/* iterate basic block to find a dead register */
static reg_id_t
bb_find_dead_reg(instrlist_t *ilist)
{
instr_t *instr;
int i;
bool reg_is_read[DR_NUM_GPR_REGS] = { false,};
for (instr = instrlist_first(ilist);
instr != NULL;
instr = instr_get_next(instr)) {
if (instr_is_syscall(instr) || instr_is_interrupt(instr))
return DR_REG_NULL;
for (i = 0; i < DR_NUM_GPR_REGS; i++) {
if (!reg_is_read[i] &&
instr_reads_from_reg(instr, (reg_id_t)(DR_REG_START_GPR + i))) {
reg_is_read[i] = true;
}
if (!reg_is_read[i] &&
instr_writes_to_exact_reg(instr,
(reg_id_t)(DR_REG_START_GPR + i))) {
return (reg_id_t)(DR_REG_START_GPR + i);
}
#ifdef X64
/* in x64, update on 32-bit register kills the whole register */
if (!reg_is_read[i] &&
instr_writes_to_exact_reg(instr,
reg_64_to_32
((reg_id_t)(DR_REG_START_GPR + i)))) {
return (reg_id_t)(DR_REG_START_GPR + i);
}
#endif
}
}
return DR_REG_NULL;
}
static
dr_emit_flags_t bb_event(void* drcontext, void *tag, instrlist_t *bb,
bool for_trace, bool translating)
{
instr_t *instr;
if (!translating)
increment(tag);
/* I'm looking for a specific BB in the test .exe. I've marked
* it with a couple nops.
*/
#ifdef WINDOWS
if ((app_pc)tag >= start && (app_pc)tag < end) {
#endif
instr = instrlist_first(bb);
if (instr_is_nop(instr)) {
instr_t *next = instr_get_next(instr);
/* The test app uses two nops as a marker to identify a specific bb. Since
* 2 nop instructions in a row aren't that uncommon on Linux (where we can't
* restrict our search to just the test.exe module) we use an unusual nop
* for the second one: xchg xbp, xbp */
if (next != NULL && instr_is_nop(next) &&
instr_get_opcode(next) == OP_xchg &&
instr_writes_to_exact_reg(next, REG_XBP, DR_QUERY_DEFAULT)) {
bb_build_count++;
if (delay_flush_at_next_build) {
delay_flush_at_next_build = false;
dr_delay_flush_region((app_pc)tag - 20, 30, callback_count, flush_event);
}
dr_insert_clean_call(drcontext, bb, instr, (void *)callback,
false, 2, OPND_CREATE_INTPTR(tag),
OPND_CREATE_INTPTR(instr_get_app_pc(instr)));
}
}
#ifdef WINDOWS
}
#endif
return DR_EMIT_DEFAULT;
}
