Commit e244145a authored by George Rokos's avatar George Rokos
Browse files

[LIBOMPTARGET] Do not increment/decrement the refcount for "declare target" objects 

The reference counter for global objects marked with declare target is INF. This patch prevents the runtime from incrementing /decrementing INF refcounts. Without it, the map(delete: global_object) directive actually deallocates the global on the device. With this patch, such a directive becomes a no-op.

Differential Revision: https://reviews.llvm.org/D72525
parent 01a4b831

openmp/libomptarget/src/device.cpp

+19 −26
Original line number Diff line number Diff line
@@ -44,16 +44,12 @@ int DeviceTy::associatePtr(void *HstPtrBegin, void *TgtPtrBegin, int64_t Size) { 
    }

  }



  // Mapping does not exist, allocate it

  HostDataToTargetTy newEntry;



  // Set up missing fields

  newEntry.HstPtrBase = (uintptr_t) HstPtrBegin;

  newEntry.HstPtrBegin = (uintptr_t) HstPtrBegin;

  newEntry.HstPtrEnd = (uintptr_t) HstPtrBegin + Size;

  newEntry.TgtPtrBegin = (uintptr_t) TgtPtrBegin;

  // refCount must be infinite

  newEntry.RefCount = INF_REF_CNT;

  // Mapping does not exist, allocate it with refCount=INF

  HostDataToTargetTy newEntry((uintptr_t) HstPtrBegin /*HstPtrBase*/,

                              (uintptr_t) HstPtrBegin /*HstPtrBegin*/,

                              (uintptr_t) HstPtrBegin + Size /*HstPtrEnd*/,

                              (uintptr_t) TgtPtrBegin /*TgtPtrBegin*/,

                              true /*IsRefCountINF*/);



  DP("Creating new map entry: HstBase=" DPxMOD ", HstBegin=" DPxMOD ", HstEnd="

      DPxMOD ", TgtBegin=" DPxMOD "\n", DPxPTR(newEntry.HstPtrBase),
@@ -74,7 +70,7 @@ int DeviceTy::disassociatePtr(void *HstPtrBegin) { 
      ii != HostDataToTargetMap.end(); ++ii) {

    if ((uintptr_t)HstPtrBegin == ii->HstPtrBegin) {

      // Mapping exists

      if (CONSIDERED_INF(ii->RefCount)) {

      if (ii->isRefCountInf()) {

        DP("Association found, removing it\n");

        HostDataToTargetMap.erase(ii);

        DataMapMtx.unlock();
@@ -94,21 +90,21 @@ int DeviceTy::disassociatePtr(void *HstPtrBegin) { 
}



// Get ref count of map entry containing HstPtrBegin

long DeviceTy::getMapEntryRefCnt(void *HstPtrBegin) {

uint64_t DeviceTy::getMapEntryRefCnt(void *HstPtrBegin) {

  uintptr_t hp = (uintptr_t)HstPtrBegin;

  long RefCnt = -1;

  uint64_t RefCnt = 0;



  DataMapMtx.lock();

  for (auto &HT : HostDataToTargetMap) {

    if (hp >= HT.HstPtrBegin && hp < HT.HstPtrEnd) {

      DP("DeviceTy::getMapEntry: requested entry found\n");

      RefCnt = HT.RefCount;

      RefCnt = HT.getRefCount();

      break;

    }

  }

  DataMapMtx.unlock();



  if (RefCnt < 0) {

  if (RefCnt == 0) {

    DP("DeviceTy::getMapEntry: requested entry not found\n");

  }
@@ -174,15 +170,14 @@ void *DeviceTy::getOrAllocTgtPtr(void *HstPtrBegin, void *HstPtrBase, 
    IsNew = false;



    if (UpdateRefCount)

      ++HT.RefCount;

      HT.incRefCount();



    uintptr_t tp = HT.TgtPtrBegin + ((uintptr_t)HstPtrBegin - HT.HstPtrBegin);

    DP("Mapping exists%s with HstPtrBegin=" DPxMOD ", TgtPtrBegin=" DPxMOD ", "

        "Size=%ld,%s RefCount=%s\n", (IsImplicit ? " (implicit)" : ""),

        DPxPTR(HstPtrBegin), DPxPTR(tp), Size,

        (UpdateRefCount ? " updated" : ""),

        (CONSIDERED_INF(HT.RefCount)) ? "INF" :

            std::to_string(HT.RefCount).c_str());

        HT.isRefCountInf() ? "INF" : std::to_string(HT.getRefCount()).c_str());

    rc = (void *)tp;

  } else if ((lr.Flags.ExtendsBefore || lr.Flags.ExtendsAfter) && !IsImplicit) {

    // Explicit extension of mapped data - not allowed.
@@ -229,17 +224,16 @@ void *DeviceTy::getTgtPtrBegin(void *HstPtrBegin, int64_t Size, bool &IsLast, 


  if (lr.Flags.IsContained || lr.Flags.ExtendsBefore || lr.Flags.ExtendsAfter) {

    auto &HT = *lr.Entry;

    IsLast = !(HT.RefCount > 1);

    IsLast = HT.getRefCount() == 1;



    if (HT.RefCount > 1 && UpdateRefCount)

      --HT.RefCount;

    if (!IsLast && UpdateRefCount)

      HT.decRefCount();



    uintptr_t tp = HT.TgtPtrBegin + ((uintptr_t)HstPtrBegin - HT.HstPtrBegin);

    DP("Mapping exists with HstPtrBegin=" DPxMOD ", TgtPtrBegin=" DPxMOD ", "

        "Size=%ld,%s RefCount=%s\n", DPxPTR(HstPtrBegin), DPxPTR(tp), Size,

        (UpdateRefCount ? " updated" : ""),

        (CONSIDERED_INF(HT.RefCount)) ? "INF" :

            std::to_string(HT.RefCount).c_str());

        HT.isRefCountInf() ? "INF" : std::to_string(HT.getRefCount()).c_str());

    rc = (void *)tp;

  } else if (RTLs.RequiresFlags & OMP_REQ_UNIFIED_SHARED_MEMORY) {

    // If the value isn't found in the mapping and unified shared memory
@@ -280,9 +274,8 @@ int DeviceTy::deallocTgtPtr(void *HstPtrBegin, int64_t Size, bool ForceDelete, 
  if (lr.Flags.IsContained || lr.Flags.ExtendsBefore || lr.Flags.ExtendsAfter) {

    auto &HT = *lr.Entry;

    if (ForceDelete)

      HT.RefCount = 1;

    if (--HT.RefCount <= 0) {

      assert(HT.RefCount == 0 && "did not expect a negative ref count");

      HT.resetRefCount();

    if (HT.decRefCount() == 0) {

      DP("Deleting tgt data " DPxMOD " of size %ld\n",

          DPxPTR(HT.TgtPtrBegin), Size);

      RTL->data_delete(RTLDeviceID, (void *)HT.TgtPtrBegin);

openmp/libomptarget/src/device.h

+41 −14
Original line number Diff line number Diff line
@@ -13,8 +13,8 @@ 
#ifndef _OMPTARGET_DEVICE_H

#define _OMPTARGET_DEVICE_H



#include <cassert>

#include <cstddef>

#include <climits>

#include <list>

#include <map>

#include <mutex>
@@ -25,9 +25,6 @@ struct RTLInfoTy; 
struct __tgt_bin_desc;

struct __tgt_target_table;



#define INF_REF_CNT (LONG_MAX>>1) // leave room for additions/subtractions

#define CONSIDERED_INF(x) (x > (INF_REF_CNT>>1))



/// Map between host data and target data.

struct HostDataToTargetTy {

  uintptr_t HstPtrBase; // host info.
@@ -36,18 +33,48 @@ struct HostDataToTargetTy { 


  uintptr_t TgtPtrBegin; // target info.



  long RefCount;

private:

  uint64_t RefCount;

  static const uint64_t INFRefCount = ~(uint64_t)0;



  HostDataToTargetTy()

      : HstPtrBase(0), HstPtrBegin(0), HstPtrEnd(0),

        TgtPtrBegin(0), RefCount(0) {}

  HostDataToTargetTy(uintptr_t BP, uintptr_t B, uintptr_t E, uintptr_t TB)

      : HstPtrBase(BP), HstPtrBegin(B), HstPtrEnd(E),

        TgtPtrBegin(TB), RefCount(1) {}

public:

  HostDataToTargetTy(uintptr_t BP, uintptr_t B, uintptr_t E, uintptr_t TB,

      long RF)

      bool IsINF = false)

      : HstPtrBase(BP), HstPtrBegin(B), HstPtrEnd(E),

        TgtPtrBegin(TB), RefCount(RF) {}

        TgtPtrBegin(TB), RefCount(IsINF ? INFRefCount : 1) {}



  uint64_t getRefCount() const {

    return RefCount;

  }



  uint64_t resetRefCount() {

    if (RefCount != INFRefCount)

      RefCount = 1;



    return RefCount;

  }



  uint64_t incRefCount() {

    if (RefCount != INFRefCount) {

      ++RefCount;

      assert(RefCount < INFRefCount && "refcount overflow");

    }



    return RefCount;

  }



  uint64_t decRefCount() {

    if (RefCount != INFRefCount) {

      assert(RefCount > 0 && "refcount underflow");

      --RefCount;

    }



    return RefCount;

  }



  bool isRefCountInf() const {

    return RefCount == INFRefCount;

  }

};



typedef std::list<HostDataToTargetTy> HostDataToTargetListTy;
@@ -129,7 +156,7 @@ struct DeviceTy { 
    return *this;

  }



  long getMapEntryRefCnt(void *HstPtrBegin);

  uint64_t getMapEntryRefCnt(void *HstPtrBegin);

  LookupResult lookupMapping(void *HstPtrBegin, int64_t Size);

  void *getOrAllocTgtPtr(void *HstPtrBegin, void *HstPtrBase, int64_t Size,

      bool &IsNew, bool &IsHostPtr, bool IsImplicit, bool UpdateRefCount = true,

openmp/libomptarget/src/omptarget.cpp

+3 −3
Original line number Diff line number Diff line
@@ -139,7 +139,7 @@ static int InitLibrary(DeviceTy& Device) { 
            (uintptr_t)CurrHostEntry->addr /*HstPtrBegin*/,

            (uintptr_t)CurrHostEntry->addr + CurrHostEntry->size /*HstPtrEnd*/,

            (uintptr_t)CurrDeviceEntry->addr /*TgtPtrBegin*/,

            INF_REF_CNT /*RefCount*/));

            true /*IsRefCountINF*/));

      }

    }

    Device.DataMapMtx.unlock();
@@ -301,7 +301,7 @@ int target_data_begin(DeviceTy &Device, int32_t arg_num, 
        } else if (arg_types[i] & OMP_TGT_MAPTYPE_MEMBER_OF) {

          // Copy data only if the "parent" struct has RefCount==1.

          int32_t parent_idx = member_of(arg_types[i]);

          long parent_rc = Device.getMapEntryRefCnt(args[parent_idx]);

          uint64_t parent_rc = Device.getMapEntryRefCnt(args[parent_idx]);

          assert(parent_rc > 0 && "parent struct not found");

          if (parent_rc == 1) {

            copy = true;
@@ -402,7 +402,7 @@ int target_data_end(DeviceTy &Device, int32_t arg_num, void **args_base, 
              !(arg_types[i] & OMP_TGT_MAPTYPE_PTR_AND_OBJ)) {

            // Copy data only if the "parent" struct has RefCount==1.

            int32_t parent_idx = member_of(arg_types[i]);

            long parent_rc = Device.getMapEntryRefCnt(args[parent_idx]);

            uint64_t parent_rc = Device.getMapEntryRefCnt(args[parent_idx]);

            assert(parent_rc > 0 && "parent struct not found");

            if (parent_rc == 1) {

              CopyMember = true;

openmp/libomptarget/test/mapping/delete_inf_refcount.c

0 → 100644
+32 −0
Original line number Diff line number Diff line 
// RUN: %libomptarget-compile-run-and-check-aarch64-unknown-linux-gnu

// RUN: %libomptarget-compile-run-and-check-powerpc64-ibm-linux-gnu

// RUN: %libomptarget-compile-run-and-check-powerpc64le-ibm-linux-gnu

// RUN: %libomptarget-compile-run-and-check-x86_64-pc-linux-gnu



#include <stdio.h>

#include <omp.h>



#pragma omp declare target

int isHost;

#pragma omp end declare target



int main(void) {

  isHost = -1;



#pragma omp target enter data map(to: isHost)



#pragma omp target

  { isHost = omp_is_initial_device(); }

#pragma omp target update from(isHost)



  if (isHost < 0) {

    printf("Runtime error, isHost=%d\n", isHost);

  }



#pragma omp target exit data map(delete: isHost)



  // CHECK: Target region executed on the device

  printf("Target region executed on the %s\n", isHost ? "host" : "device");



  return isHost;

}