Finish hooking up ClangIR code gen into the Clang control flow,
initializing enough that basic code gen is possible.
Add an almost empty `cir.func` op to the ClangIR dialect. Currently the
only property of the function is its name. Add the code necessary to
code gen a cir.func op.
Create essentially empty files
clang/lib/CIR/Dialect/IR/{CIRAttrs.cpp,CIRTypes.cpp}. These will be
filled in later as attributes and types are defined in the ClangIR
dialect.
(Part of upstreaming the ClangIR incubator project into LLVM.)
Build out the necessary infrastructure for the main entry point into
ClangIR generation -- CIRGenModule. A set of boilerplate classes exist
to facilitate this -- CIRGenerator, CIRGenAction, EmitCIRAction and
CIRGenConsumer. These all mirror the corresponding types from LLVM
generation by Clang's CodeGen.
The main entry point to CIR generation is
`CIRGenModule::buildTopLevelDecl`. It is currently just an empty
function. We've added a test to ensure that the pipeline reaches this
point and doesn't fail, but does nothing else. This will be removed in
one of the subsequent patches that'll add basic `cir.func` emission.
This patch also re-adds `-emit-cir` to the driver. lib/Driver/Driver.cpp
requires that a driver flag exists to facilirate the selection of the
right actions for the driver to create. Without a driver flag you get
the standard behaviors of `-S`, `-c`, etc. If we want to emit CIR IR
and, eventually, bytecode we'll need a driver flag to force this. This
is why `-emit-llvm` is a driver flag. Notably, `-emit-llvm-bc` as a cc1
flag doesn't ever do the right thing. Without a driver flag it is
incorrectly ignored and an executable is emitted. With `-S` a file named
`something.s` is emitted which actually contains bitcode.
Reviewers: AaronBallman, MaskRay, bcardosolopes
Reviewed By: bcardosolopes, AaronBallman
Pull Request: https://github.com/llvm/llvm-project/pull/91007
