Implementation of the tigpiler in C [Modern compiler implementation in C - Appel]

Note: The references to the code have been from the files provided by the TA and also cmcl's repository : https://github.com/cmcl/tiger

Authors : Vinayak and Ashish

[Release notes]

1. The package does not include regester allocation by coloring
2. Includes a crude implementation of two optimizations constant folding and constant propogation [needs a little bug fixing here]

[Instructions to run]

1. Compile the code by using the makefile
2. Use the executable *tiger created to compile your tiger programs
3. Use the 'h' command to display the help menu for the compiler

[MIPS instruction references]

MIPS instructions Assembly code Meaning Add add $d,$s,$t $d = $s + $t Subtract sub $d,$s,$t $d = $s - $t Add immediate addi $t,$s,C $t = $s + C (signed) Load word ld $t,C($s) $t = Memory[$s + C] Store word sw $t,C($s) Memory[$s + C] = $t And and $d,$s,$t $d = $s & $t And immediate andi $t,$s,C $t = $s & C Or or $d,$s,$t $d = $s | $t Or immediate ori $t,$s,C $t = $s | C Shift left logical sll $d,$t,shamt $d = $t << shamt Shift right logical srl $d,$t,shamt $d = $t >> shamt Shift right arithmetic sra $d,$t,shamt Branch on equal beq $s,$t,C if ($s == $t) go to PC+4+4C Branch on not equal bne $s,$t,C if ($s != $t) go to PC+4+4C Jump j C PC = PC+4[31:28] . C4 Jump register jr $s goto address $s Jump and link jal C $31 = PC + 8; PC = PC+4[31:28] . C4 (For procedure call - used to call a subroutine, $31 holds the return address; returning from a subroutine is done by: jr $31. Return address is PC + 8, not PC + 4 due to the use of a branch delay slot which forces the instruction after the jump to be executed) Move move $rt,$rs addi $rt,$rs,0 Branch if greater than bgt $rs,$rt,Label Branch if less than blt $rs,$rt,Label Branch if greater than or equal bge $rs,$rt,Label Branch if less than or equal ble $rs,$rt,Label Multiplies and returns only first 32 bits mul $d, $s, $t Divides and returns quotient div $d, $s, $t