xref: /libCEED/backends/sycl-ref/ceed-sycl-ref-operator.sycl.cpp (revision ac2269bd6b9128b5262c5b76aac90f6c3e7aeebf)
1 // Copyright (c) 2017-2024, Lawrence Livermore National Security, LLC and other
2 // CEED contributors. All Rights Reserved. See the top-level LICENSE and NOTICE
3 // files for details.
4 //
5 // SPDX-License-Identifier: BSD-2-Clause
6 //
7 // This file is part of CEED:  http://github.com/ceed
8 
9 #include <ceed/backend.h>
10 #include <ceed/ceed.h>
11 
12 #include <cassert>
13 #include <string>
14 #include <sycl/sycl.hpp>
15 
16 #include "../sycl/ceed-sycl-compile.hpp"
17 #include "ceed-sycl-ref.hpp"
18 
19 class CeedOperatorSyclLinearDiagonal;
20 class CeedOperatorSyclLinearAssemble;
21 class CeedOperatorSyclLinearAssembleFallback;
22 
23 //------------------------------------------------------------------------------
24 //  Get Basis Emode Pointer
25 //------------------------------------------------------------------------------
26 void CeedOperatorGetBasisPointer_Sycl(const CeedScalar **basis_ptr, CeedEvalMode eval_mode, const CeedScalar *identity, const CeedScalar *interp,
27                                       const CeedScalar *grad) {
28   switch (eval_mode) {
29     case CEED_EVAL_NONE:
30       *basis_ptr = identity;
31       break;
32     case CEED_EVAL_INTERP:
33       *basis_ptr = interp;
34       break;
35     case CEED_EVAL_GRAD:
36       *basis_ptr = grad;
37       break;
38     case CEED_EVAL_WEIGHT:
39     case CEED_EVAL_DIV:
40     case CEED_EVAL_CURL:
41       break;  // Caught by QF Assembly
42   }
43 }
44 
45 //------------------------------------------------------------------------------
46 // Destroy operator
47 //------------------------------------------------------------------------------
48 static int CeedOperatorDestroy_Sycl(CeedOperator op) {
49   Ceed               ceed;
50   Ceed_Sycl         *sycl_data;
51   CeedOperator_Sycl *impl;
52 
53   CeedCallBackend(CeedOperatorGetData(op, &impl));
54   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
55   CeedCallBackend(CeedGetData(ceed, &sycl_data));
56 
57   // Apply data
58   for (CeedInt i = 0; i < impl->num_e_in + impl->num_e_out; i++) {
59     CeedCallBackend(CeedVectorDestroy(&impl->e_vecs[i]));
60   }
61   CeedCallBackend(CeedFree(&impl->e_vecs));
62 
63   for (CeedInt i = 0; i < impl->num_e_in; i++) {
64     CeedCallBackend(CeedVectorDestroy(&impl->q_vecs_in[i]));
65   }
66   CeedCallBackend(CeedFree(&impl->q_vecs_in));
67 
68   for (CeedInt i = 0; i < impl->num_e_out; i++) {
69     CeedCallBackend(CeedVectorDestroy(&impl->q_vecs_out[i]));
70   }
71   CeedCallBackend(CeedFree(&impl->q_vecs_out));
72 
73   // QFunction assembly data
74   for (CeedInt i = 0; i < impl->num_active_in; i++) {
75     CeedCallBackend(CeedVectorDestroy(&impl->qf_active_in[i]));
76   }
77   CeedCallBackend(CeedFree(&impl->qf_active_in));
78 
79   // Diag data
80   if (impl->diag) {
81     CeedCallBackend(CeedFree(&impl->diag->h_eval_mode_in));
82     CeedCallBackend(CeedFree(&impl->diag->h_eval_mode_out));
83 
84     CeedCallSycl(ceed, sycl_data->sycl_queue.wait_and_throw());
85     CeedCallSycl(ceed, sycl::free(impl->diag->d_eval_mode_in, sycl_data->sycl_context));
86     CeedCallSycl(ceed, sycl::free(impl->diag->d_eval_mode_out, sycl_data->sycl_context));
87     CeedCallSycl(ceed, sycl::free(impl->diag->d_identity, sycl_data->sycl_context));
88     CeedCallSycl(ceed, sycl::free(impl->diag->d_interp_in, sycl_data->sycl_context));
89     CeedCallSycl(ceed, sycl::free(impl->diag->d_interp_out, sycl_data->sycl_context));
90     CeedCallSycl(ceed, sycl::free(impl->diag->d_grad_in, sycl_data->sycl_context));
91     CeedCallSycl(ceed, sycl::free(impl->diag->d_grad_out, sycl_data->sycl_context));
92     CeedCallBackend(CeedElemRestrictionDestroy(&impl->diag->point_block_diag_rstr));
93 
94     CeedCallBackend(CeedVectorDestroy(&impl->diag->elem_diag));
95     CeedCallBackend(CeedVectorDestroy(&impl->diag->point_block_elem_diag));
96   }
97   CeedCallBackend(CeedFree(&impl->diag));
98 
99   if (impl->asmb) {
100     CeedCallSycl(ceed, sycl_data->sycl_queue.wait_and_throw());
101     CeedCallSycl(ceed, sycl::free(impl->asmb->d_B_in, sycl_data->sycl_context));
102     CeedCallSycl(ceed, sycl::free(impl->asmb->d_B_out, sycl_data->sycl_context));
103   }
104   CeedCallBackend(CeedFree(&impl->asmb));
105 
106   CeedCallBackend(CeedFree(&impl));
107   return CEED_ERROR_SUCCESS;
108 }
109 
110 //------------------------------------------------------------------------------
111 // Setup infields or outfields
112 //------------------------------------------------------------------------------
113 static int CeedOperatorSetupFields_Sycl(CeedQFunction qf, CeedOperator op, bool is_input, CeedVector *e_vecs, CeedVector *q_vecs, CeedInt start_e,
114                                         CeedInt num_fields, CeedInt Q, CeedInt num_elem) {
115   Ceed                ceed;
116   CeedSize            q_size;
117   bool                is_strided, skip_restriction;
118   CeedInt             dim, size;
119   CeedOperatorField  *op_fields;
120   CeedQFunctionField *qf_fields;
121 
122   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
123   if (is_input) {
124     CeedCallBackend(CeedOperatorGetFields(op, NULL, &op_fields, NULL, NULL));
125     CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_fields, NULL, NULL));
126   } else {
127     CeedCallBackend(CeedOperatorGetFields(op, NULL, NULL, NULL, &op_fields));
128     CeedCallBackend(CeedQFunctionGetFields(qf, NULL, NULL, NULL, &qf_fields));
129   }
130 
131   // Loop over fields
132   for (CeedInt i = 0; i < num_fields; i++) {
133     CeedEvalMode        eval_mode;
134     CeedVector          vec;
135     CeedElemRestriction elem_rstr;
136     CeedBasis           basis;
137 
138     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
139 
140     is_strided       = false;
141     skip_restriction = false;
142     if (eval_mode != CEED_EVAL_WEIGHT) {
143       CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_fields[i], &elem_rstr));
144 
145       // Check whether this field can skip the element restriction:
146       // must be passive input, with  eval_mode NONE, and have a strided restriction with CEED_STRIDES_BACKEND.
147 
148       // First, check whether the field is input or output:
149       if (is_input) {
150         // Check for passive input:
151         CeedCallBackend(CeedOperatorFieldGetVector(op_fields[i], &vec));
152         if (vec != CEED_VECTOR_ACTIVE) {
153           // Check  eval_mode
154           if (eval_mode == CEED_EVAL_NONE) {
155             // Check for  is_strided restriction
156             CeedCallBackend(CeedElemRestrictionIsStrided(elem_rstr, &is_strided));
157             if (is_strided) {
158               // Check if vector is already in preferred backend ordering
159               CeedCallBackend(CeedElemRestrictionHasBackendStrides(elem_rstr, &skip_restriction));
160             }
161           }
162         }
163         CeedCallBackend(CeedVectorDestroy(&vec));
164       }
165       if (skip_restriction) {
166         // We do not need an E-Vector, but will use the input field vector's data directly in the operator application
167         e_vecs[i + start_e] = NULL;
168       } else {
169         CeedCallBackend(CeedElemRestrictionCreateVector(elem_rstr, NULL, &e_vecs[i + start_e]));
170       }
171       CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
172     }
173 
174     switch (eval_mode) {
175       case CEED_EVAL_NONE:
176         CeedCallBackend(CeedQFunctionFieldGetSize(qf_fields[i], &size));
177         q_size = (CeedSize)num_elem * Q * size;
178         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
179         break;
180       case CEED_EVAL_INTERP:
181         CeedCallBackend(CeedQFunctionFieldGetSize(qf_fields[i], &size));
182         q_size = (CeedSize)num_elem * Q * size;
183         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
184         break;
185       case CEED_EVAL_GRAD:
186         CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
187         CeedCallBackend(CeedQFunctionFieldGetSize(qf_fields[i], &size));
188         CeedCallBackend(CeedBasisGetDimension(basis, &dim));
189         CeedCallBackend(CeedBasisDestroy(&basis));
190         q_size = (CeedSize)num_elem * Q * size;
191         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
192         break;
193       case CEED_EVAL_WEIGHT:  // Only on input fields
194         CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
195         q_size = (CeedSize)num_elem * Q;
196         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
197         CeedCallBackend(CeedBasisApply(basis, num_elem, CEED_NOTRANSPOSE, CEED_EVAL_WEIGHT, CEED_VECTOR_NONE, q_vecs[i]));
198         CeedCallBackend(CeedBasisDestroy(&basis));
199         break;
200       case CEED_EVAL_DIV:
201         break;  // TODO: Not implemented
202       case CEED_EVAL_CURL:
203         break;  // TODO: Not implemented
204     }
205   }
206   return CEED_ERROR_SUCCESS;
207 }
208 
209 //------------------------------------------------------------------------------
210 // CeedOperator needs to connect all the named fields (be they active or
211 // passive) to the named inputs and outputs of its CeedQFunction.
212 //------------------------------------------------------------------------------
213 static int CeedOperatorSetup_Sycl(CeedOperator op) {
214   Ceed                ceed;
215   bool                is_setup_done;
216   CeedInt             Q, num_elem, num_input_fields, num_output_fields;
217   CeedQFunctionField *qf_input_fields, *qf_output_fields;
218   CeedQFunction       qf;
219   CeedOperatorField  *op_input_fields, *op_output_fields;
220   CeedOperator_Sycl  *impl;
221 
222   CeedCallBackend(CeedOperatorIsSetupDone(op, &is_setup_done));
223   if (is_setup_done) return CEED_ERROR_SUCCESS;
224 
225   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
226   CeedCallBackend(CeedOperatorGetData(op, &impl));
227   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
228   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
229   CeedCallBackend(CeedOperatorGetNumElements(op, &num_elem));
230   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
231   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
232 
233   // Allocate
234   CeedCallBackend(CeedCalloc(num_input_fields + num_output_fields, &impl->e_vecs));
235 
236   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->q_vecs_in));
237   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->q_vecs_out));
238 
239   impl->num_e_in  = num_input_fields;
240   impl->num_e_out = num_output_fields;
241 
242   // Set up infield and outfield  e_vecs and  q_vecs
243   // Infields
244   CeedCallBackend(CeedOperatorSetupFields_Sycl(qf, op, true, impl->e_vecs, impl->q_vecs_in, 0, num_input_fields, Q, num_elem));
245   // Outfields
246   CeedCallBackend(CeedOperatorSetupFields_Sycl(qf, op, false, impl->e_vecs, impl->q_vecs_out, num_input_fields, num_output_fields, Q, num_elem));
247 
248   CeedCallBackend(CeedOperatorSetSetupDone(op));
249   return CEED_ERROR_SUCCESS;
250 }
251 
252 //------------------------------------------------------------------------------
253 // Setup Operator Inputs
254 //------------------------------------------------------------------------------
255 static inline int CeedOperatorSetupInputs_Sycl(CeedInt num_input_fields, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
256                                                CeedVector in_vec, const bool skip_active, CeedScalar *e_data[2 * CEED_FIELD_MAX],
257                                                CeedOperator_Sycl *impl, CeedRequest *request) {
258   for (CeedInt i = 0; i < num_input_fields; i++) {
259     bool         is_active;
260     CeedEvalMode eval_mode;
261     CeedVector   vec;
262 
263     // Get input vector
264     CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
265     is_active = vec == CEED_VECTOR_ACTIVE;
266     if (is_active) {
267       if (skip_active) continue;
268       else vec = in_vec;
269     }
270 
271     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
272     if (eval_mode == CEED_EVAL_WEIGHT) {  // Skip
273     } else {
274       // Restrict, if necessary
275       if (!impl->e_vecs[i]) {
276         // No restriction for this field; read data directly from vec.
277         CeedCallBackend(CeedVectorGetArrayRead(vec, CEED_MEM_DEVICE, (const CeedScalar **)&e_data[i]));
278       } else {
279         CeedElemRestriction elem_rstr;
280 
281         CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_input_fields[i], &elem_rstr));
282         CeedCallBackend(CeedElemRestrictionApply(elem_rstr, CEED_NOTRANSPOSE, vec, impl->e_vecs[i], request));
283         CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
284         CeedCallBackend(CeedVectorGetArrayRead(impl->e_vecs[i], CEED_MEM_DEVICE, (const CeedScalar **)&e_data[i]));
285       }
286     }
287     if (!is_active) CeedCallBackend(CeedVectorDestroy(&vec));
288   }
289   return CEED_ERROR_SUCCESS;
290 }
291 
292 //------------------------------------------------------------------------------
293 // Input Basis Action
294 //------------------------------------------------------------------------------
295 static inline int CeedOperatorInputBasis_Sycl(CeedInt num_elem, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
296                                               CeedInt num_input_fields, const bool skip_active, CeedScalar *e_data[2 * CEED_FIELD_MAX],
297                                               CeedOperator_Sycl *impl) {
298   for (CeedInt i = 0; i < num_input_fields; i++) {
299     CeedEvalMode eval_mode;
300 
301     // Skip active input
302     if (skip_active) {
303       bool       is_active;
304       CeedVector vec;
305 
306       CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
307       is_active = vec == CEED_VECTOR_ACTIVE;
308       CeedCallBackend(CeedVectorDestroy(&vec));
309       if (is_active) continue;
310     }
311     // Basis action
312     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
313     switch (eval_mode) {
314       case CEED_EVAL_NONE:
315         CeedCallBackend(CeedVectorSetArray(impl->q_vecs_in[i], CEED_MEM_DEVICE, CEED_USE_POINTER, e_data[i]));
316         break;
317       case CEED_EVAL_INTERP:
318       case CEED_EVAL_GRAD: {
319         CeedBasis basis;
320 
321         CeedCallBackend(CeedOperatorFieldGetBasis(op_input_fields[i], &basis));
322         CeedCallBackend(CeedBasisApply(basis, num_elem, CEED_NOTRANSPOSE, eval_mode, impl->e_vecs[i], impl->q_vecs_in[i]));
323         CeedCallBackend(CeedBasisDestroy(&basis));
324         break;
325       }
326       case CEED_EVAL_WEIGHT:
327         break;  // No action
328       case CEED_EVAL_DIV:
329         break;  // TODO: Not implemented
330       case CEED_EVAL_CURL:
331         break;  // TODO: Not implemented
332     }
333   }
334   return CEED_ERROR_SUCCESS;
335 }
336 
337 //------------------------------------------------------------------------------
338 // Restore Input Vectors
339 //------------------------------------------------------------------------------
340 static inline int CeedOperatorRestoreInputs_Sycl(CeedInt num_input_fields, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
341                                                  const bool skip_active, CeedScalar *e_data[2 * CEED_FIELD_MAX], CeedOperator_Sycl *impl) {
342   for (CeedInt i = 0; i < num_input_fields; i++) {
343     bool         is_active;
344     CeedEvalMode eval_mode;
345     CeedVector   vec;
346 
347     CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
348     is_active = vec == CEED_VECTOR_ACTIVE;
349     // Skip active input
350     if (skip_active) {
351       if (is_active) continue;
352     }
353     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
354     if (eval_mode == CEED_EVAL_WEIGHT) {  // Skip
355     } else {
356       if (!impl->e_vecs[i]) {  // This was a  skip_restriction case
357         CeedCallBackend(CeedVectorRestoreArrayRead(vec, (const CeedScalar **)&e_data[i]));
358       } else {
359         CeedCallBackend(CeedVectorRestoreArrayRead(impl->e_vecs[i], (const CeedScalar **)&e_data[i]));
360       }
361     }
362     if (!is_active) CeedCallBackend(CeedVectorDestroy(&vec));
363   }
364   return CEED_ERROR_SUCCESS;
365 }
366 
367 //------------------------------------------------------------------------------
368 // Apply and add to output
369 //------------------------------------------------------------------------------
370 static int CeedOperatorApplyAdd_Sycl(CeedOperator op, CeedVector in_vec, CeedVector out_vec, CeedRequest *request) {
371   CeedInt             Q, num_elem, elem_size, num_input_fields, num_output_fields, size;
372   CeedEvalMode        eval_mode;
373   CeedScalar         *e_data[2 * CEED_FIELD_MAX] = {0};
374   CeedQFunctionField *qf_input_fields, *qf_output_fields;
375   CeedQFunction       qf;
376   CeedOperatorField  *op_input_fields, *op_output_fields;
377   CeedOperator_Sycl  *impl;
378 
379   CeedCallBackend(CeedOperatorGetData(op, &impl));
380   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
381   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
382   CeedCallBackend(CeedOperatorGetNumElements(op, &num_elem));
383   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
384   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
385 
386   // Setup
387   CeedCallBackend(CeedOperatorSetup_Sycl(op));
388 
389   // Input Evecs and Restriction
390   CeedCallBackend(CeedOperatorSetupInputs_Sycl(num_input_fields, qf_input_fields, op_input_fields, in_vec, false, e_data, impl, request));
391 
392   // Input basis apply if needed
393   CeedCallBackend(CeedOperatorInputBasis_Sycl(num_elem, qf_input_fields, op_input_fields, num_input_fields, false, e_data, impl));
394 
395   // Output pointers, as necessary
396   for (CeedInt i = 0; i < num_output_fields; i++) {
397     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_output_fields[i], &eval_mode));
398     if (eval_mode == CEED_EVAL_NONE) {
399       // Set the output Q-Vector to use the E-Vector data directly
400       CeedCallBackend(CeedVectorGetArrayWrite(impl->e_vecs[i + impl->num_e_in], CEED_MEM_DEVICE, &e_data[i + num_input_fields]));
401       CeedCallBackend(CeedVectorSetArray(impl->q_vecs_out[i], CEED_MEM_DEVICE, CEED_USE_POINTER, e_data[i + num_input_fields]));
402     }
403   }
404 
405   // Q function
406   CeedCallBackend(CeedQFunctionApply(qf, num_elem * Q, impl->q_vecs_in, impl->q_vecs_out));
407 
408   // Output basis apply if needed
409   for (CeedInt i = 0; i < num_output_fields; i++) {
410     CeedElemRestriction elem_rstr;
411 
412     // Get elem_size, eval_mode, size
413     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_output_fields[i], &elem_rstr));
414     CeedCallBackend(CeedElemRestrictionGetElementSize(elem_rstr, &elem_size));
415     CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
416     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_output_fields[i], &eval_mode));
417     CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[i], &size));
418     // Basis action
419     switch (eval_mode) {
420       case CEED_EVAL_NONE:
421         break;
422       case CEED_EVAL_INTERP:
423       case CEED_EVAL_GRAD: {
424         CeedBasis basis;
425 
426         CeedCallBackend(CeedOperatorFieldGetBasis(op_output_fields[i], &basis));
427         CeedCallBackend(CeedBasisApply(basis, num_elem, CEED_TRANSPOSE, eval_mode, impl->q_vecs_out[i], impl->e_vecs[i + impl->num_e_in]));
428         CeedCallBackend(CeedBasisDestroy(&basis));
429         break;
430       }
431       // LCOV_EXCL_START
432       case CEED_EVAL_WEIGHT: {
433         Ceed ceed;
434 
435         CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
436         return CeedError(ceed, CEED_ERROR_BACKEND, "CEED_EVAL_WEIGHT cannot be an output evaluation mode");
437         break;  // Should not occur
438       }
439       case CEED_EVAL_DIV:
440       case CEED_EVAL_CURL: {
441         Ceed ceed;
442 
443         CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
444         return CeedError(ceed, CEED_ERROR_BACKEND, "%s not supported", CeedEvalModes[eval_mode]);
445         break;  // Should not occur
446       }
447         // LCOV_EXCL_STOP
448     }
449   }
450 
451   // Output restriction
452   for (CeedInt i = 0; i < num_output_fields; i++) {
453     bool                is_active;
454     CeedEvalMode        eval_mode;
455     CeedVector          vec;
456     CeedElemRestriction elem_rstr;
457 
458     // Restore evec
459     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_output_fields[i], &eval_mode));
460     if (eval_mode == CEED_EVAL_NONE) {
461       CeedCallBackend(CeedVectorRestoreArray(impl->e_vecs[i + impl->num_e_in], &e_data[i + num_input_fields]));
462     }
463     // Restrict
464     CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[i], &vec));
465     is_active = vec == CEED_VECTOR_ACTIVE;
466     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_output_fields[i], &elem_rstr));
467     if (is_active) vec = out_vec;
468     CeedCallBackend(CeedElemRestrictionApply(elem_rstr, CEED_TRANSPOSE, impl->e_vecs[i + impl->num_e_in], vec, request));
469     if (!is_active) CeedCallBackend(CeedVectorDestroy(&vec));
470     CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
471   }
472 
473   // Restore input arrays
474   CeedCallBackend(CeedOperatorRestoreInputs_Sycl(num_input_fields, qf_input_fields, op_input_fields, false, e_data, impl));
475   return CEED_ERROR_SUCCESS;
476 }
477 
478 //------------------------------------------------------------------------------
479 // Core code for assembling linear QFunction
480 //------------------------------------------------------------------------------
481 static inline int CeedOperatorLinearAssembleQFunctionCore_Sycl(CeedOperator op, bool build_objects, CeedVector *assembled,
482                                                                CeedElemRestriction *elem_rstr, CeedRequest *request) {
483   Ceed                ceed, ceed_parent;
484   CeedSize            q_size;
485   CeedInt             num_active_in, num_active_out, Q, num_elem, num_input_fields, num_output_fields, size;
486   CeedScalar         *assembled_array, *e_data[2 * CEED_FIELD_MAX] = {NULL};
487   CeedVector         *active_in;
488   CeedQFunctionField *qf_input_fields, *qf_output_fields;
489   CeedQFunction       qf;
490   CeedOperatorField  *op_input_fields, *op_output_fields;
491   CeedOperator_Sycl  *impl;
492 
493   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
494   CeedCallBackend(CeedOperatorGetFallbackParentCeed(op, &ceed_parent));
495   CeedCallBackend(CeedOperatorGetData(op, &impl));
496   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
497   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
498   CeedCallBackend(CeedOperatorGetNumElements(op, &num_elem));
499   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
500   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
501   active_in     = impl->qf_active_in;
502   num_active_in = impl->num_active_in, num_active_out = impl->num_active_out;
503 
504   // Setup
505   CeedCallBackend(CeedOperatorSetup_Sycl(op));
506 
507   // Input Evecs and Restriction
508   CeedCallBackend(CeedOperatorSetupInputs_Sycl(num_input_fields, qf_input_fields, op_input_fields, NULL, true, e_data, impl, request));
509 
510   // Count number of active input fields
511   if (!num_active_in) {
512     for (CeedInt i = 0; i < num_input_fields; i++) {
513       CeedScalar *q_vec_array;
514       CeedVector  vec;
515 
516       // Check if active input
517       CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
518       if (vec == CEED_VECTOR_ACTIVE) {
519         CeedCallBackend(CeedQFunctionFieldGetSize(qf_input_fields[i], &size));
520         CeedCallBackend(CeedVectorSetValue(impl->q_vecs_in[i], 0.0));
521         CeedCallBackend(CeedVectorGetArray(impl->q_vecs_in[i], CEED_MEM_DEVICE, &q_vec_array));
522         CeedCallBackend(CeedRealloc(num_active_in + size, &active_in));
523         for (CeedInt field = 0; field < size; field++) {
524           q_size = (CeedSize)Q * num_elem;
525           CeedCallBackend(CeedVectorCreate(ceed, q_size, &active_in[num_active_in + field]));
526           CeedCallBackend(
527               CeedVectorSetArray(active_in[num_active_in + field], CEED_MEM_DEVICE, CEED_USE_POINTER, &q_vec_array[field * Q * num_elem]));
528         }
529         num_active_in += size;
530         CeedCallBackend(CeedVectorRestoreArray(impl->q_vecs_in[i], &q_vec_array));
531       }
532       CeedCallBackend(CeedVectorDestroy(&vec));
533     }
534     impl->num_active_in = num_active_in;
535     impl->qf_active_in  = active_in;
536   }
537 
538   // Count number of active output fields
539   if (!num_active_out) {
540     for (CeedInt i = 0; i < num_output_fields; i++) {
541       CeedVector vec;
542 
543       // Check if active output
544       CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[i], &vec));
545       if (vec == CEED_VECTOR_ACTIVE) {
546         CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[i], &size));
547         num_active_out += size;
548       }
549       CeedCallBackend(CeedVectorDestroy(&vec));
550     }
551     impl->num_active_out = num_active_out;
552   }
553 
554   // Check sizes
555   CeedCheck(num_active_in > 0 && num_active_out > 0, ceed, CEED_ERROR_BACKEND, "Cannot assemble QFunction without active inputs and outputs");
556 
557   // Build objects if needed
558   if (build_objects) {
559     CeedSize l_size     = (CeedSize)num_elem * Q * num_active_in * num_active_out;
560     CeedInt  strides[3] = {1, num_elem * Q, Q}; /* *NOPAD* */
561 
562     // Create output restriction
563     CeedCallBackend(CeedElemRestrictionCreateStrided(ceed_parent, num_elem, Q, num_active_in * num_active_out, l_size, strides, elem_rstr));
564     // Create assembled vector
565     CeedCallBackend(CeedVectorCreate(ceed_parent, l_size, assembled));
566   }
567   CeedCallBackend(CeedVectorSetValue(*assembled, 0.0));
568   CeedCallBackend(CeedVectorGetArray(*assembled, CEED_MEM_DEVICE, &assembled_array));
569 
570   // Input basis apply
571   CeedCallBackend(CeedOperatorInputBasis_Sycl(num_elem, qf_input_fields, op_input_fields, num_input_fields, true, e_data, impl));
572 
573   // Assemble QFunction
574   for (CeedInt in = 0; in < num_active_in; in++) {
575     // Set Inputs
576     CeedCallBackend(CeedVectorSetValue(active_in[in], 1.0));
577     if (num_active_in > 1) {
578       CeedCallBackend(CeedVectorSetValue(active_in[(in + num_active_in - 1) % num_active_in], 0.0));
579     }
580     // Set Outputs
581     for (CeedInt out = 0; out < num_output_fields; out++) {
582       CeedVector vec;
583 
584       // Check if active output
585       CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[out], &vec));
586       if (vec == CEED_VECTOR_ACTIVE) {
587         CeedCallBackend(CeedVectorSetArray(impl->q_vecs_out[out], CEED_MEM_DEVICE, CEED_USE_POINTER, assembled_array));
588         CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[out], &size));
589         assembled_array += size * Q * num_elem;  // Advance the pointer by the size of the output
590       }
591       CeedCallBackend(CeedVectorDestroy(&vec));
592     }
593     // Apply QFunction
594     CeedCallBackend(CeedQFunctionApply(qf, Q * num_elem, impl->q_vecs_in, impl->q_vecs_out));
595   }
596 
597   // Un-set output Qvecs to prevent accidental overwrite of Assembled
598   for (CeedInt out = 0; out < num_output_fields; out++) {
599     CeedVector vec;
600 
601     // Check if active output
602     CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[out], &vec));
603     if (vec == CEED_VECTOR_ACTIVE) {
604       CeedCallBackend(CeedVectorTakeArray(impl->q_vecs_out[out], CEED_MEM_DEVICE, NULL));
605     }
606     CeedCallBackend(CeedVectorDestroy(&vec));
607   }
608 
609   // Restore input arrays
610   CeedCallBackend(CeedOperatorRestoreInputs_Sycl(num_input_fields, qf_input_fields, op_input_fields, true, e_data, impl));
611 
612   // Restore output
613   CeedCallBackend(CeedVectorRestoreArray(*assembled, &assembled_array));
614   return CEED_ERROR_SUCCESS;
615 }
616 
617 //------------------------------------------------------------------------------
618 // Assemble Linear QFunction
619 //------------------------------------------------------------------------------
620 static int CeedOperatorLinearAssembleQFunction_Sycl(CeedOperator op, CeedVector *assembled, CeedElemRestriction *elem_rstr, CeedRequest *request) {
621   return CeedOperatorLinearAssembleQFunctionCore_Sycl(op, true, assembled, elem_rstr, request);
622 }
623 
624 //------------------------------------------------------------------------------
625 // Update Assembled Linear QFunction
626 //------------------------------------------------------------------------------
627 static int CeedOperatorLinearAssembleQFunctionUpdate_Sycl(CeedOperator op, CeedVector assembled, CeedElemRestriction elem_rstr,
628                                                           CeedRequest *request) {
629   return CeedOperatorLinearAssembleQFunctionCore_Sycl(op, false, &assembled, &elem_rstr, request);
630 }
631 
632 //------------------------------------------------------------------------------
633 // Assemble diagonal setup
634 //------------------------------------------------------------------------------
635 static inline int CeedOperatorAssembleDiagonalSetup_Sycl(CeedOperator op) {
636   Ceed                ceed;
637   Ceed_Sycl          *sycl_data;
638   CeedInt             num_input_fields, num_output_fields, num_eval_mode_in = 0, num_comp = 0, dim = 1, num_eval_mode_out = 0;
639   CeedEvalMode       *eval_mode_in = NULL, *eval_mode_out = NULL;
640   CeedBasis           basis_in = NULL, basis_out = NULL;
641   CeedQFunctionField *qf_fields;
642   CeedQFunction       qf;
643   CeedOperatorField  *op_fields;
644   CeedOperator_Sycl  *impl;
645 
646   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
647   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
648   CeedCallBackend(CeedQFunctionGetNumArgs(qf, &num_input_fields, &num_output_fields));
649 
650   // Determine active input basis
651   CeedCallBackend(CeedOperatorGetFields(op, NULL, &op_fields, NULL, NULL));
652   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_fields, NULL, NULL));
653   for (CeedInt i = 0; i < num_input_fields; i++) {
654     CeedVector vec;
655 
656     CeedCallBackend(CeedOperatorFieldGetVector(op_fields[i], &vec));
657     if (vec == CEED_VECTOR_ACTIVE) {
658       CeedEvalMode eval_mode;
659       CeedBasis    basis;
660 
661       CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
662       CeedCheck(!basis_in || basis_in == basis, ceed, CEED_ERROR_BACKEND,
663                 "Backend does not implement operator diagonal assembly with multiple active bases");
664       if (!basis_in) CeedCallBackend(CeedBasisReferenceCopy(basis, &basis_in));
665       CeedCallBackend(CeedBasisDestroy(&basis));
666       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
667       switch (eval_mode) {
668         case CEED_EVAL_NONE:
669         case CEED_EVAL_INTERP:
670           CeedCallBackend(CeedRealloc(num_eval_mode_in + 1, &eval_mode_in));
671           eval_mode_in[num_eval_mode_in] = eval_mode;
672           num_eval_mode_in += 1;
673           break;
674         case CEED_EVAL_GRAD:
675           CeedCallBackend(CeedRealloc(num_eval_mode_in + dim, &eval_mode_in));
676           for (CeedInt d = 0; d < dim; d++) eval_mode_in[num_eval_mode_in + d] = eval_mode;
677           num_eval_mode_in += dim;
678           break;
679         case CEED_EVAL_WEIGHT:
680         case CEED_EVAL_DIV:
681         case CEED_EVAL_CURL:
682           break;  // Caught by QF Assembly
683       }
684     }
685     CeedCallBackend(CeedVectorDestroy(&vec));
686   }
687 
688   // Determine active output basis
689   CeedCallBackend(CeedOperatorGetFields(op, NULL, NULL, NULL, &op_fields));
690   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, NULL, NULL, &qf_fields));
691   for (CeedInt i = 0; i < num_output_fields; i++) {
692     CeedVector vec;
693 
694     CeedCallBackend(CeedOperatorFieldGetVector(op_fields[i], &vec));
695     if (vec == CEED_VECTOR_ACTIVE) {
696       CeedEvalMode eval_mode;
697       CeedBasis    basis;
698 
699       CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
700       CeedCheck(!basis_out || basis_out == basis, ceed, CEED_ERROR_BACKEND,
701                 "Backend does not implement operator diagonal assembly with multiple active bases");
702       if (!basis_out) CeedCallBackend(CeedBasisReferenceCopy(basis, &basis_out));
703       CeedCallBackend(CeedBasisDestroy(&basis));
704       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
705       switch (eval_mode) {
706         case CEED_EVAL_NONE:
707         case CEED_EVAL_INTERP:
708           CeedCallBackend(CeedRealloc(num_eval_mode_in + 1, &eval_mode_in));
709           eval_mode_in[num_eval_mode_in] = eval_mode;
710           num_eval_mode_in += 1;
711           break;
712         case CEED_EVAL_GRAD:
713           CeedCallBackend(CeedRealloc(num_eval_mode_in + dim, &eval_mode_in));
714           for (CeedInt d = 0; d < dim; d++) eval_mode_in[num_eval_mode_in + d] = eval_mode;
715           num_eval_mode_in += dim;
716           break;
717         case CEED_EVAL_WEIGHT:
718         case CEED_EVAL_DIV:
719         case CEED_EVAL_CURL:
720           break;  // Caught by QF Assembly
721       }
722     }
723     CeedCallBackend(CeedVectorDestroy(&vec));
724   }
725 
726   // Operator data struct
727   CeedCallBackend(CeedOperatorGetData(op, &impl));
728   CeedCallBackend(CeedGetData(ceed, &sycl_data));
729   CeedCallBackend(CeedCalloc(1, &impl->diag));
730   CeedOperatorDiag_Sycl *diag = impl->diag;
731 
732   diag->basis_in          = basis_in;
733   diag->basis_out         = basis_out;
734   diag->h_eval_mode_in    = eval_mode_in;
735   diag->h_eval_mode_out   = eval_mode_out;
736   diag->num_eval_mode_in  = num_eval_mode_in;
737   diag->num_eval_mode_out = num_eval_mode_out;
738 
739   // Kernel parameters
740   CeedInt num_nodes, num_qpts;
741   CeedCallBackend(CeedBasisGetNumNodes(basis_in, &num_nodes));
742   CeedCallBackend(CeedBasisGetNumQuadraturePoints(basis_in, &num_qpts));
743   diag->num_nodes = num_nodes;
744   diag->num_qpts  = num_qpts;
745   diag->num_comp  = num_comp;
746 
747   // Basis matrices
748   const CeedInt     i_len = num_qpts * num_nodes;
749   const CeedInt     g_len = num_qpts * num_nodes * dim;
750   const CeedScalar *interp_in, *interp_out, *grad_in, *grad_out;
751 
752   // CEED_EVAL_NONE
753   CeedScalar *identity      = NULL;
754   bool        has_eval_none = false;
755   for (CeedInt i = 0; i < num_eval_mode_in; i++) has_eval_none = has_eval_none || (eval_mode_in[i] == CEED_EVAL_NONE);
756   for (CeedInt i = 0; i < num_eval_mode_out; i++) has_eval_none = has_eval_none || (eval_mode_out[i] == CEED_EVAL_NONE);
757 
758   std::vector<sycl::event> e;
759 
760   if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
761 
762   std::vector<sycl::event> copy_events;
763 
764   if (has_eval_none) {
765     CeedCallBackend(CeedCalloc(num_qpts * num_nodes, &identity));
766     for (CeedSize i = 0; i < (num_nodes < num_qpts ? num_nodes : num_qpts); i++) identity[i * num_nodes + i] = 1.0;
767     CeedCallSycl(ceed, diag->d_identity = sycl::malloc_device<CeedScalar>(i_len, sycl_data->sycl_device, sycl_data->sycl_context));
768     sycl::event identity_copy = sycl_data->sycl_queue.copy<CeedScalar>(identity, diag->d_identity, i_len, e);
769     copy_events.push_back(identity_copy);
770   }
771 
772   // CEED_EVAL_INTERP
773   CeedCallBackend(CeedBasisGetInterp(basis_in, &interp_in));
774   CeedCallSycl(ceed, diag->d_interp_in = sycl::malloc_device<CeedScalar>(i_len, sycl_data->sycl_device, sycl_data->sycl_context));
775   sycl::event interp_in_copy = sycl_data->sycl_queue.copy<CeedScalar>(interp_in, diag->d_interp_in, i_len, e);
776   copy_events.push_back(interp_in_copy);
777 
778   CeedCallBackend(CeedBasisGetInterp(basis_out, &interp_out));
779   CeedCallSycl(ceed, diag->d_interp_out = sycl::malloc_device<CeedScalar>(i_len, sycl_data->sycl_device, sycl_data->sycl_context));
780   sycl::event interp_out_copy = sycl_data->sycl_queue.copy<CeedScalar>(interp_out, diag->d_interp_out, i_len, e);
781   copy_events.push_back(interp_out_copy);
782 
783   // CEED_EVAL_GRAD
784   CeedCallBackend(CeedBasisGetGrad(basis_in, &grad_in));
785   CeedCallSycl(ceed, diag->d_grad_in = sycl::malloc_device<CeedScalar>(g_len, sycl_data->sycl_device, sycl_data->sycl_context));
786   sycl::event grad_in_copy = sycl_data->sycl_queue.copy<CeedScalar>(grad_in, diag->d_grad_in, g_len, e);
787   copy_events.push_back(grad_in_copy);
788 
789   CeedCallBackend(CeedBasisGetGrad(basis_out, &grad_out));
790   CeedCallSycl(ceed, diag->d_grad_out = sycl::malloc_device<CeedScalar>(g_len, sycl_data->sycl_device, sycl_data->sycl_context));
791   sycl::event grad_out_copy = sycl_data->sycl_queue.copy<CeedScalar>(grad_out, diag->d_grad_out, g_len, e);
792   copy_events.push_back(grad_out_copy);
793 
794   // Arrays of  eval_modes
795   CeedCallSycl(ceed, diag->d_eval_mode_in = sycl::malloc_device<CeedEvalMode>(num_eval_mode_in, sycl_data->sycl_device, sycl_data->sycl_context));
796   sycl::event eval_mode_in_copy = sycl_data->sycl_queue.copy<CeedEvalMode>(eval_mode_in, diag->d_eval_mode_in, num_eval_mode_in, e);
797   copy_events.push_back(eval_mode_in_copy);
798 
799   CeedCallSycl(ceed, diag->d_eval_mode_out = sycl::malloc_device<CeedEvalMode>(num_eval_mode_out, sycl_data->sycl_device, sycl_data->sycl_context));
800   sycl::event eval_mode_out_copy = sycl_data->sycl_queue.copy<CeedEvalMode>(eval_mode_out, diag->d_eval_mode_out, num_eval_mode_out, e);
801   copy_events.push_back(eval_mode_out_copy);
802 
803   // Restriction
804   {
805     CeedElemRestriction rstr_out;
806 
807     CeedCallBackend(CeedOperatorGetActiveElemRestrictions(op, NULL, &rstr_out));
808     diag->diag_rstr = rstr_out;
809     CeedCallBackend(CeedElemRestrictionDestroy(&rstr_out));
810   }
811 
812   // Wait for all copies to complete and handle exceptions
813   CeedCallSycl(ceed, sycl::event::wait_and_throw(copy_events));
814   return CEED_ERROR_SUCCESS;
815 }
816 
817 //------------------------------------------------------------------------------
818 //  Kernel for diagonal assembly
819 //------------------------------------------------------------------------------
820 static int CeedOperatorLinearDiagonal_Sycl(sycl::queue &sycl_queue, const bool is_point_block, const CeedInt num_elem,
821                                            const CeedOperatorDiag_Sycl *diag, const CeedScalar *assembled_qf_array, CeedScalar *elem_diag_array) {
822   const CeedSize      num_nodes         = diag->num_nodes;
823   const CeedSize      num_qpts          = diag->num_qpts;
824   const CeedSize      num_comp          = diag->num_comp;
825   const CeedSize      num_eval_mode_in  = diag->num_eval_mode_in;
826   const CeedSize      num_eval_mode_out = diag->num_eval_mode_out;
827   const CeedScalar   *identity          = diag->d_identity;
828   const CeedScalar   *interp_in         = diag->d_interp_in;
829   const CeedScalar   *grad_in           = diag->d_grad_in;
830   const CeedScalar   *interp_out        = diag->d_interp_out;
831   const CeedScalar   *grad_out          = diag->d_grad_out;
832   const CeedEvalMode *eval_mode_in      = diag->d_eval_mode_in;
833   const CeedEvalMode *eval_mode_out     = diag->d_eval_mode_out;
834 
835   sycl::range<1> kernel_range(num_elem * num_nodes);
836 
837   std::vector<sycl::event> e;
838 
839   if (!sycl_queue.is_in_order()) e = {sycl_queue.ext_oneapi_submit_barrier()};
840 
841   sycl_queue.parallel_for<CeedOperatorSyclLinearDiagonal>(kernel_range, e, [=](sycl::id<1> idx) {
842     const CeedInt tid = idx % num_nodes;
843     const CeedInt e   = idx / num_nodes;
844 
845     // Compute the diagonal of B^T D B
846     // Each element
847     CeedInt d_out = -1;
848     // Each basis eval mode pair
849     for (CeedSize e_out = 0; e_out < num_eval_mode_out; e_out++) {
850       const CeedScalar *bt = NULL;
851 
852       if (eval_mode_out[e_out] == CEED_EVAL_GRAD) ++d_out;
853       CeedOperatorGetBasisPointer_Sycl(&bt, eval_mode_out[e_out], identity, interp_out, &grad_out[d_out * num_qpts * num_nodes]);
854       CeedInt d_in = -1;
855 
856       for (CeedSize e_in = 0; e_in < num_eval_mode_in; e_in++) {
857         const CeedScalar *b = NULL;
858 
859         if (eval_mode_in[e_in] == CEED_EVAL_GRAD) ++d_in;
860         CeedOperatorGetBasisPointer_Sycl(&b, eval_mode_in[e_in], identity, interp_in, &grad_in[d_in * num_qpts * num_nodes]);
861         // Each component
862         for (CeedSize comp_out = 0; comp_out < num_comp; comp_out++) {
863           // Each qpoint/node pair
864           if (is_point_block) {
865             // Point Block Diagonal
866             for (CeedInt comp_in = 0; comp_in < num_comp; comp_in++) {
867               CeedScalar e_value = 0.0;
868 
869               for (CeedSize q = 0; q < num_qpts; q++) {
870                 const CeedScalar qf_value =
871                     assembled_qf_array[((((e_in * num_comp + comp_in) * num_eval_mode_out + e_out) * num_comp + comp_out) * num_elem + e) * num_qpts +
872                                        q];
873 
874                 e_value += bt[q * num_nodes + tid] * qf_value * b[q * num_nodes + tid];
875               }
876               elem_diag_array[((comp_out * num_comp + comp_in) * num_elem + e) * num_nodes + tid] += e_value;
877             }
878           } else {
879             // Diagonal Only
880             CeedScalar e_value = 0.0;
881 
882             for (CeedSize q = 0; q < num_qpts; q++) {
883               const CeedScalar qf_value =
884                   assembled_qf_array[((((e_in * num_comp + comp_out) * num_eval_mode_out + e_out) * num_comp + comp_out) * num_elem + e) * num_qpts +
885                                      q];
886               e_value += bt[q * num_nodes + tid] * qf_value * b[q * num_nodes + tid];
887             }
888             elem_diag_array[(comp_out * num_elem + e) * num_nodes + tid] += e_value;
889           }
890         }
891       }
892     }
893   });
894   return CEED_ERROR_SUCCESS;
895 }
896 
897 //------------------------------------------------------------------------------
898 // Assemble diagonal common code
899 //------------------------------------------------------------------------------
900 static inline int CeedOperatorAssembleDiagonalCore_Sycl(CeedOperator op, CeedVector assembled, CeedRequest *request, const bool is_point_block) {
901   Ceed               ceed;
902   Ceed_Sycl         *sycl_data;
903   CeedInt            num_elem;
904   CeedScalar        *elem_diag_array;
905   const CeedScalar  *assembled_qf_array;
906   CeedVector         assembled_qf = NULL;
907   CeedOperator_Sycl *impl;
908 
909   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
910   CeedCallBackend(CeedOperatorGetData(op, &impl));
911   CeedCallBackend(CeedGetData(ceed, &sycl_data));
912 
913   // Assemble QFunction
914   {
915     CeedElemRestriction elem_rstr = NULL;
916 
917     CeedCallBackend(CeedOperatorLinearAssembleQFunctionBuildOrUpdate(op, &assembled_qf, &elem_rstr, request));
918     CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
919   }
920 
921   // Setup
922   if (!impl->diag) {
923     CeedCallBackend(CeedOperatorAssembleDiagonalSetup_Sycl(op));
924   }
925   CeedOperatorDiag_Sycl *diag = impl->diag;
926 
927   assert(diag != NULL);
928 
929   // Restriction
930   if (is_point_block && !diag->point_block_diag_rstr) {
931     CeedCallBackend(CeedOperatorCreateActivePointBlockRestriction(diag->diag_rstr, &diag->point_block_diag_rstr));
932   }
933   CeedElemRestriction diag_rstr = is_point_block ? diag->point_block_diag_rstr : diag->diag_rstr;
934 
935   // Create diagonal vector
936   CeedVector elem_diag = is_point_block ? diag->point_block_elem_diag : diag->elem_diag;
937 
938   if (!elem_diag) {
939     CeedCallBackend(CeedElemRestrictionCreateVector(diag_rstr, NULL, &elem_diag));
940     if (is_point_block) diag->point_block_elem_diag = elem_diag;
941     else diag->elem_diag = elem_diag;
942   }
943   CeedCallBackend(CeedVectorSetValue(elem_diag, 0.0));
944 
945   // Assemble element operator diagonals
946   CeedCallBackend(CeedVectorGetArray(elem_diag, CEED_MEM_DEVICE, &elem_diag_array));
947   CeedCallBackend(CeedVectorGetArrayRead(assembled_qf, CEED_MEM_DEVICE, &assembled_qf_array));
948   CeedCallBackend(CeedElemRestrictionGetNumElements(diag_rstr, &num_elem));
949 
950   // Compute the diagonal of B^T D B
951   CeedCallBackend(CeedOperatorLinearDiagonal_Sycl(sycl_data->sycl_queue, is_point_block, num_elem, diag, assembled_qf_array, elem_diag_array));
952 
953   // Wait for queue to complete and handle exceptions
954   sycl_data->sycl_queue.wait_and_throw();
955 
956   // Restore arrays
957   CeedCallBackend(CeedVectorRestoreArray(elem_diag, &elem_diag_array));
958   CeedCallBackend(CeedVectorRestoreArrayRead(assembled_qf, &assembled_qf_array));
959 
960   // Assemble local operator diagonal
961   CeedCallBackend(CeedElemRestrictionApply(diag_rstr, CEED_TRANSPOSE, elem_diag, assembled, request));
962 
963   // Cleanup
964   CeedCallBackend(CeedVectorDestroy(&assembled_qf));
965   return CEED_ERROR_SUCCESS;
966 }
967 
968 //------------------------------------------------------------------------------
969 // Assemble Linear Diagonal
970 //------------------------------------------------------------------------------
971 static int CeedOperatorLinearAssembleAddDiagonal_Sycl(CeedOperator op, CeedVector assembled, CeedRequest *request) {
972   CeedCallBackend(CeedOperatorAssembleDiagonalCore_Sycl(op, assembled, request, false));
973   return CEED_ERROR_SUCCESS;
974 }
975 
976 //------------------------------------------------------------------------------
977 // Assemble Linear Point Block Diagonal
978 //------------------------------------------------------------------------------
979 static int CeedOperatorLinearAssembleAddPointBlockDiagonal_Sycl(CeedOperator op, CeedVector assembled, CeedRequest *request) {
980   CeedCallBackend(CeedOperatorAssembleDiagonalCore_Sycl(op, assembled, request, true));
981   return CEED_ERROR_SUCCESS;
982 }
983 
984 //------------------------------------------------------------------------------
985 // Single operator assembly setup
986 //------------------------------------------------------------------------------
987 static int CeedSingleOperatorAssembleSetup_Sycl(CeedOperator op) {
988   Ceed    ceed;
989   CeedInt num_input_fields, num_output_fields, num_eval_mode_in = 0, dim = 1, num_B_in_mats_to_load = 0, size_B_in = 0, num_eval_mode_out = 0,
990                                                num_B_out_mats_to_load = 0, size_B_out = 0, num_qpts = 0, elem_size = 0, num_elem, num_comp,
991                                                mat_start = 0;
992   CeedEvalMode       *eval_mode_in = NULL, *eval_mode_out = NULL;
993   const CeedScalar   *interp_in, *grad_in;
994   CeedElemRestriction rstr_in = NULL, rstr_out = NULL;
995   CeedBasis           basis_in = NULL, basis_out = NULL;
996   CeedQFunctionField *qf_fields;
997   CeedQFunction       qf;
998   CeedOperatorField  *input_fields, *output_fields;
999   CeedOperator_Sycl  *impl;
1000 
1001   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
1002   CeedCallBackend(CeedOperatorGetData(op, &impl));
1003 
1004   // Get input and output fields
1005   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &input_fields, &num_output_fields, &output_fields));
1006 
1007   // Determine active input basis eval mode
1008   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
1009   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_fields, NULL, NULL));
1010   // Note that the kernel will treat each dimension of a gradient action separately;
1011   // i.e., when an active input has a CEED_EVAL_GRAD mode, num_ eval_mode_in will increment by dim.
1012   // However, for the purposes of loading the B matrices, it will be treated as one mode, and we will load/copy the entire gradient matrix at once,
1013   // so num_B_in_mats_to_load will be incremented by 1.
1014   for (CeedInt i = 0; i < num_input_fields; i++) {
1015     CeedVector vec;
1016 
1017     CeedCallBackend(CeedOperatorFieldGetVector(input_fields[i], &vec));
1018     if (vec == CEED_VECTOR_ACTIVE) {
1019       CeedEvalMode        eval_mode;
1020       CeedElemRestriction elem_rstr;
1021       CeedBasis           basis;
1022 
1023       CeedCallBackend(CeedOperatorFieldGetBasis(input_fields[i], &basis));
1024       CeedCheck(!basis_in || basis_in == basis, ceed, CEED_ERROR_BACKEND, "Backend does not implement operator assembly with multiple active bases");
1025       if (!basis_in) CeedCallBackend(CeedBasisReferenceCopy(basis, &basis_in));
1026       CeedCallBackend(CeedBasisDestroy(&basis));
1027       CeedCallBackend(CeedBasisGetDimension(basis_in, &dim));
1028       CeedCallBackend(CeedBasisGetNumQuadraturePoints(basis_in, &num_qpts));
1029       CeedCallBackend(CeedOperatorFieldGetElemRestriction(input_fields[i], &elem_rstr));
1030       if (!rstr_in) CeedCallBackend(CeedElemRestrictionReferenceCopy(elem_rstr, &rstr_in));
1031       CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
1032       CeedCallBackend(CeedElemRestrictionGetElementSize(rstr_in, &elem_size));
1033       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
1034       if (eval_mode != CEED_EVAL_NONE) {
1035         CeedCallBackend(CeedRealloc(num_B_in_mats_to_load + 1, &eval_mode_in));
1036         eval_mode_in[num_B_in_mats_to_load] = eval_mode;
1037         num_B_in_mats_to_load += 1;
1038         if (eval_mode == CEED_EVAL_GRAD) {
1039           num_eval_mode_in += dim;
1040           size_B_in += dim * elem_size * num_qpts;
1041         } else {
1042           num_eval_mode_in += 1;
1043           size_B_in += elem_size * num_qpts;
1044         }
1045       }
1046     }
1047     CeedCallBackend(CeedVectorDestroy(&vec));
1048   }
1049 
1050   // Determine active output basis; basis_out and rstr_out only used if same as input, TODO
1051   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, NULL, NULL, &qf_fields));
1052   for (CeedInt i = 0; i < num_output_fields; i++) {
1053     CeedVector vec;
1054 
1055     CeedCallBackend(CeedOperatorFieldGetVector(output_fields[i], &vec));
1056     if (vec == CEED_VECTOR_ACTIVE) {
1057       CeedEvalMode        eval_mode;
1058       CeedElemRestriction elem_rstr;
1059       CeedBasis           basis;
1060 
1061       CeedCallBackend(CeedOperatorFieldGetBasis(output_fields[i], &basis));
1062       CeedCheck(!basis_out || basis_out == basis, ceed, CEED_ERROR_BACKEND,
1063                 "Backend does not implement operator assembly with multiple active bases");
1064       if (!basis_out) CeedCallBackend(CeedBasisReferenceCopy(basis, &basis_out));
1065       CeedCallBackend(CeedBasisDestroy(&basis));
1066       CeedCallBackend(CeedOperatorFieldGetElemRestriction(output_fields[i], &elem_rstr));
1067       if (!rstr_out) CeedCallBackend(CeedElemRestrictionReferenceCopy(elem_rstr, &rstr_out));
1068       CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
1069       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
1070       if (eval_mode != CEED_EVAL_NONE) {
1071         CeedCallBackend(CeedRealloc(num_B_out_mats_to_load + 1, &eval_mode_out));
1072         eval_mode_out[num_B_out_mats_to_load] = eval_mode;
1073         num_B_out_mats_to_load += 1;
1074         if (eval_mode == CEED_EVAL_GRAD) {
1075           num_eval_mode_out += dim;
1076           size_B_out += dim * elem_size * num_qpts;
1077         } else {
1078           num_eval_mode_out += 1;
1079           size_B_out += elem_size * num_qpts;
1080         }
1081       }
1082     }
1083     CeedCallBackend(CeedVectorDestroy(&vec));
1084   }
1085   CeedCheck(num_eval_mode_in > 0 && num_eval_mode_out > 0, ceed, CEED_ERROR_UNSUPPORTED, "Cannot assemble operator without inputs/outputs");
1086 
1087   CeedCallBackend(CeedElemRestrictionGetNumElements(rstr_in, &num_elem));
1088   CeedCallBackend(CeedElemRestrictionGetNumComponents(rstr_in, &num_comp));
1089 
1090   CeedCallBackend(CeedCalloc(1, &impl->asmb));
1091   CeedOperatorAssemble_Sycl *asmb = impl->asmb;
1092   asmb->num_elem                  = num_elem;
1093 
1094   Ceed_Sycl *sycl_data;
1095   CeedCallBackend(CeedGetData(ceed, &sycl_data));
1096 
1097   // Kernel setup
1098   int elems_per_block     = 1;
1099   asmb->elems_per_block   = elems_per_block;
1100   asmb->block_size_x      = elem_size;
1101   asmb->block_size_y      = elem_size;
1102   asmb->num_eval_mode_in  = num_eval_mode_in;
1103   asmb->num_eval_mode_out = num_eval_mode_out;
1104   asmb->num_qpts          = num_qpts;
1105   asmb->num_nodes         = elem_size;
1106   asmb->block_size        = elem_size * elem_size * elems_per_block;
1107   asmb->num_comp          = num_comp;
1108 
1109   // Build 'full' B matrices (not 1D arrays used for tensor-product matrices
1110   CeedCallBackend(CeedBasisGetInterp(basis_in, &interp_in));
1111   CeedCallBackend(CeedBasisGetGrad(basis_in, &grad_in));
1112 
1113   // Load into B_in, in order that they will be used in eval_mode
1114   CeedCallSycl(ceed, asmb->d_B_in = sycl::malloc_device<CeedScalar>(size_B_in, sycl_data->sycl_device, sycl_data->sycl_context));
1115   for (int i = 0; i < num_B_in_mats_to_load; i++) {
1116     CeedEvalMode eval_mode = eval_mode_in[i];
1117 
1118     if (eval_mode == CEED_EVAL_INTERP) {
1119       std::vector<sycl::event> e;
1120 
1121       if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
1122       sycl_data->sycl_queue.copy<CeedScalar>(interp_in, &asmb->d_B_in[mat_start], elem_size * num_qpts, e);
1123       mat_start += elem_size * num_qpts;
1124     } else if (eval_mode == CEED_EVAL_GRAD) {
1125       std::vector<sycl::event> e;
1126 
1127       if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
1128       sycl_data->sycl_queue.copy<CeedScalar>(grad_in, &asmb->d_B_in[mat_start], dim * elem_size * num_qpts, e);
1129       mat_start += dim * elem_size * num_qpts;
1130     }
1131   }
1132 
1133   const CeedScalar *interp_out, *grad_out;
1134   // Note that this function currently assumes 1 basis, so this should always be true
1135   // for now
1136   if (basis_out == basis_in) {
1137     interp_out = interp_in;
1138     grad_out   = grad_in;
1139   } else {
1140     CeedCallBackend(CeedBasisGetInterp(basis_out, &interp_out));
1141     CeedCallBackend(CeedBasisGetGrad(basis_out, &grad_out));
1142   }
1143 
1144   // Load into B_out, in order that they will be used in eval_mode
1145   mat_start = 0;
1146   CeedCallSycl(ceed, asmb->d_B_out = sycl::malloc_device<CeedScalar>(size_B_out, sycl_data->sycl_device, sycl_data->sycl_context));
1147   for (int i = 0; i < num_B_out_mats_to_load; i++) {
1148     CeedEvalMode eval_mode = eval_mode_out[i];
1149 
1150     if (eval_mode == CEED_EVAL_INTERP) {
1151       std::vector<sycl::event> e;
1152 
1153       if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
1154       sycl_data->sycl_queue.copy<CeedScalar>(interp_out, &asmb->d_B_out[mat_start], elem_size * num_qpts, e);
1155       mat_start += elem_size * num_qpts;
1156     } else if (eval_mode == CEED_EVAL_GRAD) {
1157       std::vector<sycl::event> e;
1158 
1159       if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
1160       sycl_data->sycl_queue.copy<CeedScalar>(grad_out, &asmb->d_B_out[mat_start], dim * elem_size * num_qpts, e);
1161       mat_start += dim * elem_size * num_qpts;
1162     }
1163   }
1164   CeedCallBackend(CeedElemRestrictionDestroy(&rstr_in));
1165   CeedCallBackend(CeedElemRestrictionDestroy(&rstr_out));
1166   CeedCallBackend(CeedBasisDestroy(&basis_in));
1167   CeedCallBackend(CeedBasisDestroy(&basis_out));
1168   return CEED_ERROR_SUCCESS;
1169 }
1170 
1171 //------------------------------------------------------------------------------
1172 // Matrix assembly kernel for low-order elements (3D thread block)
1173 //------------------------------------------------------------------------------
1174 static int CeedOperatorLinearAssemble_Sycl(sycl::queue &sycl_queue, const CeedOperator_Sycl *impl, const CeedScalar *qf_array,
1175                                            CeedScalar *values_array) {
1176   // This kernels assumes B_in and B_out have the same number of quadrature points and basis points.
1177   // TODO: expand to more general cases
1178   CeedOperatorAssemble_Sycl *asmb              = impl->asmb;
1179   const CeedInt              num_elem          = asmb->num_elem;
1180   const CeedSize             num_nodes         = asmb->num_nodes;
1181   const CeedSize             num_comp          = asmb->num_comp;
1182   const CeedSize             num_qpts          = asmb->num_qpts;
1183   const CeedSize             num_eval_mode_in  = asmb->num_eval_mode_in;
1184   const CeedSize             num_eval_mode_out = asmb->num_eval_mode_out;
1185 
1186   // Strides for final output ordering, determined by the reference (inference) implementation of the symbolic assembly, slowest --> fastest: element,
1187   // comp_in, comp_out, node_row, node_col
1188   const CeedSize comp_out_stride = num_nodes * num_nodes;
1189   const CeedSize comp_in_stride  = comp_out_stride * num_comp;
1190   const CeedSize e_stride        = comp_in_stride * num_comp;
1191   // Strides for QF array, slowest --> fastest:  eval_mode_in, comp_in,  eval_mode_out, comp_out, elem, qpt
1192   const CeedSize q_e_stride             = num_qpts;
1193   const CeedSize q_comp_out_stride      = num_elem * q_e_stride;
1194   const CeedSize q_eval_mode_out_stride = q_comp_out_stride * num_comp;
1195   const CeedSize q_comp_in_stride       = q_eval_mode_out_stride * num_eval_mode_out;
1196   const CeedSize q_eval_mode_in_stride  = q_comp_in_stride * num_comp;
1197 
1198   CeedScalar *B_in, *B_out;
1199   B_in                       = asmb->d_B_in;
1200   B_out                      = asmb->d_B_out;
1201   const CeedInt block_size_x = asmb->block_size_x;
1202   const CeedInt block_size_y = asmb->block_size_y;
1203 
1204   sycl::range<3> kernel_range(num_elem, block_size_y, block_size_x);
1205 
1206   std::vector<sycl::event> e;
1207 
1208   if (!sycl_queue.is_in_order()) e = {sycl_queue.ext_oneapi_submit_barrier()};
1209   sycl_queue.parallel_for<CeedOperatorSyclLinearAssemble>(kernel_range, e, [=](sycl::id<3> idx) {
1210     const int e = idx.get(0);  // Element index
1211     const int l = idx.get(1);  // The output column index of each B^TDB operation
1212     const int i = idx.get(2);  // The output row index of each B^TDB operation
1213                                // such that we have (Bout^T)_ij D_jk Bin_kl = C_il
1214     for (CeedSize comp_in = 0; comp_in < num_comp; comp_in++) {
1215       for (CeedSize comp_out = 0; comp_out < num_comp; comp_out++) {
1216         CeedScalar result        = 0.0;
1217         CeedSize   qf_index_comp = q_comp_in_stride * comp_in + q_comp_out_stride * comp_out + q_e_stride * e;
1218 
1219         for (CeedSize eval_mode_in = 0; eval_mode_in < num_eval_mode_in; eval_mode_in++) {
1220           CeedSize b_in_index = eval_mode_in * num_qpts * num_nodes;
1221 
1222           for (CeedSize eval_mode_out = 0; eval_mode_out < num_eval_mode_out; eval_mode_out++) {
1223             CeedSize b_out_index = eval_mode_out * num_qpts * num_nodes;
1224             CeedSize qf_index    = qf_index_comp + q_eval_mode_out_stride * eval_mode_out + q_eval_mode_in_stride * eval_mode_in;
1225 
1226             // Perform the B^T D B operation for this 'chunk' of D (the qf_array)
1227             for (CeedSize j = 0; j < num_qpts; j++) {
1228               result += B_out[b_out_index + j * num_nodes + i] * qf_array[qf_index + j] * B_in[b_in_index + j * num_nodes + l];
1229             }
1230           }  // end of  eval_mode_out
1231         }  // end of  eval_mode_in
1232         CeedSize val_index = comp_in_stride * comp_in + comp_out_stride * comp_out + e_stride * e + num_nodes * i + l;
1233 
1234         values_array[val_index] = result;
1235       }  // end of out component
1236     }  // end of in component
1237   });
1238   return CEED_ERROR_SUCCESS;
1239 }
1240 
1241 //------------------------------------------------------------------------------
1242 // Fallback kernel for larger orders (1D thread block)
1243 //------------------------------------------------------------------------------
1244 /*
1245 static int CeedOperatorLinearAssembleFallback_Sycl(sycl::queue &sycl_queue, const CeedOperator_Sycl *impl, const CeedScalar *qf_array,
1246                                                    CeedScalar *values_array) {
1247   // This kernel assumes B_in and B_out have the same number of quadrature points and basis points.
1248   // TODO: expand to more general cases
1249   CeedOperatorAssemble_Sycl *asmb        = impl->asmb;
1250   const CeedInt              num_elem       = asmb->num_elem;
1251   const CeedInt              num_nodes      = asmb->num_nodes;
1252   const CeedInt              num_comp       = asmb->num_comp;
1253   const CeedInt              num_qpts       = asmb->num_qpts;
1254   const CeedInt              num_eval_mode_in  = asmb->num_eval_mode_in;
1255   const CeedInt              num_eval_mode_out = asmb->num_eval_mode_out;
1256 
1257   // Strides for final output ordering, determined by the reference (interface) implementation of the symbolic assembly, slowest --> fastest: elememt,
1258   // comp_in, comp_out, node_row, node_col
1259   const CeedInt comp_out_stride = num_nodes * num_nodes;
1260   const CeedInt comp_in_stride  = comp_out_stride * num_comp;
1261   const CeedInt e_stride        = comp_in_stride * num_comp;
1262   // Strides for QF array, slowest --> fastest:  eval_mode_in, comp_in,  eval_mode_out, comp_out, elem, qpt
1263   const CeedInt q_e_stride         = num_qpts;
1264   const CeedInt q_comp_out_stride  = num_elem * q_e_stride;
1265   const CeedInt q_eval_mode_out_stride = q_comp_out_stride * num_comp;
1266   const CeedInt q_comp_in_stride   = q_eval_mode_out_stride * num_eval_mode_out;
1267   const CeedInt q_eval_mode_in_stride  = q_comp_in_stride * num_comp;
1268 
1269   CeedScalar *B_in, *B_out;
1270   B_in                        = asmb->d_B_in;
1271   B_out                       = asmb->d_B_out;
1272   const CeedInt elems_per_block = asmb->elems_per_block;
1273   const CeedInt block_size_x  = asmb->block_size_x;
1274   const CeedInt block_size_y  = asmb->block_size_y;  // This will be 1 for the fallback kernel
1275 
1276   const CeedInt     grid = num_elem / elems_per_block + ((num_elem / elems_per_block * elems_per_block < num_elem) ? 1 : 0);
1277   sycl::range<3>    local_range(block_size_x, block_size_y, elems_per_block);
1278   sycl::range<3>    global_range(grid * block_size_x, block_size_y, elems_per_block);
1279   sycl::nd_range<3> kernel_range(global_range, local_range);
1280 
1281   sycl_queue.parallel_for<CeedOperatorSyclLinearAssembleFallback>(kernel_range, [=](sycl::nd_item<3> work_item) {
1282     const CeedInt blockIdx  = work_item.get_group(0);
1283     const CeedInt gridDimx  = work_item.get_group_range(0);
1284     const CeedInt threadIdx = work_item.get_local_id(0);
1285     const CeedInt threadIdz = work_item.get_local_id(2);
1286     const CeedInt blockDimz = work_item.get_local_range(2);
1287 
1288     const int l = threadIdx;  // The output column index of each B^TDB operation
1289                               // such that we have (Bout^T)_ij D_jk Bin_kl = C_il
1290     for (CeedInt e = blockIdx * blockDimz + threadIdz; e < num_elem; e += gridDimx * blockDimz) {
1291       for (CeedInt comp_in = 0; comp_in < num_comp; comp_in++) {
1292         for (CeedInt comp_out = 0; comp_out < num_comp; comp_out++) {
1293           for (CeedInt i = 0; i < num_nodes; i++) {
1294             CeedScalar result        = 0.0;
1295             CeedInt    qf_index_comp = q_comp_in_stride * comp_in + q_comp_out_stride * comp_out + q_e_stride * e;
1296             for (CeedInt  eval_mode_in = 0;  eval_mode_in < num_eval_mode_in;  eval_mode_in++) {
1297               CeedInt b_in_index =  eval_mode_in * num_qpts * num_nodes;
1298               for (CeedInt  eval_mode_out = 0;  eval_mode_out < num_eval_mode_out;  eval_mode_out++) {
1299                 CeedInt b_out_index =  eval_mode_out * num_qpts * num_nodes;
1300                 CeedInt qf_index    = qf_index_comp + q_eval_mode_out_stride *  eval_mode_out + q_eval_mode_in_stride *  eval_mode_in;
1301                 // Perform the B^T D B operation for this 'chunk' of D (the qf_array)
1302                 for (CeedInt j = 0; j < num_qpts; j++) {
1303                   result += B_out[b_out_index + j * num_nodes + i] * qf_array[qf_index + j] * B_in[b_in_index + j * num_nodes + l];
1304                 }
1305               }  // end of  eval_mode_out
1306             }    // end of  eval_mode_in
1307             CeedInt val_index       = comp_in_stride * comp_in + comp_out_stride * comp_out + e_stride * e + num_nodes * i + l;
1308             values_array[val_index] = result;
1309           }  // end of loop over element node index, i
1310         }    // end of out component
1311       }      // end of in component
1312     }        // end of element loop
1313   });
1314   return CEED_ERROR_SUCCESS;
1315 }*/
1316 
1317 //------------------------------------------------------------------------------
1318 // Assemble matrix data for COO matrix of assembled operator.
1319 // The sparsity pattern is set by CeedOperatorLinearAssembleSymbolic.
1320 //
1321 // Note that this (and other assembly routines) currently assume only one active
1322 // input restriction/basis per operator (could have multiple basis eval modes).
1323 // TODO: allow multiple active input restrictions/basis objects
1324 //------------------------------------------------------------------------------
1325 static int CeedSingleOperatorAssemble_Sycl(CeedOperator op, CeedInt offset, CeedVector values) {
1326   Ceed                ceed;
1327   Ceed_Sycl          *sycl_data;
1328   CeedScalar         *values_array;
1329   const CeedScalar   *qf_array;
1330   CeedVector          assembled_qf = NULL;
1331   CeedElemRestriction rstr_q       = NULL;
1332   CeedOperator_Sycl  *impl;
1333 
1334   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
1335   CeedCallBackend(CeedOperatorGetData(op, &impl));
1336   CeedCallBackend(CeedGetData(ceed, &sycl_data));
1337 
1338   // Setup
1339   if (!impl->asmb) {
1340     CeedCallBackend(CeedSingleOperatorAssembleSetup_Sycl(op));
1341     assert(impl->asmb != NULL);
1342   }
1343 
1344   // Assemble QFunction
1345   CeedCallBackend(CeedOperatorLinearAssembleQFunctionBuildOrUpdate(op, &assembled_qf, &rstr_q, CEED_REQUEST_IMMEDIATE));
1346   CeedCallBackend(CeedElemRestrictionDestroy(&rstr_q));
1347   CeedCallBackend(CeedVectorGetArrayWrite(values, CEED_MEM_DEVICE, &values_array));
1348   values_array += offset;
1349   CeedCallBackend(CeedVectorGetArrayRead(assembled_qf, CEED_MEM_DEVICE, &qf_array));
1350 
1351   // Compute B^T D B
1352   CeedCallBackend(CeedOperatorLinearAssemble_Sycl(sycl_data->sycl_queue, impl, qf_array, values_array));
1353 
1354   // Wait for kernels to be completed
1355   // Kris: Review if this is necessary -- enqueing an async barrier may be sufficient
1356   sycl_data->sycl_queue.wait_and_throw();
1357 
1358   // Restore arrays
1359   CeedCallBackend(CeedVectorRestoreArray(values, &values_array));
1360   CeedCallBackend(CeedVectorRestoreArrayRead(assembled_qf, &qf_array));
1361 
1362   // Cleanup
1363   CeedCallBackend(CeedVectorDestroy(&assembled_qf));
1364   return CEED_ERROR_SUCCESS;
1365 }
1366 
1367 //------------------------------------------------------------------------------
1368 // Create operator
1369 //------------------------------------------------------------------------------
1370 int CeedOperatorCreate_Sycl(CeedOperator op) {
1371   Ceed               ceed;
1372   CeedOperator_Sycl *impl;
1373 
1374   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
1375 
1376   CeedCallBackend(CeedCalloc(1, &impl));
1377   CeedCallBackend(CeedOperatorSetData(op, impl));
1378 
1379   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleQFunction", CeedOperatorLinearAssembleQFunction_Sycl));
1380   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleQFunctionUpdate", CeedOperatorLinearAssembleQFunctionUpdate_Sycl));
1381   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleAddDiagonal", CeedOperatorLinearAssembleAddDiagonal_Sycl));
1382   CeedCallBackend(
1383       CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleAddPointBlockDiagonal", CeedOperatorLinearAssembleAddPointBlockDiagonal_Sycl));
1384   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleSingle", CeedSingleOperatorAssemble_Sycl));
1385   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "ApplyAdd", CeedOperatorApplyAdd_Sycl));
1386   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "Destroy", CeedOperatorDestroy_Sycl));
1387   return CEED_ERROR_SUCCESS;
1388 }
1389 
1390 //------------------------------------------------------------------------------
1391