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:   PetscErrorCode       ierr;
 10:   PetscSFLink          link;
 11:   PetscMPIInt          sendcount;
 12:   MPI_Comm             comm;
 13:   void                 *rootbuf = NULL,*leafbuf = NULL;
 14:   MPI_Request          *req;

 17:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_BCAST,&link);
 18:   PetscSFLinkPackRootData(sf,link,PETSCSF_REMOTE,rootdata);
 19:   PetscSFLinkCopyRootBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */);
 20:   PetscObjectGetComm((PetscObject)sf,&comm);
 21:   PetscMPIIntCast(sf->nroots,&sendcount);
 22:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_../../../../../..2LEAF,&rootbuf,&leafbuf,&req,NULL);
 23:   PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_../../../../../..2LEAF);
 24:   MPIU_Igather(rootbuf,sendcount,unit,leafbuf,sendcount,unit,0/*rank 0*/,comm,req);
 25:   return(0);
 26: }

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

 38:   PetscSFLinkCreate(sf,unit,rootmtype,rootdata,leafmtype,leafdata,op,PETSCSF_REDUCE,&link);
 39:   PetscSFLinkPackLeafData(sf,link,PETSCSF_REMOTE,leafdata);
 40:   PetscSFLinkCopyLeafBufferInCaseNotUseGpuAwareMPI(sf,link,PETSC_TRUE/* device2host before sending */);
 41:   PetscObjectGetComm((PetscObject)sf,&comm);
 42:   PetscMPIIntCast(sf->nroots,&recvcount);
 43:   PetscSFLinkGetMPIBuffersAndRequests(sf,link,PETSCSF_LEAF2../../../../../..,&rootbuf,&leafbuf,&req,NULL);
 44:   PetscSFLinkSyncStreamBeforeCallMPI(sf,link,PETSCSF_LEAF2../../../../../..);
 45:   MPIU_Iscatter(leafbuf,recvcount,unit,rootbuf,recvcount,unit,0/*rank 0*/,comm,req);
 46:   return(0);
 47: }

 49: PETSC_INTERN PetscErrorCode PetscSFCreate_Gather(PetscSF sf)
 50: {
 51:   PetscErrorCode  ierr;
 52:   PetscSF_Gather  *dat = (PetscSF_Gather*)sf->data;

 55:   sf->ops->BcastEnd        = PetscSFBcastEnd_Basic;
 56:   sf->ops->ReduceEnd       = PetscSFReduceEnd_Basic;

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

 67:   /* Inherit from Allgather */
 68:   sf->ops->SetUp           = PetscSFSetUp_Allgather;

 70:   /* Inherit from Gatherv */
 71:   sf->ops->FetchAndOpBegin = PetscSFFetchAndOpBegin_Gatherv;

 73:   /* Gather stuff */
 74:   sf->ops->BcastBegin      = PetscSFBcastBegin_Gather;
 75:   sf->ops->ReduceBegin     = PetscSFReduceBegin_Gather;

 77:   PetscNewLog(sf,&dat);
 78:   sf->data = (void*)dat;
 79:   return(0);
 80: }