Add work-around for MPICH 3.3 defect.

src/pio_posixfpguardsendrecv.c

@@ -336,6 +336,19 @@ initSharedFP(struct sharedFP *bfd, int nProcsColl)
   bfd->unfinished = nProcsColl;
 }
 
+/* MPICH 3.3 has a problem in its implementation of MPI_Testany and
+ * MPI_Waitany, see commit 0f7be7196cc05bf0c908761e148628e88d635190
+ * at https://github.com/pmodels/mpich */
+#ifdef MPICH_CALC_VERSION
+#if MPICH_NUMVERSION >= MPICH_CALC_VERSION(3, 3, 0, 0, 0) && MPI_NUMVERSION < MPICH_CALC_VERSION(3, 3, 1, 0, 0)
+#define CDIPIO_MPICH33_WORKAROUND(code) code
+#else
+#define CDIPIO_MPICH33_WORKAROUND(code) code
+#endif
+#else
+#define CDIPIO_MPICH33_WORKAROUND(code)
+#endif
+
 static void
 fpgPOSIXFPGUARDSENDRECV(void)
 {
@@ -346,16 +359,20 @@ fpgPOSIXFPGUARDSENDRECV(void)
   MPI_Comm commPio = commInqCommPio();
   size_t nProcsColl = (size_t) (commInqSizeColl()), sentFinalize = nProcsColl;
   struct syncMsg *msgWords = Malloc(sizeof(*msgWords) * nProcsColl);
-  MPI_Request *msgReq = Malloc(sizeof(*msgReq) * nProcsColl);
+  size_t numReq = nProcsColl;
+  CDIPIO_MPICH33_WORKAROUND(++numReq);
+  MPI_Request *msgReq = Malloc(sizeof(*msgReq) * numReq);
 
   xdebug("ncollectors=%zu", nProcsColl);
 
+  CDIPIO_MPICH33_WORKAROUND(msgReq[0] = MPI_REQUEST_NULL; ++msgReq);
   for (size_t i = 0; i < nProcsColl; ++i)
     xmpi(MPI_Irecv(msgWords + i, 1, cdiPioSyncMsgDt, (int) i, collGuardTag, commPio, msgReq + i));
-
   for (;;)
     {
+      CDIPIO_MPICH33_WORKAROUND(--msgReq; ++nProcsColl);
       xmpiStat(MPI_Waitany((int) nProcsColl, msgReq, &source, &status), &status);
+      CDIPIO_MPICH33_WORKAROUND(++msgReq; --nProcsColl; --source);
       int fileID = msgWords[source].fileID;
       assert(fileID >= 0);
       int opcode = msgWords[source].command;
@@ -404,6 +421,7 @@ fpgPOSIXFPGUARDSENDRECV(void)
             {
               if (sharedFPsFill) xabort("still files open");
               Free(sharedFPs);
+              CDIPIO_MPICH33_WORKAROUND(--msgReq);
               Free(msgReq);
               Free(msgWords);
               cdiPioDestroySyncMsgDt();