This change adds support for function linkage and visibility and related
attributes. Most of the test changes are generalizations to allow
'dso_local' to be accepted where we aren't specifically testing for it.
Some tests based on CIR inputs have been updated to add 'private' to
function declarations where required by newly supported interfaces.
The dso-local.c test has been updated to add specific tests for
dso_local being set correctly, and a new test, func-linkage.cpp tests
other linkage settings.
This change sets `comdat` correctly in CIR, but it is not yet applied to
functions when lowering to LLVM IR. That will be handled in a later
change.
We have been using the default names for global symbols to this point.
This change introduces proper name mangling for functions.
This requires introducing a CXXABI class in the CIRGenModule. Because
only target independent name mangling is handled in this patch, the
CXXABI class does not require a target-specific implementation. The
general mechanism for selecting an implementation is introduced here,
but the actual target-specific subclasses are deferred until needed.
Upstream the parts of class `CIRGenFunction::LexicalScope` that
implement function return values. There is a bit of other functionality
in here, such as the implicit `cir.yield` at the end of a non-function
scope, but this is mostly about function returns.
The parts of `LexicalScope` that handle calling destructors, switch
statements, ternary expressions, and exception handling still need to be
upstreamed.
There is a change in the generated ClangIR (which is why many of the
tests needed updating). Return values are stored in the
compiler-generated variable `__retval` rather than being passed to the
`cir.return` op directly. But there should be no change in the behavior
of the generated code.
When a C or C++ function has a return type of `void`, the function type
is now represented in MLIR as having no return type rather than having a
return type of `!cir.void`. This avoids breaking MLIR invariants that
require the number of return types and the number of return values to
match.
Change the assembly format for `cir::FuncType` from having a leading
return type to having a trailing return type. In other words, change
```
!cir.func<!returnType (!argTypes)>
```
to
```
!cir.func<(!argTypes) -> !returnType)>
```
Unless the function returns `void`, in which case change
```
!cir.func<!cir.void (!argTypes)>
```
to
```
!cir.func<(!argTypes)>
```
Support the type `bool` and the literals `true` and `false`. Add the
type `cir::BoolType` and the attribute `cir::BoolAttr` to ClangIR. Add
code in all the necessary places in ClangIR CodeGen to handle and to
recognize the type and the attribute.
Add test cases to existing tests func-simple.cpp and
global-var-simple.cpp.
Enable ClangIR generation for very simple functions. The functions have
to return `void` or an integral type, contain only compound statements
or `return` statements, and `return` statement expressions can only be
integral literals of the correct type. The functions can have
parameters, but those are currently ignored because there is no way to
access them.
This change intentionally focuses on breadth (introducing scopes,
statements, and expressions) rather than depth, because it enables
people to work on upstreaming in parallel without interference.
The new ClangIR ops in this change are `ReturnOp`, `YieldOp`, `ScopeOp`,
and `TrapOp`. These operations are complete (except for the
`ParentOneOf` property) and shouldn't require further upstreaming
changes. Significant additions were made to `FuncOp`, adding a type and
a region, but that operation is still far from complete.
The classes `ScalarExprEmitter` and `CIRGenFunction`, along with the
`emit*` functions in `CIRGenFunction` that generate ClangIR for
statements, are new in this change. All of these are very incomplete and
will be filled out in later upstreaming patches.
Existing test `hello.c` is removed and replaced by the new test
`func-simple.cpp`. This tests all forms of functions that are currently
supported.
