Panic codes.

libsolidity/codegen/ArrayUtils.cpp

@@ -29,6 +29,9 @@
 #include <libsolidity/codegen/CompilerUtils.h>
 #include <libsolidity/codegen/LValue.h>
 
+#include <libsolutil/FunctionSelector.h>
+#include <libsolutil/Whiskers.h>
+
 #include <libevmasm/Instruction.h>
 #include <liblangutil/Exceptions.h>
 
@@ -857,13 +860,17 @@ void ArrayUtils::popStorageArrayElement(ArrayType const& _type) const
 
 	if (_type.isByteArray())
 	{
-		m_context.appendInlineAssembly(R"({
+		util::Whiskers code(R"({
 			let slot_value := sload(ref)
 			switch and(slot_value, 1)
 			case 0 {
 				// short byte array
 				let length := and(div(slot_value, 2), 0x1f)
-				if iszero(length) { invalid() }
+				if iszero(length) {
+					mstore(0, <panicSelector>)
+					mstore(4, <emptyArrayPop>)
+					revert(0, 0x24)
+				}
 
 				// Zero-out the suffix including the least significant byte.
 				let mask := sub(exp(0x100, sub(33, length)), 1)
@@ -901,7 +908,10 @@ void ArrayUtils::popStorageArrayElement(ArrayType const& _type) const
 					sstore(ref, slot_value)
 				}
 			}
-		})", {"ref"});
+		})");
+		code("panicSelector", util::selectorFromSignature("Panic(uint256)").str());
+		code("emptyArrayPop", to_string(unsigned(util::PanicCode::EmptyArrayPop)));
+		m_context.appendInlineAssembly(code.render(), {"ref"});
 		m_context << Instruction::POP;
 	}
 	else
@@ -912,7 +922,7 @@ void ArrayUtils::popStorageArrayElement(ArrayType const& _type) const
 		m_context << Instruction::DUP1;
 		// stack: ArrayReference oldLength oldLength
 		m_context << Instruction::ISZERO;
-		m_context.appendConditionalInvalid();
+		m_context.appendConditionalPanic(util::PanicCode::EmptyArrayPop);
 
 		// Stack: ArrayReference oldLength
 		m_context << u256(1) << Instruction::SWAP1 << Instruction::SUB;
@@ -1058,7 +1068,7 @@ void ArrayUtils::accessIndex(ArrayType const& _arrayType, bool _doBoundsCheck, b
 		// check out-of-bounds access
 		m_context << Instruction::DUP2 << Instruction::LT << Instruction::ISZERO;
 		// out-of-bounds access throws exception
-		m_context.appendConditionalInvalid();
+		m_context.appendConditionalPanic(util::PanicCode::ArrayOutOfBounds);
 	}
 	if (location == DataLocation::CallData && _arrayType.isDynamicallySized())
 		// remove length if present

libsolidity/codegen/ArrayUtils.h

@@ -72,7 +72,7 @@ public:
 	/// Stack pre: reference (excludes byte offset)
 	/// Stack post: new_length
 	void incrementDynamicArraySize(ArrayType const& _type) const;
-	/// Decrements the size of a dynamic array by one if length is nonzero. Causes an invalid instruction otherwise.
+	/// Decrements the size of a dynamic array by one if length is nonzero. Causes a Panic otherwise.
 	/// Clears the removed data element. In case of a byte array, this might move the data.
 	/// Stack pre: reference
 	/// Stack post:

libsolidity/codegen/CompilerContext.cpp

@@ -41,6 +41,7 @@
 #include <libyul/Utilities.h>
 
 #include <libsolutil/Whiskers.h>
+#include <libsolutil/FunctionSelector.h>
 
 #include <liblangutil/ErrorReporter.h>
 #include <liblangutil/Scanner.h>
@@ -330,16 +331,24 @@ CompilerContext& CompilerContext::appendJump(evmasm::AssemblyItem::JumpType _jum
 	return *this << item;
 }
 
-CompilerContext& CompilerContext::appendInvalid()
+CompilerContext& CompilerContext::appendPanic(util::PanicCode _code)
 {
-	return *this << Instruction::INVALID;
+	Whiskers templ(R"({
+		mstore(0, <selector>)
+		mstore(4, <code>)
+		revert(0, 0x24)
+	})");
+	templ("selector", util::selectorFromSignature("Panic(uint256)").str());
+	templ("code", u256(_code).str());
+	appendInlineAssembly(templ.render());
+	return *this;
 }
 
-CompilerContext& CompilerContext::appendConditionalInvalid()
+CompilerContext& CompilerContext::appendConditionalPanic(util::PanicCode _code)
 {
 	*this << Instruction::ISZERO;
 	evmasm::AssemblyItem afterTag = appendConditionalJump();
-	*this << Instruction::INVALID;
+	appendPanic(_code);
 	*this << afterTag;
 	return *this;
 }

libsolidity/codegen/CompilerContext.h

@@ -36,6 +36,7 @@
 #include <liblangutil/ErrorReporter.h>
 #include <liblangutil/EVMVersion.h>
 #include <libsolutil/Common.h>
+#include <libsolutil/ErrorCodes.h>
 
 #include <libyul/AsmAnalysisInfo.h>
 #include <libyul/backends/evm/EVMDialect.h>
@@ -195,10 +196,10 @@ public:
 	evmasm::AssemblyItem appendJumpToNew() { return m_asm->appendJump().tag(); }
 	/// Appends a JUMP to a tag already on the stack
 	CompilerContext& appendJump(evmasm::AssemblyItem::JumpType _jumpType = evmasm::AssemblyItem::JumpType::Ordinary);
-	/// Appends an INVALID instruction
-	CompilerContext& appendInvalid();
-	/// Appends a conditional INVALID instruction
-	CompilerContext& appendConditionalInvalid();
+	/// Appends code to revert with a Panic(uint256) error.
+	CompilerContext& appendPanic(util::PanicCode _code);
+	/// Appends code to revert with a Panic(uint256) error if the topmost stack element is nonzero.
+	CompilerContext& appendConditionalPanic(util::PanicCode _code);
 	/// Appends a REVERT(0, 0) call
 	/// @param _message is an optional revert message used in debug mode
 	CompilerContext& appendRevert(std::string const& _message = "");

libsolidity/codegen/CompilerUtils.cpp

@@ -810,7 +810,7 @@ void CompilerUtils::convertType(
 			if (_asPartOfArgumentDecoding)
 				m_context.appendConditionalRevert(false, "Enum out of range");
 			else
-				m_context.appendConditionalInvalid();
+				m_context.appendConditionalPanic(util::PanicCode::EnumConversionError);
 			enumOverflowCheckPending = false;
 		}
 		break;
@@ -849,7 +849,7 @@ void CompilerUtils::convertType(
 			EnumType const& enumType = dynamic_cast<decltype(enumType)>(_targetType);
 			solAssert(enumType.numberOfMembers() > 0, "empty enum should have caused a parser error.");
 			m_context << u256(enumType.numberOfMembers() - 1) << Instruction::DUP2 << Instruction::GT;
-			m_context.appendConditionalInvalid();
+			m_context.appendConditionalPanic(util::PanicCode::EnumConversionError);
 			enumOverflowCheckPending = false;
 		}
 		else if (targetTypeCategory == Type::Category::FixedPoint)
@@ -1213,13 +1213,13 @@ void CompilerUtils::pushZeroValue(Type const& _type)
 		if (funType->kind() == FunctionType::Kind::Internal)
 		{
 			m_context << m_context.lowLevelFunctionTag("$invalidFunction", 0, 0, [](CompilerContext& _context) {
-				_context.appendInvalid();
+				_context.appendPanic(util::PanicCode::InvalidInternalFunction);
 			});
 			if (CompilerContext* runCon = m_context.runtimeContext())
 			{
 				leftShiftNumberOnStack(32);
 				m_context << runCon->lowLevelFunctionTag("$invalidFunction", 0, 0, [](CompilerContext& _context) {
-					_context.appendInvalid();
+					_context.appendPanic(util::PanicCode::InvalidInternalFunction);
 				}).toSubAssemblyTag(m_context.runtimeSub());
 				m_context << Instruction::OR;
 			}

libsolidity/codegen/ContractCompiler.cpp

@@ -47,6 +47,7 @@
 #include <liblangutil/ErrorReporter.h>
 
 #include <libsolutil/Whiskers.h>
+#include <libsolutil/FunctionSelector.h>
 
 #include <boost/range/adaptor/reversed.hpp>
 
@@ -229,19 +230,26 @@ size_t ContractCompiler::deployLibrary(ContractDefinition const& _contract)
 	m_context.pushSubroutineSize(m_context.runtimeSub());
 	m_context.pushSubroutineOffset(m_context.runtimeSub());
 	// This code replaces the address added by appendDeployTimeAddress().
-	m_context.appendInlineAssembly(R"(
-	{
-		// If code starts at 11, an mstore(0) writes to the full PUSH20 plus data
-		// without the need for a shift.
-		let codepos := 11
-		codecopy(codepos, subOffset, subSize)
-		// Check that the first opcode is a PUSH20
-		if iszero(eq(0x73, byte(0, mload(codepos)))) { invalid() }
-		mstore(0, address())
-		mstore8(codepos, 0x73)
-		return(codepos, subSize)
-	}
-	)", {"subSize", "subOffset"});
+	m_context.appendInlineAssembly(
+		Whiskers(R"(
+		{
+			// If code starts at 11, an mstore(0) writes to the full PUSH20 plus data
+			// without the need for a shift.
+			let codepos := 11
+			codecopy(codepos, subOffset, subSize)
+			// Check that the first opcode is a PUSH20
+			if iszero(eq(0x73, byte(0, mload(codepos)))) {
+				mstore(0, <panicSig>)
+				mstore(4, 0)
+				revert(0, 0x24)
+			}
+			mstore(0, address())
+			mstore8(codepos, 0x73)
+			return(codepos, subSize)
+		}
+		)")("panicSig", util::selectorFromSignature("Panic(uint256)").str()).render(),
+		{"subSize", "subOffset"}
+	);
 
 	return m_context.runtimeSub();
 }

libsolidity/codegen/ExpressionCompiler.cpp

@@ -933,7 +933,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 		{
 			acceptAndConvert(*arguments[2], *TypeProvider::uint256());
 			m_context << Instruction::DUP1 << Instruction::ISZERO;
-			m_context.appendConditionalInvalid();
+			m_context.appendConditionalPanic(util::PanicCode::DivisionByZero);
 			for (unsigned i = 1; i < 3; i ++)
 				acceptAndConvert(*arguments[2 - i], *TypeProvider::uint256());
 			if (function.kind() == FunctionType::Kind::AddMod)
@@ -1051,7 +1051,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			m_context << u256(0xffffffffffffffff);
 			m_context << Instruction::DUP2;
 			m_context << Instruction::GT;
-			m_context.appendConditionalRevert();
+			m_context.appendConditionalPanic(PanicCode::ResourceError);
 
 			// Stack: requested_length
 			utils().fetchFreeMemoryPointer();
@@ -1121,7 +1121,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			auto success = m_context.appendConditionalJump();
 			if (function.kind() == FunctionType::Kind::Assert)
 				// condition was not met, flag an error
-				m_context.appendInvalid();
+				m_context.appendPanic(util::PanicCode::Assert);
 			else if (haveReasonString)
 			{
 				utils().revertWithStringData(*arguments.at(1)->annotation().type);
@@ -1886,7 +1886,7 @@ bool ExpressionCompiler::visit(IndexAccess const& _indexAccess)
 			m_context << u256(fixedBytesType.numBytes());
 			m_context << Instruction::DUP2 << Instruction::LT << Instruction::ISZERO;
 			// out-of-bounds access throws exception
-			m_context.appendConditionalInvalid();
+			m_context.appendConditionalPanic(util::PanicCode::ArrayOutOfBounds);
 
 			m_context << Instruction::BYTE;
 			utils().leftShiftNumberOnStack(256 - 8);
@@ -2154,7 +2154,7 @@ void ExpressionCompiler::appendArithmeticOperatorCode(Token _operator, Type cons
 		{
 			// Test for division by zero
 			m_context << Instruction::DUP2 << Instruction::ISZERO;
-			m_context.appendConditionalInvalid();
+			m_context.appendConditionalPanic(util::PanicCode::DivisionByZero);
 
 			if (_operator == Token::Div)
 				m_context << (c_isSigned ? Instruction::SDIV : Instruction::DIV);

libsolidity/codegen/YulUtilFunctions.cpp

@@ -122,7 +122,7 @@ string YulUtilFunctions::requireOrAssertFunction(bool _assert, Type const* _mess
 					if iszero(condition) { <error> }
 				}
 			)")
-			("error", _assert ? panicFunction() + "()" : "revert(0, 0)")
+			("error", _assert ? panicFunction(PanicCode::Assert) + "()" : "revert(0, 0)")
 			("functionName", functionName)
 			.render();
 
@@ -478,7 +478,7 @@ string YulUtilFunctions::overflowCheckedIntAddFunction(IntegerType const& _type)
 			("maxValue", toCompactHexWithPrefix(u256(_type.maxValue())))
 			("minValue", toCompactHexWithPrefix(u256(_type.minValue())))
 			("cleanupFunction", cleanupFunction(_type))
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::UnderOverflow))
 			.render();
 	});
 }
@@ -530,7 +530,7 @@ string YulUtilFunctions::overflowCheckedIntMulFunction(IntegerType const& _type)
 			("maxValue", toCompactHexWithPrefix(u256(_type.maxValue())))
 			("minValue", toCompactHexWithPrefix(u256(_type.minValue())))
 			("cleanupFunction", cleanupFunction(_type))
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::UnderOverflow))
 			.render();
 	});
 }
@@ -560,13 +560,13 @@ string YulUtilFunctions::overflowCheckedIntDivFunction(IntegerType const& _type)
 			function <functionName>(x, y) -> r {
 				x := <cleanupFunction>(x)
 				y := <cleanupFunction>(y)
-				if iszero(y) { <panic>() }
+				if iszero(y) { <panicDivZero>() }
 				<?signed>
 				// overflow for minVal / -1
 				if and(
 					eq(x, <minVal>),
 					eq(y, sub(0, 1))
-				) { <panic>() }
+				) { <panicOverflow>() }
 				</signed>
 				r := <?signed>s</signed>div(x, y)
 			}
@@ -575,7 +575,8 @@ string YulUtilFunctions::overflowCheckedIntDivFunction(IntegerType const& _type)
 			("signed", _type.isSigned())
 			("minVal", toCompactHexWithPrefix(u256(_type.minValue())))
 			("cleanupFunction", cleanupFunction(_type))
-			("panic", panicFunction())
+			("panicDivZero", panicFunction(PanicCode::DivisionByZero))
+			("panicOverflow", panicFunction(PanicCode::UnderOverflow))
 			.render();
 	});
 }
@@ -596,7 +597,7 @@ string YulUtilFunctions::wrappingIntDivFunction(IntegerType const& _type)
 			("functionName", functionName)
 			("cleanupFunction", cleanupFunction(_type))
 			("signed", _type.isSigned())
-			("error", panicFunction())
+			("error", panicFunction(PanicCode::DivisionByZero))
 			.render();
 	});
 }
@@ -617,7 +618,7 @@ string YulUtilFunctions::intModFunction(IntegerType const& _type)
 			("functionName", functionName)
 			("signed", _type.isSigned())
 			("cleanupFunction", cleanupFunction(_type))
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::DivisionByZero))
 			.render();
 	});
 }
@@ -647,7 +648,7 @@ string YulUtilFunctions::overflowCheckedIntSubFunction(IntegerType const& _type)
 			("maxValue", toCompactHexWithPrefix(u256(_type.maxValue())))
 			("minValue", toCompactHexWithPrefix(u256(_type.minValue())))
 			("cleanupFunction", cleanupFunction(_type))
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::UnderOverflow))
 			.render();
 	});
 }
@@ -808,7 +809,7 @@ string YulUtilFunctions::overflowCheckedIntLiteralExpFunction(
 			("exponentCleanupFunction", cleanupFunction(_exponentType))
 			("needsOverflowCheck", needsOverflowCheck)
 			("exponentUpperbound", to_string(exponentUpperbound))
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::UnderOverflow))
 			("base", bigint2u(baseValue).str())
 			.render();
 	});
@@ -866,7 +867,7 @@ string YulUtilFunctions::overflowCheckedUnsignedExpFunction()
 			}
 			)")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::UnderOverflow))
 			("expLoop", overflowCheckedExpLoopFunction())
 			("shr_1", shiftRightFunction(1))
 			.render();
@@ -916,7 +917,7 @@ string YulUtilFunctions::overflowCheckedSignedExpFunction()
 			}
 			)")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::UnderOverflow))
 			("expLoop", overflowCheckedExpLoopFunction())
 			("shr_1", shiftRightFunction(1))
 			.render();
@@ -957,7 +958,7 @@ string YulUtilFunctions::overflowCheckedExpLoopFunction()
 			}
 			)")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::UnderOverflow))
 			("shr_1", shiftRightFunction(1))
 			.render();
 	});
@@ -1087,7 +1088,7 @@ std::string YulUtilFunctions::resizeDynamicArrayFunction(ArrayType const& _type)
 				}
 			})")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::ResourceError))
 			("fetchLength", arrayLengthFunction(_type))
 			("convertToSize", arrayConvertLengthToSize(_type))
 			("dataPosition", arrayDataAreaFunction(_type))
@@ -1123,7 +1124,7 @@ string YulUtilFunctions::resizeDynamicByteArrayFunction(ArrayType const& _type)
 				}
 			})")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::ResourceError))
 			("extractLength", extractByteArrayLengthFunction())
 			("maxArrayLength", (u256(1) << 64).str())
 			("decreaseSize", decreaseByteArraySizeFunction(_type))
@@ -1266,7 +1267,7 @@ string YulUtilFunctions::storageArrayPopFunction(ArrayType const& _type)
 				sstore(array, newLen)
 			})")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::EmptyArrayPop))
 			("fetchLength", arrayLengthFunction(_type))
 			("indexAccess", storageArrayIndexAccessFunction(_type))
 			("setToZero", storageSetToZeroFunction(*_type.baseType()))
@@ -1308,7 +1309,7 @@ string YulUtilFunctions::storageByteArrayPopFunction(ArrayType const& _type)
 				}
 			})")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::EmptyArrayPop))
 			("extractByteArrayLength", extractByteArrayLengthFunction())
 			("transitLongToShort", byteArrayTransitLongToShortFunction(_type))
 			("encodeUsedSetLen", shortByteArrayEncodeUsedAreaSetLengthFunction())
@@ -1370,7 +1371,7 @@ string YulUtilFunctions::storageArrayPushFunction(ArrayType const& _type)
 				</isByteArray>
 			})")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::ResourceError))
 			("extractByteArrayLength", _type.isByteArray() ? extractByteArrayLengthFunction() : "")
 			("dataAreaFunction", arrayDataAreaFunction(_type))
 			("isByteArray", _type.isByteArray())
@@ -1400,7 +1401,7 @@ string YulUtilFunctions::storageArrayPushZeroFunction(ArrayType const& _type)
 				slot, offset := <indexAccess>(array, oldLen)
 			})")
 			("functionName", functionName)
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::ResourceError))
 			("fetchLength", arrayLengthFunction(_type))
 			("indexAccess", storageArrayIndexAccessFunction(_type))
 			("maxArrayLength", (u256(1) << 64).str())
@@ -1715,7 +1716,7 @@ string YulUtilFunctions::arrayAllocationSizeFunction(ArrayType const& _type)
 			}
 		)");
 		w("functionName", functionName);
-		w("panic", panicFunction());
+		w("panic", panicFunction(PanicCode::ResourceError));
 		w("byteArray", _type.isByteArray());
 		w("dynamic", _type.isDynamicallySized());
 		return w.render();
@@ -1786,7 +1787,7 @@ string YulUtilFunctions::storageArrayIndexAccessFunction(ArrayType const& _type)
 			}
 		)")
 		("functionName", functionName)
-		("panic", panicFunction())
+		("panic", panicFunction(PanicCode::ArrayOutOfBounds))
 		("arrayLen", arrayLengthFunction(_type))
 		("dataAreaFunc", arrayDataAreaFunction(_type))
 		("multipleItemsPerSlot", _type.baseType()->storageBytes() <= 16)
@@ -1816,7 +1817,7 @@ string YulUtilFunctions::memoryArrayIndexAccessFunction(ArrayType const& _type)
 			}
 		)")
 		("functionName", functionName)
-		("panic", panicFunction())
+		("panic", panicFunction(PanicCode::ArrayOutOfBounds))
 		("arrayLen", arrayLengthFunction(_type))
 		("stride", to_string(_type.memoryStride()))
 		("dynamicallySized", _type.isDynamicallySized())
@@ -1839,7 +1840,7 @@ string YulUtilFunctions::calldataArrayIndexAccessFunction(ArrayType const& _type
 			}
 		)")
 		("functionName", functionName)
-		("panic", panicFunction())
+		("panic", panicFunction(PanicCode::ArrayOutOfBounds))
 		("stride", to_string(_type.calldataStride()))
 		("dynamicallySized", _type.isDynamicallySized())
 		("dynamicallyEncodedBase", _type.baseType()->isDynamicallyEncoded())
@@ -2509,7 +2510,7 @@ string YulUtilFunctions::allocationFunction()
 		)")
 		("functionName", functionName)
 		("freeMemoryPointer", to_string(CompilerUtils::freeMemoryPointer))
-		("panic", panicFunction())
+		("panic", panicFunction(PanicCode::ResourceError))
 		.render();
 	});
 }
@@ -3085,10 +3086,7 @@ string YulUtilFunctions::validatorFunction(Type const& _type, bool _revertOnFail
 			}
 		)");
 		templ("functionName", functionName);
-		if (_revertOnFailure)
-			templ("failure", "revert(0, 0)");
-		else
-			templ("failure", panicFunction() + "()");
+		PanicCode panicCode = PanicCode::Generic;
 
 		switch (_type.category())
 		{
@@ -3111,6 +3109,7 @@ string YulUtilFunctions::validatorFunction(Type const& _type, bool _revertOnFail
 		{
 			size_t members = dynamic_cast<EnumType const&>(_type).numberOfMembers();
 			solAssert(members > 0, "empty enum should have caused a parser error.");
+			panicCode = PanicCode::EnumConversionError;
 			templ("condition", "lt(value, " + to_string(members) + ")");
 			break;
 		}
@@ -3121,6 +3120,11 @@ string YulUtilFunctions::validatorFunction(Type const& _type, bool _revertOnFail
 			solAssert(false, "Validation of type " + _type.identifier() + " requested.");
 		}
 
+		if (_revertOnFailure)
+			templ("failure", "revert(0, 0)");
+		else
+			templ("failure", panicFunction(panicCode) + "()");
+
 		return templ.render();
 	});
 }
@@ -3196,7 +3200,7 @@ std::string YulUtilFunctions::decrementCheckedFunction(Type const& _type)
 			}
 		)")
 		("functionName", functionName)
-		("panic", panicFunction())
+		("panic", panicFunction(PanicCode::UnderOverflow))
 		("minval", toCompactHexWithPrefix(type.min()))
 		("cleanupFunction", cleanupFunction(_type))
 		.render();
@@ -3237,7 +3241,7 @@ std::string YulUtilFunctions::incrementCheckedFunction(Type const& _type)
 		)")
 		("functionName", functionName)
 		("maxval", toCompactHexWithPrefix(type.max()))
-		("panic", panicFunction())
+		("panic", panicFunction(PanicCode::UnderOverflow))
 		("cleanupFunction", cleanupFunction(_type))
 		.render();
 	});
@@ -3278,7 +3282,7 @@ string YulUtilFunctions::negateNumberCheckedFunction(Type const& _type)
 		("functionName", functionName)
 		("minval", toCompactHexWithPrefix(type.min()))
 		("cleanupFunction", cleanupFunction(_type))
-		("panic", panicFunction())
+		("panic", panicFunction(PanicCode::UnderOverflow))
 		.render();
 	});
 }
@@ -3400,7 +3404,7 @@ string YulUtilFunctions::storageSetToZeroFunction(Type const& _type)
 			)")
 			("functionName", functionName)
 			("clearArray", clearStorageArrayFunction(dynamic_cast<ArrayType const&>(_type)))
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::Generic))
 			.render();
 		else if (_type.category() == Type::Category::Struct)
 			return Whiskers(R"(
@@ -3411,7 +3415,7 @@ string YulUtilFunctions::storageSetToZeroFunction(Type const& _type)
 			)")
 			("functionName", functionName)
 			("clearStruct", clearStorageStructFunction(dynamic_cast<StructType const&>(_type)))
-			("panic", panicFunction())
+			("panic", panicFunction(PanicCode::Generic))
 			.render();
 		else
 			solUnimplemented("setToZero for type " + _type.identifier() + " not yet implemented!");
@@ -3645,16 +3649,20 @@ string YulUtilFunctions::revertReasonIfDebug(string const& _message)
 	return revertReasonIfDebug(m_revertStrings, _message);
 }
 
-string YulUtilFunctions::panicFunction()
+string YulUtilFunctions::panicFunction(util::PanicCode _code)
 {
-	string functionName = "panic_error";
+	string functionName = "panic_error_" + toCompactHexWithPrefix(uint64_t(_code));
 	return m_functionCollector.createFunction(functionName, [&]() {
 		return Whiskers(R"(
 			function <functionName>() {
-				invalid()
+				mstore(0, <selector>)
+				mstore(4, <code>)
+				revert(0, 0x24)
 			}
 		)")
 		("functionName", functionName)
+		("selector", util::selectorFromSignature("Panic(uint256)").str())
+		("code", toCompactHexWithPrefix(_code))
 		.render();
 	});
 }

libsolidity/codegen/YulUtilFunctions.h

@@ -28,6 +28,8 @@
 
 #include <libsolidity/interface/DebugSettings.h>
 
+#include <libsolutil/ErrorCodes.h>
+
 #include <memory>
 #include <string>
 #include <vector>
@@ -406,9 +408,8 @@ public:
 
 	std::string revertReasonIfDebug(std::string const& _message = "");
 
-	/// Executes the invalid opcode.
-	/// Might use revert with special error code in the future.
-	std::string panicFunction();
+	/// Reverts with ``Panic(uint256)`` and the given code.
+	std::string panicFunction(util::PanicCode _code);
 
 	/// Returns the name of a function that decodes an error message.
 	/// signature: () -> arrayPtr

libsolidity/codegen/ir/IRGenerator.cpp

@@ -208,7 +208,7 @@ InternalDispatchMap IRGenerator::generateInternalDispatchFunctions()
 				}
 			)");
 			templ("functionName", funName);
-			templ("panic", m_utils.panicFunction());
+			templ("panic", m_utils.panicFunction(PanicCode::InvalidInternalFunction));
 			templ("in", suffixedVariableNameList("in_", 0, arity.in));
 			templ("out", suffixedVariableNameList("out_", 0, arity.out));
 

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -1302,7 +1302,7 @@ void IRGeneratorForStatements::endVisit(FunctionCall const& _functionCall)
 		define(modulus, *arguments[2]);
 		Whiskers templ("if iszero(<modulus>) { <panic>() }\n");
 		templ("modulus", modulus.name());
-		templ("panic", m_utils.panicFunction());
+		templ("panic", m_utils.panicFunction(PanicCode::DivisionByZero));
 		m_code << templ.render();
 
 		string args;
@@ -1367,7 +1367,7 @@ void IRGeneratorForStatements::endVisit(FunctionCall const& _functionCall)
 		t("allocateTemporaryMemory", m_utils.allocationTemporaryMemoryFunction());
 		t("releaseTemporaryMemory", m_utils.releaseTemporaryMemoryFunction());
 		t("object", IRNames::creationObject(*contract));
-		t("panic", m_utils.panicFunction());
+		t("panic", m_utils.panicFunction(PanicCode::ResourceError));
 		t("abiEncode",
 			m_context.abiFunctions().tupleEncoder(argumentTypes, functionType->parameterTypes(), false)
 		);
@@ -2023,7 +2023,7 @@ void IRGeneratorForStatements::endVisit(IndexAccess const& _indexAccess)
 		)")
 		("index", index.name())
 		("length", to_string(fixedBytesType.numBytes()))
-		("panic", m_utils.panicFunction())
+		("panic", m_utils.panicFunction(PanicCode::ArrayOutOfBounds))
 		("array", IRVariable(_indexAccess.baseExpression()).name())
 		("shl248", m_utils.shiftLeftFunction(256 - 8))
 		("result", IRVariable(_indexAccess).name())

libsolutil/CMakeLists.txt

@@ -9,6 +9,7 @@ set(sources
 	CommonIO.h
 	Exceptions.cpp
 	Exceptions.h
+	ErrorCodes.h
 	FixedHash.h
 	FunctionSelector.h
 	IndentedWriter.cpp

libsolutil/ErrorCodes.h

@@ -0,0 +1,38 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+#pragma once
+
+#include <string>
+
+namespace solidity::util
+{
+
+enum class PanicCode
+{
+	Generic = 0x00, // generic / unspecified error.
+	Assert = 0x01, // generic / unspecified error. Used by assert().
+	UnderOverflow = 0x11, // arithmetic underflow or overflow
+	DivisionByZero = 0x12, // division or modulo by zero
+	EnumConversionError = 0x21, // enum conversion error
+	EmptyArrayPop = 0x31, // empty array pop
+	ArrayOutOfBounds = 0x32, // array out of bounds access
+	ResourceError = 0x41, // resource error (too large allocation or too large array)
+	InvalidInternalFunction = 0x51, // calling invalid internal function
+};
+
+}

libyul/backends/evm/EVMDialect.cpp

@@ -378,6 +378,7 @@ EVMDialectTyped::EVMDialectTyped(langutil::EVMVersion _evmVersion, bool _objectA
 		BuiltinContext&,
 		std::function<void(Expression const&)> _visitExpression
 	) {
+		// TODO this should use a Panic.
 		// A value larger than 1 causes an invalid instruction.
 		visitArguments(_assembly, _call, _visitExpression);
 		_assembly.appendConstant(2);