1: #include <../src/vec/is/sf/impls/basic/gatherv/sfgatherv.h>
  2: #include <../src/vec/is/sf/impls/basic/allgather/sfallgather.h>

  4: /* Reuse the type. The difference is some fields (i.e., displs, recvcounts) are not used in Gather, which is not a big deal */
  5: typedef PetscSF_Allgatherv PetscSF_Gather;

  7: PETSC_INTERN PetscErrorCode PetscSFBcastBegin_Gather(PetscSF sf, MPI_Datatype unit, PetscMemType rootmtype, const void *rootdata, PetscMemType leafmtype, void *leafdata, MPI_Op op)
  8: {
  9:   PetscSFLink  link;
 10:   PetscMPIInt  sendcount;
 11:   MPI_Comm     comm;
 12:   void        *rootbuf = NULL, *leafbuf = NULL;
 13:   MPI_Request *req;

 15:   PetscFunctionBegin;
 16:   PetscCall(PetscSFLinkCreate(sf, unit, rootmtype, rootdata, leafmtype, leafdata, op, PETSCSF_BCAST, &link));
 17:   PetscCall(PetscSFLinkPackRootData(sf, link, PETSCSF_REMOTE, rootdata));
 18:   PetscCall(PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf, link, PETSC_TRUE /* device2host before sending */));
 19:   PetscCall(PetscObjectGetComm((PetscObject)sf, &comm));
 20:   PetscCall(PetscMPIIntCast(sf->nroots, &sendcount));
 21:   PetscCall(PetscSFLinkGetMPIBuffersAndRequests(sf, link, PETSCSF_ROOT2LEAF, &rootbuf, &leafbuf, &req, NULL));
 22:   PetscCall(PetscSFLinkSyncStreamBeforeCallMPI(sf, link, PETSCSF_ROOT2LEAF));
 23:   PetscCallMPI(MPIU_Igather(rootbuf == leafbuf ? MPI_IN_PLACE : rootbuf, sendcount, unit, leafbuf, sendcount, unit, 0 /*rank 0*/, comm, req));
 24:   PetscFunctionReturn(PETSC_SUCCESS);
 25: }

 27: static PetscErrorCode PetscSFReduceBegin_Gather(PetscSF sf, MPI_Datatype unit, PetscMemType leafmtype, const void *leafdata, PetscMemType rootmtype, void *rootdata, MPI_Op op)
 28: {
 29:   PetscSFLink  link;
 30:   PetscMPIInt  recvcount;
 31:   MPI_Comm     comm;
 32:   void        *rootbuf = NULL, *leafbuf = NULL;
 33:   MPI_Request *req;

 35:   PetscFunctionBegin;
 36:   PetscCall(PetscSFLinkCreate(sf, unit, rootmtype, rootdata, leafmtype, leafdata, op, PETSCSF_REDUCE, &link));
 37:   PetscCall(PetscSFLinkPackLeafData(sf, link, PETSCSF_REMOTE, leafdata));
 38:   PetscCall(PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf, link, PETSC_TRUE /* device2host before sending */));
 39:   PetscCall(PetscObjectGetComm((PetscObject)sf, &comm));
 40:   PetscCall(PetscMPIIntCast(sf->nroots, &recvcount));
 41:   PetscCall(PetscSFLinkGetMPIBuffersAndRequests(sf, link, PETSCSF_LEAF2ROOT, &rootbuf, &leafbuf, &req, NULL));
 42:   PetscCall(PetscSFLinkSyncStreamBeforeCallMPI(sf, link, PETSCSF_LEAF2ROOT));
 43:   PetscCallMPI(MPIU_Iscatter(leafbuf, recvcount, unit, rootbuf == leafbuf ? MPI_IN_PLACE : rootbuf, recvcount, unit, 0 /*rank 0*/, comm, req));
 44:   PetscFunctionReturn(PETSC_SUCCESS);
 45: }

 47: PETSC_INTERN PetscErrorCode PetscSFCreate_Gather(PetscSF sf)
 48: {
 49:   PetscSF_Gather *dat = (PetscSF_Gather *)sf->data;

 51:   PetscFunctionBegin;
 52:   sf->ops->BcastEnd  = PetscSFBcastEnd_Basic;
 53:   sf->ops->ReduceEnd = PetscSFReduceEnd_Basic;

 55:   /* Inherit from Allgatherv */
 56:   sf->ops->Reset         = PetscSFReset_Allgatherv;
 57:   sf->ops->Destroy       = PetscSFDestroy_Allgatherv;
 58:   sf->ops->GetGraph      = PetscSFGetGraph_Allgatherv;
 59:   sf->ops->GetRootRanks  = PetscSFGetRootRanks_Allgatherv;
 60:   sf->ops->GetLeafRanks  = PetscSFGetLeafRanks_Allgatherv;
 61:   sf->ops->FetchAndOpEnd = PetscSFFetchAndOpEnd_Allgatherv;
 62:   sf->ops->CreateLocalSF = PetscSFCreateLocalSF_Allgatherv;

 64:   /* Inherit from Allgather */
 65:   sf->ops->SetUp = PetscSFSetUp_Allgather;

 67:   /* Inherit from Gatherv */
 68:   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Gatherv;

 70:   /* Gather stuff */
 71:   sf->ops->BcastBegin  = PetscSFBcastBegin_Gather;
 72:   sf->ops->ReduceBegin = PetscSFReduceBegin_Gather;

 74:   PetscCall(PetscNew(&dat));
 75:   sf->data = (void *)dat;
 76:   PetscFunctionReturn(PETSC_SUCCESS);
 77: }