Commit Graph

5 Commits

Author SHA1 Message Date
Jake Hillion
55989a9156 oilgen: migrate to source parsing (#421)
Summary:
oilgen: migrate to source parsing

Using debug information generated from partial source (that is, not the final
binary) has been insufficient to generally generate OIL code.

A particular example is pointers to templates:
```cpp
#include <oi/oi.h>
template <typename T>
struct Foo {
  T t;
};
template <typename T>
struct Bar {
  Foo<T>& f;
};
void foo(const Bar<int>& b) {
  oi::introspect(b);
}
```

The pointer/reference to `Foo<int>` appears in DWARF with
`DW_AT_declaration(true)` because it could be specialised before its usage.
However, with OIL, we are creating an implicit usage site in the
`oi::introspect` call that the compiler is unable to see.

This change reworks OILGen to work from a Clang command line rather than debug
information. We setup and run a compiler on the source, giving us access to an
AST and Semantic Analyser. We then:
- Find the `oi::introspect` template.
- Iterate through each of its callsites for their type.
- Run `ClangTypeParser::parse` on each type.
- Run codegen.
- Compile into an object file.

Having access to the semantic analyser allows us to forcefully complete a type,
as it would be if it was used in the initial code.


Test Plan:
hope

`buck2 run fbcode//mode/opt fbcode//object-introspection/oil/examples/compile-time:compile-time`

Reviewed By: tyroguru

Differential Revision: D51854477

Pulled By: JakeHillion
2023-12-19 13:26:25 -08:00
Alastair Robertson
784b900218 TypeGraph: Replace allocators with DummyAllocator
When we were previously removing allocators, we were only able to work
with containers whose allocators appeared as their last template
parameter.

Now we can replace allocators in the middle of a parameter list.

This fixes tests for folly::sorted_vector_set.
2023-05-31 15:49:37 +01:00
Alastair Robertson
3d91603c8e TypeGraph: Fix std::string container
std::basic_string takes three template parameters:
1. CharT
2. Traits
3. Allocator

The Traits parameter was causing issues, as it requires a type which
exposes certain things, e.g. `Traits::value_type`.

We have a few options to resolve this:
1. Remove this parameter, as we do for allocators
    Cons: removing a template parameter doesn't work if other
    parameters appear after it

2. Stub this parameter, as we do for hashers/comparators
    Cons: we need to hardcode an implementation that satisfies the
    `Traits::value_type` requirements

3. Leave the parameter as-is
    Cons: will not work if a non-standard Traits is used

    By using the real implementation of this Traits parameter
    (normally `std::char_traits<CharT>`), we get one that we know will
    work as long as it is defined in a stdlib header.

Option 3 is what we use in this patch. Instead of adding more
configuration options to the container TOML file format (e.g.
`params_to_keep = [1]`), we add `std::char_traits` as a dummy
container type. Now, whenever `std::char_traits` appears, it will be
left as-is, i.e. not removed, replaced or reverse-engineered.

This is the same approach previously used for Thrift's isset_bitset.
2023-05-30 17:17:29 +01:00
Alastair Robertson
68290655b1 TypeGraph: Update container TOML files to new format
This change is fully backwards compatible with the old ContainerInfo
parser, as it is just adding new fields.

The old fields will continue to be used by legacy OICodeGen until that
is removed.

Also add a README to document the format.
2023-05-26 18:21:59 +01:00
Jon Haslam
db90326c4b Initial commit 2022-12-19 06:37:51 -08:00