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bfjit-64k-postpone.c
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#ifndef __x86_64__
#error "Only x86-64 architecture, please!"
#endif
#define _GNU_SOURCE
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <stdint.h>
#define B1(x) (x&0xFF)
#define B2(x) ((x>>8)&0xFF)
#define B3(x) ((x>>16)&0xFF)
#define B4(x) ((x>>24)&0xFF)
struct addr_node {
unsigned int pos; // position in source space
uint64_t addr; // addr in "assembly" space
uint64_t placeholder_addr;
struct addr_node *next;
};
struct addr_node *addr_node_first = NULL, *addr_node_last = NULL;
// tape
#define TAPE_SIZE 0xffff
uint8_t tape[TAPE_SIZE];
void init_tape() {
memset(tape, 0, TAPE_SIZE);
}
// file
#define is_legal_char(ch) (ch == '+' || ch == '-' || ch == '<' || ch == '>' || ch == '[' || ch == ']' || ch == '.' || ch == ',' || ch == '#')
char *read_file(FILE *f) {
char buf[128];
char *str = malloc(sizeof(buf)+1);
size_t cap = sizeof(buf), size = 0, s = 0;
while((s = fread(buf,1,sizeof(buf),f)) > 0) {
if(size+s>cap) {
cap *= 2;
str = realloc(str, cap+1);
}
for(unsigned int i = 0; i < s; i++) {
if(is_legal_char(buf[i])) {
str[size] = buf[i];
size++;
}
}
}
str[size] = 0;
return str;
}
// jit function
uint64_t (*_bfjit)(uint8_t *tape);
uint8_t *_bfjit_mem;
uint64_t _bfjit_mem_ptr, _bfjit_mem_max;
void init_jit() {
_bfjit_mem_ptr = 0;
_bfjit_mem_max = 4096;
_bfjit = mmap(NULL, 4096, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if(_bfjit == (void*)-1) {
perror("mmap()");
exit(1);
}
_bfjit_mem = (uint8_t*)_bfjit;
}
void jit_append(uint8_t *buf, size_t size) {
if(_bfjit_mem_ptr+size > _bfjit_mem_max) {
_bfjit = mremap(_bfjit, _bfjit_mem_max, _bfjit_mem_max+4096, MREMAP_MAYMOVE);
if(_bfjit == (void*)-1) {
perror("mremap()");
exit(1);
}
_bfjit_mem = (uint8_t*)_bfjit;
_bfjit_mem_max += 4096;
}
memcpy(_bfjit_mem+_bfjit_mem_ptr, buf, size);
_bfjit_mem_ptr += size;
}
void jit_fill_placeholders(char *str) {
for (struct addr_node *addr_node = addr_node_first; addr_node != NULL; addr_node = addr_node->next) {
char ch = str[addr_node->pos];
#ifdef DEBUG
printf("%c\n", ch);
printf("MAGIC: %x%x%x%x\n", *(_bfjit_mem+addr_node->placeholder_addr),
*(_bfjit_mem+addr_node->placeholder_addr+1),
*(_bfjit_mem+addr_node->placeholder_addr+2),
*(_bfjit_mem+addr_node->placeholder_addr+3)
);
#endif
uint64_t delta;
uint64_t matching_addr = (uint64_t)-1;
if(ch == '[') {
unsigned int j = addr_node->pos, count = 1;
while(count && str[j]) {
j++;
if(str[j] == '[') count++;
if(str[j] == ']') count--;
}
for (struct addr_node *addr_node_m = addr_node; addr_node_m != NULL; addr_node_m = addr_node_m->next) {
if(addr_node_m->pos == j) {
matching_addr = addr_node_m->addr;
}
}
if(matching_addr == (uint64_t)-1) {
printf("unmatching bracket for [");
exit(1);
}
delta = matching_addr-addr_node->addr-5;
} else if (ch == ']') {
unsigned int j = addr_node->pos, count = 1;
while(count && str[j]) {
j--;
if(str[j] == ']') count++;
if(str[j] == '[') count--;
}
for (struct addr_node *addr_node_m = addr_node_first; addr_node_m != addr_node; addr_node_m = addr_node_m->next) {
if(addr_node_m->pos == j) {
matching_addr = addr_node_m->addr;
}
}
if(matching_addr == (uint64_t)-1) {
printf("unmatching bracket for [");
exit(1);
}
delta = matching_addr-addr_node->addr-6;
}
//printf("delta: 0x%x\n", delta);
*(_bfjit_mem+addr_node->placeholder_addr+0) = B1(delta);
*(_bfjit_mem+addr_node->placeholder_addr+1) = B2(delta);
*(_bfjit_mem+addr_node->placeholder_addr+2) = B3(delta);
*(_bfjit_mem+addr_node->placeholder_addr+3) = B4(delta);
}
}
#define jit_append_buf(...) \
do{ char buf[] = { __VA_ARGS__ }; \
jit_append(buf, sizeof(buf)); } while(0)
static inline void jit_append_variable_length_addr(int n) {
// i didn't want to do this
// but goddamn intel and their variable length instructions!!!
// why isnt x86 a simple architecture??
uint16_t a = B1(n), b = B2(n);
if(n < 0) {
//printf("%x\n", n);
n = -n;
if(n < 0xff) {
jit_append_buf(0xff-n+1);
} else {
jit_append_buf(0xff-a,0xff-b,0xff,0xff);
}
} else {
jit_append_buf(a,b,0x00,0x00);
}
}
// addr vector
struct addr_node *addr_node_create(unsigned int pos, uint64_t addr, uint64_t placeholder_addr) {
struct addr_node *addr_node = malloc(sizeof(struct addr_node));
addr_node->pos = pos;
addr_node->addr = addr;
addr_node->placeholder_addr = placeholder_addr;
addr_node->next = NULL;
return addr_node;
}
void addr_node_append(unsigned int pos, uint64_t addr, uint64_t placeholder_addr) {
struct addr_node *addr_node = addr_node_create(pos,addr,placeholder_addr);
if(addr_node_first == NULL) {
addr_node_first = addr_node_last = addr_node;
} else {
addr_node_last->next = addr_node;
addr_node_last = addr_node;
}
}
// breakpoint
asm("bp: nop; retq");
void bp(); // noop
int main(int argc, char **argv) {
init_tape();
init_jit();
if(argc < 2) {
printf("usage: <%s> source\n", argv[0]);
return 1;
}
FILE *f;
if(argv[1][0] == '-' && argv[1][1] == 0) f = stdin;
else f = fopen(argv[1], "r");
if(f == NULL) {
perror("fopen()");
return 1;
}
char *str = read_file(f);
//printf("%s\n",str);
if(str == NULL) {
printf("unable to read\n");
return 1;
}
jit_append_buf(0x48, 0x31, 0xc9); // xor %rcx, %rcx
int postpone_ptr = 0; // relative
unsigned int i = 0;
char c;
if((c = str[i]) == '[') {
// skip dead code or comments
i++;
int count = 1;
while(count && (c = str[i])) {
i++;
if(str[i] == '[') count++;
if(str[i] == ']') count--;
}
}
while((c = str[i])) {
// https://www.nayuki.io/page/optimizing-brainfuck-compiler
// http://www.wilfred.me.uk/blog/2015/08/29/an-optimising-bf-compiler/
// http://calmerthanyouare.org/2015/01/07/optimizing-brainfuck.html
//printf("C: %c\n",c);
char next_ch = str[i+1], next_ch1 = next_ch ? str[i+2] : 0;
// BUG: somehow rdi = 0
// sar $0xff,%edi
// FIXME: B1,B2 not work for negative
#define flush_ptr() if(postpone_ptr!=0){ \
uint16_t sign = (postpone_ptr<0?0xe9:0xc1); \
postpone_ptr = (postpone_ptr<0?-postpone_ptr:postpone_ptr); \
jit_append_buf(0x66, 0x81, sign, B1(postpone_ptr), B2(postpone_ptr)); /* addw $postpone_ptr, %cx */ \
postpone_ptr = 0; \
}
//printf("C:%c\n",c);
if(c=='#') {
//flush_ptr();
jit_append_buf(0x90);
/*#ifdef DEBUG
jit_append_buf(0x48, 0x89, 0xc8); //mov %rcx,%rax
#endif
jit_append_buf(0xc3);*/
}
#ifdef OPTIMIZE
// fusing incs/decs
if((c == '+' || c == '-') && (next_ch == '+' || next_ch == '-')) {
uint8_t value_delta = 0;
while((c = str[i])) {
if(c == '+') value_delta++;
else if(c == '-') value_delta--;
else break;
i++;
}
if(value_delta == 0) continue;
if(postpone_ptr) {
jit_append_buf(0x80, postpone_ptr<0?0x44:0x84, 0x39);
jit_append_variable_length_addr(postpone_ptr);
jit_append_buf(value_delta); // addb $delta, (%rcx,%rdi,1)
} else
jit_append_buf(0x80, 0x04, 0x39, value_delta); // addb $delta, (%rcx,%rdi,1)
continue;
}
// fusing ptr movement
if((c == '>' || c == '<') && (next_ch == '>' || next_ch == '<')) {
while((c = str[i])) {
if(c == '>') postpone_ptr++;
else if(c == '<') postpone_ptr--;
else break;
i++;
}
continue;
}
// clear loops
if(c == '[' && next_ch == '-' && next_ch1 == ']' && 0) {
i += 3;
c = str[i];
uint8_t value_delta = 0;
while((c = str[i])) {
if(c == '+') value_delta++;
else if(c == '-') value_delta--;
else break;
i++;
}
flush_ptr();
jit_append_buf(0xc6, 0x04, 0x39, value_delta);
/*
if(postpone_ptr) {
int tmp = 0;
if(postpone_ptr > 0 && postpone_ptr<0xff) tmp = 0x44;
else if(postpone_ptr < 0 && (-postpone_ptr)>0xff) tmp = 0x44;
else tmp = 0x84;
jit_append_buf(0xc6, tmp, 0x39);
if(postpone_ptr < 0 && (-postpone_ptr)>0xff) {
printf("%d", postpone_ptr);
jit_append_buf(0xff-postpone_ptr+1);
}
else if(postpone_ptr < 0xff)
jit_append_buf(postpone_ptr);
else
jit_append_variable_length_addr(postpone_ptr);
jit_append_buf(value_delta); // movb $0x0, $...(%rsi,%rdi,1)
} else
jit_append_buf(0xc6, 0x04, 0x39, value_delta); // movb $0x0, (%rsi,%rdi,1)
*/
// chained clear loops
if(str[i] == '>' && str[i+1] == '[' && str[i+2] == '-' && str[i+3] == ']') { // forwards
int j = 0;
uint64_t arg = 0x00ffffff;
// 1: arg=0x00ffffff
// 2: arg=0x0000ffff
// 3: arg=0x000000ff
// 4: arg=0x00000000
while(str[i]) {
if(j < 3 && str[i] == '>' && str[i+1] == '[' && str[i+2] == '-' && str[i+3] == ']') {
arg = arg >> 8;
j++;
i+= 4;
} else break;
}
//printf("0x%08x\n", arg);
if(postpone_ptr) {
uint16_t b2;
uint64_t tmp = (uint64_t)postpone_ptr;
if(tmp < 0xff) b2 = 0x64;
else b2 = 0xa4;
jit_append_buf(0x81, 0xa4, 0x39);
jit_append_variable_length_addr(postpone_ptr);
jit_append_buf(B4(arg),B3(arg),B2(arg),B1(arg));
postpone_ptr += j;
} else {
jit_append_buf(0x81,0x24,0x39,B4(arg),B3(arg),B2(arg),B1(arg)); // andl $arg,(%rcx,%rdi,1)
jit_append_buf(0x66, 0x83, 0xc1, j); // add $j,%cx
}
continue;
} else if(str[i] == '<' && str[i+1] == '[' && str[i+2] == '-' && str[i+3] == ']' && 0) { // backwards
int j = 0;
uint64_t arg = 0xffffff00;
// 1: arg=0xffffff00
// 2: arg=0xffff0000
// 3: arg=0xff000000
// 4: arg=0x00000000
while(str[i]) {
if(j < 3 && str[i] == '<' && str[i+1] == '[' && str[i+2] == '-' && str[i+3] == ']') {
arg = (arg << 8) & 0xffffffff;
j++;
i+= 4;
} else break;
}
//printf("0x%08x\n", arg);
jit_append_buf(0x66, 0x83, 0xe9, j); // sub $j,%cx
jit_append_buf(0x81,0x24,0x39,B1(arg),B2(arg),B3(arg),B4(arg)); // andl $arg,(%rcx,%rdi,1)
continue;
}
continue;
}
#endif
if(c == '>') {
postpone_ptr++;
} else if(c == '<') {
postpone_ptr--;
} else if(c == '+') {
if(postpone_ptr) {
jit_append_buf(0xfe, postpone_ptr<0?0x44:0x84, 0x39); //incb 0x1337(%rcx,%rdi,1)
jit_append_variable_length_addr(postpone_ptr);
} else
jit_append_buf(0xfe, 0x04, 0x39); // incb (%rcx,%rdi,1)
} else if(c == '-') {
//fe 8c 39 c9 ec ff ff decb -0x1337(%rcx,%rdi,1)
if(postpone_ptr) {
jit_append_buf(0xfe, postpone_ptr<0?0x4c:0x8c, 0x39); //decb 0x1337(%rcx,%rdi,1)
#ifdef DEBUG
printf("postpone %d\n",postpone_ptr); // somehow, if postpone_ptr < -1 then prints out 0x0
#endif
jit_append_variable_length_addr(postpone_ptr);
} else
jit_append_buf(0xfe, 0x0c, 0x39); // decb (%rcx,%rdi,1)
} else if(c == '.') {
/* 111d: 48 c7 c0 01 00 00 00 mov $0x1,%rax
* 1124: 48 89 fb mov %rdi,%rbx
* 1127: 48 01 cf add %rcx,%rdi
* 112a: 48 89 fe mov %rdi,%rsi
* 112d: 48 c7 c7 01 00 00 00 mov $0x1,%rdi
* 1134: 48 c7 c2 01 00 00 00 mov $0x1,%rdx
* 113b: 51 push %rcx
* 113c: 0f 05 syscall
* 113e: 59 pop %rcx
* 113f: 48 89 df mov %rbx,%rdi
*
*/
flush_ptr();
jit_append_buf(
0x48, 0xc7, 0xc0, 0x01, 0x00, 0x00, 0x00,
0x48, 0x89, 0xfb,
0x48, 0x01, 0xcf,
0x48, 0x89, 0xfe,
0x48, 0xc7, 0xc7, 0x01, 0x00, 0x00, 0x00,
0x48, 0xc7, 0xc2, 0x01, 0x00, 0x00, 0x00,
0x51,
0x0f, 0x05,
0x59,
0x48, 0x89, 0xdf
);
} else if (c==',') {
/* 111d: 48 31 c0 xor %rax,%rax
* 1124: 48 89 fb mov %rdi,%rbx
* 1127: 48 01 cf add %rcx,%rdi
* 112a: 48 89 fe mov %rdi,%rsi
* 112d: 48 c7 c7 01 00 00 00 mov $0x1,%rdi
* 1134: 48 c7 c2 01 00 00 00 mov $0x1,%rdx
* 113b: 51 push %rcx
* 113c: 0f 05 syscall
* 113e: 59 pop %rcx
* 113f: 48 89 df mov %rbx,%rdi
*
*/
flush_ptr();
jit_append_buf(
0x48, 0x31, 0xc0,
0x48, 0x89, 0xfb,
0x48, 0x01, 0xcf,
0x48, 0x89, 0xfe,
0x48, 0xc7, 0xc7, 0x01, 0x00, 0x00, 0x00,
0x48, 0xc7, 0xc2, 0x01, 0x00, 0x00, 0x00,
0x51,
0x0f, 0x05,
0x59,
0x48, 0x89, 0xdf
);
} else if (c=='[') { // start while loop
flush_ptr();
// empty while loop
if(next_ch == ']') {
/*
* 111d: 8a 04 39 mov (%rcx,%rdi,1),%al #
* 1120: 3c 00 cmp $0x0,%al
*
* 0000000000001122 <l>:
* 1122: 90 nop
* 1123: 75 fd jne 1122 <l>
*/
jit_append_buf(
0x8a, 0x04, 0x39,
0x3c, 0x00,
0x90,
0x75, 0xfd
);
i += 2;
continue;
}
// simple optimisation
int simple_opt = 0;
do {
unsigned int j = i+1;
int delta_ptr = 0, delta_mem = 0;
while(str[j]) {
if(str[j] == '[' || str[j] == '.' || str[j] == ',') { // can only contain mem/ptr manip
delta_ptr = -1;
break;
}
else if(str[j] == ']') break;
else if(str[j] == '+' && delta_ptr == 0) delta_mem++;
else if(str[j] == '-' && delta_ptr == 0) delta_mem--;
else if(str[j] == '>') delta_ptr++;
else if(str[j] == '<') delta_ptr--;
j++;
}
#ifdef DEBUG
printf("delta = %d\n", delta_mem);
#endif
if(delta_ptr != 0 || delta_mem != -1) // not a balanced loop
break;
i++; // skip [
uint64_t rela_ptr = 0;
while((c = str[i]) && i < j) {
#ifdef DEBUG
printf("%c\n",c);
#endif
if(c == '+' || c == '-') {
uint8_t value_delta = 0; // "normalized" value
while((c = str[i])) {
if(c == '+') value_delta++;
else if(c == '-') value_delta--;
else {i--; break; } // also a problem here <--
i++;
}
if(rela_ptr == 0) {i++; continue;}
#ifdef DEBUG
printf("delta: %d, rela_ptr: 0x%x\n", value_delta, rela_ptr);
#endif
// *(tape+ptr+rela_ptr) = value_delta*rela_ptr
jit_append_buf(0xb0, value_delta); // movb $value_delta,%al
//jit_append_buf(0xb3, rela_ptr+1); // movb $rela_ptr,%bl
jit_append_buf(0x8a,0x1c,0x39); //mov (%rcx,%rdi,1),%bl
jit_append_buf(0xf6, 0xe3); // mul %bl
jit_append_buf(0x48, 0x89, 0xcb); // mov %rcx, %rbx
jit_append_buf(0x48, 0x81, 0xc3, B1(rela_ptr),B2(rela_ptr),B3(rela_ptr),B4(rela_ptr)); // add $rela_ptr,%rbx
jit_append_buf(0x00, 0x04, 0x3b); // add %al,(%rbx,%rdi,1)
// add, not mov!
}
else if (c=='>') rela_ptr++;
else if (c=='<') rela_ptr--;
i++;
}
jit_append_buf(0xc6, 0x04, 0x39, 0x00); // movb $0x00, (%rcx,%rdi,1)
i++; // skip ]
simple_opt = 1;
} while(0);
if(simple_opt) continue;
uint64_t addr = _bfjit_mem_ptr;
uint64_t placeholder = _bfjit_mem_ptr+1;
jit_append_buf(0xe9, 0xde, 0xad, 0xbe, 0xef); // jmpq [condition]
// [condition] is where the matching ']' is in asm space
addr_node_append(i, addr, placeholder);
} else if (c==']') { // end while loop
flush_ptr();
// while loop jump condition: *ptr != 0
uint64_t addr = _bfjit_mem_ptr;
jit_append_buf(0x8a, 0x04, 0x39, // mov (%rcx,%rdi,1),%al
0x3c, 0x00); // cmp $0x0, %al
uint64_t placeholder = _bfjit_mem_ptr+2;
jit_append_buf(0x0f, 0x85, 0xde, 0xad, 0xbe, 0xef); // jne [while contents]
// [while contents] is where the matching '[' is in asm space
addr_node_append(i, addr, placeholder);
}
i++;
}
flush_ptr();
#ifdef DEBUG
jit_append_buf(0x48, 0x89, 0xc8); //mov %rcx,%rax
#endif
jit_append_buf(0xc3); // retq
jit_fill_placeholders(str);
#ifdef DEBUG
printf("Execute...\n");
bp();
uint64_t ptr = _bfjit(tape); // %rdi = tape;
#else
bp();
_bfjit(tape);
#endif
#ifdef DEBUG
printf("\n\n(ptr: %ju) ", ptr);
for(int i = 0; i < 10; i++) {
printf("%d ", tape[i]);
}
#endif
return 0;
}