[OpenMP] Use IsHostPtr where needed in rest of omptarget.cpp

[jdenny]

Summary

As started in D107925, this patch replaces the remaining occurrences of
UNIFIED_SHARED_MEMORY && TgtPtrBegin == HstPtrBegin in
omptarget.cpp with IsHostPtr. The former condition is broken in
the rare case that the device and host happen to use the same address
for their mapped allocations. I don't know how to write a test that's
likely to reveal this case.

[grokos]

I don't think it is at all possible to write a test emulating this rare case of TgtPtr in GPU memory having the same value as HstPtr in host memory, so this is good to go even without a test. LGTM.

openmp/libomptarget/src/omptarget.cpp

if (ArgType & OMP_TGT_MAPTYPE_PRESENT) {
       MESSAGE("device mapping required by 'present' motion modifier does not "
               "exist for host address " DPxMOD " (%" PRId64 " bytes)",
               DPxPTR(HstPtrBegin), ArgSize);
       return OFFLOAD_FAIL;
     }
     return OFFLOAD_SUCCESS;
   }
 
-  if (PM->RTLs.RequiresFlags & OMP_REQ_UNIFIED_SHARED_MEMORY &&
-      TgtPtrBegin == HstPtrBegin) {
+  if (IsHostPtr) {
     DP("hst data:" DPxMOD " unified and shared, becomes a noop\n",
        DPxPTR(HstPtrBegin));
     return OFFLOAD_SUCCESS;
   }
 
   if (ArgType & OMP_TGT_MAPTYPE_FROM) {
     DP("Moving %" PRId64 " bytes (tgt:" DPxMOD ") -> (hst:" DPxMOD ")\n",
        ArgSize, DPxPTR(TgtPtrBegin), DPxPTR(HstPtrBegin));
if (!(ArgTypes[I] & OMP_TGT_MAPTYPE_TARGET_PARAM)) {
         unsigned Idx = getParentIndex(ArgTypes[I]);
         int TgtIdx = TgtArgsPositions[Idx];
         assert(TgtIdx != -1 && "Base address must be translated already.");
         // The parent lambda must be processed already and it must be the last
         // in TgtArgs and TgtOffsets arrays.
         void *HstPtrVal = Args[I];
         void *HstPtrBegin = ArgBases[I];
         void *HstPtrBase = Args[Idx];
-        bool IsLast, IsHostPtr; // unused.
+        bool IsLast, IsHostPtr; // IsLast is unused.
         void *TgtPtrBase =
             (void *)((intptr_t)TgtArgs[TgtIdx] + TgtOffsets[TgtIdx]);
         DP("Parent lambda base " DPxMOD "\n", DPxPTR(TgtPtrBase));
         uint64_t Delta = (uint64_t)HstPtrBegin - (uint64_t)HstPtrBase;
         void *TgtPtrBegin = (void *)((uintptr_t)TgtPtrBase + Delta);
         void *&PointerTgtPtrBegin = AsyncInfo.getVoidPtrLocation();
         PointerTgtPtrBegin = Device.getTgtPtrBegin(
             HstPtrVal, ArgSizes[I], IsLast, /*UpdateRefCount=*/false,
             /*UseHoldRefCount=*/false, IsHostPtr);
         if (!PointerTgtPtrBegin) {
           DP("No lambda captured variable mapped (" DPxMOD ") - ignored\n",
              DPxPTR(HstPtrVal));
           continue;
         }
-        if (PM->RTLs.RequiresFlags & OMP_REQ_UNIFIED_SHARED_MEMORY &&
-            TgtPtrBegin == HstPtrBegin) {
+        if (IsHostPtr) {
           DP("Unified memory is active, no need to map lambda captured"
              "variable (" DPxMOD ")\n",
              DPxPTR(HstPtrVal));
           continue;
         }
         DP("Update lambda reference (" DPxMOD ") -> [" DPxMOD "]\n",
            DPxPTR(PointerTgtPtrBegin), DPxPTR(TgtPtrBegin));
         Ret = Device.submitData(TgtPtrBegin, &PointerTgtPtrBegin,