This is a SysY to RISC-V complier project for the course Compiler Principles of Peking University.
An example SysY code1 is like this:
int fib(int n) {
if (n <= 2) {
return 1;
} else {
return fib(n - 1) + fib(n - 2);
}
}
int main() {
int input = getint();
putint(fib(input));
putch(10);
return 0;
}
The corresponding RISC-V code is like this:
.text
.align 2
.globl fib
fib:
sw ra, -4(sp)
addi sp, sp, -16
li t1, 2
bgt a0, t1, .l0
li a0, 1
addi sp, sp, 16
lw ra, -4(sp)
ret
.l0:
addi s4, a0, -1
sw a0, 0(sp)
mv a0, s4
call fib
mv a3, a0
lw a0, 0(sp)
addi s4, a0, -2
sw a3, 0(sp)
mv a0, s4
call fib
mv s4, a0
lw a3, 0(sp)
add s4, a3, s4
mv a0, s4
addi sp, sp, 16
lw ra, -4(sp)
ret
.globl main
main:
sw ra, -4(sp)
addi sp, sp, -16
call getint
call fib
call putint
li a0, 10
call putch
li a0, 0
addi sp, sp, 16
lw ra, -4(sp)
ret
The compiling process are splited into three stages:
- stage 1: SysY --> Eeyore
- stage 2: Eeyore --> Tiger
- stage 3: Tiger --> RISCV
The file structure are shown as below, in each stage the structures are similar. Take stage 1 as an example, the folder is composed of 5 files, source.lex for lexical analysis, source.yacc for syntactic analysis, while the process of constructing and scanning the syntax tree through the data structures is defined in parse.c and parse.h.
.
├── Stage1 // sysY -> eeyore
│ ├── parse.c // Parse the generated syntax tree
│ ├── parse.h // Definition of global data structure, key functions and symbol tables
│ ├── run.sh // shell script for running
│ ├── source.l // for lexical analysis
│ └── source.y // for syntactic analysis
├── Stage2 // eeyore -> tiger
└── Stage3 // tiger -> RISCV
3 directories, 15 files