coll: refactor barrier_intra_k_dissemination

Because the compiler can't figure out the arithmetics, it is warning: ‘MPIC_Waitall’ accessing 8 bytes in a region of size 0 [-Wstringop-overflow=] Refactor to suppress warning and for better readability.
pmodels · Aug 24, 2024 · cefbfd9 · cefbfd9
1 parent 794bc65
commit cefbfd9
Showing 1 changed file with 10 additions and 7 deletions.
diff --git a/src/mpi/coll/barrier/barrier_intra_k_dissemination.c b/src/mpi/coll/barrier/barrier_intra_k_dissemination.c
@@ -84,6 +84,8 @@ int MPIR_Barrier_intra_k_dissemination(MPIR_Comm * comm, int coll_group, int k,
         nphases++;
     }
 
+    MPIR_Request **rreqs = recv_reqs;
+    MPIR_Request **prev_rreqs = recv_reqs + (k - 1);
     shift = 1;
     for (i = 0; i < nphases; i++) {
         for (j = 1; j < k; j++) {
@@ -95,14 +97,12 @@ int MPIR_Barrier_intra_k_dissemination(MPIR_Comm * comm, int coll_group, int k,
             MPIR_Assert(to >= 0 && to < nranks);
 
             /* recv from (k-1) nbrs */
-            mpi_errno =
-                MPIC_Irecv(NULL, 0, MPI_BYTE, from, MPIR_BARRIER_TAG, comm, coll_group,
-                           &recv_reqs[(j - 1) + ((k - 1) * (i & 1))]);
+            mpi_errno = MPIC_Irecv(NULL, 0, MPI_BYTE, from, MPIR_BARRIER_TAG, comm, coll_group,
+                                   &rreqs[j - 1]);
             MPIR_ERR_COLL_CHECKANDCONT(mpi_errno, errflag, mpi_errno_ret);
             /* wait on recvs from prev phase */
             if (i > 0 && j == 1) {
-                mpi_errno =
-                    MPIC_Waitall(k - 1, &recv_reqs[((k - 1) * ((i - 1) & 1))], MPI_STATUSES_IGNORE);
+                mpi_errno = MPIC_Waitall(k - 1, prev_rreqs, MPI_STATUSES_IGNORE);
                 MPIR_ERR_COLL_CHECKANDCONT(mpi_errno, errflag, mpi_errno_ret);
             }
 
@@ -114,10 +114,13 @@ int MPIR_Barrier_intra_k_dissemination(MPIR_Comm * comm, int coll_group, int k,
         mpi_errno = MPIC_Waitall(k - 1, send_reqs, MPI_STATUSES_IGNORE);
         MPIR_ERR_COLL_CHECKANDCONT(mpi_errno, errflag, mpi_errno_ret);
         shift *= k;
+
+        MPIR_Request **tmp = rreqs;
+        rreqs = prev_rreqs;
+        prev_rreqs = tmp;
     }
 
-    mpi_errno =
-        MPIC_Waitall(k - 1, recv_reqs + ((k - 1) * ((nphases - 1) & 1)), MPI_STATUSES_IGNORE);
+    mpi_errno = MPIC_Waitall(k - 1, prev_rreqs, MPI_STATUSES_IGNORE);
     MPIR_ERR_COLL_CHECKANDCONT(mpi_errno, errflag, mpi_errno_ret);
 
   fn_exit: