[pph] Fix method lookups (part 1) (issue4997042)

[Diego Novillo]

On Sat, Sep 10, 2011 at 11:30, Gabriel Charette <gcharette1@gmail.com> wrote:
> On Fri, Sep 9, 2011 at 4:37 PM, Diego Novillo <dnovillo@google.com> wrote:
>>
>> The main problem fixed here is that name lookups for class methods
>> uses a binary search that assumes that the methods in
>> CLASSTYPE_METHOD_VEC are sorted by pointer value.
>>
>> Since the reader typically allocates trees in a different pattern than
>> the writer, it is common for the symbols in the vector to have
>> different pointer values, so the order used by the writer is different
>> than the reader.
>>
>> This was causing us to fail name lookups when generating the pph image
>> for x6dynarray5.h and x6dynarray6.h.
>>
>> To fix this, I am making finish_struct_methods an extern function and
>> calling it after reading a type that has a CLASSTYPE_METHOD_VEC.
>>
>> This exposed another failure that was simple enough to roll in
>> together with this patch.  We should not emit preloaded symbols when
>> writing the names in the global namespace.  This was causing a
>> DECL_CHAIN cycle.  I added a new filter PPHF_NO_PREFS to skip the
>> preloaded symbols when needed.
>>
>
> The loop in the DECL_CHAIN in x6dynarray5 was already there before.
> This is why I had introduced the preloaded cache to do something along
> those lines.
>
> However I don't think simply filtering it out is sufficient in this
> case.

It is for this case.  But you are right that it isn't for state
mutations like the one you describe later.  I'm trying to fix this by
detecting state changes between read-time and write-time.  I'm
thinking of checksumming the input tree and create a merge record when
we notice that the tree has mutated during write.  We would only
checksum the input when generating PPH images, so this would never
slow down the reader.

> Anyways, just can't help it, but keep reading all the patches coming in :)!

Heh.  I can send you the copyright assignments for you to fill out.
Don't think you can escape so easily ;)


Diego.