diff options
Diffstat (limited to 'sjit_c.c')
| -rw-r--r-- | sjit_c.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/sjit_c.c b/sjit_c.c new file mode 100644 index 0000000..85702fc --- /dev/null +++ b/sjit_c.c @@ -0,0 +1,218 @@ +#include <inttypes.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/mman.h> + +enum instr { + PushRef, + PushI, + Put, + Pop, + + Call, + Ret, + Halt, + + IAddRet, + IMulRet, + ISubRet, + IDivRet +}; + +static uint32_t instr_size(enum instr instr) { + switch (instr) { + case PushRef: return 5+1; + case PushI: return 7+1; + case Put: return 1+5; + case Pop: return 4; + + case Call: return 5; + case Ret: return 1; + case Halt: return 1+1; + + case IAddRet: + case ISubRet: return 5+5+3+5+1; + case IMulRet: return 5+5+4+5+1; + case IDivRet: return 5+5+3+3+5+1; + } +} + +static inline void gen_instr(char *full_code, char **code_p, uint64_t **pgm_p, uint32_t *mapping) { + uint64_t arg; + + char *code=*code_p; + uint64_t *pgm=*pgm_p; + + switch (*pgm) { + case PushRef: + arg=pgm[1]; +#ifdef DEBUG_JIT_INSTRUCTIONS + fprintf(stderr,"PushRef %lu\n",arg); +#endif + code[0]='\x48'; /* mov rbx,[rsp+ARG*8] */ + code[1]='\x8b'; + code[2]='\x5c'; + code[3]='\x24'; + code[4]=(unsigned char)arg*8; + code[5]='\x53'; /* push rbx */ + pgm+=2; + code+=6; + break; + case PushI: + arg=pgm[1]; +#ifdef DEBUG_JIT_INSTRUCTIONS + fprintf(stderr,"PushI %lu\n",arg); +#endif + code[0]='\x48'; /* mov rbx,ARG */ + code[1]='\xc7'; + code[2]='\xc3'; + *(uint32_t*)&code[3]=(uint32_t)arg; + code[7]='\x53'; /* push rbx */ + pgm+=2; + code+=8; + break; + case Put: + arg=pgm[1]; +#ifdef DEBUG_JIT_INSTRUCTIONS + fprintf(stderr,"Put %lu\n",arg); +#endif + code[0]='\x5b'; /* pop rbx */ + code[1]='\x48'; /* mov [rsp+ARG*8],rbx */ + code[2]='\x89'; + code[3]='\x5c'; + code[4]='\x24'; + code[5]=(unsigned char)(arg-1)*8; + pgm+=2; + code+=6; + break; + case Pop: + arg=pgm[1]; +#ifdef DEBUG_JIT_INSTRUCTIONS + fprintf(stderr,"Pop %lu\n",arg); +#endif + code[0]='\x48'; /* add rsp,ARG*8 */ + code[1]='\x83'; + code[2]='\xc4'; + code[3]=(unsigned char)arg*8; + pgm+=2; + code+=4; + break; + + case Call: + arg=pgm[1]; +#ifdef DEBUG_JIT_INSTRUCTIONS + fprintf(stderr,"Call %lu -> %d\n",arg,mapping[arg]-(&code[5]-full_code)); +#endif + code[0]='\xe8'; /* callq ARG */ + *(uint32_t*)&code[1]=mapping[arg]-(&code[5]-full_code); + pgm+=2; + code+=5; + break; + case Ret: +#ifdef DEBUG_JIT_INSTRUCTIONS + fprintf(stderr,"Ret\n"); +#endif + code[0]='\xc3'; /* retq */ + pgm++; + code+=1; + break; + case Halt: +#ifdef DEBUG_JIT_INSTRUCTIONS + fprintf(stderr,"Halt\n"); +#endif + code[0]='\x58'; /* pop rax */ + code[1]='\xc3'; /* retq */ + pgm++; + code+=2; + break; + + case IAddRet: + case IMulRet: + case ISubRet: + case IDivRet: +#ifdef DEBUG_JIT_INSTRUCTIONS + fprintf(stderr,"I<Op>Ret\n"); +#endif + /* mov rax,[rsp+8] */ + code[0]='\x48'; code[1]='\x8b'; code[2]='\x44'; code[3]='\x24'; code[4]='\x08'; + /* mov rbx,[rsp+16] */ + code[5]='\x48'; code[6]='\x8b'; code[7]='\x5c'; code[8]='\x24'; code[9]='\x10'; + switch (*pgm) { + case IAddRet: + case ISubRet: + /* {add,sub} rax,rbx */ + code[10]='\x48'; + code[11]=*pgm==IAddRet ? '\x01' : '\x29'; + code[12]='\xd8'; + code+=13; + break; + case IMulRet: + /* imul rax,rbx */ + code[10]='\x48'; code[11]='\x0f'; code[12]='\xaf'; code[13]='\xc3'; + code+=14; + break; + case IDivRet: + /* xor rdx,rdx */ + code[10]='\x48'; code[11]='\x31'; code[12]='\xd2'; + /* idiv rbx */ + code[13]='\x48'; code[14]='\xf7'; code[15]='\xfb'; + code+=16; + break; + } + /* mov [rsp+16],rax */ + code[0]='\x48'; code[1]='\x89'; code[2]='\x44'; code[3]='\x24'; code[4]='\x10'; + /* retq */ + code[5]='\xc3'; + pgm++; + code+=6; + break; + + default: + fprintf(stderr,"unknown instruction %lu\n",pgm[-1]); + exit(1); + } + + *code_p=code; + *pgm_p=pgm; +} + +unsigned int jit(uint64_t *pgm) { + uint32_t len=*pgm++; + uint32_t i; + + uint32_t *mapping=malloc(len*sizeof(uint32_t)); + uint32_t code_i=0; + + uint64_t *pgm_p=pgm; + for (i=0; i<len; i++) { + enum instr instr=(enum instr)*pgm_p; + + mapping[i]=code_i; + code_i+=instr_size(instr); + + switch (instr) { + case PushRef: + case PushI: + case Put: + case Pop: + case Call: + pgm_p+=2; + break; + default: + pgm_p+=1; + break; + } + } + + char *code=mmap(NULL, code_i, PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); + char *code_wr=code; + pgm_p=pgm; + for (i=0; i<len; i++) + gen_instr(code, &code_wr, &pgm_p, mapping); + + mprotect(code, code_i, PROT_READ | PROT_EXEC); + int (*fun)(void) = (int(*)(void)) code; + + return fun(); +} |