xref: /petsc/src/mat/impls/baij/mpi/baijov.c (revision 5d7a6ebe9dde080aedbe86be0085708de8f97bb7)
1 
2 /*
3    Routines to compute overlapping regions of a parallel MPI matrix
4   and to find submatrices that were shared across processors.
5 */
6 #include <../src/mat/impls/baij/mpi/mpibaij.h>
7 #include <petscbt.h>
8 
9 static PetscErrorCode MatIncreaseOverlap_MPIBAIJ_Local(Mat, PetscInt, char **, PetscInt *, PetscInt **);
10 static PetscErrorCode MatIncreaseOverlap_MPIBAIJ_Receive(Mat, PetscInt, PetscInt **, PetscInt **, PetscInt *);
11 extern PetscErrorCode MatGetRow_MPIBAIJ(Mat, PetscInt, PetscInt *, PetscInt **, PetscScalar **);
12 extern PetscErrorCode MatRestoreRow_MPIBAIJ(Mat, PetscInt, PetscInt *, PetscInt **, PetscScalar **);
13 
14 PetscErrorCode MatIncreaseOverlap_MPIBAIJ(Mat C, PetscInt imax, IS is[], PetscInt ov)
15 {
16   PetscInt        i, N = C->cmap->N, bs = C->rmap->bs, n;
17   const PetscInt *idx;
18   IS             *is_new;
19 
20   PetscFunctionBegin;
21   PetscCall(PetscMalloc1(imax, &is_new));
22   /* Convert the indices into block format */
23   PetscCall(ISCompressIndicesGeneral(N, C->rmap->n, bs, imax, is, is_new));
24   PetscCheck(ov >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Negative overlap specified");
25   for (i = 0; i < ov; ++i) PetscCall(MatIncreaseOverlap_MPIBAIJ_Once(C, imax, is_new));
26   for (i = 0; i < imax; i++) {
27     PetscCall(ISDestroy(&is[i]));
28     PetscCall(ISGetLocalSize(is_new[i], &n));
29     PetscCall(ISGetIndices(is_new[i], &idx));
30     PetscCall(ISCreateBlock(PetscObjectComm((PetscObject)is_new[i]), bs, n, idx, PETSC_COPY_VALUES, &is[i]));
31     PetscCall(ISDestroy(&is_new[i]));
32   }
33   PetscCall(PetscFree(is_new));
34   PetscFunctionReturn(PETSC_SUCCESS);
35 }
36 
37 /*
38   Sample message format:
39   If a processor A wants processor B to process some elements corresponding
40   to index sets is[1], is[5]
41   mesg [0] = 2   (no of index sets in the mesg)
42   -----------
43   mesg [1] = 1 => is[1]
44   mesg [2] = sizeof(is[1]);
45   -----------
46   mesg [5] = 5  => is[5]
47   mesg [6] = sizeof(is[5]);
48   -----------
49   mesg [7]
50   mesg [n]  data(is[1])
51   -----------
52   mesg[n+1]
53   mesg[m]  data(is[5])
54   -----------
55 
56   Notes:
57   nrqs - no of requests sent (or to be sent out)
58   nrqr - no of requests received (which have to be or which have been processed)
59 */
60 PetscErrorCode MatIncreaseOverlap_MPIBAIJ_Once(Mat C, PetscInt imax, IS is[])
61 {
62   Mat_MPIBAIJ     *c = (Mat_MPIBAIJ *)C->data;
63   const PetscInt **idx, *idx_i;
64   PetscInt        *n, *w3, *w4, **data, len;
65   PetscMPIInt      size, rank, tag1, tag2, *w2, *w1, nrqr;
66   PetscInt         Mbs, i, j, k, **rbuf, row, nrqs, msz, **outdat, **ptr;
67   PetscInt        *ctr, *pa, *tmp, *isz, *isz1, **xdata, **rbuf2, *d_p;
68   PetscMPIInt     *onodes1, *olengths1, *onodes2, *olengths2, proc = -1;
69   PetscBT         *table;
70   MPI_Comm         comm, *iscomms;
71   MPI_Request     *s_waits1, *r_waits1, *s_waits2, *r_waits2;
72   char            *t_p;
73 
74   PetscFunctionBegin;
75   PetscCall(PetscObjectGetComm((PetscObject)C, &comm));
76   size = c->size;
77   rank = c->rank;
78   Mbs  = c->Mbs;
79 
80   PetscCall(PetscObjectGetNewTag((PetscObject)C, &tag1));
81   PetscCall(PetscObjectGetNewTag((PetscObject)C, &tag2));
82 
83   PetscCall(PetscMalloc2(imax, (PetscInt ***)&idx, imax, &n));
84 
85   for (i = 0; i < imax; i++) {
86     PetscCall(ISGetIndices(is[i], &idx[i]));
87     PetscCall(ISGetLocalSize(is[i], &n[i]));
88   }
89 
90   /* evaluate communication - mesg to who,length of mesg, and buffer space
91      required. Based on this, buffers are allocated, and data copied into them*/
92   PetscCall(PetscCalloc4(size, &w1, size, &w2, size, &w3, size, &w4));
93   for (i = 0; i < imax; i++) {
94     PetscCall(PetscArrayzero(w4, size)); /* initialise work vector*/
95     idx_i = idx[i];
96     len   = n[i];
97     for (j = 0; j < len; j++) {
98       row = idx_i[j];
99       PetscCheck(row >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Index set cannot have negative entries");
100       PetscCall(PetscLayoutFindOwner(C->rmap, row * C->rmap->bs, &proc));
101       w4[proc]++;
102     }
103     for (j = 0; j < size; j++) {
104       if (w4[j]) {
105         w1[j] += w4[j];
106         w3[j]++;
107       }
108     }
109   }
110 
111   nrqs     = 0; /* no of outgoing messages */
112   msz      = 0; /* total mesg length (for all proc */
113   w1[rank] = 0; /* no mesg sent to itself */
114   w3[rank] = 0;
115   for (i = 0; i < size; i++) {
116     if (w1[i]) {
117       w2[i] = 1;
118       nrqs++;
119     } /* there exists a message to proc i */
120   }
121   /* pa - is list of processors to communicate with */
122   PetscCall(PetscMalloc1(nrqs, &pa));
123   for (i = 0, j = 0; i < size; i++) {
124     if (w1[i]) {
125       pa[j] = i;
126       j++;
127     }
128   }
129 
130   /* Each message would have a header = 1 + 2*(no of IS) + data */
131   for (i = 0; i < nrqs; i++) {
132     j = pa[i];
133     w1[j] += w2[j] + 2 * w3[j];
134     msz += w1[j];
135   }
136 
137   /* Determine the number of messages to expect, their lengths, from from-ids */
138   PetscCall(PetscGatherNumberOfMessages(comm, w2, w1, &nrqr));
139   PetscCall(PetscGatherMessageLengths(comm, nrqs, nrqr, w1, &onodes1, &olengths1));
140 
141   /* Now post the Irecvs corresponding to these messages */
142   PetscCall(PetscPostIrecvInt(comm, tag1, nrqr, onodes1, olengths1, &rbuf, &r_waits1));
143 
144   /* Allocate Memory for outgoing messages */
145   PetscCall(PetscMalloc4(size, &outdat, size, &ptr, msz, &tmp, size, &ctr));
146   PetscCall(PetscArrayzero(outdat, size));
147   PetscCall(PetscArrayzero(ptr, size));
148   {
149     PetscInt *iptr = tmp, ict = 0;
150     for (i = 0; i < nrqs; i++) {
151       j = pa[i];
152       iptr += ict;
153       outdat[j] = iptr;
154       ict       = w1[j];
155     }
156   }
157 
158   /* Form the outgoing messages */
159   /*plug in the headers*/
160   for (i = 0; i < nrqs; i++) {
161     j            = pa[i];
162     outdat[j][0] = 0;
163     PetscCall(PetscArrayzero(outdat[j] + 1, 2 * w3[j]));
164     ptr[j] = outdat[j] + 2 * w3[j] + 1;
165   }
166 
167   /* Memory for doing local proc's work*/
168   {
169     PetscCall(PetscCalloc5(imax, &table, imax, &data, imax, &isz, Mbs * imax, &d_p, (Mbs / PETSC_BITS_PER_BYTE + 1) * imax, &t_p));
170 
171     for (i = 0; i < imax; i++) {
172       table[i] = t_p + (Mbs / PETSC_BITS_PER_BYTE + 1) * i;
173       data[i]  = d_p + (Mbs)*i;
174     }
175   }
176 
177   /* Parse the IS and update local tables and the outgoing buf with the data*/
178   {
179     PetscInt n_i, *data_i, isz_i, *outdat_j, ctr_j;
180     PetscBT  table_i;
181 
182     for (i = 0; i < imax; i++) {
183       PetscCall(PetscArrayzero(ctr, size));
184       n_i     = n[i];
185       table_i = table[i];
186       idx_i   = idx[i];
187       data_i  = data[i];
188       isz_i   = isz[i];
189       for (j = 0; j < n_i; j++) { /* parse the indices of each IS */
190         row = idx_i[j];
191         PetscCall(PetscLayoutFindOwner(C->rmap, row * C->rmap->bs, &proc));
192         if (proc != rank) { /* copy to the outgoing buffer */
193           ctr[proc]++;
194           *ptr[proc] = row;
195           ptr[proc]++;
196         } else { /* Update the local table */
197           if (!PetscBTLookupSet(table_i, row)) data_i[isz_i++] = row;
198         }
199       }
200       /* Update the headers for the current IS */
201       for (j = 0; j < size; j++) { /* Can Optimise this loop by using pa[] */
202         if ((ctr_j = ctr[j])) {
203           outdat_j            = outdat[j];
204           k                   = ++outdat_j[0];
205           outdat_j[2 * k]     = ctr_j;
206           outdat_j[2 * k - 1] = i;
207         }
208       }
209       isz[i] = isz_i;
210     }
211   }
212 
213   /*  Now  post the sends */
214   PetscCall(PetscMalloc1(nrqs, &s_waits1));
215   for (i = 0; i < nrqs; ++i) {
216     j = pa[i];
217     PetscCallMPI(MPI_Isend(outdat[j], w1[j], MPIU_INT, j, tag1, comm, s_waits1 + i));
218   }
219 
220   /* No longer need the original indices*/
221   for (i = 0; i < imax; ++i) PetscCall(ISRestoreIndices(is[i], idx + i));
222   PetscCall(PetscFree2(*(PetscInt ***)&idx, n));
223 
224   PetscCall(PetscMalloc1(imax, &iscomms));
225   for (i = 0; i < imax; ++i) {
226     PetscCall(PetscCommDuplicate(PetscObjectComm((PetscObject)is[i]), &iscomms[i], NULL));
227     PetscCall(ISDestroy(&is[i]));
228   }
229 
230   /* Do Local work*/
231   PetscCall(MatIncreaseOverlap_MPIBAIJ_Local(C, imax, table, isz, data));
232 
233   /* Receive messages*/
234   PetscCallMPI(MPI_Waitall(nrqr, r_waits1, MPI_STATUSES_IGNORE));
235   PetscCallMPI(MPI_Waitall(nrqs, s_waits1, MPI_STATUSES_IGNORE));
236 
237   /* Phase 1 sends are complete - deallocate buffers */
238   PetscCall(PetscFree4(outdat, ptr, tmp, ctr));
239   PetscCall(PetscFree4(w1, w2, w3, w4));
240 
241   PetscCall(PetscMalloc1(nrqr, &xdata));
242   PetscCall(PetscMalloc1(nrqr, &isz1));
243   PetscCall(MatIncreaseOverlap_MPIBAIJ_Receive(C, nrqr, rbuf, xdata, isz1));
244   if (rbuf) {
245     PetscCall(PetscFree(rbuf[0]));
246     PetscCall(PetscFree(rbuf));
247   }
248 
249   /* Send the data back*/
250   /* Do a global reduction to know the buffer space req for incoming messages*/
251   {
252     PetscMPIInt *rw1;
253 
254     PetscCall(PetscCalloc1(size, &rw1));
255 
256     for (i = 0; i < nrqr; ++i) {
257       proc      = onodes1[i];
258       rw1[proc] = isz1[i];
259     }
260 
261     /* Determine the number of messages to expect, their lengths, from from-ids */
262     PetscCall(PetscGatherMessageLengths(comm, nrqr, nrqs, rw1, &onodes2, &olengths2));
263     PetscCall(PetscFree(rw1));
264   }
265   /* Now post the Irecvs corresponding to these messages */
266   PetscCall(PetscPostIrecvInt(comm, tag2, nrqs, onodes2, olengths2, &rbuf2, &r_waits2));
267 
268   /*  Now  post the sends */
269   PetscCall(PetscMalloc1(nrqr, &s_waits2));
270   for (i = 0; i < nrqr; ++i) {
271     j = onodes1[i];
272     PetscCallMPI(MPI_Isend(xdata[i], isz1[i], MPIU_INT, j, tag2, comm, s_waits2 + i));
273   }
274 
275   PetscCall(PetscFree(onodes1));
276   PetscCall(PetscFree(olengths1));
277 
278   /* receive work done on other processors*/
279   {
280     PetscMPIInt idex;
281     PetscInt    is_no, ct1, max, *rbuf2_i, isz_i, *data_i, jmax;
282     PetscBT     table_i;
283 
284     for (i = 0; i < nrqs; ++i) {
285       PetscCallMPI(MPI_Waitany(nrqs, r_waits2, &idex, MPI_STATUS_IGNORE));
286       /* Process the message*/
287       rbuf2_i = rbuf2[idex];
288       ct1     = 2 * rbuf2_i[0] + 1;
289       jmax    = rbuf2[idex][0];
290       for (j = 1; j <= jmax; j++) {
291         max     = rbuf2_i[2 * j];
292         is_no   = rbuf2_i[2 * j - 1];
293         isz_i   = isz[is_no];
294         data_i  = data[is_no];
295         table_i = table[is_no];
296         for (k = 0; k < max; k++, ct1++) {
297           row = rbuf2_i[ct1];
298           if (!PetscBTLookupSet(table_i, row)) data_i[isz_i++] = row;
299         }
300         isz[is_no] = isz_i;
301       }
302     }
303     PetscCallMPI(MPI_Waitall(nrqr, s_waits2, MPI_STATUSES_IGNORE));
304   }
305 
306   for (i = 0; i < imax; ++i) {
307     PetscCall(ISCreateGeneral(iscomms[i], isz[i], data[i], PETSC_COPY_VALUES, is + i));
308     PetscCall(PetscCommDestroy(&iscomms[i]));
309   }
310 
311   PetscCall(PetscFree(iscomms));
312   PetscCall(PetscFree(onodes2));
313   PetscCall(PetscFree(olengths2));
314 
315   PetscCall(PetscFree(pa));
316   if (rbuf2) {
317     PetscCall(PetscFree(rbuf2[0]));
318     PetscCall(PetscFree(rbuf2));
319   }
320   PetscCall(PetscFree(s_waits1));
321   PetscCall(PetscFree(r_waits1));
322   PetscCall(PetscFree(s_waits2));
323   PetscCall(PetscFree(r_waits2));
324   PetscCall(PetscFree5(table, data, isz, d_p, t_p));
325   if (xdata) {
326     PetscCall(PetscFree(xdata[0]));
327     PetscCall(PetscFree(xdata));
328   }
329   PetscCall(PetscFree(isz1));
330   PetscFunctionReturn(PETSC_SUCCESS);
331 }
332 
333 /*
334    MatIncreaseOverlap_MPIBAIJ_Local - Called by MatincreaseOverlap, to do
335        the work on the local processor.
336 
337      Inputs:
338       C      - MAT_MPIBAIJ;
339       imax - total no of index sets processed at a time;
340       table  - an array of char - size = Mbs bits.
341 
342      Output:
343       isz    - array containing the count of the solution elements corresponding
344                to each index set;
345       data   - pointer to the solutions
346 */
347 static PetscErrorCode MatIncreaseOverlap_MPIBAIJ_Local(Mat C, PetscInt imax, PetscBT *table, PetscInt *isz, PetscInt **data)
348 {
349   Mat_MPIBAIJ *c = (Mat_MPIBAIJ *)C->data;
350   Mat          A = c->A, B = c->B;
351   Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data, *b = (Mat_SeqBAIJ *)B->data;
352   PetscInt     start, end, val, max, rstart, cstart, *ai, *aj;
353   PetscInt    *bi, *bj, *garray, i, j, k, row, *data_i, isz_i;
354   PetscBT      table_i;
355 
356   PetscFunctionBegin;
357   rstart = c->rstartbs;
358   cstart = c->cstartbs;
359   ai     = a->i;
360   aj     = a->j;
361   bi     = b->i;
362   bj     = b->j;
363   garray = c->garray;
364 
365   for (i = 0; i < imax; i++) {
366     data_i  = data[i];
367     table_i = table[i];
368     isz_i   = isz[i];
369     for (j = 0, max = isz[i]; j < max; j++) {
370       row   = data_i[j] - rstart;
371       start = ai[row];
372       end   = ai[row + 1];
373       for (k = start; k < end; k++) { /* Amat */
374         val = aj[k] + cstart;
375         if (!PetscBTLookupSet(table_i, val)) data_i[isz_i++] = val;
376       }
377       start = bi[row];
378       end   = bi[row + 1];
379       for (k = start; k < end; k++) { /* Bmat */
380         val = garray[bj[k]];
381         if (!PetscBTLookupSet(table_i, val)) data_i[isz_i++] = val;
382       }
383     }
384     isz[i] = isz_i;
385   }
386   PetscFunctionReturn(PETSC_SUCCESS);
387 }
388 /*
389       MatIncreaseOverlap_MPIBAIJ_Receive - Process the received messages,
390          and return the output
391 
392          Input:
393            C    - the matrix
394            nrqr - no of messages being processed.
395            rbuf - an array of pointers to the received requests
396 
397          Output:
398            xdata - array of messages to be sent back
399            isz1  - size of each message
400 
401   For better efficiency perhaps we should malloc separately each xdata[i],
402 then if a remalloc is required we need only copy the data for that one row
403 rather than all previous rows as it is now where a single large chunk of
404 memory is used.
405 
406 */
407 static PetscErrorCode MatIncreaseOverlap_MPIBAIJ_Receive(Mat C, PetscInt nrqr, PetscInt **rbuf, PetscInt **xdata, PetscInt *isz1)
408 {
409   Mat_MPIBAIJ *c = (Mat_MPIBAIJ *)C->data;
410   Mat          A = c->A, B = c->B;
411   Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data, *b = (Mat_SeqBAIJ *)B->data;
412   PetscInt     rstart, cstart, *ai, *aj, *bi, *bj, *garray, i, j, k;
413   PetscInt     row, total_sz, ct, ct1, ct2, ct3, mem_estimate, oct2, l, start, end;
414   PetscInt     val, max1, max2, Mbs, no_malloc = 0, *tmp, new_estimate, ctr;
415   PetscInt    *rbuf_i, kmax, rbuf_0;
416   PetscBT      xtable;
417 
418   PetscFunctionBegin;
419   Mbs    = c->Mbs;
420   rstart = c->rstartbs;
421   cstart = c->cstartbs;
422   ai     = a->i;
423   aj     = a->j;
424   bi     = b->i;
425   bj     = b->j;
426   garray = c->garray;
427 
428   for (i = 0, ct = 0, total_sz = 0; i < nrqr; ++i) {
429     rbuf_i = rbuf[i];
430     rbuf_0 = rbuf_i[0];
431     ct += rbuf_0;
432     for (j = 1; j <= rbuf_0; j++) total_sz += rbuf_i[2 * j];
433   }
434 
435   if (c->Mbs) max1 = ct * (a->nz + b->nz) / c->Mbs;
436   else max1 = 1;
437   mem_estimate = 3 * ((total_sz > max1 ? total_sz : max1) + 1);
438   if (nrqr) {
439     PetscCall(PetscMalloc1(mem_estimate, &xdata[0]));
440     ++no_malloc;
441   }
442   PetscCall(PetscBTCreate(Mbs, &xtable));
443   PetscCall(PetscArrayzero(isz1, nrqr));
444 
445   ct3 = 0;
446   for (i = 0; i < nrqr; i++) { /* for easch mesg from proc i */
447     rbuf_i = rbuf[i];
448     rbuf_0 = rbuf_i[0];
449     ct1    = 2 * rbuf_0 + 1;
450     ct2    = ct1;
451     ct3 += ct1;
452     for (j = 1; j <= rbuf_0; j++) { /* for each IS from proc i*/
453       PetscCall(PetscBTMemzero(Mbs, xtable));
454       oct2 = ct2;
455       kmax = rbuf_i[2 * j];
456       for (k = 0; k < kmax; k++, ct1++) {
457         row = rbuf_i[ct1];
458         if (!PetscBTLookupSet(xtable, row)) {
459           if (!(ct3 < mem_estimate)) {
460             new_estimate = (PetscInt)(1.5 * mem_estimate) + 1;
461             PetscCall(PetscMalloc1(new_estimate, &tmp));
462             PetscCall(PetscArraycpy(tmp, xdata[0], mem_estimate));
463             PetscCall(PetscFree(xdata[0]));
464             xdata[0]     = tmp;
465             mem_estimate = new_estimate;
466             ++no_malloc;
467             for (ctr = 1; ctr <= i; ctr++) xdata[ctr] = xdata[ctr - 1] + isz1[ctr - 1];
468           }
469           xdata[i][ct2++] = row;
470           ct3++;
471         }
472       }
473       for (k = oct2, max2 = ct2; k < max2; k++) {
474         row   = xdata[i][k] - rstart;
475         start = ai[row];
476         end   = ai[row + 1];
477         for (l = start; l < end; l++) {
478           val = aj[l] + cstart;
479           if (!PetscBTLookupSet(xtable, val)) {
480             if (!(ct3 < mem_estimate)) {
481               new_estimate = (PetscInt)(1.5 * mem_estimate) + 1;
482               PetscCall(PetscMalloc1(new_estimate, &tmp));
483               PetscCall(PetscArraycpy(tmp, xdata[0], mem_estimate));
484               PetscCall(PetscFree(xdata[0]));
485               xdata[0]     = tmp;
486               mem_estimate = new_estimate;
487               ++no_malloc;
488               for (ctr = 1; ctr <= i; ctr++) xdata[ctr] = xdata[ctr - 1] + isz1[ctr - 1];
489             }
490             xdata[i][ct2++] = val;
491             ct3++;
492           }
493         }
494         start = bi[row];
495         end   = bi[row + 1];
496         for (l = start; l < end; l++) {
497           val = garray[bj[l]];
498           if (!PetscBTLookupSet(xtable, val)) {
499             if (!(ct3 < mem_estimate)) {
500               new_estimate = (PetscInt)(1.5 * mem_estimate) + 1;
501               PetscCall(PetscMalloc1(new_estimate, &tmp));
502               PetscCall(PetscArraycpy(tmp, xdata[0], mem_estimate));
503               PetscCall(PetscFree(xdata[0]));
504               xdata[0]     = tmp;
505               mem_estimate = new_estimate;
506               ++no_malloc;
507               for (ctr = 1; ctr <= i; ctr++) xdata[ctr] = xdata[ctr - 1] + isz1[ctr - 1];
508             }
509             xdata[i][ct2++] = val;
510             ct3++;
511           }
512         }
513       }
514       /* Update the header*/
515       xdata[i][2 * j]     = ct2 - oct2; /* Undo the vector isz1 and use only a var*/
516       xdata[i][2 * j - 1] = rbuf_i[2 * j - 1];
517     }
518     xdata[i][0] = rbuf_0;
519     if (i + 1 < nrqr) xdata[i + 1] = xdata[i] + ct2;
520     isz1[i] = ct2; /* size of each message */
521   }
522   PetscCall(PetscBTDestroy(&xtable));
523   PetscCall(PetscInfo(C, "Allocated %" PetscInt_FMT " bytes, required %" PetscInt_FMT ", no of mallocs = %" PetscInt_FMT "\n", mem_estimate, ct3, no_malloc));
524   PetscFunctionReturn(PETSC_SUCCESS);
525 }
526 
527 PetscErrorCode MatCreateSubMatrices_MPIBAIJ(Mat C, PetscInt ismax, const IS isrow[], const IS iscol[], MatReuse scall, Mat *submat[])
528 {
529   IS          *isrow_block, *iscol_block;
530   Mat_MPIBAIJ *c = (Mat_MPIBAIJ *)C->data;
531   PetscInt     nmax, nstages_local, nstages, i, pos, max_no, N = C->cmap->N, bs = C->rmap->bs;
532   Mat_SeqBAIJ *subc;
533   Mat_SubSppt *smat;
534 
535   PetscFunctionBegin;
536   /* The compression and expansion should be avoided. Doesn't point
537      out errors, might change the indices, hence buggey */
538   PetscCall(PetscMalloc2(ismax, &isrow_block, ismax, &iscol_block));
539   PetscCall(ISCompressIndicesGeneral(C->rmap->N, C->rmap->n, bs, ismax, isrow, isrow_block));
540   if (isrow == iscol) {
541     for (i = 0; i < ismax; i++) {
542       iscol_block[i] = isrow_block[i];
543       PetscCall(PetscObjectReference((PetscObject)iscol_block[i]));
544     }
545   } else PetscCall(ISCompressIndicesGeneral(N, C->cmap->n, bs, ismax, iscol, iscol_block));
546 
547   /* Determine the number of stages through which submatrices are done */
548   if (!C->cmap->N) nmax = 20 * 1000000 / sizeof(PetscInt);
549   else nmax = 20 * 1000000 / (c->Nbs * sizeof(PetscInt));
550   if (!nmax) nmax = 1;
551 
552   if (scall == MAT_INITIAL_MATRIX) {
553     nstages_local = ismax / nmax + ((ismax % nmax) ? 1 : 0); /* local nstages */
554 
555     /* Make sure every processor loops through the nstages */
556     PetscCall(MPIU_Allreduce(&nstages_local, &nstages, 1, MPIU_INT, MPI_MAX, PetscObjectComm((PetscObject)C)));
557 
558     /* Allocate memory to hold all the submatrices and dummy submatrices */
559     PetscCall(PetscCalloc1(ismax + nstages, submat));
560   } else { /* MAT_REUSE_MATRIX */
561     if (ismax) {
562       subc = (Mat_SeqBAIJ *)((*submat)[0]->data);
563       smat = subc->submatis1;
564     } else { /* (*submat)[0] is a dummy matrix */
565       smat = (Mat_SubSppt *)(*submat)[0]->data;
566     }
567     PetscCheck(smat, PETSC_COMM_SELF, PETSC_ERR_ARG_NULL, "MatCreateSubMatrices(...,MAT_REUSE_MATRIX,...) requires submat");
568     nstages = smat->nstages;
569   }
570 
571   for (i = 0, pos = 0; i < nstages; i++) {
572     if (pos + nmax <= ismax) max_no = nmax;
573     else if (pos >= ismax) max_no = 0;
574     else max_no = ismax - pos;
575 
576     PetscCall(MatCreateSubMatrices_MPIBAIJ_local(C, max_no, isrow_block + pos, iscol_block + pos, scall, *submat + pos));
577     if (!max_no) {
578       if (scall == MAT_INITIAL_MATRIX) { /* submat[pos] is a dummy matrix */
579         smat          = (Mat_SubSppt *)(*submat)[pos]->data;
580         smat->nstages = nstages;
581       }
582       pos++; /* advance to next dummy matrix if any */
583     } else pos += max_no;
584   }
585 
586   if (scall == MAT_INITIAL_MATRIX && ismax) {
587     /* save nstages for reuse */
588     subc          = (Mat_SeqBAIJ *)((*submat)[0]->data);
589     smat          = subc->submatis1;
590     smat->nstages = nstages;
591   }
592 
593   for (i = 0; i < ismax; i++) {
594     PetscCall(ISDestroy(&isrow_block[i]));
595     PetscCall(ISDestroy(&iscol_block[i]));
596   }
597   PetscCall(PetscFree2(isrow_block, iscol_block));
598   PetscFunctionReturn(PETSC_SUCCESS);
599 }
600 
601 /* This code is used for BAIJ and SBAIJ matrices (unfortunate dependency) */
602 PetscErrorCode MatCreateSubMatrices_MPIBAIJ_local(Mat C, PetscInt ismax, const IS isrow[], const IS iscol[], MatReuse scall, Mat *submats)
603 {
604   Mat_MPIBAIJ     *c = (Mat_MPIBAIJ *)C->data;
605   Mat              A = c->A;
606   Mat_SeqBAIJ     *a = (Mat_SeqBAIJ *)A->data, *b = (Mat_SeqBAIJ *)c->B->data, *subc;
607   const PetscInt **icol, **irow;
608   PetscInt        *nrow, *ncol, start;
609   PetscMPIInt      rank, size, tag0, tag2, tag3, tag4, *w1, *w2, *w3, *w4, nrqr;
610   PetscInt       **sbuf1, **sbuf2, *sbuf2_i, i, j, k, l, ct1, ct2, **rbuf1, row, proc = -1;
611   PetscInt         nrqs = 0, msz, **ptr = NULL, *req_size = NULL, *ctr = NULL, *pa, *tmp = NULL, tcol;
612   PetscInt       **rbuf3 = NULL, *req_source1 = NULL, *req_source2, **sbuf_aj, **rbuf2 = NULL, max1, max2;
613   PetscInt       **lens, is_no, ncols, *cols, mat_i, *mat_j, tmp2, jmax;
614 #if defined(PETSC_USE_CTABLE)
615   PetscHMapI *cmap, cmap_i = NULL, *rmap, rmap_i;
616 #else
617   PetscInt **cmap, *cmap_i = NULL, **rmap, *rmap_i;
618 #endif
619   const PetscInt *irow_i, *icol_i;
620   PetscInt        ctr_j, *sbuf1_j, *sbuf_aj_i, *rbuf1_i, kmax, *lens_i;
621   MPI_Request    *s_waits1, *r_waits1, *s_waits2, *r_waits2, *r_waits3;
622   MPI_Request    *r_waits4, *s_waits3, *s_waits4;
623   MPI_Comm        comm;
624   PetscScalar   **rbuf4, *rbuf4_i = NULL, **sbuf_aa, *vals, *mat_a = NULL, *imat_a = NULL, *sbuf_aa_i;
625   PetscMPIInt    *onodes1, *olengths1, end;
626   PetscInt      **row2proc, *row2proc_i, *imat_ilen, *imat_j, *imat_i;
627   Mat_SubSppt    *smat_i;
628   PetscBool      *issorted, colflag, iscsorted = PETSC_TRUE;
629   PetscInt       *sbuf1_i, *rbuf2_i, *rbuf3_i, ilen;
630   PetscInt        bs = C->rmap->bs, bs2 = c->bs2, rstart = c->rstartbs;
631   PetscBool       ijonly = c->ijonly; /* private flag indicates only matrix data structures are requested */
632   PetscInt        nzA, nzB, *a_i = a->i, *b_i = b->i, *a_j = a->j, *b_j = b->j, ctmp, imark, *cworkA, *cworkB;
633   PetscScalar    *vworkA = NULL, *vworkB = NULL, *a_a = a->a, *b_a = b->a;
634   PetscInt        cstart = c->cstartbs, *bmap = c->garray;
635   PetscBool      *allrows, *allcolumns;
636 
637   PetscFunctionBegin;
638   PetscCall(PetscObjectGetComm((PetscObject)C, &comm));
639   size = c->size;
640   rank = c->rank;
641 
642   PetscCall(PetscMalloc5(ismax, &row2proc, ismax, &cmap, ismax, &rmap, ismax + 1, &allcolumns, ismax, &allrows));
643   PetscCall(PetscMalloc5(ismax, (PetscInt ***)&irow, ismax, (PetscInt ***)&icol, ismax, &nrow, ismax, &ncol, ismax, &issorted));
644 
645   for (i = 0; i < ismax; i++) {
646     PetscCall(ISSorted(iscol[i], &issorted[i]));
647     if (!issorted[i]) iscsorted = issorted[i]; /* columns are not sorted! */
648     PetscCall(ISSorted(isrow[i], &issorted[i]));
649 
650     /* Check for special case: allcolumns */
651     PetscCall(ISIdentity(iscol[i], &colflag));
652     PetscCall(ISGetLocalSize(iscol[i], &ncol[i]));
653 
654     if (colflag && ncol[i] == c->Nbs) {
655       allcolumns[i] = PETSC_TRUE;
656       icol[i]       = NULL;
657     } else {
658       allcolumns[i] = PETSC_FALSE;
659       PetscCall(ISGetIndices(iscol[i], &icol[i]));
660     }
661 
662     /* Check for special case: allrows */
663     PetscCall(ISIdentity(isrow[i], &colflag));
664     PetscCall(ISGetLocalSize(isrow[i], &nrow[i]));
665     if (colflag && nrow[i] == c->Mbs) {
666       allrows[i] = PETSC_TRUE;
667       irow[i]    = NULL;
668     } else {
669       allrows[i] = PETSC_FALSE;
670       PetscCall(ISGetIndices(isrow[i], &irow[i]));
671     }
672   }
673 
674   if (scall == MAT_REUSE_MATRIX) {
675     /* Assumes new rows are same length as the old rows */
676     for (i = 0; i < ismax; i++) {
677       subc = (Mat_SeqBAIJ *)(submats[i]->data);
678       PetscCheck(subc->mbs == nrow[i] && subc->nbs == ncol[i], PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Cannot reuse matrix. wrong size");
679 
680       /* Initial matrix as if empty */
681       PetscCall(PetscArrayzero(subc->ilen, subc->mbs));
682 
683       /* Initial matrix as if empty */
684       submats[i]->factortype = C->factortype;
685 
686       smat_i = subc->submatis1;
687 
688       nrqs        = smat_i->nrqs;
689       nrqr        = smat_i->nrqr;
690       rbuf1       = smat_i->rbuf1;
691       rbuf2       = smat_i->rbuf2;
692       rbuf3       = smat_i->rbuf3;
693       req_source2 = smat_i->req_source2;
694 
695       sbuf1 = smat_i->sbuf1;
696       sbuf2 = smat_i->sbuf2;
697       ptr   = smat_i->ptr;
698       tmp   = smat_i->tmp;
699       ctr   = smat_i->ctr;
700 
701       pa          = smat_i->pa;
702       req_size    = smat_i->req_size;
703       req_source1 = smat_i->req_source1;
704 
705       allcolumns[i] = smat_i->allcolumns;
706       allrows[i]    = smat_i->allrows;
707       row2proc[i]   = smat_i->row2proc;
708       rmap[i]       = smat_i->rmap;
709       cmap[i]       = smat_i->cmap;
710     }
711 
712     if (!ismax) { /* Get dummy submatrices and retrieve struct submatis1 */
713       PetscCheck(submats[0], PETSC_COMM_SELF, PETSC_ERR_ARG_NULL, "submats are null, cannot reuse");
714       smat_i = (Mat_SubSppt *)submats[0]->data;
715 
716       nrqs        = smat_i->nrqs;
717       nrqr        = smat_i->nrqr;
718       rbuf1       = smat_i->rbuf1;
719       rbuf2       = smat_i->rbuf2;
720       rbuf3       = smat_i->rbuf3;
721       req_source2 = smat_i->req_source2;
722 
723       sbuf1 = smat_i->sbuf1;
724       sbuf2 = smat_i->sbuf2;
725       ptr   = smat_i->ptr;
726       tmp   = smat_i->tmp;
727       ctr   = smat_i->ctr;
728 
729       pa          = smat_i->pa;
730       req_size    = smat_i->req_size;
731       req_source1 = smat_i->req_source1;
732 
733       allcolumns[0] = PETSC_FALSE;
734     }
735   } else { /* scall == MAT_INITIAL_MATRIX */
736     /* Get some new tags to keep the communication clean */
737     PetscCall(PetscObjectGetNewTag((PetscObject)C, &tag2));
738     PetscCall(PetscObjectGetNewTag((PetscObject)C, &tag3));
739 
740     /* evaluate communication - mesg to who, length of mesg, and buffer space
741      required. Based on this, buffers are allocated, and data copied into them*/
742     PetscCall(PetscCalloc4(size, &w1, size, &w2, size, &w3, size, &w4)); /* mesg size, initialize work vectors */
743 
744     for (i = 0; i < ismax; i++) {
745       jmax   = nrow[i];
746       irow_i = irow[i];
747 
748       PetscCall(PetscMalloc1(jmax, &row2proc_i));
749       row2proc[i] = row2proc_i;
750 
751       if (issorted[i]) proc = 0;
752       for (j = 0; j < jmax; j++) {
753         if (!issorted[i]) proc = 0;
754         if (allrows[i]) row = j;
755         else row = irow_i[j];
756 
757         while (row >= c->rangebs[proc + 1]) proc++;
758         w4[proc]++;
759         row2proc_i[j] = proc; /* map row index to proc */
760       }
761       for (j = 0; j < size; j++) {
762         if (w4[j]) {
763           w1[j] += w4[j];
764           w3[j]++;
765           w4[j] = 0;
766         }
767       }
768     }
769 
770     nrqs     = 0; /* no of outgoing messages */
771     msz      = 0; /* total mesg length (for all procs) */
772     w1[rank] = 0; /* no mesg sent to self */
773     w3[rank] = 0;
774     for (i = 0; i < size; i++) {
775       if (w1[i]) {
776         w2[i] = 1;
777         nrqs++;
778       } /* there exists a message to proc i */
779     }
780     PetscCall(PetscMalloc1(nrqs, &pa)); /*(proc -array)*/
781     for (i = 0, j = 0; i < size; i++) {
782       if (w1[i]) {
783         pa[j] = i;
784         j++;
785       }
786     }
787 
788     /* Each message would have a header = 1 + 2*(no of IS) + data */
789     for (i = 0; i < nrqs; i++) {
790       j = pa[i];
791       w1[j] += w2[j] + 2 * w3[j];
792       msz += w1[j];
793     }
794     PetscCall(PetscInfo(0, "Number of outgoing messages %" PetscInt_FMT " Total message length %" PetscInt_FMT "\n", nrqs, msz));
795 
796     /* Determine the number of messages to expect, their lengths, from from-ids */
797     PetscCall(PetscGatherNumberOfMessages(comm, w2, w1, &nrqr));
798     PetscCall(PetscGatherMessageLengths(comm, nrqs, nrqr, w1, &onodes1, &olengths1));
799 
800     /* Now post the Irecvs corresponding to these messages */
801     PetscCall(PetscObjectGetNewTag((PetscObject)C, &tag0));
802     PetscCall(PetscPostIrecvInt(comm, tag0, nrqr, onodes1, olengths1, &rbuf1, &r_waits1));
803 
804     /* Allocate Memory for outgoing messages */
805     PetscCall(PetscMalloc4(size, &sbuf1, size, &ptr, 2 * msz, &tmp, size, &ctr));
806     PetscCall(PetscArrayzero(sbuf1, size));
807     PetscCall(PetscArrayzero(ptr, size));
808 
809     {
810       PetscInt *iptr = tmp;
811       k              = 0;
812       for (i = 0; i < nrqs; i++) {
813         j = pa[i];
814         iptr += k;
815         sbuf1[j] = iptr;
816         k        = w1[j];
817       }
818     }
819 
820     /* Form the outgoing messages. Initialize the header space */
821     for (i = 0; i < nrqs; i++) {
822       j           = pa[i];
823       sbuf1[j][0] = 0;
824       PetscCall(PetscArrayzero(sbuf1[j] + 1, 2 * w3[j]));
825       ptr[j] = sbuf1[j] + 2 * w3[j] + 1;
826     }
827 
828     /* Parse the isrow and copy data into outbuf */
829     for (i = 0; i < ismax; i++) {
830       row2proc_i = row2proc[i];
831       PetscCall(PetscArrayzero(ctr, size));
832       irow_i = irow[i];
833       jmax   = nrow[i];
834       for (j = 0; j < jmax; j++) { /* parse the indices of each IS */
835         proc = row2proc_i[j];
836         if (allrows[i]) row = j;
837         else row = irow_i[j];
838 
839         if (proc != rank) { /* copy to the outgoing buf*/
840           ctr[proc]++;
841           *ptr[proc] = row;
842           ptr[proc]++;
843         }
844       }
845       /* Update the headers for the current IS */
846       for (j = 0; j < size; j++) { /* Can Optimise this loop too */
847         if ((ctr_j = ctr[j])) {
848           sbuf1_j            = sbuf1[j];
849           k                  = ++sbuf1_j[0];
850           sbuf1_j[2 * k]     = ctr_j;
851           sbuf1_j[2 * k - 1] = i;
852         }
853       }
854     }
855 
856     /*  Now  post the sends */
857     PetscCall(PetscMalloc1(nrqs, &s_waits1));
858     for (i = 0; i < nrqs; ++i) {
859       j = pa[i];
860       PetscCallMPI(MPI_Isend(sbuf1[j], w1[j], MPIU_INT, j, tag0, comm, s_waits1 + i));
861     }
862 
863     /* Post Receives to capture the buffer size */
864     PetscCall(PetscMalloc1(nrqs, &r_waits2));
865     PetscCall(PetscMalloc3(nrqs, &req_source2, nrqs, &rbuf2, nrqs, &rbuf3));
866     if (nrqs) rbuf2[0] = tmp + msz;
867     for (i = 1; i < nrqs; ++i) rbuf2[i] = rbuf2[i - 1] + w1[pa[i - 1]];
868     for (i = 0; i < nrqs; ++i) {
869       j = pa[i];
870       PetscCallMPI(MPI_Irecv(rbuf2[i], w1[j], MPIU_INT, j, tag2, comm, r_waits2 + i));
871     }
872 
873     /* Send to other procs the buf size they should allocate */
874     /* Receive messages*/
875     PetscCall(PetscMalloc1(nrqr, &s_waits2));
876     PetscCall(PetscMalloc3(nrqr, &sbuf2, nrqr, &req_size, nrqr, &req_source1));
877 
878     PetscCallMPI(MPI_Waitall(nrqr, r_waits1, MPI_STATUSES_IGNORE));
879     for (i = 0; i < nrqr; ++i) {
880       req_size[i] = 0;
881       rbuf1_i     = rbuf1[i];
882       start       = 2 * rbuf1_i[0] + 1;
883       end         = olengths1[i];
884       PetscCall(PetscMalloc1(end, &sbuf2[i]));
885       sbuf2_i = sbuf2[i];
886       for (j = start; j < end; j++) {
887         row        = rbuf1_i[j] - rstart;
888         ncols      = a_i[row + 1] - a_i[row] + b_i[row + 1] - b_i[row];
889         sbuf2_i[j] = ncols;
890         req_size[i] += ncols;
891       }
892       req_source1[i] = onodes1[i];
893       /* form the header */
894       sbuf2_i[0] = req_size[i];
895       for (j = 1; j < start; j++) sbuf2_i[j] = rbuf1_i[j];
896 
897       PetscCallMPI(MPI_Isend(sbuf2_i, end, MPIU_INT, req_source1[i], tag2, comm, s_waits2 + i));
898     }
899 
900     PetscCall(PetscFree(onodes1));
901     PetscCall(PetscFree(olengths1));
902 
903     PetscCall(PetscFree(r_waits1));
904     PetscCall(PetscFree4(w1, w2, w3, w4));
905 
906     /* Receive messages*/
907     PetscCall(PetscMalloc1(nrqs, &r_waits3));
908 
909     PetscCallMPI(MPI_Waitall(nrqs, r_waits2, MPI_STATUSES_IGNORE));
910     for (i = 0; i < nrqs; ++i) {
911       PetscCall(PetscMalloc1(rbuf2[i][0], &rbuf3[i]));
912       req_source2[i] = pa[i];
913       PetscCallMPI(MPI_Irecv(rbuf3[i], rbuf2[i][0], MPIU_INT, req_source2[i], tag3, comm, r_waits3 + i));
914     }
915     PetscCall(PetscFree(r_waits2));
916 
917     /* Wait on sends1 and sends2 */
918     PetscCallMPI(MPI_Waitall(nrqs, s_waits1, MPI_STATUSES_IGNORE));
919     PetscCallMPI(MPI_Waitall(nrqr, s_waits2, MPI_STATUSES_IGNORE));
920     PetscCall(PetscFree(s_waits1));
921     PetscCall(PetscFree(s_waits2));
922 
923     /* Now allocate sending buffers for a->j, and send them off */
924     PetscCall(PetscMalloc1(nrqr, &sbuf_aj));
925     for (i = 0, j = 0; i < nrqr; i++) j += req_size[i];
926     if (nrqr) PetscCall(PetscMalloc1(j, &sbuf_aj[0]));
927     for (i = 1; i < nrqr; i++) sbuf_aj[i] = sbuf_aj[i - 1] + req_size[i - 1];
928 
929     PetscCall(PetscMalloc1(nrqr, &s_waits3));
930     {
931       for (i = 0; i < nrqr; i++) {
932         rbuf1_i   = rbuf1[i];
933         sbuf_aj_i = sbuf_aj[i];
934         ct1       = 2 * rbuf1_i[0] + 1;
935         ct2       = 0;
936         for (j = 1, max1 = rbuf1_i[0]; j <= max1; j++) {
937           kmax = rbuf1[i][2 * j];
938           for (k = 0; k < kmax; k++, ct1++) {
939             row    = rbuf1_i[ct1] - rstart;
940             nzA    = a_i[row + 1] - a_i[row];
941             nzB    = b_i[row + 1] - b_i[row];
942             ncols  = nzA + nzB;
943             cworkA = a_j + a_i[row];
944             cworkB = b_j + b_i[row];
945 
946             /* load the column indices for this row into cols */
947             cols = sbuf_aj_i + ct2;
948             for (l = 0; l < nzB; l++) {
949               if ((ctmp = bmap[cworkB[l]]) < cstart) cols[l] = ctmp;
950               else break;
951             }
952             imark = l;
953             for (l = 0; l < nzA; l++) cols[imark + l] = cstart + cworkA[l];
954             for (l = imark; l < nzB; l++) cols[nzA + l] = bmap[cworkB[l]];
955             ct2 += ncols;
956           }
957         }
958         PetscCallMPI(MPI_Isend(sbuf_aj_i, req_size[i], MPIU_INT, req_source1[i], tag3, comm, s_waits3 + i));
959       }
960     }
961 
962     /* create col map: global col of C -> local col of submatrices */
963 #if defined(PETSC_USE_CTABLE)
964     for (i = 0; i < ismax; i++) {
965       if (!allcolumns[i]) {
966         PetscCall(PetscHMapICreateWithSize(ncol[i], cmap + i));
967 
968         jmax   = ncol[i];
969         icol_i = icol[i];
970         cmap_i = cmap[i];
971         for (j = 0; j < jmax; j++) PetscCall(PetscHMapISet(cmap[i], icol_i[j] + 1, j + 1));
972       } else cmap[i] = NULL;
973     }
974 #else
975     for (i = 0; i < ismax; i++) {
976       if (!allcolumns[i]) {
977         PetscCall(PetscCalloc1(c->Nbs, &cmap[i]));
978         jmax   = ncol[i];
979         icol_i = icol[i];
980         cmap_i = cmap[i];
981         for (j = 0; j < jmax; j++) cmap_i[icol_i[j]] = j + 1;
982       } else cmap[i] = NULL;
983     }
984 #endif
985 
986     /* Create lens which is required for MatCreate... */
987     for (i = 0, j = 0; i < ismax; i++) j += nrow[i];
988     PetscCall(PetscMalloc1(ismax, &lens));
989 
990     if (ismax) PetscCall(PetscCalloc1(j, &lens[0]));
991     for (i = 1; i < ismax; i++) lens[i] = lens[i - 1] + nrow[i - 1];
992 
993     /* Update lens from local data */
994     for (i = 0; i < ismax; i++) {
995       row2proc_i = row2proc[i];
996       jmax       = nrow[i];
997       if (!allcolumns[i]) cmap_i = cmap[i];
998       irow_i = irow[i];
999       lens_i = lens[i];
1000       for (j = 0; j < jmax; j++) {
1001         if (allrows[i]) row = j;
1002         else row = irow_i[j]; /* global blocked row of C */
1003 
1004         proc = row2proc_i[j];
1005         if (proc == rank) {
1006           /* Get indices from matA and then from matB */
1007 #if defined(PETSC_USE_CTABLE)
1008           PetscInt tt;
1009 #endif
1010           row    = row - rstart;
1011           nzA    = a_i[row + 1] - a_i[row];
1012           nzB    = b_i[row + 1] - b_i[row];
1013           cworkA = a_j + a_i[row];
1014           cworkB = b_j + b_i[row];
1015 
1016           if (!allcolumns[i]) {
1017 #if defined(PETSC_USE_CTABLE)
1018             for (k = 0; k < nzA; k++) {
1019               PetscCall(PetscHMapIGetWithDefault(cmap_i, cstart + cworkA[k] + 1, 0, &tt));
1020               if (tt) lens_i[j]++;
1021             }
1022             for (k = 0; k < nzB; k++) {
1023               PetscCall(PetscHMapIGetWithDefault(cmap_i, bmap[cworkB[k]] + 1, 0, &tt));
1024               if (tt) lens_i[j]++;
1025             }
1026 
1027 #else
1028             for (k = 0; k < nzA; k++) {
1029               if (cmap_i[cstart + cworkA[k]]) lens_i[j]++;
1030             }
1031             for (k = 0; k < nzB; k++) {
1032               if (cmap_i[bmap[cworkB[k]]]) lens_i[j]++;
1033             }
1034 #endif
1035           } else { /* allcolumns */
1036             lens_i[j] = nzA + nzB;
1037           }
1038         }
1039       }
1040     }
1041 
1042     /* Create row map: global row of C -> local row of submatrices */
1043     for (i = 0; i < ismax; i++) {
1044       if (!allrows[i]) {
1045 #if defined(PETSC_USE_CTABLE)
1046         PetscCall(PetscHMapICreateWithSize(nrow[i], rmap + i));
1047         irow_i = irow[i];
1048         jmax   = nrow[i];
1049         for (j = 0; j < jmax; j++) {
1050           if (allrows[i]) {
1051             PetscCall(PetscHMapISet(rmap[i], j + 1, j + 1));
1052           } else {
1053             PetscCall(PetscHMapISet(rmap[i], irow_i[j] + 1, j + 1));
1054           }
1055         }
1056 #else
1057         PetscCall(PetscCalloc1(c->Mbs, &rmap[i]));
1058         rmap_i = rmap[i];
1059         irow_i = irow[i];
1060         jmax   = nrow[i];
1061         for (j = 0; j < jmax; j++) {
1062           if (allrows[i]) rmap_i[j] = j;
1063           else rmap_i[irow_i[j]] = j;
1064         }
1065 #endif
1066       } else rmap[i] = NULL;
1067     }
1068 
1069     /* Update lens from offproc data */
1070     {
1071       PetscInt *rbuf2_i, *rbuf3_i, *sbuf1_i;
1072 
1073       PetscCallMPI(MPI_Waitall(nrqs, r_waits3, MPI_STATUSES_IGNORE));
1074       for (tmp2 = 0; tmp2 < nrqs; tmp2++) {
1075         sbuf1_i = sbuf1[pa[tmp2]];
1076         jmax    = sbuf1_i[0];
1077         ct1     = 2 * jmax + 1;
1078         ct2     = 0;
1079         rbuf2_i = rbuf2[tmp2];
1080         rbuf3_i = rbuf3[tmp2];
1081         for (j = 1; j <= jmax; j++) {
1082           is_no  = sbuf1_i[2 * j - 1];
1083           max1   = sbuf1_i[2 * j];
1084           lens_i = lens[is_no];
1085           if (!allcolumns[is_no]) cmap_i = cmap[is_no];
1086           rmap_i = rmap[is_no];
1087           for (k = 0; k < max1; k++, ct1++) {
1088             if (allrows[is_no]) {
1089               row = sbuf1_i[ct1];
1090             } else {
1091 #if defined(PETSC_USE_CTABLE)
1092               PetscCall(PetscHMapIGetWithDefault(rmap_i, sbuf1_i[ct1] + 1, 0, &row));
1093               row--;
1094               PetscCheck(row >= 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "row not found in table");
1095 #else
1096               row = rmap_i[sbuf1_i[ct1]]; /* the val in the new matrix to be */
1097 #endif
1098             }
1099             max2 = rbuf2_i[ct1];
1100             for (l = 0; l < max2; l++, ct2++) {
1101               if (!allcolumns[is_no]) {
1102 #if defined(PETSC_USE_CTABLE)
1103                 PetscCall(PetscHMapIGetWithDefault(cmap_i, rbuf3_i[ct2] + 1, 0, &tcol));
1104 #else
1105                 tcol = cmap_i[rbuf3_i[ct2]];
1106 #endif
1107                 if (tcol) lens_i[row]++;
1108               } else {         /* allcolumns */
1109                 lens_i[row]++; /* lens_i[row] += max2 ? */
1110               }
1111             }
1112           }
1113         }
1114       }
1115     }
1116     PetscCall(PetscFree(r_waits3));
1117     PetscCallMPI(MPI_Waitall(nrqr, s_waits3, MPI_STATUSES_IGNORE));
1118     PetscCall(PetscFree(s_waits3));
1119 
1120     /* Create the submatrices */
1121     for (i = 0; i < ismax; i++) {
1122       PetscInt bs_tmp;
1123       if (ijonly) bs_tmp = 1;
1124       else bs_tmp = bs;
1125 
1126       PetscCall(MatCreate(PETSC_COMM_SELF, submats + i));
1127       PetscCall(MatSetSizes(submats[i], nrow[i] * bs_tmp, ncol[i] * bs_tmp, PETSC_DETERMINE, PETSC_DETERMINE));
1128 
1129       PetscCall(MatSetType(submats[i], ((PetscObject)A)->type_name));
1130       PetscCall(MatSeqBAIJSetPreallocation(submats[i], bs_tmp, 0, lens[i]));
1131       PetscCall(MatSeqSBAIJSetPreallocation(submats[i], bs_tmp, 0, lens[i])); /* this subroutine is used by SBAIJ routines */
1132 
1133       /* create struct Mat_SubSppt and attached it to submat */
1134       PetscCall(PetscNew(&smat_i));
1135       subc            = (Mat_SeqBAIJ *)submats[i]->data;
1136       subc->submatis1 = smat_i;
1137 
1138       smat_i->destroy          = submats[i]->ops->destroy;
1139       submats[i]->ops->destroy = MatDestroySubMatrix_SeqBAIJ;
1140       submats[i]->factortype   = C->factortype;
1141 
1142       smat_i->id          = i;
1143       smat_i->nrqs        = nrqs;
1144       smat_i->nrqr        = nrqr;
1145       smat_i->rbuf1       = rbuf1;
1146       smat_i->rbuf2       = rbuf2;
1147       smat_i->rbuf3       = rbuf3;
1148       smat_i->sbuf2       = sbuf2;
1149       smat_i->req_source2 = req_source2;
1150 
1151       smat_i->sbuf1 = sbuf1;
1152       smat_i->ptr   = ptr;
1153       smat_i->tmp   = tmp;
1154       smat_i->ctr   = ctr;
1155 
1156       smat_i->pa          = pa;
1157       smat_i->req_size    = req_size;
1158       smat_i->req_source1 = req_source1;
1159 
1160       smat_i->allcolumns = allcolumns[i];
1161       smat_i->allrows    = allrows[i];
1162       smat_i->singleis   = PETSC_FALSE;
1163       smat_i->row2proc   = row2proc[i];
1164       smat_i->rmap       = rmap[i];
1165       smat_i->cmap       = cmap[i];
1166     }
1167 
1168     if (!ismax) { /* Create dummy submats[0] for reuse struct subc */
1169       PetscCall(MatCreate(PETSC_COMM_SELF, &submats[0]));
1170       PetscCall(MatSetSizes(submats[0], 0, 0, PETSC_DETERMINE, PETSC_DETERMINE));
1171       PetscCall(MatSetType(submats[0], MATDUMMY));
1172 
1173       /* create struct Mat_SubSppt and attached it to submat */
1174       PetscCall(PetscNew(&smat_i));
1175       submats[0]->data = (void *)smat_i;
1176 
1177       smat_i->destroy          = submats[0]->ops->destroy;
1178       submats[0]->ops->destroy = MatDestroySubMatrix_Dummy;
1179       submats[0]->factortype   = C->factortype;
1180 
1181       smat_i->id          = 0;
1182       smat_i->nrqs        = nrqs;
1183       smat_i->nrqr        = nrqr;
1184       smat_i->rbuf1       = rbuf1;
1185       smat_i->rbuf2       = rbuf2;
1186       smat_i->rbuf3       = rbuf3;
1187       smat_i->sbuf2       = sbuf2;
1188       smat_i->req_source2 = req_source2;
1189 
1190       smat_i->sbuf1 = sbuf1;
1191       smat_i->ptr   = ptr;
1192       smat_i->tmp   = tmp;
1193       smat_i->ctr   = ctr;
1194 
1195       smat_i->pa          = pa;
1196       smat_i->req_size    = req_size;
1197       smat_i->req_source1 = req_source1;
1198 
1199       smat_i->allcolumns = PETSC_FALSE;
1200       smat_i->singleis   = PETSC_FALSE;
1201       smat_i->row2proc   = NULL;
1202       smat_i->rmap       = NULL;
1203       smat_i->cmap       = NULL;
1204     }
1205 
1206     if (ismax) PetscCall(PetscFree(lens[0]));
1207     PetscCall(PetscFree(lens));
1208     if (sbuf_aj) {
1209       PetscCall(PetscFree(sbuf_aj[0]));
1210       PetscCall(PetscFree(sbuf_aj));
1211     }
1212 
1213   } /* endof scall == MAT_INITIAL_MATRIX */
1214 
1215   /* Post recv matrix values */
1216   if (!ijonly) {
1217     PetscCall(PetscObjectGetNewTag((PetscObject)C, &tag4));
1218     PetscCall(PetscMalloc1(nrqs, &rbuf4));
1219     PetscCall(PetscMalloc1(nrqs, &r_waits4));
1220     for (i = 0; i < nrqs; ++i) {
1221       PetscCall(PetscMalloc1(rbuf2[i][0] * bs2, &rbuf4[i]));
1222       PetscCallMPI(MPI_Irecv(rbuf4[i], rbuf2[i][0] * bs2, MPIU_SCALAR, req_source2[i], tag4, comm, r_waits4 + i));
1223     }
1224 
1225     /* Allocate sending buffers for a->a, and send them off */
1226     PetscCall(PetscMalloc1(nrqr, &sbuf_aa));
1227     for (i = 0, j = 0; i < nrqr; i++) j += req_size[i];
1228 
1229     if (nrqr) PetscCall(PetscMalloc1(j * bs2, &sbuf_aa[0]));
1230     for (i = 1; i < nrqr; i++) sbuf_aa[i] = sbuf_aa[i - 1] + req_size[i - 1] * bs2;
1231 
1232     PetscCall(PetscMalloc1(nrqr, &s_waits4));
1233 
1234     for (i = 0; i < nrqr; i++) {
1235       rbuf1_i   = rbuf1[i];
1236       sbuf_aa_i = sbuf_aa[i];
1237       ct1       = 2 * rbuf1_i[0] + 1;
1238       ct2       = 0;
1239       for (j = 1, max1 = rbuf1_i[0]; j <= max1; j++) {
1240         kmax = rbuf1_i[2 * j];
1241         for (k = 0; k < kmax; k++, ct1++) {
1242           row    = rbuf1_i[ct1] - rstart;
1243           nzA    = a_i[row + 1] - a_i[row];
1244           nzB    = b_i[row + 1] - b_i[row];
1245           ncols  = nzA + nzB;
1246           cworkB = b_j + b_i[row];
1247           vworkA = a_a + a_i[row] * bs2;
1248           vworkB = b_a + b_i[row] * bs2;
1249 
1250           /* load the column values for this row into vals*/
1251           vals = sbuf_aa_i + ct2 * bs2;
1252           for (l = 0; l < nzB; l++) {
1253             if ((bmap[cworkB[l]]) < cstart) {
1254               PetscCall(PetscArraycpy(vals + l * bs2, vworkB + l * bs2, bs2));
1255             } else break;
1256           }
1257           imark = l;
1258           for (l = 0; l < nzA; l++) PetscCall(PetscArraycpy(vals + (imark + l) * bs2, vworkA + l * bs2, bs2));
1259           for (l = imark; l < nzB; l++) PetscCall(PetscArraycpy(vals + (nzA + l) * bs2, vworkB + l * bs2, bs2));
1260 
1261           ct2 += ncols;
1262         }
1263       }
1264       PetscCallMPI(MPI_Isend(sbuf_aa_i, req_size[i] * bs2, MPIU_SCALAR, req_source1[i], tag4, comm, s_waits4 + i));
1265     }
1266   }
1267 
1268   /* Assemble the matrices */
1269   /* First assemble the local rows */
1270   for (i = 0; i < ismax; i++) {
1271     row2proc_i = row2proc[i];
1272     subc       = (Mat_SeqBAIJ *)submats[i]->data;
1273     imat_ilen  = subc->ilen;
1274     imat_j     = subc->j;
1275     imat_i     = subc->i;
1276     imat_a     = subc->a;
1277 
1278     if (!allcolumns[i]) cmap_i = cmap[i];
1279     rmap_i = rmap[i];
1280     irow_i = irow[i];
1281     jmax   = nrow[i];
1282     for (j = 0; j < jmax; j++) {
1283       if (allrows[i]) row = j;
1284       else row = irow_i[j];
1285       proc = row2proc_i[j];
1286 
1287       if (proc == rank) {
1288         row    = row - rstart;
1289         nzA    = a_i[row + 1] - a_i[row];
1290         nzB    = b_i[row + 1] - b_i[row];
1291         cworkA = a_j + a_i[row];
1292         cworkB = b_j + b_i[row];
1293         if (!ijonly) {
1294           vworkA = a_a + a_i[row] * bs2;
1295           vworkB = b_a + b_i[row] * bs2;
1296         }
1297 
1298         if (allrows[i]) {
1299           row = row + rstart;
1300         } else {
1301 #if defined(PETSC_USE_CTABLE)
1302           PetscCall(PetscHMapIGetWithDefault(rmap_i, row + rstart + 1, 0, &row));
1303           row--;
1304 
1305           PetscCheck(row >= 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "row not found in table");
1306 #else
1307           row = rmap_i[row + rstart];
1308 #endif
1309         }
1310         mat_i = imat_i[row];
1311         if (!ijonly) mat_a = imat_a + mat_i * bs2;
1312         mat_j = imat_j + mat_i;
1313         ilen  = imat_ilen[row];
1314 
1315         /* load the column indices for this row into cols*/
1316         if (!allcolumns[i]) {
1317           for (l = 0; l < nzB; l++) {
1318             if ((ctmp = bmap[cworkB[l]]) < cstart) {
1319 #if defined(PETSC_USE_CTABLE)
1320               PetscCall(PetscHMapIGetWithDefault(cmap_i, ctmp + 1, 0, &tcol));
1321               if (tcol) {
1322 #else
1323               if ((tcol = cmap_i[ctmp])) {
1324 #endif
1325                 *mat_j++ = tcol - 1;
1326                 PetscCall(PetscArraycpy(mat_a, vworkB + l * bs2, bs2));
1327                 mat_a += bs2;
1328                 ilen++;
1329               }
1330             } else break;
1331           }
1332           imark = l;
1333           for (l = 0; l < nzA; l++) {
1334 #if defined(PETSC_USE_CTABLE)
1335             PetscCall(PetscHMapIGetWithDefault(cmap_i, cstart + cworkA[l] + 1, 0, &tcol));
1336             if (tcol) {
1337 #else
1338             if ((tcol = cmap_i[cstart + cworkA[l]])) {
1339 #endif
1340               *mat_j++ = tcol - 1;
1341               if (!ijonly) {
1342                 PetscCall(PetscArraycpy(mat_a, vworkA + l * bs2, bs2));
1343                 mat_a += bs2;
1344               }
1345               ilen++;
1346             }
1347           }
1348           for (l = imark; l < nzB; l++) {
1349 #if defined(PETSC_USE_CTABLE)
1350             PetscCall(PetscHMapIGetWithDefault(cmap_i, bmap[cworkB[l]] + 1, 0, &tcol));
1351             if (tcol) {
1352 #else
1353             if ((tcol = cmap_i[bmap[cworkB[l]]])) {
1354 #endif
1355               *mat_j++ = tcol - 1;
1356               if (!ijonly) {
1357                 PetscCall(PetscArraycpy(mat_a, vworkB + l * bs2, bs2));
1358                 mat_a += bs2;
1359               }
1360               ilen++;
1361             }
1362           }
1363         } else { /* allcolumns */
1364           for (l = 0; l < nzB; l++) {
1365             if ((ctmp = bmap[cworkB[l]]) < cstart) {
1366               *mat_j++ = ctmp;
1367               PetscCall(PetscArraycpy(mat_a, vworkB + l * bs2, bs2));
1368               mat_a += bs2;
1369               ilen++;
1370             } else break;
1371           }
1372           imark = l;
1373           for (l = 0; l < nzA; l++) {
1374             *mat_j++ = cstart + cworkA[l];
1375             if (!ijonly) {
1376               PetscCall(PetscArraycpy(mat_a, vworkA + l * bs2, bs2));
1377               mat_a += bs2;
1378             }
1379             ilen++;
1380           }
1381           for (l = imark; l < nzB; l++) {
1382             *mat_j++ = bmap[cworkB[l]];
1383             if (!ijonly) {
1384               PetscCall(PetscArraycpy(mat_a, vworkB + l * bs2, bs2));
1385               mat_a += bs2;
1386             }
1387             ilen++;
1388           }
1389         }
1390         imat_ilen[row] = ilen;
1391       }
1392     }
1393   }
1394 
1395   /* Now assemble the off proc rows */
1396   if (!ijonly) PetscCallMPI(MPI_Waitall(nrqs, r_waits4, MPI_STATUSES_IGNORE));
1397   for (tmp2 = 0; tmp2 < nrqs; tmp2++) {
1398     sbuf1_i = sbuf1[pa[tmp2]];
1399     jmax    = sbuf1_i[0];
1400     ct1     = 2 * jmax + 1;
1401     ct2     = 0;
1402     rbuf2_i = rbuf2[tmp2];
1403     rbuf3_i = rbuf3[tmp2];
1404     if (!ijonly) rbuf4_i = rbuf4[tmp2];
1405     for (j = 1; j <= jmax; j++) {
1406       is_no  = sbuf1_i[2 * j - 1];
1407       rmap_i = rmap[is_no];
1408       if (!allcolumns[is_no]) cmap_i = cmap[is_no];
1409       subc      = (Mat_SeqBAIJ *)submats[is_no]->data;
1410       imat_ilen = subc->ilen;
1411       imat_j    = subc->j;
1412       imat_i    = subc->i;
1413       if (!ijonly) imat_a = subc->a;
1414       max1 = sbuf1_i[2 * j];
1415       for (k = 0; k < max1; k++, ct1++) { /* for each recved block row */
1416         row = sbuf1_i[ct1];
1417 
1418         if (allrows[is_no]) {
1419           row = sbuf1_i[ct1];
1420         } else {
1421 #if defined(PETSC_USE_CTABLE)
1422           PetscCall(PetscHMapIGetWithDefault(rmap_i, row + 1, 0, &row));
1423           row--;
1424           PetscCheck(row >= 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "row not found in table");
1425 #else
1426           row = rmap_i[row];
1427 #endif
1428         }
1429         ilen  = imat_ilen[row];
1430         mat_i = imat_i[row];
1431         if (!ijonly) mat_a = imat_a + mat_i * bs2;
1432         mat_j = imat_j + mat_i;
1433         max2  = rbuf2_i[ct1];
1434         if (!allcolumns[is_no]) {
1435           for (l = 0; l < max2; l++, ct2++) {
1436 #if defined(PETSC_USE_CTABLE)
1437             PetscCall(PetscHMapIGetWithDefault(cmap_i, rbuf3_i[ct2] + 1, 0, &tcol));
1438 #else
1439             tcol = cmap_i[rbuf3_i[ct2]];
1440 #endif
1441             if (tcol) {
1442               *mat_j++ = tcol - 1;
1443               if (!ijonly) {
1444                 PetscCall(PetscArraycpy(mat_a, rbuf4_i + ct2 * bs2, bs2));
1445                 mat_a += bs2;
1446               }
1447               ilen++;
1448             }
1449           }
1450         } else { /* allcolumns */
1451           for (l = 0; l < max2; l++, ct2++) {
1452             *mat_j++ = rbuf3_i[ct2]; /* same global column index of C */
1453             if (!ijonly) {
1454               PetscCall(PetscArraycpy(mat_a, rbuf4_i + ct2 * bs2, bs2));
1455               mat_a += bs2;
1456             }
1457             ilen++;
1458           }
1459         }
1460         imat_ilen[row] = ilen;
1461       }
1462     }
1463   }
1464 
1465   if (!iscsorted) { /* sort column indices of the rows */
1466     MatScalar *work;
1467 
1468     PetscCall(PetscMalloc1(bs2, &work));
1469     for (i = 0; i < ismax; i++) {
1470       subc      = (Mat_SeqBAIJ *)submats[i]->data;
1471       imat_ilen = subc->ilen;
1472       imat_j    = subc->j;
1473       imat_i    = subc->i;
1474       if (!ijonly) imat_a = subc->a;
1475       if (allcolumns[i]) continue;
1476 
1477       jmax = nrow[i];
1478       for (j = 0; j < jmax; j++) {
1479         mat_i = imat_i[j];
1480         mat_j = imat_j + mat_i;
1481         ilen  = imat_ilen[j];
1482         if (ijonly) {
1483           PetscCall(PetscSortInt(ilen, mat_j));
1484         } else {
1485           mat_a = imat_a + mat_i * bs2;
1486           PetscCall(PetscSortIntWithDataArray(ilen, mat_j, mat_a, bs2 * sizeof(MatScalar), work));
1487         }
1488       }
1489     }
1490     PetscCall(PetscFree(work));
1491   }
1492 
1493   if (!ijonly) {
1494     PetscCall(PetscFree(r_waits4));
1495     PetscCallMPI(MPI_Waitall(nrqr, s_waits4, MPI_STATUSES_IGNORE));
1496     PetscCall(PetscFree(s_waits4));
1497   }
1498 
1499   /* Restore the indices */
1500   for (i = 0; i < ismax; i++) {
1501     if (!allrows[i]) PetscCall(ISRestoreIndices(isrow[i], irow + i));
1502     if (!allcolumns[i]) PetscCall(ISRestoreIndices(iscol[i], icol + i));
1503   }
1504 
1505   for (i = 0; i < ismax; i++) {
1506     PetscCall(MatAssemblyBegin(submats[i], MAT_FINAL_ASSEMBLY));
1507     PetscCall(MatAssemblyEnd(submats[i], MAT_FINAL_ASSEMBLY));
1508   }
1509 
1510   PetscCall(PetscFree5(*(PetscInt ***)&irow, *(PetscInt ***)&icol, nrow, ncol, issorted));
1511   PetscCall(PetscFree5(row2proc, cmap, rmap, allcolumns, allrows));
1512 
1513   if (!ijonly) {
1514     if (sbuf_aa) {
1515       PetscCall(PetscFree(sbuf_aa[0]));
1516       PetscCall(PetscFree(sbuf_aa));
1517     }
1518 
1519     for (i = 0; i < nrqs; ++i) PetscCall(PetscFree(rbuf4[i]));
1520     PetscCall(PetscFree(rbuf4));
1521   }
1522   c->ijonly = PETSC_FALSE; /* set back to the default */
1523   PetscFunctionReturn(PETSC_SUCCESS);
1524 }
1525