void asm_x64_mov_reg_pcrel(asm_x64_t *as, int dest_r64, mp_uint_t label) {
assert(dest_r64 < 8);
mp_uint_t dest = get_label_dest(as, label);
mp_int_t rel = dest - (as->base.code_offset + 7);
asm_x64_write_byte_3(as, REX_PREFIX | REX_W, OPCODE_LEA_MEM_TO_R64, MODRM_R64(dest_r64) | MODRM_RM_R64(5));
asm_x64_write_word32(as, rel);
}
void asm_x64_jcc_label(asm_x64_t *as, int jcc_type, int label) {
int dest = get_label_dest(as, label);
int rel = dest - as->code_offset;
if (dest >= 0 && rel < 0) {
// is a backwards jump, so we know the size of the jump on the first pass
// calculate rel assuming 8 bit relative jump
rel -= 2;
if (SIGNED_FIT8(rel)) {
asm_x64_write_byte_2(as, OPCODE_JCC_REL8 | jcc_type, rel & 0xff);
} else {
rel += 2;
goto large_jump;
}
} else {
// is a forwards jump, so need to assume it's large
large_jump:
rel -= 6;
asm_x64_write_byte_2(as, OPCODE_JCC_REL32_A, OPCODE_JCC_REL32_B | jcc_type);
asm_x64_write_word32(as, rel);
}
}
void asm_x64_jmp_label(asm_x64_t *as, mp_uint_t label) {
mp_uint_t dest = get_label_dest(as, label);
mp_int_t rel = dest - as->base.code_offset;
if (dest != (mp_uint_t)-1 && rel < 0) {
// is a backwards jump, so we know the size of the jump on the first pass
// calculate rel assuming 8 bit relative jump
rel -= 2;
if (SIGNED_FIT8(rel)) {
asm_x64_write_byte_2(as, OPCODE_JMP_REL8, rel & 0xff);
} else {
rel += 2;
goto large_jump;
}
} else {
// is a forwards jump, so need to assume it's large
large_jump:
rel -= 5;
asm_x64_write_byte_1(as, OPCODE_JMP_REL32);
asm_x64_write_word32(as, rel);
}
}
