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
Currently we rely on `SymbolService::getTypeName` for getting the hash that's
included in the generated function's name. The value of this must stay the same
to match with the value expected by OIDebugger - changing it causes failure to
relocate when attaching with OID and JIT OIL.
Calculate this name in the `codegenFromDrgn` method and pass it through where
appropriate rather than passing the `drgn_type` itself through.
We don't need to name the type like that when using AoT OIL. Let's
hash the linkage name instead as that is more unique.
Test Plan:
- CI
Leave it to the new mutator pass IdentifyContainers to replace Class
nodes with Container nodes where appropriate.
This will allow us to run passes over the type graph before identifying
containers, and therefore before we have lost information about the
internal details of the container (e.g. alignment of member variables).
Lots of places rely on reference stability of ContainerInfo objects
(CodeGen's deduplication, Container nodes' containerInfo_ member).
In the key capture work, we need to be able to append to this list,
which would invalidate references before this change.
Summary:
Update `OIGenerator` and out BUCK stuff for compile time OIL with OIL v2. Main things:
- Switch `OIGenerator` from the `getObjectSize` call to the new `introspect` call.
- Switch from looking at template parameters to looking at function parameters, as this was exposing a bug in our elfutils/drgn and this way it's the same as OID.
- Migrate `OIGenerator` to CodeGen v2 and update CodeGen v2 to accept a linkage name.
- Update the compile time example to be the same as the JIT example, using the new interface and the JSON exporter.
- Clean up the `ObjectIntrospection.h` header.
Differential Revision: D48687728
fbshipit-source-id: 2c3c041fd1b6499c5e02eb5e2082a977bfa529d7
As we now store ContainerInfo objects in OICodeGen::Config, we can not
copy it any more. Change all places that took copies to take const
references instead.
The copy in OICodeGen modified membersToStub, the contents of which form
part of OICache's hash. However, as OICache also previously had its own
copy, it would not have been OICodeGen's modifications.
