Change translation of implicit throws (issue #1589).

This adds a new invalid instruction that is used for encoding
implicit throws that are emitted by the compiler. This makes it
possible to distinguish such runtime errors from user-provided,
explicit throws.

libevmasm/Instruction.cpp

@@ -154,6 +154,7 @@ const std::map<std::string, Instruction> dev::solidity::c_instructions =
 	{ "LOG2", Instruction::LOG2 },
 	{ "LOG3", Instruction::LOG3 },
 	{ "LOG4", Instruction::LOG4 },
+	{ "INVALID", Instruction::INVALID },
 	{ "CREATE", Instruction::CREATE },
 	{ "CALL", Instruction::CALL },
 	{ "CALLCODE", Instruction::CALLCODE },
@@ -288,6 +289,7 @@ static const std::map<Instruction, InstructionInfo> c_instructionInfo =
 	{ Instruction::LOG2,		{ "LOG2",			0, 4, 0, true, Tier::Special } },
 	{ Instruction::LOG3,		{ "LOG3",			0, 5, 0, true, Tier::Special } },
 	{ Instruction::LOG4,		{ "LOG4",			0, 6, 0, true, Tier::Special } },
+	{ Instruction::INVALID,		{ "INVALID",		0, 0, 0, true, Tier::Zero } },
 	{ Instruction::CREATE,		{ "CREATE",			0, 3, 1, true, Tier::Special } },
 	{ Instruction::CALL,		{ "CALL",			0, 7, 1, true, Tier::Special } },
 	{ Instruction::CALLCODE,	{ "CALLCODE",		0, 7, 1, true, Tier::Special } },

libevmasm/Instruction.h

@@ -171,6 +171,8 @@ enum class Instruction: uint8_t
 	LOG3,				///< Makes a log entry; 3 topics.
 	LOG4,				///< Makes a log entry; 4 topics.
 
+	INVALID = 0xef,		///< invalid instruction for expressing runtime errors (e.g., division-by-zero)
+
 	CREATE = 0xf0,		///< create a new account with associated code
 	CALL,				///< message-call into an account
 	CALLCODE,			///< message-call with another account's code only