Mark gc.relocate and gc.result as readnone (try 2)

[reames]

Summary

As noted in the LangRef, these are semantically readnone projections from the result value of the associated statepoint. However, it turned out we had a few latent bugs being covered up by the fact we were only marking them readonly (see PR49607 for context).

As of this change, all known issues are resolved. This is a deliberately minimal patch to make it easy to test downstream and revert with minimal change if that turns out to be necessary.

Depends on:

• D98728 [LICM] Fix a crash when sinking instructions w/token operands

[skatkov]

Hi Philip, at the moment my downstream testing did not show any problems.

So I guess we can try and land it. In case some troubles I'll revert this change back.

llvm/include/llvm/IR/Intrinsics.td

def int_experimental_gc_statepoint : Intrinsic<[llvm_token_ty],
                                [llvm_i64_ty, llvm_i32_ty,
                                 llvm_anyptr_ty, llvm_i32_ty,
                                 llvm_i32_ty, llvm_vararg_ty],
                                [Throws, ImmArg<ArgIndex<0>>,
                                 ImmArg<ArgIndex<1>>, ImmArg<ArgIndex<3>>,
                                 ImmArg<ArgIndex<4>>]>;
 
 def int_experimental_gc_result   : Intrinsic<[llvm_any_ty], [llvm_token_ty],
-                                             [IntrReadMem]>;
+                                             [IntrNoMem]>;
 def int_experimental_gc_relocate : Intrinsic<[llvm_any_ty],
                                              [llvm_token_ty, llvm_i32_ty,
                                               llvm_i32_ty],
-                                             [IntrReadMem, ImmArg<ArgIndex<1>>,
+                                             [IntrNoMem, ImmArg<ArgIndex<1>>,
                                               ImmArg<ArgIndex<2>>]>;
 
 //===------------------------ Coroutine Intrinsics ---------------===//
 // These are documented in docs/Coroutines.rst
 
 // Coroutine Structure Intrinsics.
 
 def int_coro_id : Intrinsic<[llvm_token_ty], [llvm_i32_ty, llvm_ptr_ty,