << Instruction::DUP1;
+		rightShiftNumberOnStack(32, false);
 		m_context << ((u256(1) << 160) - 1) << Instruction::AND << Instruction::SWAP1;
 	}
 	m_context << u256(0xffffffffUL) << Instruction::AND;
@@ -371,10 +374,10 @@ void CompilerUtils::combineExternalFunctionType(bool _leftAligned)
 	m_context << u256(0xffffffffUL) << Instruction::AND << Instruction::SWAP1;
 	if (!_leftAligned)
 		m_context << ((u256(1) << 160) - 1) << Instruction::AND;
-	m_context << (u256(1) << 32) << Instruction::MUL;
+	leftShiftNumberOnStack(32);
 	m_context << Instruction::OR;
 	if (_leftAligned)
-		m_context << (u256(1) << 64) << Instruction::MUL;
+		leftShiftNumberOnStack(64);
 }
 
 void CompilerUtils::pushCombinedFunctionEntryLabel(Declaration const& _function)
@@ -383,11 +386,12 @@ void CompilerUtils::pushCombinedFunctionEntryLabel(Declaration const& _function)
 	// If there is a runtime context, we have to merge both labels into the same
 	// stack slot in case we store it in storage.
 	if (CompilerContext* rtc = m_context.runtimeContext())
+	{
+		leftShiftNumberOnStack(32);
 		m_context <<
-			(u256(1) << 32) <<
-			Instruction::MUL <<
 			rtc->functionEntryLabel(_function).toSubAssemblyTag(m_context.runtimeSub()) <<
 			Instruction::OR;
+	}
 }
 
 void CompilerUtils::convertType(
@@ -425,7 +429,7 @@ void CompilerUtils::convertType(
 			// conversion from bytes to integer. no need to clean the high bit
 			// only to shift right because of opposite alignment
 			IntegerType const& targetIntegerType = dynamic_cast<IntegerType const&>(_targetType);
-			m_context << (u256(1) << (256 - typeOnStack.numBytes() * 8)) << Instruction::SWAP1 << Instruction::DIV;
+			rightShiftNumberOnStack(256 - typeOnStack.numBytes() * 8, false);
 			if (targetIntegerType.numBits() < typeOnStack.numBytes() * 8)
 				convertType(IntegerType(typeOnStack.numBytes() * 8), _targetType, _cleanupNeeded);
 		}
@@ -476,7 +480,7 @@ void CompilerUtils::convertType(
 			if (auto typeOnStack = dynamic_cast<IntegerType const*>(&_typeOnStack))
 				if (targetBytesType.numBytes() * 8 > typeOnStack->numBits())
 					cleanHigherOrderBits(*typeOnStack);
-			m_context << (u256(1) << (256 - targetBytesType.numBytes() * 8)) << Instruction::MUL;
+			leftShiftNumberOnStack(256 - targetBytesType.numBytes() * 8);
 		}
 		else if (targetTypeCategory == Type::Category::Enum)
 		{
@@ -986,10 +990,10 @@ unsigned CompilerUtils::loadFromMemoryHelper(Type const& _type, bool _fromCallda
 	{
 		bool leftAligned = _type.category() == Type::Category::FixedBytes;
 		// add leading or trailing zeros by dividing/multiplying depending on alignment
-		u256 shiftFactor = u256(1) << ((32 - numBytes) * 8);
-		m_context << shiftFactor << Instruction::SWAP1 << Instruction::DIV;
+		int shiftFactor = (32 - numBytes) * 8;
+		rightShiftNumberOnStack(shiftFactor, false);
 		if (leftAligned)
-			m_context << shiftFactor << Instruction::MUL;
+			leftShiftNumberOnStack(shiftFactor);
 	}
 	if (_fromCalldata)
 		convertType(_type, _type, true, false, true);
@@ -1007,6 +1011,18 @@ void CompilerUtils::cleanHigherOrderBits(IntegerType const& _typeOnStack)
 		m_context << ((u256(1) << _typeOnStack.numBits()) - 1) << Instruction::AND;
 }
 
+void CompilerUtils::leftShiftNumberOnStack(unsigned _bits)
+{
+	solAssert(_bits < 256, "");
+	m_context << (u256(1) << _bits) << Instruction::MUL;
+}
+
+void CompilerUtils::rightShiftNumberOnStack(unsigned _bits, bool _isSigned)
+{
+	solAssert(_bits < 256, "");
+	m_context << (u256(1) << _bits) << Instruction::SWAP1 << (_isSigned ? Instruction::SDIV : Instruction::DIV);
+}
+
 unsigned CompilerUtils::prepareMemoryStore(Type const& _type, bool _padToWords)
 {
 	unsigned numBytes = _type.calldataEncodedSize(_padToWords);
@@ -1019,7 +1035,7 @@ unsigned CompilerUtils::prepareMemoryStore(Type const& _type, bool _padToWords)
 		convertType(_type, _type, true);
 		if (numBytes != 32 && !leftAligned && !_padToWords)
 			// shift the value accordingly before storing
-			m_context << (u256(1) << ((32 - numBytes) * 8)) << Instruction::MUL;
+			leftShiftNumberOnStack((32 - numBytes) * 8);
 	}
 	return numBytes;
 }
diff --git a/libsolidity/codegen/CompilerUtils.h b/libsolidity/codegen/CompilerUtils.h
index 0ee053a9..fb169463 100644
--- a/libsolidity/codegen/CompilerUtils.h
+++ b/libsolidity/codegen/CompilerUtils.h
@@ -176,6 +176,12 @@ public:
 	static unsigned sizeOnStack(std::vector<T> const& _variables);
 	static unsigned sizeOnStack(std::vector<std::shared_ptr<Type const>> const& _variableTypes);
 
+	/// Helper function to shift top value on the stack to the left.
+	void leftShiftNumberOnStack(unsigned _bits);
+
+	/// Helper function to shift top value on the stack to the right.
+	void rightShiftNumberOnStack(unsigned _bits, bool _isSigned = false);
+
 	/// Appends code that computes tha Keccak-256 hash of the topmost stack element of 32 byte type.
 	void computeHashStatic();
 
diff --git a/libsolidity/codegen/ExpressionCompiler.cpp b/libsolidity/codegen/ExpressionCompiler.cpp
index 9d4024c9..82518e8c 100644
--- a/libsolidity/codegen/ExpressionCompiler.cpp
+++ b/libsolidity/codegen/ExpressionCompiler.cpp
@@ -526,7 +526,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 
 			if (m_context.runtimeContext())
 				// We have a runtime context, so we need the creation part.
-				m_context << (u256(1) << 32) << Instruction::SWAP1 << Instruction::DIV;
+				utils().rightShiftNumberOnStack(32, false);
 			else
 				// Extract the runtime part.
 				m_context << ((u256(1) << 32) - 1) << Instruction::AND;
@@ -1269,7 +1269,7 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 		m_context.appendConditionalInvalid();
 
 		m_context << Instruction::BYTE;
-		m_context << (u256(1) << (256 - 8)) << Instruction::MUL;
+		utils().leftShiftNumberOnStack(256 - 8);
 	}
 	else if (baseType.category() == Type::Category::TypeType)
 	{
diff --git a/libsolidity/codegen/LValue.cpp b/libsolidity/codegen/LValue.cpp
index a74a3d74..e19cf41e 100644
--- a/libsolidity/codegen/LValue.cpp
+++ b/libsolidity/codegen/LValue.cpp
@@ -186,7 +186,7 @@ void StorageItem::retrieveValue(SourceLocation const&, bool _remove) const
 			solUnimplemented("Not yet implemented - FixedPointType.");
 		if (m_dataType->category() == Type::Category::FixedBytes)
 		{
-			m_context << (u256(0x1) << (256 - 8 * m_dataType->storageBytes())) << Instruction::MUL;
+			CompilerUtils(m_context).leftShiftNumberOnStack(256 - 8 * m_dataType->storageBytes());
 			cleaned = true;
 		}
 		else if (
@@ -267,9 +267,7 @@ void StorageItem::storeValue(Type const& _sourceType, SourceLocation const& _loc
 			else if (m_dataType->category() == Type::Category::FixedBytes)
 			{
 				solAssert(_sourceType.category() == Type::Category::FixedBytes, "source not fixed bytes");
-				m_context
-					<< (u256(0x1) << (256 - 8 * dynamic_cast<FixedBytesType const&>(*m_dataType).numBytes()))
-					<< Instruction::SWAP1 << Instruction::DIV;
+				CompilerUtils(m_context).rightShiftNumberOnStack(256 - 8 * dynamic_cast<FixedBytesType const&>(*m_dataType).numBytes(), false);
 			}
 			else
 			{