Improve error checking for buffer aliasing

If the user isn't using MPI_IN_PLACE when they should, this check will do a
better job of warning them about it.

See #2049
Signed-off-by: Antonio J. Pena <apenya@mcs.anl.gov>

src/mpi/coll/ireduce.c

@@ -862,6 +862,8 @@ int MPI_Ireduce(const void *sendbuf, void *recvbuf, int count, MPI_Datatype data
     {
         MPID_BEGIN_ERROR_CHECKS
         {
+            int rank;
+
             MPID_Comm_valid_ptr(comm_ptr, mpi_errno);
             if (HANDLE_GET_KIND(datatype) != HANDLE_KIND_BUILTIN) {
                 MPID_Datatype *datatype_ptr = NULL;
@@ -883,7 +885,24 @@ int MPI_Ireduce(const void *sendbuf, void *recvbuf, int count, MPI_Datatype data
             if (mpi_errno != MPI_SUCCESS) goto fn_fail;
 
             MPIR_ERRTEST_ARGNULL(request,"request", mpi_errno);
-            /* TODO more checks may be appropriate (counts, in_place, buffer aliasing, etc) */
+
+            if (comm_ptr->comm_kind == MPID_INTRACOMM) {
+                if (sendbuf != MPI_IN_PLACE)
+                    MPIR_ERRTEST_USERBUFFER(sendbuf,count,datatype,mpi_errno);
+
+                rank = comm_ptr->rank;
+                if (rank == root) {
+                    MPIR_ERRTEST_RECVBUF_INPLACE(recvbuf, count, mpi_errno);
+                    MPIR_ERRTEST_USERBUFFER(recvbuf,count,datatype,mpi_errno);
+                    if (count != 0 && sendbuf != MPI_IN_PLACE) {
+                        MPIR_ERRTEST_ALIAS_COLL(sendbuf, recvbuf, mpi_errno);
+                    }
+                }
+                else
+                    MPIR_ERRTEST_SENDBUF_INPLACE(sendbuf, count, mpi_errno);
+            }
+
+            /* TODO more checks may be appropriate (counts, in_place, etc) */
         }
         MPID_END_ERROR_CHECKS
     }

src/mpi/coll/iscan.c

@@ -441,7 +441,10 @@ int MPI_Iscan(const void *sendbuf, void *recvbuf, int count, MPI_Datatype dataty
             if (mpi_errno != MPI_SUCCESS) goto fn_fail;
 
             MPIR_ERRTEST_ARGNULL(request,"request", mpi_errno);
-            /* TODO more checks may be appropriate (counts, in_place, buffer aliasing, etc) */
+
+            if (sendbuf != MPI_IN_PLACE)
+                MPIR_ERRTEST_ALIAS_COLL(sendbuf, recvbuf, mpi_errno);
+            /* TODO more checks may be appropriate (counts, in_place, etc) */
         }
         MPID_END_ERROR_CHECKS
     }

src/mpi/coll/iscatter.c

@@ -665,8 +665,11 @@ int MPI_Iscatter(const void *sendbuf, int sendcount, MPI_Datatype sendtype,
                     MPIR_ERRTEST_SENDBUF_INPLACE(sendbuf, sendcount, mpi_errno);
 
                     /* catch common aliasing cases */
-                    if (recvbuf != MPI_IN_PLACE && sendtype == recvtype && sendcount == recvcount && recvcount != 0)
-                        MPIR_ERRTEST_ALIAS_COLL(sendbuf,recvbuf,mpi_errno);
+                    if (recvbuf != MPI_IN_PLACE && sendtype == recvtype && sendcount == recvcount && recvcount != 0) {
+                        int sendtype_size;
+                        MPID_Datatype_get_size_macro(sendtype, sendtype_size);
+                        MPIR_ERRTEST_ALIAS_COLL(recvbuf, (char*)sendbuf + comm_ptr->rank*sendcount*sendtype_size, mpi_errno);
+                    }
                 }
                 else
                     MPIR_ERRTEST_RECVBUF_INPLACE(recvbuf, recvcount, mpi_errno);

src/mpi/coll/iscatterv.c

@@ -256,6 +256,13 @@ int MPI_Iscatterv(const void *sendbuf, const int sendcounts[], const int displs[
                             break;
                         }
                     }
+                    /* catch common aliasing cases */
+                    if (recvbuf != MPI_IN_PLACE && sendtype == recvtype && sendcounts[comm_ptr->rank] != 0 && recvcount != 0) {
+                        int sendtype_size;
+                        MPID_Datatype_get_size_macro(sendtype, sendtype_size);
+                        MPIR_ERRTEST_ALIAS_COLL(recvbuf, (char*)sendbuf + displs[comm_ptr->rank]*sendtype_size, mpi_errno);
+                    }
+
                 }
                 else
                     MPIR_ERRTEST_RECVBUF_INPLACE(recvbuf, recvcount, mpi_errno);

src/mpi/coll/red_scat.c

@@ -1172,8 +1172,10 @@ int MPI_Reduce_scatter(const void *sendbuf, void *recvbuf, const int recvcounts[
             }
 
             MPIR_ERRTEST_RECVBUF_INPLACE(recvbuf, recvcounts[comm_ptr->rank], mpi_errno);
-	    if (comm_ptr->comm_kind == MPID_INTERCOMM) 
+            if (comm_ptr->comm_kind == MPID_INTERCOMM) {
                 MPIR_ERRTEST_SENDBUF_INPLACE(sendbuf, sum, mpi_errno);
+            } else if (sendbuf != MPI_IN_PLACE)
+                MPIR_ERRTEST_ALIAS_COLL(sendbuf, recvbuf, mpi_errno)
 
             MPIR_ERRTEST_USERBUFFER(recvbuf,recvcounts[comm_ptr->rank],datatype,mpi_errno);
             MPIR_ERRTEST_USERBUFFER(sendbuf,sum,datatype,mpi_errno); 

src/mpi/coll/red_scat_block.c

@@ -1136,8 +1136,10 @@ int MPI_Reduce_scatter_block(const void *sendbuf, void *recvbuf,
             }
 
             MPIR_ERRTEST_RECVBUF_INPLACE(recvbuf, recvcount, mpi_errno);
-	    if (comm_ptr->comm_kind == MPID_INTERCOMM) 
+            if (comm_ptr->comm_kind == MPID_INTERCOMM) {
                 MPIR_ERRTEST_SENDBUF_INPLACE(sendbuf, recvcount, mpi_errno);
+            } else if (sendbuf != MPI_IN_PLACE)
+                MPIR_ERRTEST_ALIAS_COLL(sendbuf, recvbuf, mpi_errno)
 
             MPIR_ERRTEST_USERBUFFER(recvbuf,recvcount,datatype,mpi_errno);
             MPIR_ERRTEST_USERBUFFER(sendbuf,recvcount,datatype,mpi_errno); 

src/mpi/coll/scan.c

@@ -548,6 +548,9 @@ int MPI_Scan(const void *sendbuf, void *recvbuf, int count, MPI_Datatype datatyp
                     ( * MPIR_OP_HDL_TO_DTYPE_FN(op) )(datatype); 
             }
             if (mpi_errno != MPI_SUCCESS) goto fn_fail;
+
+            if (sendbuf != MPI_IN_PLACE)
+                MPIR_ERRTEST_ALIAS_COLL(sendbuf, recvbuf, mpi_errno);
         }
         MPID_END_ERROR_CHECKS;
     }

src/mpi/coll/scatter.c

@@ -724,10 +724,13 @@ int MPI_Scatter(const void *sendbuf, int sendcount, MPI_Datatype sendtype,
                     MPIR_ERRTEST_SENDBUF_INPLACE(sendbuf, sendcount, mpi_errno);
 
                     /* catch common aliasing cases */
-                    if (recvbuf != MPI_IN_PLACE && sendtype == recvtype && sendcount == recvcount && recvcount != 0)
-                        MPIR_ERRTEST_ALIAS_COLL(sendbuf,recvbuf,mpi_errno);
+                    if (recvbuf != MPI_IN_PLACE && sendtype == recvtype && sendcount == recvcount && recvcount != 0) {
+                        int sendtype_size;
+                        MPID_Datatype_get_size_macro(sendtype, sendtype_size);
+                        MPIR_ERRTEST_ALIAS_COLL(recvbuf, (char*)sendbuf + comm_ptr->rank*sendcount*sendtype_size, mpi_errno);
+                    }
                 }
-                else 
+                else
                     MPIR_ERRTEST_RECVBUF_INPLACE(recvbuf, recvcount, mpi_errno);
 
                 if (recvbuf != MPI_IN_PLACE) {

src/mpi/coll/scatterv.c

@@ -293,6 +293,12 @@ int MPI_Scatterv(const void *sendbuf, const int *sendcounts, const int *displs,
                             break;
                         }
                     }
+                    /* catch common aliasing cases */
+                    if (recvbuf != MPI_IN_PLACE && sendtype == recvtype && sendcounts[comm_ptr->rank] != 0 && recvcount != 0) {
+                        int sendtype_size;
+                        MPID_Datatype_get_size_macro(sendtype, sendtype_size);
+                        MPIR_ERRTEST_ALIAS_COLL(recvbuf, (char*)sendbuf + displs[comm_ptr->rank]*sendtype_size, mpi_errno);
+                    }
                 }
                 else 
                     MPIR_ERRTEST_RECVBUF_INPLACE(recvbuf, recvcount, mpi_errno);