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:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_BCAST,&link);
 16:   PetscSFLinkPackRootData(sf,link,PETSCSF_REMOTE,rootdata);
 17:   PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */);
 18:   PetscObjectGetComm((PetscObject)sf,&comm);
 19:   PetscMPIIntCast(sf->nroots,&sendcount);
 20:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_../../../../../..2LEAF,&rootbuf,&leafbuf,&req,NULL);
 21:   PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_../../../../../..2LEAF);
 22:   MPIU_Igather(rootbuf == leafbuf ? MPI_IN_PLACE : rootbuf,sendcount,unit,leafbuf,sendcount,unit,0/*rank 0*/,comm,req);
 23:   return 0;
 24: }

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

 34:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_REDUCE,&link);
 35:   PetscSFLinkPackLeafData(sf,link,PETSCSF_REMOTE,leafdata);
 36:   PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */);
 37:   PetscObjectGetComm((PetscObject)sf,&comm);
 38:   PetscMPIIntCast(sf->nroots,&recvcount);
 39:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_LEAF2../../../../../..,&rootbuf,&leafbuf,&req,NULL);
 40:   PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_LEAF2../../../../../..);
 41:   MPIU_Iscatter(leafbuf,recvcount,unit,rootbuf == leafbuf ? MPI_IN_PLACE : rootbuf,recvcount,unit,0/*rank 0*/,comm,req);
 42:   return 0;
 43: }

 45: PETSC_INTERN PetscErrorCode PetscSFCreate_Gather(PetscSF sf)
 46: {
 47:   PetscSF_Gather  *dat = (PetscSF_Gather*)sf->data;

 49:   sf->ops->BcastEnd        = PetscSFBcastEnd_Basic;
 50:   sf->ops->ReduceEnd       = PetscSFReduceEnd_Basic;

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

 61:   /* Inherit from Allgather */
 62:   sf->ops->SetUp           = PetscSFSetUp_Allgather;

 64:   /* Inherit from Gatherv */
 65:   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Gatherv;

 67:   /* Gather stuff */
 68:   sf->ops->BcastBegin      = PetscSFBcastBegin_Gather;
 69:   sf->ops->ReduceBegin     = PetscSFReduceBegin_Gather;

 71:   PetscNewLog(sf,&dat);
 72:   sf->data = (void*)dat;
 73:   return 0;
 74: }