[all-commits] [llvm/llvm-project] d222c5: [C API] Fix LLVMGetOrdering/LLVMIsAtomicSingleThre...

[Benji Smith via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d222c5ec47a09a3e120000e4a1006f4da7741256
      https://github.com/llvm/llvm-project/commit/d222c5ec47a09a3e120000e4a1006f4da7741256
  Author: Benji Smith <6193112+Benjins at users.noreply.github.com>
  Date:   2023-09-30 (Sat, 30 Sep 2023)

  Changed paths:
    M llvm/lib/IR/Core.cpp
    M llvm/test/Bindings/llvm-c/atomics.ll
    M llvm/tools/llvm-c-test/echo.cpp

  Log Message:
  -----------
  [C API] Fix LLVMGetOrdering/LLVMIsAtomicSingleThread for fence/memory instrs (#65228)

Fixes https://github.com/llvm/llvm-project/issues/65227

LLVMGetOrdering previously did not support Fence instructions, and
calling it on a fence would lead to a bad cast as it
assumed a load/store, or an AtomicRMWInst. This would either read a
garbage memory order, or assertion

LLVMIsAtomicSingleThread did not support either Fence instructions,
loads, or stores, and would similarly lead to a bad cast.
It happened to work out since the relevant types all have their synch
scope ID at the same offset, but it still should be fixed

These cases are now fixed for the C API, and tests for these
instructions are added. The echo test utility now also supports cloning
Fence instructions, which it did not previously

-----

>From what I can tell, there's no unified API to pull
`getOrdering`/`getSyncScopeID` from, and instead requires casting to
individual types: if there is a better way of handling this I can switch
to that