Compiler Micro/Ex

How to run

• Change directory into src

•   make 
    make run
  

• The results are shown with stdout
• To run with or without stderr message:

	./compiler < $input 
	./compiler < $input 2> /dev/null

• The demo input is data/testfile.micro, output is data/testfile.out.

Micro/Ex functions

Declare Statement

• Declare var_list As type ;
  • var_list: a list of variables seperated by comma
    • variables: variable or array variable
  • type: Integer or Float
• For example:

	Declare a, arr[100] as float;

The compiler should generate the assembly code:

	Declare a, Float
	Declare arr, Float_array, 100

Assignment Statement

• var := expression ;
  • var: the assigned variable should be declared before use, otherwise error message would show.
  • expression: support +, -, *, / with precedence, also parenthesis can be use to have higher precedence.
• For example:

	arr[0] := 1;
	arr[1] := 2;
	a := -arr[0] + arr[1] * (arr[0] + arr[1]);

The compiler should generate the assembly code:

	F_STORE 1, arr[0]
	F_STORE 2, arr[1]
	F_UMINUS arr[0], T&1
	F_ADD arr[0], arr[1], T&2
	F_MUL arr[1], T&2, T&3
	F_ADD T&1, T&3, T&2
	F_STORE T&2, a

Note that T&[number] is free register.

For Loop Statement

• FOR (var := expression to expression [STEP number] ) statement_list ENDFOR
  • expression: returns a variable name or number in literal
  • statement_list: a sequence of statements including all the statements.
  • to: TO (increment by 1) or DOWNTO (decrease by 1)
• For example:

	Declare i, sum as Integer;
	sum := 0;
	FOR ( i := 1 TO 10 ) 
		sum := sum + i;
	ENDFOR

The compiler should generate the assembly code:

	Declare i, Integer
	Declare sum, Integer
	I_STORE 0, sum
	I_STORE 1, i
lb&1:	I_ADD sum, i, T&1
	I_STORE T&1, sum
	INC i
	I_CMP i, 10
	JL lb&1

If Else Statement

• IF ( comparison_expression ) THEN statement_list ENDIF
• IF ( comparison_expression ) THEN statement_list ELSE statement_list ENDIF
  • comparison_expression: support <, >, <=, >=, ==, != of logical operator
• For example:

	IF ( sum > 50 ) THEN
		print ( sum );
	ELSE
		print( a );
	ENDIF

The compiler should generate the assembly code:

	I_CMP sum, 50
	JLE lb&2
	CALL print, sum
	J lb&3
lb&2:	CALL print, a
lb&3:

Comments

• %% to comment one line
• %{ comments }% to comment multiple lines

Extra functions

• Support Step of for loop
  • for for_head step [number]
  • number can be float type
• Support nested IF statement
• Support nested for loop statement
• Reuse unused registers
  • When a register is used as temporary memory, it is freed after the temporary use is finished.
• Check Invalid usage of variables
  • reference before declaration
  • array bound exceed

Environment

• mac OS
• bison (GNU Bison) 2.3
• flex 2.5.35 Apple(flex-31)
• gcc version
  • Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
  • Apple LLVM version 10.0.0 (clang-1000.10.44.4)
  • Target: x86_64-apple-darwin17.7.0
  • Thread model: posix