Summary:
In LLVM it is possible for struct constant values to be directly
recursive, with no pointer dereference to close the cycle. These
appear for example as the values of vtables from C++ code.
Currently such recursive records in the Exp and Term languages are
represented as genuinely cyclic values. Compared to a standard term
representation, the presence of cyclic values is a significant
complication everywhere. Since the backend solver does not do anything
such as induction over these, they have to be treated as essentially
atomic.
This patch changes the representation to a standard non-recursive tree
term structure. Instead of cyclic references, an explicit constructor
is added for the "non-tree edges", which simply indicates which
ancestor record value to which the recursive reference points.
There is a potential issue with this representation, since for
mutually recursive records, the representation is not canonical: it
chooses one of the records in the cycle to start from and expresses
the cycles relative to that. Currently the choice of representation is
dictated by the frontend. For the case of vtables, the frontend
translates globals in the same order they appear in the LLVM IR, so
the representation choice is fixed.
It may turn out that other potential uses require more reasoning
support in the backend solver, which would involve a theory of
equality of record values induced by equating the representations
resulting from different rotations of the cycle of records.
Reviewed By: jvillard
Differential Revision: D21441533
fbshipit-source-id: 0c5a11378
Summary:
Having `val size_of : Typ.t -> t` in the signature of `Term` and `val
size_of : t -> t` in the signature of `Exp` gives the impression that
`Term` and `Exp` know something about `Typ`. But they don't, those
functions are only trivial convenience wrappers, and only have a few
uses, so just inline them to clarify that it is `Typ` that knows about
the sizes of types.
Reviewed By: jvillard
Differential Revision: D21441535
fbshipit-source-id: 09b135a8c
Summary:
Work on the containers revealed that 1b8746d21 was premature, and this
diff is in part a revert of that. The objectives for the global
namespace are:
- self-consistent as much as possible
- rich data type operations
- does not require maintaining lots of tedious library wrapping code
- has Marshalable containers
- has containers with functorial interfaces
For these aims, it's best to stick with Core. Base isn't enough to
define functorial interfaces for collections (without a lot of tedious
wrapping code to keep in sync manually), and since a few modules not
in Core_kernel are needed anyhow.
Reviewed By: ngorogiannis
Differential Revision: D20583756
fbshipit-source-id: d939be7d0
Summary:
The term "vector" evokes expectations of being automatically growable,
and these are just immutable arrays.
Reviewed By: ngorogiannis
Differential Revision: D20482762
fbshipit-source-id: 0cd2c9c23
Summary:
Move files, adjust build system, etc.
This also separates out the ppx_trace conditional compilation debug
tracing machinery into an independent package and library.
Reviewed By: jvillard
Differential Revision: D20322876
fbshipit-source-id: a50522462
Josh Berdine