Merge pull request #8719 from ethereum/ir-shifts

IR generation for shifts

libsolidity/codegen/YulUtilFunctions.cpp

@@ -299,9 +299,6 @@ string YulUtilFunctions::shiftRightFunction(size_t _numBits)
 
 string YulUtilFunctions::shiftRightFunctionDynamic()
 {
-	// Note that if this is extended with signed shifts,
-	// the opcodes SAR and SDIV behave differently with regards to rounding!
-
 	string const functionName = "shift_right_unsigned_dynamic";
 	return m_functionCollector.createFunction(functionName, [&]() {
 		return
@@ -321,6 +318,86 @@ string YulUtilFunctions::shiftRightFunctionDynamic()
 	});
 }
 
+string YulUtilFunctions::shiftRightSignedFunctionDynamic()
+{
+	string const functionName = "shift_right_signed_dynamic";
+	return m_functionCollector.createFunction(functionName, [&]() {
+		return
+			Whiskers(R"(
+			function <functionName>(bits, value) -> result {
+				<?hasShifts>
+					result := sar(bits, value)
+				<!hasShifts>
+					let divisor := exp(2, bits)
+					let xor_mask := sub(0, slt(value, 0))
+					result := xor(div(xor(value, xor_mask), divisor), xor_mask)
+					// combined version of
+					//   switch slt(value, 0)
+					//   case 0 { result := div(value, divisor) }
+					//   default { result := not(div(not(value), divisor)) }
+				</hasShifts>
+			}
+			)")
+			("functionName", functionName)
+			("hasShifts", m_evmVersion.hasBitwiseShifting())
+			.render();
+	});
+}
+
+
+string YulUtilFunctions::typedShiftLeftFunction(Type const& _type, Type const& _amountType)
+{
+	solAssert(_type.category() == Type::Category::FixedBytes || _type.category() == Type::Category::Integer, "");
+	solAssert(_amountType.category() == Type::Category::Integer, "");
+	string const functionName = "shift_left_" + _type.identifier() + "_" + _amountType.identifier();
+	return m_functionCollector.createFunction(functionName, [&]() {
+		return
+			Whiskers(R"(
+			function <functionName>(value, bits) -> result {
+				bits := <cleanAmount>(bits)
+				<?amountSigned>
+					if slt(bits, 0) { invalid() }
+				</amountSigned>
+				result := <cleanup>(<shift>(bits, value))
+			}
+			)")
+			("functionName", functionName)
+			("amountSigned", dynamic_cast<IntegerType const&>(_amountType).isSigned())
+			("cleanAmount", cleanupFunction(_amountType))
+			("shift", shiftLeftFunctionDynamic())
+			("cleanup", cleanupFunction(_type))
+			.render();
+	});
+}
+
+string YulUtilFunctions::typedShiftRightFunction(Type const& _type, Type const& _amountType)
+{
+	solAssert(_type.category() == Type::Category::FixedBytes || _type.category() == Type::Category::Integer, "");
+	solAssert(_amountType.category() == Type::Category::Integer, "");
+	IntegerType const* integerType = dynamic_cast<IntegerType const*>(&_type);
+	bool valueSigned = integerType && integerType->isSigned();
+
+	string const functionName = "shift_right_" + _type.identifier() + "_" + _amountType.identifier();
+	return m_functionCollector.createFunction(functionName, [&]() {
+		return
+			Whiskers(R"(
+			function <functionName>(value, bits) -> result {
+				bits := <cleanAmount>(bits)
+				<?amountSigned>
+					if slt(bits, 0) { invalid() }
+				</amountSigned>
+				result := <cleanup>(<shift>(bits, <cleanup>(value)))
+			}
+			)")
+			("functionName", functionName)
+			("amountSigned", dynamic_cast<IntegerType const&>(_amountType).isSigned())
+			("cleanAmount", cleanupFunction(_amountType))
+			("shift", valueSigned ? shiftRightSignedFunctionDynamic() : shiftRightFunctionDynamic())
+			("cleanup", cleanupFunction(_type))
+			.render();
+	});
+}
+
 string YulUtilFunctions::updateByteSliceFunction(size_t _numBytes, size_t _shiftBytes)
 {
 	solAssert(_numBytes <= 32, "");

libsolidity/codegen/YulUtilFunctions.h

@@ -81,6 +81,14 @@ public:
 	std::string shiftLeftFunctionDynamic();
 	std::string shiftRightFunction(size_t _numBits);
 	std::string shiftRightFunctionDynamic();
+	std::string shiftRightSignedFunctionDynamic();
+
+	/// @returns the name of a function that performs a left shift and subsequent cleanup
+	/// and, if needed, prior cleanup.
+	/// If the amount to shift by is signed, a check for negativeness is performed.
+	/// signature: (value, amountToShift) -> result
+	std::string typedShiftLeftFunction(Type const& _type, Type const& _amountType);
+	std::string typedShiftRightFunction(Type const& _type, Type const& _amountType);
 
 	/// @returns the name of a function which replaces the
 	/// _numBytes bytes starting at byte position _shiftBytes (counted from the least significant

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -254,29 +254,53 @@ bool IRGeneratorForStatements::visit(Conditional const& _conditional)
 bool IRGeneratorForStatements::visit(Assignment const& _assignment)
 {
 	_assignment.rightHandSide().accept(*this);
-	Type const* intermediateType = type(_assignment.rightHandSide()).closestTemporaryType(
+
+	Token assignmentOperator = _assignment.assignmentOperator();
+	Token binaryOperator =
+		assignmentOperator == Token::Assign ?
+		assignmentOperator :
+		TokenTraits::AssignmentToBinaryOp(assignmentOperator);
+
+	Type const* rightIntermediateType =
+		TokenTraits::isShiftOp(binaryOperator) ?
+		type(_assignment.rightHandSide()).mobileType() :
+		type(_assignment.rightHandSide()).closestTemporaryType(
 			&type(_assignment.leftHandSide())
 		);
-	IRVariable value = convert(_assignment.rightHandSide(), *intermediateType);
-
+	solAssert(rightIntermediateType, "");
+	IRVariable value = convert(_assignment.rightHandSide(), *rightIntermediateType);
 	_assignment.leftHandSide().accept(*this);
 	solAssert(!!m_currentLValue, "LValue not retrieved.");
 
-	if (_assignment.assignmentOperator() != Token::Assign)
+	if (assignmentOperator != Token::Assign)
 	{
-		solAssert(type(_assignment.leftHandSide()) == *intermediateType, "");
-		solAssert(intermediateType->isValueType(), "Compound operators only available for value types.");
-
+		solAssert(type(_assignment.leftHandSide()).isValueType(), "Compound operators only available for value types.");
+		solAssert(rightIntermediateType->isValueType(), "Compound operators only available for value types.");
 		IRVariable leftIntermediate = readFromLValue(*m_currentLValue);
+		if (TokenTraits::isShiftOp(binaryOperator))
+		{
+			solAssert(type(_assignment) == leftIntermediate.type(), "");
+			solAssert(type(_assignment) == type(_assignment.leftHandSide()), "");
+			define(_assignment) << shiftOperation(binaryOperator, leftIntermediate, value);
+
+			writeToLValue(*m_currentLValue, IRVariable(_assignment));
+			m_currentLValue.reset();
+			return false;
+		}
+		else
+		{
+			solAssert(type(_assignment.leftHandSide()) == *rightIntermediateType, "");
 			m_code << value.name() << " := " << binaryOperation(
-			TokenTraits::AssignmentToBinaryOp(_assignment.assignmentOperator()),
-			*intermediateType,
+				binaryOperator,
+				*rightIntermediateType,
 				leftIntermediate.name(),
 				value.name()
 			);
 		}
+	}
 
 	writeToLValue(*m_currentLValue, value);
+
 	m_currentLValue.reset();
 	if (*_assignment.annotation().type != *TypeProvider::emptyTuple())
 		define(_assignment, value);
@@ -541,6 +565,12 @@ bool IRGeneratorForStatements::visit(BinaryOperation const& _binOp)
 			solAssert(false, "Unknown comparison operator.");
 		define(_binOp) << expr << "\n";
 	}
+	else if (TokenTraits::isShiftOp(op))
+	{
+		IRVariable left = convert(_binOp.leftExpression(), *commonType);
+		IRVariable right = convert(_binOp.rightExpression(), *type(_binOp.rightExpression()).mobileType());
+		define(_binOp) << shiftOperation(_binOp.getOperator(), left, right) << "\n";
+	}
 	else
 	{
 		string left = expressionAsType(_binOp.leftExpression(), *commonType);
@@ -1921,6 +1951,10 @@ string IRGeneratorForStatements::binaryOperation(
 	string const& _right
 )
 {
+	solAssert(
+		!TokenTraits::isShiftOp(_operator),
+		"Have to use specific shift operation function for shifts."
+	);
 	if (IntegerType const* type = dynamic_cast<IntegerType const*>(&_type))
 	{
 		string fun;
@@ -1964,6 +1998,31 @@ string IRGeneratorForStatements::binaryOperation(
 	return {};
 }
 
+std::string IRGeneratorForStatements::shiftOperation(
+	langutil::Token _operator,
+	IRVariable const& _value,
+	IRVariable const& _amountToShift
+)
+{
+	IntegerType const* amountType = dynamic_cast<IntegerType const*>(&_amountToShift.type());
+	solAssert(amountType, "");
+
+	solAssert(_operator == Token::SHL || _operator == Token::SAR, "");
+
+	return
+		Whiskers(R"(
+			<shift>(<value>, <amount>)
+		)")
+		("shift",
+			_operator == Token::SHL ?
+			m_utils.typedShiftLeftFunction(_value.type(), *amountType) :
+			m_utils.typedShiftRightFunction(_value.type(), *amountType)
+		)
+		("value", _value.name())
+		("amount", _amountToShift.name())
+		.render();
+}
+
 void IRGeneratorForStatements::appendAndOrOperatorCode(BinaryOperation const& _binOp)
 {
 	langutil::Token const op = _binOp.getOperator();

libsolidity/codegen/ir/IRGeneratorForStatements.h

@@ -147,6 +147,11 @@ private:
 		std::string const& _right
 	);
 
+	/// @returns code to perform the given shift operation.
+	/// The operation itself will be performed in the type of the value,
+	/// while the amount to shift can have its own type.
+	std::string shiftOperation(langutil::Token _op, IRVariable const& _value, IRVariable const& _shiftAmount);
+
 	/// Assigns the value of @a _value to the lvalue @a _lvalue.
 	void writeToLValue(IRLValue const& _lvalue, IRVariable const& _value);
 	/// @returns a fresh IR variable containing the value of the lvalue @a _lvalue.

test/libsolidity/semanticTests/shifts/shift_cleanup_garbled.sol

@@ -7,5 +7,7 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f() -> 0x0

test/libsolidity/semanticTests/shifts/shift_constant_left_assignment.sol

@@ -5,5 +5,7 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f() -> 0x4200

test/libsolidity/semanticTests/shifts/shift_constant_right_assignment.sol

@@ -5,5 +5,7 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f() -> 0x42

test/libsolidity/semanticTests/shifts/shift_left.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint256,uint256): 0x4266, 0x0 -> 0x4266
 // f(uint256,uint256): 0x4266, 0x8 -> 0x426600

test/libsolidity/semanticTests/shifts/shift_left_assignment.sol

@@ -5,6 +5,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint256,uint256): 0x4266, 0x0 -> 0x4266
 // f(uint256,uint256): 0x4266, 0x8 -> 0x426600

test/libsolidity/semanticTests/shifts/shift_left_assignment_different_type.sol

@@ -5,6 +5,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint256,uint8): 0x4266, 0x0 -> 0x4266
 // f(uint256,uint8): 0x4266, 0x8 -> 0x426600

test/libsolidity/semanticTests/shifts/shift_left_larger_type.sol

@@ -6,6 +6,7 @@ contract C {
         return y << x;
     }
 }
-
+// ====
+// compileViaYul: also
 // ----
 // f() -> 0

test/libsolidity/semanticTests/shifts/shift_left_uint32.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint32,uint32): 0x4266, 0x0 -> 0x4266
 // f(uint32,uint32): 0x4266, 0x8 -> 0x426600

test/libsolidity/semanticTests/shifts/shift_left_uint8.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint8,uint8): 0x66, 0x0 -> 0x66
 // f(uint8,uint8): 0x66, 0x8 -> 0

test/libsolidity/semanticTests/shifts/shift_negative_rvalue.sol

@@ -8,6 +8,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(int256,int256): 1, -1 -> FAILURE
 // g(int256,int256): 1, -1 -> FAILURE

test/libsolidity/semanticTests/shifts/shift_negative_rvalue_assignment.sol

@@ -10,6 +10,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(int256,int256): 1, -1 -> FAILURE
 // g(int256,int256): 1, -1 -> FAILURE

test/libsolidity/semanticTests/shifts/shift_overflow.sol

@@ -8,6 +8,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // leftU(uint8,uint8): 255, 8 -> 0
 // leftU(uint8,uint8): 255, 1 -> 254

test/libsolidity/semanticTests/shifts/shift_right.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint256,uint256): 0x4266, 0x0 -> 0x4266
 // f(uint256,uint256): 0x4266, 0x8 -> 0x42

test/libsolidity/semanticTests/shifts/shift_right_assignment.sol

@@ -5,6 +5,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint256,uint256): 0x4266, 0x0 -> 0x4266
 // f(uint256,uint256): 0x4266, 0x8 -> 0x42

test/libsolidity/semanticTests/shifts/shift_right_assignment_signed.sol

@@ -5,6 +5,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(int256,int256): 0x4266, 0x0 -> 0x4266
 // f(int256,int256): 0x4266, 0x8 -> 0x42

test/libsolidity/semanticTests/shifts/shift_right_garbled_signed_v2.sol

@@ -18,6 +18,8 @@ contract C {
         return a >> b;
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // f(int8,uint8): 0x00, 0x03 -> 0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe
 // f(int8,uint8): 0x00, 0x04 -> 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff

test/libsolidity/semanticTests/shifts/shift_right_garbled_v2.sol

@@ -10,6 +10,8 @@ contract C {
         return a >> b;
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // f(uint8,uint8): 0x00, 0x04 -> 0x0f
 // f(uint8,uint8): 0x00, 0x1004 -> FAILURE

test/libsolidity/semanticTests/shifts/shift_right_negative_lvalue.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(int256,int256): -4266, 0 -> -4266
 // f(int256,int256): -4266, 1 -> -2133

test/libsolidity/semanticTests/shifts/shift_right_negative_lvalue_assignment.sol

@@ -5,6 +5,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(int256,int256): -4266, 0 -> -4266
 // f(int256,int256): -4266, 1 -> -2133

test/libsolidity/semanticTests/shifts/shift_right_negative_lvalue_int16.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(int16,int16): -4266, 0 -> -4266
 // f(int16,int16): -4266, 1 -> -2133

test/libsolidity/semanticTests/shifts/shift_right_negative_lvalue_int32.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(int32,int32): -4266, 0 -> -4266
 // f(int32,int32): -4266, 1 -> -2133

test/libsolidity/semanticTests/shifts/shift_right_negative_lvalue_int8.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(int8,int8): -66, 0 -> -66
 // f(int8,int8): -66, 1 -> -33

test/libsolidity/semanticTests/shifts/shift_right_negative_lvalue_signextend_int16_v2.sol

@@ -6,6 +6,8 @@ contract C {
         return a >> b;
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // f(int16,int16): 0xff99, 0x00 -> FAILURE
 // f(int16,int16): 0xff99, 0x01 -> FAILURE

test/libsolidity/semanticTests/shifts/shift_right_negative_lvalue_signextend_int32_v2.sol

@@ -6,6 +6,8 @@ contract C {
         return a >> b;
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // f(int32,int32): 0xffffff99, 0x00 -> FAILURE
 // f(int32,int32): 0xffffff99, 0x01 -> FAILURE

test/libsolidity/semanticTests/shifts/shift_right_negative_lvalue_signextend_int8_v2.sol

@@ -6,6 +6,8 @@ contract C {
         return a >> b;
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // f(int8,int8): 0x99, 0x00 -> FAILURE
 // f(int8,int8): 0x99, 0x01 -> FAILURE

test/libsolidity/semanticTests/shifts/shift_right_uint32.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint32,uint32): 0x4266, 0x0 -> 0x4266
 // f(uint32,uint32): 0x4266, 0x8 -> 0x42

test/libsolidity/semanticTests/shifts/shift_right_uint8.sol

@@ -4,6 +4,8 @@ contract C {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // f(uint8,uint8): 0x66, 0x0 -> 0x66
 // f(uint8,uint8): 0x66, 0x8 -> 0x0

test/libsolidity/semanticTests/shifts/shift_signed_cleanup_amount.sol

@@ -0,0 +1,16 @@
+contract C {
+    function f(uint256 a, int8 b) public returns (uint256) {
+        assembly { b := 0xff }
+        return a << b;
+    }
+    function g(uint256 a, int8 b) public returns (uint256) {
+        assembly { b := 0xff }
+        return a >> b;
+    }
+}
+
+// ====
+// compileViaYul: also
+// ----
+// f(uint256,int8): 0x1234, 0x0 -> FAILURE
+// g(uint256,int8): 0x1234, 0x0 -> FAILURE