[OpenMP] Restore backwards compatibility for libomptarget

[jhuber6]

Summary

The changes introduced in D87946 changed the API for libomptarget
functions. __kmpc_push_target_tripcount was a function in Clang 11.x
but was not given a backward-compatible interface accidentally. This
will make it backwards compatible, but will require Clang 12 to recompile.

[jdoerfert]

LG. We should have a test that references the entire interface so we realize if something breaks.

[cchen]

I think some existing Clang OpenMP codegen tests will break if they are testing against __kmpc_push_target_tripcount.

[jhuber6]

In D98358#2617152, @cchen wrote:

I think some existing Clang OpenMP codegen tests will break if they are testing against __kmpc_push_target_tripcount.

I'm working on fixing the tests, I also forgot to include it in the exports

[jhuber6]

Updating tests and adding the new function to the exports.

[cchen]

LGTM.

clang/lib/CodeGen/CGOpenMPRuntime.cpp

       llvm::Value *Args[] = {RTLoc, DeviceID, NumIterations};
       CGF.EmitRuntimeCall(
           OMPBuilder.getOrCreateRuntimeFunction(
-              CGM.getModule(), OMPRTL___kmpc_push_target_tripcount),
+              CGM.getModule(), OMPRTL___kmpc_push_target_tripcount_mapper),
           Args);
     }
   };

llvm/include/llvm/Frontend/OpenMP/OMPKinds.def

 __OMP_RTL(__kmpc_destroy_allocator, false, Void, /* Int */ Int32,
           /* omp_allocator_handle_t */ VoidPtr)
 
-__OMP_RTL(__kmpc_push_target_tripcount, false, Void, IdentPtr, Int64, Int64)
+__OMP_RTL(__kmpc_push_target_tripcount_mapper, false, Void, IdentPtr, Int64, Int64)
 __OMP_RTL(__tgt_target_mapper, false, Int32, IdentPtr, Int64, VoidPtr, Int32, VoidPtrPtr,
           VoidPtrPtr, Int64Ptr, Int64Ptr, VoidPtrPtr, VoidPtrPtr)
 __OMP_RTL(__tgt_target_nowait_mapper, false, Int32, IdentPtr, Int64, VoidPtr, Int32,

 __OMP_RTL_ATTRS(__kmpc_init_allocator, DefaultAttrs, ReturnPtrAttrs, {})
 __OMP_RTL_ATTRS(__kmpc_destroy_allocator, AllocAttrs, AttributeSet(), {})
 
-__OMP_RTL_ATTRS(__kmpc_push_target_tripcount, SetterAttrs, AttributeSet(), {})
+__OMP_RTL_ATTRS(__kmpc_push_target_tripcount_mapper, SetterAttrs, AttributeSet(), {})
 __OMP_RTL_ATTRS(__tgt_target_mapper, ForkAttrs, AttributeSet(), {})
 __OMP_RTL_ATTRS(__tgt_target_nowait_mapper, ForkAttrs, AttributeSet(), {})
 __OMP_RTL_ATTRS(__tgt_target_teams_mapper, ForkAttrs, AttributeSet(), {})

openmp/libomptarget/include/omptarget.h

     int32_t thread_limit, int32_t depNum, void *depList, int32_t noAliasDepNum,
     void *noAliasDepList);
 
-void __kmpc_push_target_tripcount(ident_t *loc, int64_t device_id,
+void __kmpc_push_target_tripcount(int64_t device_id,
                                   uint64_t loop_tripcount);
 
+void __kmpc_push_target_tripcount_mapper(ident_t *loc, int64_t device_id,
+                                         uint64_t loop_tripcount);
+
 #ifdef __cplusplus
 }
 #endif

openmp/libomptarget/src/interface.cpp

       MapComponentInfoTy(base, begin, size, type, name));
 }
 
-EXTERN void __kmpc_push_target_tripcount(ident_t *loc, int64_t device_id,
+EXTERN void __kmpc_push_target_tripcount(int64_t device_id,
                                          uint64_t loop_tripcount) {
+  __kmpc_push_target_tripcount_mapper(nullptr, device_id, loop_tripcount);
+}
+
+EXTERN void __kmpc_push_target_tripcount_mapper(ident_t *loc, int64_t device_id,
+                                                uint64_t loop_tripcount) {
   TIMESCOPE_WITH_IDENT(loc);
   if (checkDeviceAndCtors(device_id, loc) != OFFLOAD_SUCCESS) {
     DP("Not offloading to device %" PRId64 "\n", device_id);