rlldlbf / compiler

Compiler for C--

Building Source

Prerequisites

The following libraries are required to build:

• flex
• bison

Please make sure that all dependancies are installed and linked properly to your PATH before building.

Linux

If you use Debian/Ubuntu, simply cut'n paste:

sudo apt-get install flex bison

Usage

1. Generate Abstract Syntax Tree (AST)

build

make gen_AST

usage:

out/gen_AST path-to-source-file [output-path]

sample AST output

Program (1)
  ExtDefList (1)
    ExtDef (1)
      Specifier (1)
        TYPE: int
      FunDec (1)
        ID: main
        LP
        RP
      CompSt (2)
        LC
        DefList (3)
          Def (3)
            Specifier (3)
              TYPE: float
            DecList (3)
              Dec (3)
                VarDec (3)
                  ID: i
                ASSIGNOP
                Exp (3)
                  FLOAT: 0.000105
            SEMI
        RC

2. Semantic analysis

build

make semantic_check

usage:

out/semantic_check path-to-source-file

3. Generate IR

build

make gen_ir [output-path]       # with optimization
make gen_raw_ir [output-path]   # without optimization

usage:

out/gen_ir path-to-source-file

Optimization techniques:

• Copy propagation
• Constant propagation
• Constant folding
• Dead code elimination
• Redundant label elimination
• Other heuristic algorithms

sample IR output

FUNCTION main :
READ t1
v_n := t1
t2 := v_n
t3 := #0
IF t2 <= t3 GOTO label1
t4 := #1
WRITE t4
GOTO label2
LABEL label1 :
t5 := v_n
t6 := #0
IF t5 >= t6 GOTO label3
t8 := #1
t7 := #0 - t8
WRITE t7
GOTO label4
LABEL label3 :
t9 := #0
WRITE t9
LABEL label4 :
LABEL label2 :
t10 := #0
RETURN t10

4. generate MIPS code

build

make gen_oc

usage:

out/gen_oc path-to-source-file [output-path]

sample MIPS code output

.data
_prompt: .asciiz "Enter an integer:"
_ret: .asciiz "\n"
.globl main
.text
read:
li $v0, 4
la $a0, _prompt
syscall
li $v0, 5
syscall
jr $ra

write:
li $v0, 1
syscall
li $v0, 4
la $a0, _ret
syscall
move $v0, $0
jr $ra

main:
li $t5, 0
li $t4, 1
li $t3, 0
addi $sp, $sp, -4
sw $ra, 0($sp)
jal read
lw $ra, 0($sp)
addi $sp, $sp, 4
move $t1, $v0
move $t2, $t1
label1:
blt $t3, $t2, label2
j label3
label2:
add $t1, $t5, $t4
move $a0, $t4
addi $sp, $sp, -4
sw $ra, 0($sp)
jal write
lw $ra, 0($sp)
addi $sp, $sp, 4
move $t5, $t4
move $t4, $t1
addi $t1, $t3, 1
move $t3, $t1
j label1
label3:
move $v0, $0
jr $ra