I've seen a few people try to enable opaque pointers with LLVM 14
already. While LLVM 14 has pretty good baseline support, there are
enough missing pieces that you're definitely going to hit assertion
failures if you try this.
Add some wording to make it clear what the support (or planned
support) for opaque/typed pointers is across LLVM 14, 15, and 16.
This enabled opaque pointers by default in LLVM. The effect of this
is twofold:
* If IR that contains *neither* explicit ptr nor %T* types is passed
to tools, we will now use opaque pointer mode, unless
-opaque-pointers=0 has been explicitly passed.
* Users of LLVM as a library will now default to opaque pointers.
It is possible to opt-out by calling setOpaquePointers(false) on
LLVMContext.
A cmake option to toggle this default will not be provided. Frontends
or other tools that want to (temporarily) keep using typed pointers
should disable opaque pointers via LLVMContext.
Differential Revision: https://reviews.llvm.org/D126689
LTO code may end up mixing bitcode files from various sources varying in
their use of opaque pointer types. The current strategy to decide
between opaque / typed pointers upon the first bitcode file loaded does
not work here, since we could be loading a non-opaque bitcode file first
and would then be unable to load any files with opaque pointer types
later.
So for LTO this:
- Adds an `lto::Config::OpaquePointer` option and enforces an upfront
decision between the two modes.
- Adds `-opaque-pointers`/`-no-opaque-pointers` options to the gold
plugin; disabled by default.
- `--opaque-pointers`/`--no-opaque-pointers` options with
`-plugin-opt=-opaque-pointers`/`-plugin-opt=-no-opaque-pointers`
aliases to lld; disabled by default.
- Adds an `-lto-opaque-pointers` option to the `llvm-lto2` tool.
- Changes the clang driver to pass `-plugin-opt=-opaque-pointers` to
the linker in LTO modes when clang was configured with opaque
pointers enabled by default.
This fixes https://github.com/llvm/llvm-project/issues/55377
Differential Revision: https://reviews.llvm.org/D125847
While it originally did, this option no longer affects the cc1
interface. For the cc1 interface, -no-opaque-pointers has to be
passed, there is no cmake option.
Point people to the cc1 instead of the mllvm flag, as the mllvm
flag will stop working for clang usage at some point.
Update transition state to mention that support in Clang/LLVM is
complete, and only the default switch is pending.
Mention automatic enablement of opaque pointers mode that was
recently implemented. Update wording in the transition state,
because it seems like my overly cautious wording has given some
people an incorrect impression of the state of opaque pointer
support in clang.
Emphasize that this is basically an attempt to remove
``PointerType::getElementType`` and ``Type::getPointerElementType()``.
Add a couple more subtasks.
Differential Revision: https://reviews.llvm.org/D104151
Arthur Eubanks