Merge pull request #1875 from chriseth/sol_invertIf

Reverse if and else body.

libsolidity/Compiler.cpp

@@ -377,12 +377,16 @@ bool Compiler::visit(IfStatement const& _ifStatement)
 	StackHeightChecker checker(m_context);
 	CompilerContext::LocationSetter locationSetter(m_context, _ifStatement);
 	compileExpression(_ifStatement.getCondition());
-	eth::AssemblyItem trueTag = m_context.appendConditionalJump();
+	m_context << eth::Instruction::ISZERO;
+	eth::AssemblyItem falseTag = m_context.appendConditionalJump();
+	eth::AssemblyItem endTag = falseTag;
+	_ifStatement.getTrueStatement().accept(*this);
 	if (_ifStatement.getFalseStatement())
+	{
+		endTag = m_context.appendJumpToNew();
+		m_context << falseTag;
 		_ifStatement.getFalseStatement()->accept(*this);
-	eth::AssemblyItem endTag = m_context.appendJumpToNew();
-	m_context << trueTag;
-	_ifStatement.getTrueStatement().accept(*this);
+	}
 	m_context << endTag;
 
 	checker.check();

test/libsolidity/SolidityCompiler.cpp

@@ -116,36 +116,35 @@ BOOST_AUTO_TEST_CASE(ifStatement)
 	bytes code = compileContract(sourceCode);
 	unsigned shift = 60;
 	unsigned boilerplateSize = 73;
-	bytes expectation({byte(Instruction::JUMPDEST),
-					   byte(Instruction::PUSH1), 0x0,
-					   byte(Instruction::DUP1),
-					   byte(Instruction::PUSH1), byte(0x1b + shift), // "true" target
-					   byte(Instruction::JUMPI),
-					   // new check "else if" condition
-					   byte(Instruction::DUP1),
-					   byte(Instruction::ISZERO),
-					   byte(Instruction::PUSH1), byte(0x13 + shift),
-					   byte(Instruction::JUMPI),
-					   // "else" body
-					   byte(Instruction::PUSH1), 0x4f,
-					   byte(Instruction::POP),
-					   byte(Instruction::PUSH1), byte(0x17 + shift), // exit path of second part
-					   byte(Instruction::JUMP),
-					   // "else if" body
-					   byte(Instruction::JUMPDEST),
-					   byte(Instruction::PUSH1), 0x4e,
-					   byte(Instruction::POP),
-					   byte(Instruction::JUMPDEST),
-					   byte(Instruction::PUSH1), byte(0x1f + shift),
-					   byte(Instruction::JUMP),
-					   // "if" body
-					   byte(Instruction::JUMPDEST),
-					   byte(Instruction::PUSH1), 0x4d,
-					   byte(Instruction::POP),
-					   byte(Instruction::JUMPDEST),
-					   byte(Instruction::JUMPDEST),
-					   byte(Instruction::POP),
-					   byte(Instruction::JUMP)});
+	bytes expectation({
+		byte(Instruction::JUMPDEST),
+		byte(Instruction::PUSH1), 0x0,
+		byte(Instruction::DUP1),
+		byte(Instruction::ISZERO),
+		byte(Instruction::PUSH1), byte(0x0f + shift), // "false" target
+		byte(Instruction::JUMPI),
+		// "if" body
+		byte(Instruction::PUSH1), 0x4d,
+		byte(Instruction::POP),
+		byte(Instruction::PUSH1), byte(0x21 + shift),
+		byte(Instruction::JUMP),
+		// new check "else if" condition
+		byte(Instruction::JUMPDEST),
+		byte(Instruction::DUP1),
+		byte(Instruction::ISZERO),
+		byte(Instruction::ISZERO),
+		byte(Instruction::PUSH1), byte(0x1c + shift),
+		byte(Instruction::JUMPI),
+		// "else if" body
+		byte(Instruction::PUSH1), 0x4e,
+		byte(Instruction::POP),
+		byte(Instruction::PUSH1), byte(0x20 + shift),
+		byte(Instruction::JUMP),
+		// "else" body
+		byte(Instruction::JUMPDEST),
+		byte(Instruction::PUSH1), 0x4f,
+		byte(Instruction::POP),
+	});
 	checkCodePresentAt(code, expectation, boilerplateSize);
 }