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.
Lowering of int-to-bool casts had been left as NYI because the incubator
implemented it by lowering to cir.cmp, which hasn't been upstreamed yet,
but there is no reason this cast can't be lowered directly to LLVM's
compare operation when we're lowering directly to the LLVM dialect.
This change lowers the cast directly to an LLVM compare to zero.
