https://bugs.llvm.org/show_bug.cgi?id=49207
Bug ID: 49207
Summary: Misuse of libomptarget plugin interface
Product: OpenMP
Version: unspecified
Hardware: PC
OS: All
Status: NEW
Severity: release blocker
Priority: P
Component: Runtime Library
Assignee: unassignedb...@nondot.org
Reporter: tianshilei1...@gmail.com
CC: llvm-bugs@lists.llvm.org
This bug was reported by Guilherme Valarini via Openmp-dev
(openmp-...@lists.llvm.org). The link is
https://lists.llvm.org/pipermail/openmp-dev/2021-February/003867.html
The following is the bug description.
In both cases, the address to a local variable is passed as the host data to be
copied to the target device, but since this function can be asynchronously
executed, such variables can get out of scope when the actual submission is
done.
```
// File: openmp/libomptarget/src/omptarget.cpp:419
if (arg_types[i] & OMP_TGT_MAPTYPE_PTR_AND_OBJ && !IsHostPtr) {
DP("Update pointer (" DPxMOD ") -> [" DPxMOD "]\n",
DPxPTR(PointerTgtPtrBegin), DPxPTR(TgtPtrBegin));
uint64_t Delta = (uint64_t)HstPtrBegin - (uint64_t)HstPtrBase;
void *TgtPtrBase = (void *)((uint64_t)TgtPtrBegin - Delta);
int rt = Device.submitData(PointerTgtPtrBegin, &TgtPtrBase,
sizeof(void *), async_info_ptr);
if (rt != OFFLOAD_SUCCESS) {
REPORT("Copying data to device failed.\n");
return OFFLOAD_FAIL;
}
// create shadow pointers for this entry
Device.ShadowMtx.lock();
Device.ShadowPtrMap[Pointer_HstPtrBegin] = {
HstPtrBase, PointerTgtPtrBegin, TgtPtrBase};
Device.ShadowMtx.unlock();
}
```
```
// File: openmp/libomptarget/src/omptarget.cpp:1141
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 = Device.getTgtPtrBegin(
HstPtrVal, ArgSizes[I], IsLast, 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) {
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,
sizeof(void *), AsyncInfo);
if (Ret != OFFLOAD_SUCCESS) {
REPORT("Copying data to device failed.\n");
return OFFLOAD_FAIL;
}
```
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