r233156 - [Modules] When writing out the on-disk hash table for the decl context

[Richard Trieu]

On Tue, Mar 24, 2015 at 5:34 PM, Chandler Carruth <chandlerc at gmail.com>
wrote:

> Author: chandlerc
> Date: Tue Mar 24 19:34:51 2015
> New Revision: 233156
>
> URL: http://llvm.org/viewvc/llvm-project?rev=233156&view=rev
> Log:
> [Modules] When writing out the on-disk hash table for the decl context
> lookup tables, we need to establish a stable ordering for constructing
> the hash table. This is trickier than it might seem.
>
> Most of these cases are easily handled by sorting the lookup results
> associated with a specific name that has an identifier. However for
> constructors and conversion functions, the story is more complicated.
> Here we need to merge all of the constructors or conversion functions
> together and this merge needs to be stable. We don't have any stable
> ordering for either constructors or conversion functions as both would
> require a stable ordering across types.
>
> Instead, when we have constructors or conversion functions in the
> results, we reconstruct a stable order by walking the decl context in
> lexical order and merging them in the order their particular declaration
> names are encountered. This doesn't generalize as there might be found
> declaration names which don't actually occur within the lexical context,
> but for constructors and conversion functions it is safe. It does
> require loading the entire decl context if necessary to establish the
> ordering but there doesn't seem to be a meaningful way around that.
>
> Many thanks to Richard for talking through all of the design choices
> here. While I wrote the code, he guided all the actual decisions about
> how to establish the order of things.
>
> No test case yet because the test case I have doesn't pass yet -- there
> are still more sources of non-determinism. However, this is complex
> enough that I wanted it to go into its own commit in case it causes some
> unforseen issue or needs to be reverted.
>
> This patch is causing several tests to fail.  However, reverting also
seems to cause a test to fail.

Release build compiled with Clang
Failing Tests (2):
    Clang :: Modules/cxx-decls.cpp
    Clang :: PCH/cxx11-inheriting-ctors.cpp

Release build compiled with GCC
Failing Tests (1):
    Clang :: PCH/cxx-method.cpp

Debug build compiled with Clang with revision 233156 reverted
Failing Tests (1):
    Clang :: Modules/stress1.cpp
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