Connor Abbott <cwabbo...@gmail.com> writes:
> On Thu, Dec 18, 2014 at 2:01 AM, Eric Anholt <e...@anholt.net> wrote:
>> Jason Ekstrand <ja...@jlekstrand.net> writes:
>>
>>> From: Connor Abbott <connor.abb...@intel.com>
>>>
>>> This is similar to ir_validate.cpp.
>>>
>>> v2: Jason Ekstrand <jason.ekstr...@intel.com>:
>>> whitespace fixes
>>
>> I have again not reviewed the control flow bits. Couple of questions I
>> had, though:
>>
>>> +static void
>>> +validate_var_use(nir_variable *var, validate_state *state)
>>> +{
>>> + if (var->data.mode == nir_var_local) {
>>> + struct hash_entry *entry =
>>> + _mesa_hash_table_search(state->var_defs, _mesa_hash_pointer(var),
>>> + var);
>>> +
>>> + assert(entry);
>>> + assert((nir_function_impl *) entry->data == state->impl);
>>> + }
>>> +}
>>
>> Is there guaranteed to be a def of a local variable before a use? It
>> would be undefined execution behavior, but not assertion failure
>> quality, right?
>
> Yes, that's correct - there are no guarantees about this for variables
> and registers. For SSA values, the definition should always dominate
> the use (see the TODO about that) because a lot of SSA algorithms
> assume that, so we model the use-before-def case by pointing the use
> to a nir_ssa_undef_instr.
OK, so it seems like this validation needs to be dropped.
>>> +static void
>>> +postvalidate_reg_decl(nir_register *reg, validate_state *state)
>>> +{
>>> + struct hash_entry *entry = _mesa_hash_table_search(state->regs,
>>> +
>>> _mesa_hash_pointer(reg),
>>> + reg);
>>> +
>>> + reg_validate_state *reg_state = (reg_validate_state *) entry->data;
>>> +
>>> + if (reg_state->uses->entries != reg->uses->entries) {
>>> + printf("extra entries in register uses:\n");
>>> + struct set_entry *entry;
>>> + set_foreach(reg->uses, entry) {
>>> + struct set_entry *entry2 =
>>> + _mesa_set_search(reg_state->uses,
>>> _mesa_hash_pointer(entry->key),
>>> + entry->key);
>>> +
>>> + if (entry2 == NULL) {
>>> + printf("%p\n", entry->key);
>>> + }
>>> + }
>>> +
>>> + abort();
>>> + }
>>> +
>>> + if (reg_state->defs->entries != reg->defs->entries) {
>>> + printf("extra entries in register defs:\n");
>>> + struct set_entry *entry;
>>> + set_foreach(reg->defs, entry) {
>>> + struct set_entry *entry2 =
>>> + _mesa_set_search(reg_state->defs,
>>> _mesa_hash_pointer(entry->key),
>>> + entry->key);
>>> +
>>> + if (entry2 == NULL) {
>>> + printf("%p\n", entry->key);
>>> + }
>>> + }
>>
>> Couldn't these failures go the other way and there be, for example,
>> defs that weren't tracked in the reg?
>>
>> (Not necessarily important to fix, since you'll at least get the
>> abort())
>
> Yeah, the point here is that we've already validated that all the
> actual definitions (i.e. everything in reg_state->defs) are already in
> reg->defs, so once we've gotten to this point the only possible reason
> for them not being the same is that reg->defs has extra entries, which
> we check for here.
I must have skimmed right past that.
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