xref: /libCEED/rust/libceed-sys/c-src/backends/sycl-ref/ceed-sycl-ref-operator.sycl.cpp (revision 9bc663991d6482bcb1d60b1f116148f11db83fa1)
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 
93     CeedCallBackend(CeedVectorDestroy(&impl->diag->elem_diag));
94     CeedCallBackend(CeedVectorDestroy(&impl->diag->point_block_elem_diag));
95     CeedCallBackend(CeedElemRestrictionDestroy(&impl->diag->diag_rstr));
96     CeedCallBackend(CeedElemRestrictionDestroy(&impl->diag->point_block_diag_rstr));
97     CeedCallBackend(CeedBasisDestroy(&impl->diag->basis_in));
98     CeedCallBackend(CeedBasisDestroy(&impl->diag->basis_out));
99   }
100   CeedCallBackend(CeedFree(&impl->diag));
101 
102   if (impl->asmb) {
103     CeedCallSycl(ceed, sycl_data->sycl_queue.wait_and_throw());
104     CeedCallSycl(ceed, sycl::free(impl->asmb->d_B_in, sycl_data->sycl_context));
105     CeedCallSycl(ceed, sycl::free(impl->asmb->d_B_out, sycl_data->sycl_context));
106   }
107   CeedCallBackend(CeedFree(&impl->asmb));
108 
109   CeedCallBackend(CeedFree(&impl));
110   CeedCallBackend(CeedDestroy(&ceed));
111   return CEED_ERROR_SUCCESS;
112 }
113 
114 //------------------------------------------------------------------------------
115 // Setup infields or outfields
116 //------------------------------------------------------------------------------
117 static int CeedOperatorSetupFields_Sycl(CeedQFunction qf, CeedOperator op, bool is_input, CeedVector *e_vecs, CeedVector *q_vecs, CeedInt start_e,
118                                         CeedInt num_fields, CeedInt Q, CeedInt num_elem) {
119   Ceed                ceed;
120   CeedSize            q_size;
121   bool                is_strided, skip_restriction;
122   CeedInt             size;
123   CeedOperatorField  *op_fields;
124   CeedQFunctionField *qf_fields;
125 
126   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
127   if (is_input) {
128     CeedCallBackend(CeedOperatorGetFields(op, NULL, &op_fields, NULL, NULL));
129     CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_fields, NULL, NULL));
130   } else {
131     CeedCallBackend(CeedOperatorGetFields(op, NULL, NULL, NULL, &op_fields));
132     CeedCallBackend(CeedQFunctionGetFields(qf, NULL, NULL, NULL, &qf_fields));
133   }
134 
135   // Loop over fields
136   for (CeedInt i = 0; i < num_fields; i++) {
137     CeedEvalMode        eval_mode;
138     CeedVector          vec;
139     CeedElemRestriction elem_rstr;
140 
141     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
142 
143     is_strided       = false;
144     skip_restriction = false;
145     if (eval_mode != CEED_EVAL_WEIGHT) {
146       CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_fields[i], &elem_rstr));
147 
148       // Check whether this field can skip the element restriction:
149       // must be passive input, with  eval_mode NONE, and have a strided restriction with CEED_STRIDES_BACKEND.
150 
151       // First, check whether the field is input or output:
152       if (is_input) {
153         // Check for passive input:
154         CeedCallBackend(CeedOperatorFieldGetVector(op_fields[i], &vec));
155         if (vec != CEED_VECTOR_ACTIVE) {
156           // Check  eval_mode
157           if (eval_mode == CEED_EVAL_NONE) {
158             // Check for  is_strided restriction
159             CeedCallBackend(CeedElemRestrictionIsStrided(elem_rstr, &is_strided));
160             if (is_strided) {
161               // Check if vector is already in preferred backend ordering
162               CeedCallBackend(CeedElemRestrictionHasBackendStrides(elem_rstr, &skip_restriction));
163             }
164           }
165         }
166         CeedCallBackend(CeedVectorDestroy(&vec));
167       }
168       if (skip_restriction) {
169         // We do not need an E-Vector, but will use the input field vector's data directly in the operator application
170         e_vecs[i + start_e] = NULL;
171       } else {
172         CeedCallBackend(CeedElemRestrictionCreateVector(elem_rstr, NULL, &e_vecs[i + start_e]));
173       }
174       CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
175     }
176 
177     switch (eval_mode) {
178       case CEED_EVAL_NONE:
179         CeedCallBackend(CeedQFunctionFieldGetSize(qf_fields[i], &size));
180         q_size = (CeedSize)num_elem * Q * size;
181         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
182         break;
183       case CEED_EVAL_INTERP:
184         CeedCallBackend(CeedQFunctionFieldGetSize(qf_fields[i], &size));
185         q_size = (CeedSize)num_elem * Q * size;
186         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
187         break;
188       case CEED_EVAL_GRAD:
189         CeedCallBackend(CeedQFunctionFieldGetSize(qf_fields[i], &size));
190         q_size = (CeedSize)num_elem * Q * size;
191         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
192         break;
193       case CEED_EVAL_WEIGHT: {
194         CeedBasis basis;
195 
196         // Note: only on input fields
197         q_size = (CeedSize)num_elem * Q;
198         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
199         CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
200         CeedCallBackend(CeedBasisApply(basis, num_elem, CEED_NOTRANSPOSE, CEED_EVAL_WEIGHT, CEED_VECTOR_NONE, q_vecs[i]));
201         CeedCallBackend(CeedBasisDestroy(&basis));
202         break;
203       }
204       case CEED_EVAL_DIV:
205         break;  // TODO: Not implemented
206       case CEED_EVAL_CURL:
207         break;  // TODO: Not implemented
208     }
209   }
210   CeedCallBackend(CeedDestroy(&ceed));
211   return CEED_ERROR_SUCCESS;
212 }
213 
214 //------------------------------------------------------------------------------
215 // CeedOperator needs to connect all the named fields (be they active or
216 // passive) to the named inputs and outputs of its CeedQFunction.
217 //------------------------------------------------------------------------------
218 static int CeedOperatorSetup_Sycl(CeedOperator op) {
219   bool                is_setup_done;
220   CeedInt             Q, num_elem, num_input_fields, num_output_fields;
221   CeedQFunctionField *qf_input_fields, *qf_output_fields;
222   CeedQFunction       qf;
223   CeedOperatorField  *op_input_fields, *op_output_fields;
224   CeedOperator_Sycl  *impl;
225 
226   CeedCallBackend(CeedOperatorIsSetupDone(op, &is_setup_done));
227   if (is_setup_done) return CEED_ERROR_SUCCESS;
228 
229   CeedCallBackend(CeedOperatorGetData(op, &impl));
230   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
231   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
232   CeedCallBackend(CeedOperatorGetNumElements(op, &num_elem));
233   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
234   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
235 
236   // Allocate
237   CeedCallBackend(CeedCalloc(num_input_fields + num_output_fields, &impl->e_vecs));
238 
239   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->q_vecs_in));
240   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->q_vecs_out));
241 
242   impl->num_e_in  = num_input_fields;
243   impl->num_e_out = num_output_fields;
244 
245   // Set up infield and outfield  e_vecs and  q_vecs
246   // Infields
247   CeedCallBackend(CeedOperatorSetupFields_Sycl(qf, op, true, impl->e_vecs, impl->q_vecs_in, 0, num_input_fields, Q, num_elem));
248   // Outfields
249   CeedCallBackend(CeedOperatorSetupFields_Sycl(qf, op, false, impl->e_vecs, impl->q_vecs_out, num_input_fields, num_output_fields, Q, num_elem));
250 
251   CeedCallBackend(CeedOperatorSetSetupDone(op));
252   return CEED_ERROR_SUCCESS;
253 }
254 
255 //------------------------------------------------------------------------------
256 // Setup Operator Inputs
257 //------------------------------------------------------------------------------
258 static inline int CeedOperatorSetupInputs_Sycl(CeedInt num_input_fields, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
259                                                CeedVector in_vec, const bool skip_active, CeedScalar *e_data[2 * CEED_FIELD_MAX],
260                                                CeedOperator_Sycl *impl, CeedRequest *request) {
261   for (CeedInt i = 0; i < num_input_fields; i++) {
262     bool         is_active;
263     CeedEvalMode eval_mode;
264     CeedVector   vec;
265 
266     // Get input vector
267     CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
268     is_active = vec == CEED_VECTOR_ACTIVE;
269     if (is_active) {
270       if (skip_active) continue;
271       else vec = in_vec;
272     }
273 
274     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
275     if (eval_mode == CEED_EVAL_WEIGHT) {  // Skip
276     } else {
277       // Restrict, if necessary
278       if (!impl->e_vecs[i]) {
279         // No restriction for this field; read data directly from vec.
280         CeedCallBackend(CeedVectorGetArrayRead(vec, CEED_MEM_DEVICE, (const CeedScalar **)&e_data[i]));
281       } else {
282         CeedElemRestriction elem_rstr;
283 
284         CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_input_fields[i], &elem_rstr));
285         CeedCallBackend(CeedElemRestrictionApply(elem_rstr, CEED_NOTRANSPOSE, vec, impl->e_vecs[i], request));
286         CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
287         CeedCallBackend(CeedVectorGetArrayRead(impl->e_vecs[i], CEED_MEM_DEVICE, (const CeedScalar **)&e_data[i]));
288       }
289     }
290     if (!is_active) CeedCallBackend(CeedVectorDestroy(&vec));
291   }
292   return CEED_ERROR_SUCCESS;
293 }
294 
295 //------------------------------------------------------------------------------
296 // Input Basis Action
297 //------------------------------------------------------------------------------
298 static inline int CeedOperatorInputBasis_Sycl(CeedInt num_elem, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
299                                               CeedInt num_input_fields, const bool skip_active, CeedScalar *e_data[2 * CEED_FIELD_MAX],
300                                               CeedOperator_Sycl *impl) {
301   for (CeedInt i = 0; i < num_input_fields; i++) {
302     CeedEvalMode eval_mode;
303 
304     // Skip active input
305     if (skip_active) {
306       bool       is_active;
307       CeedVector vec;
308 
309       CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
310       is_active = vec == CEED_VECTOR_ACTIVE;
311       CeedCallBackend(CeedVectorDestroy(&vec));
312       if (is_active) continue;
313     }
314     // Basis action
315     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
316     switch (eval_mode) {
317       case CEED_EVAL_NONE:
318         CeedCallBackend(CeedVectorSetArray(impl->q_vecs_in[i], CEED_MEM_DEVICE, CEED_USE_POINTER, e_data[i]));
319         break;
320       case CEED_EVAL_INTERP:
321       case CEED_EVAL_GRAD: {
322         CeedBasis basis;
323 
324         CeedCallBackend(CeedOperatorFieldGetBasis(op_input_fields[i], &basis));
325         CeedCallBackend(CeedBasisApply(basis, num_elem, CEED_NOTRANSPOSE, eval_mode, impl->e_vecs[i], impl->q_vecs_in[i]));
326         CeedCallBackend(CeedBasisDestroy(&basis));
327         break;
328       }
329       case CEED_EVAL_WEIGHT:
330         break;  // No action
331       case CEED_EVAL_DIV:
332         break;  // TODO: Not implemented
333       case CEED_EVAL_CURL:
334         break;  // TODO: Not implemented
335     }
336   }
337   return CEED_ERROR_SUCCESS;
338 }
339 
340 //------------------------------------------------------------------------------
341 // Restore Input Vectors
342 //------------------------------------------------------------------------------
343 static inline int CeedOperatorRestoreInputs_Sycl(CeedInt num_input_fields, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
344                                                  const bool skip_active, CeedScalar *e_data[2 * CEED_FIELD_MAX], CeedOperator_Sycl *impl) {
345   for (CeedInt i = 0; i < num_input_fields; i++) {
346     bool         is_active;
347     CeedEvalMode eval_mode;
348     CeedVector   vec;
349 
350     CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
351     is_active = vec == CEED_VECTOR_ACTIVE;
352     // Skip active input
353     if (skip_active) {
354       if (is_active) continue;
355     }
356     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
357     if (eval_mode == CEED_EVAL_WEIGHT) {  // Skip
358     } else {
359       if (!impl->e_vecs[i]) {  // This was a  skip_restriction case
360         CeedCallBackend(CeedVectorRestoreArrayRead(vec, (const CeedScalar **)&e_data[i]));
361       } else {
362         CeedCallBackend(CeedVectorRestoreArrayRead(impl->e_vecs[i], (const CeedScalar **)&e_data[i]));
363       }
364     }
365     if (!is_active) CeedCallBackend(CeedVectorDestroy(&vec));
366   }
367   return CEED_ERROR_SUCCESS;
368 }
369 
370 //------------------------------------------------------------------------------
371 // Apply and add to output
372 //------------------------------------------------------------------------------
373 static int CeedOperatorApplyAdd_Sycl(CeedOperator op, CeedVector in_vec, CeedVector out_vec, CeedRequest *request) {
374   CeedInt             Q, num_elem, elem_size, num_input_fields, num_output_fields, size;
375   CeedEvalMode        eval_mode;
376   CeedScalar         *e_data[2 * CEED_FIELD_MAX] = {0};
377   CeedQFunctionField *qf_input_fields, *qf_output_fields;
378   CeedQFunction       qf;
379   CeedOperatorField  *op_input_fields, *op_output_fields;
380   CeedOperator_Sycl  *impl;
381 
382   CeedCallBackend(CeedOperatorGetData(op, &impl));
383   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
384   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
385   CeedCallBackend(CeedOperatorGetNumElements(op, &num_elem));
386   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
387   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
388 
389   // Setup
390   CeedCallBackend(CeedOperatorSetup_Sycl(op));
391 
392   // Input Evecs and Restriction
393   CeedCallBackend(CeedOperatorSetupInputs_Sycl(num_input_fields, qf_input_fields, op_input_fields, in_vec, false, e_data, impl, request));
394 
395   // Input basis apply if needed
396   CeedCallBackend(CeedOperatorInputBasis_Sycl(num_elem, qf_input_fields, op_input_fields, num_input_fields, false, e_data, impl));
397 
398   // Output pointers, as necessary
399   for (CeedInt i = 0; i < num_output_fields; i++) {
400     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_output_fields[i], &eval_mode));
401     if (eval_mode == CEED_EVAL_NONE) {
402       // Set the output Q-Vector to use the E-Vector data directly
403       CeedCallBackend(CeedVectorGetArrayWrite(impl->e_vecs[i + impl->num_e_in], CEED_MEM_DEVICE, &e_data[i + num_input_fields]));
404       CeedCallBackend(CeedVectorSetArray(impl->q_vecs_out[i], CEED_MEM_DEVICE, CEED_USE_POINTER, e_data[i + num_input_fields]));
405     }
406   }
407 
408   // Q function
409   CeedCallBackend(CeedQFunctionApply(qf, num_elem * Q, impl->q_vecs_in, impl->q_vecs_out));
410 
411   // Output basis apply if needed
412   for (CeedInt i = 0; i < num_output_fields; i++) {
413     CeedElemRestriction elem_rstr;
414 
415     // Get elem_size, eval_mode, size
416     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_output_fields[i], &elem_rstr));
417     CeedCallBackend(CeedElemRestrictionGetElementSize(elem_rstr, &elem_size));
418     CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
419     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_output_fields[i], &eval_mode));
420     CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[i], &size));
421     // Basis action
422     switch (eval_mode) {
423       case CEED_EVAL_NONE:
424         break;
425       case CEED_EVAL_INTERP:
426       case CEED_EVAL_GRAD: {
427         CeedBasis basis;
428 
429         CeedCallBackend(CeedOperatorFieldGetBasis(op_output_fields[i], &basis));
430         CeedCallBackend(CeedBasisApply(basis, num_elem, CEED_TRANSPOSE, eval_mode, impl->q_vecs_out[i], impl->e_vecs[i + impl->num_e_in]));
431         CeedCallBackend(CeedBasisDestroy(&basis));
432         break;
433       }
434       // LCOV_EXCL_START
435       case CEED_EVAL_WEIGHT:
436         return CeedError(CeedOperatorReturnCeed(op), CEED_ERROR_BACKEND, "CEED_EVAL_WEIGHT cannot be an output evaluation mode");
437         break;  // Should not occur
438       case CEED_EVAL_DIV:
439       case CEED_EVAL_CURL:
440         return CeedError(CeedOperatorReturnCeed(op), CEED_ERROR_BACKEND, "%s not supported", CeedEvalModes[eval_mode]);
441         break;  // Should not occur
442                 // LCOV_EXCL_STOP
443     }
444   }
445 
446   // Output restriction
447   for (CeedInt i = 0; i < num_output_fields; i++) {
448     bool                is_active;
449     CeedEvalMode        eval_mode;
450     CeedVector          vec;
451     CeedElemRestriction elem_rstr;
452 
453     // Restore evec
454     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_output_fields[i], &eval_mode));
455     if (eval_mode == CEED_EVAL_NONE) {
456       CeedCallBackend(CeedVectorRestoreArray(impl->e_vecs[i + impl->num_e_in], &e_data[i + num_input_fields]));
457     }
458     // Restrict
459     CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[i], &vec));
460     is_active = vec == CEED_VECTOR_ACTIVE;
461     if (is_active) vec = out_vec;
462     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_output_fields[i], &elem_rstr));
463     CeedCallBackend(CeedElemRestrictionApply(elem_rstr, CEED_TRANSPOSE, impl->e_vecs[i + impl->num_e_in], vec, request));
464     if (!is_active) CeedCallBackend(CeedVectorDestroy(&vec));
465     CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
466   }
467 
468   // Restore input arrays
469   CeedCallBackend(CeedOperatorRestoreInputs_Sycl(num_input_fields, qf_input_fields, op_input_fields, false, e_data, impl));
470   return CEED_ERROR_SUCCESS;
471 }
472 
473 //------------------------------------------------------------------------------
474 // Core code for assembling linear QFunction
475 //------------------------------------------------------------------------------
476 static inline int CeedOperatorLinearAssembleQFunctionCore_Sycl(CeedOperator op, bool build_objects, CeedVector *assembled,
477                                                                CeedElemRestriction *elem_rstr, CeedRequest *request) {
478   Ceed                ceed_parent;
479   CeedSize            q_size;
480   CeedInt             num_active_in, num_active_out, Q, num_elem, num_input_fields, num_output_fields, size;
481   CeedScalar         *assembled_array, *e_data[2 * CEED_FIELD_MAX] = {NULL};
482   CeedVector         *active_in;
483   CeedQFunctionField *qf_input_fields, *qf_output_fields;
484   CeedQFunction       qf;
485   CeedOperatorField  *op_input_fields, *op_output_fields;
486   CeedOperator_Sycl  *impl;
487 
488   CeedCallBackend(CeedOperatorGetFallbackParentCeed(op, &ceed_parent));
489   CeedCallBackend(CeedOperatorGetData(op, &impl));
490   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
491   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
492   CeedCallBackend(CeedOperatorGetNumElements(op, &num_elem));
493   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
494   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
495   active_in     = impl->qf_active_in;
496   num_active_in = impl->num_active_in, num_active_out = impl->num_active_out;
497 
498   // Setup
499   CeedCallBackend(CeedOperatorSetup_Sycl(op));
500 
501   // Input Evecs and Restriction
502   CeedCallBackend(CeedOperatorSetupInputs_Sycl(num_input_fields, qf_input_fields, op_input_fields, NULL, true, e_data, impl, request));
503 
504   // Count number of active input fields
505   if (!num_active_in) {
506     for (CeedInt i = 0; i < num_input_fields; i++) {
507       CeedScalar *q_vec_array;
508       CeedVector  vec;
509 
510       // Check if active input
511       CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
512       if (vec == CEED_VECTOR_ACTIVE) {
513         CeedCallBackend(CeedQFunctionFieldGetSize(qf_input_fields[i], &size));
514         CeedCallBackend(CeedVectorSetValue(impl->q_vecs_in[i], 0.0));
515         CeedCallBackend(CeedVectorGetArray(impl->q_vecs_in[i], CEED_MEM_DEVICE, &q_vec_array));
516         CeedCallBackend(CeedRealloc(num_active_in + size, &active_in));
517         for (CeedInt field = 0; field < size; field++) {
518           q_size = (CeedSize)Q * num_elem;
519           CeedCallBackend(CeedVectorCreate(ceed_parent, q_size, &active_in[num_active_in + field]));
520           CeedCallBackend(
521               CeedVectorSetArray(active_in[num_active_in + field], CEED_MEM_DEVICE, CEED_USE_POINTER, &q_vec_array[field * Q * num_elem]));
522         }
523         num_active_in += size;
524         CeedCallBackend(CeedVectorRestoreArray(impl->q_vecs_in[i], &q_vec_array));
525       }
526       CeedCallBackend(CeedVectorDestroy(&vec));
527     }
528     impl->num_active_in = num_active_in;
529     impl->qf_active_in  = active_in;
530   }
531 
532   // Count number of active output fields
533   if (!num_active_out) {
534     for (CeedInt i = 0; i < num_output_fields; i++) {
535       CeedVector vec;
536 
537       // Check if active output
538       CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[i], &vec));
539       if (vec == CEED_VECTOR_ACTIVE) {
540         CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[i], &size));
541         num_active_out += size;
542       }
543       CeedCallBackend(CeedVectorDestroy(&vec));
544     }
545     impl->num_active_out = num_active_out;
546   }
547 
548   // Check sizes
549   CeedCheck(num_active_in > 0 && num_active_out > 0, CeedOperatorReturnCeed(op), CEED_ERROR_BACKEND,
550             "Cannot assemble QFunction without active inputs and outputs");
551 
552   // Build objects if needed
553   if (build_objects) {
554     CeedSize l_size     = (CeedSize)num_elem * Q * num_active_in * num_active_out;
555     CeedInt  strides[3] = {1, num_elem * Q, Q}; /* *NOPAD* */
556 
557     // Create output restriction
558     CeedCallBackend(CeedElemRestrictionCreateStrided(ceed_parent, num_elem, Q, num_active_in * num_active_out, l_size, strides, elem_rstr));
559     // Create assembled vector
560     CeedCallBackend(CeedVectorCreate(ceed_parent, l_size, assembled));
561   }
562   CeedCallBackend(CeedVectorSetValue(*assembled, 0.0));
563   CeedCallBackend(CeedVectorGetArray(*assembled, CEED_MEM_DEVICE, &assembled_array));
564 
565   // Input basis apply
566   CeedCallBackend(CeedOperatorInputBasis_Sycl(num_elem, qf_input_fields, op_input_fields, num_input_fields, true, e_data, impl));
567 
568   // Assemble QFunction
569   for (CeedInt in = 0; in < num_active_in; in++) {
570     // Set Inputs
571     CeedCallBackend(CeedVectorSetValue(active_in[in], 1.0));
572     if (num_active_in > 1) {
573       CeedCallBackend(CeedVectorSetValue(active_in[(in + num_active_in - 1) % num_active_in], 0.0));
574     }
575     // Set Outputs
576     for (CeedInt out = 0; out < num_output_fields; out++) {
577       CeedVector vec;
578 
579       // Check if active output
580       CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[out], &vec));
581       if (vec == CEED_VECTOR_ACTIVE) {
582         CeedCallBackend(CeedVectorSetArray(impl->q_vecs_out[out], CEED_MEM_DEVICE, CEED_USE_POINTER, assembled_array));
583         CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[out], &size));
584         assembled_array += size * Q * num_elem;  // Advance the pointer by the size of the output
585       }
586       CeedCallBackend(CeedVectorDestroy(&vec));
587     }
588     // Apply QFunction
589     CeedCallBackend(CeedQFunctionApply(qf, Q * num_elem, impl->q_vecs_in, impl->q_vecs_out));
590   }
591 
592   // Un-set output Qvecs to prevent accidental overwrite of Assembled
593   for (CeedInt out = 0; out < num_output_fields; out++) {
594     CeedVector vec;
595 
596     // Check if active output
597     CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[out], &vec));
598     if (vec == CEED_VECTOR_ACTIVE) {
599       CeedCallBackend(CeedVectorTakeArray(impl->q_vecs_out[out], CEED_MEM_DEVICE, NULL));
600     }
601     CeedCallBackend(CeedVectorDestroy(&vec));
602   }
603 
604   // Restore input arrays
605   CeedCallBackend(CeedOperatorRestoreInputs_Sycl(num_input_fields, qf_input_fields, op_input_fields, true, e_data, impl));
606 
607   // Restore output
608   CeedCallBackend(CeedVectorRestoreArray(*assembled, &assembled_array));
609   CeedCallBackend(CeedDestroy(&ceed_parent));
610   return CEED_ERROR_SUCCESS;
611 }
612 
613 //------------------------------------------------------------------------------
614 // Assemble Linear QFunction
615 //------------------------------------------------------------------------------
616 static int CeedOperatorLinearAssembleQFunction_Sycl(CeedOperator op, CeedVector *assembled, CeedElemRestriction *elem_rstr, CeedRequest *request) {
617   return CeedOperatorLinearAssembleQFunctionCore_Sycl(op, true, assembled, elem_rstr, request);
618 }
619 
620 //------------------------------------------------------------------------------
621 // Update Assembled Linear QFunction
622 //------------------------------------------------------------------------------
623 static int CeedOperatorLinearAssembleQFunctionUpdate_Sycl(CeedOperator op, CeedVector assembled, CeedElemRestriction elem_rstr,
624                                                           CeedRequest *request) {
625   return CeedOperatorLinearAssembleQFunctionCore_Sycl(op, false, &assembled, &elem_rstr, request);
626 }
627 
628 //------------------------------------------------------------------------------
629 // Assemble diagonal setup
630 //------------------------------------------------------------------------------
631 static inline int CeedOperatorAssembleDiagonalSetup_Sycl(CeedOperator op) {
632   Ceed                ceed;
633   Ceed_Sycl          *sycl_data;
634   CeedInt             num_input_fields, num_output_fields, num_eval_mode_in = 0, num_comp = 0, dim = 1, num_eval_mode_out = 0;
635   CeedEvalMode       *eval_mode_in = NULL, *eval_mode_out = NULL;
636   CeedElemRestriction rstr_in = NULL, rstr_out = NULL;
637   CeedBasis           basis_in = NULL, basis_out = NULL;
638   CeedQFunctionField *qf_fields;
639   CeedQFunction       qf;
640   CeedOperatorField  *op_fields;
641   CeedOperator_Sycl  *impl;
642 
643   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
644   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
645   CeedCallBackend(CeedQFunctionGetNumArgs(qf, &num_input_fields, &num_output_fields));
646 
647   // Determine active input basis
648   CeedCallBackend(CeedOperatorGetFields(op, NULL, &op_fields, NULL, NULL));
649   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_fields, NULL, NULL));
650   for (CeedInt i = 0; i < num_input_fields; i++) {
651     CeedVector vec;
652 
653     CeedCallBackend(CeedOperatorFieldGetVector(op_fields[i], &vec));
654     if (vec == CEED_VECTOR_ACTIVE) {
655       CeedEvalMode        eval_mode;
656       CeedElemRestriction elem_rstr;
657       CeedBasis           basis;
658 
659       CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_fields[i], &elem_rstr));
660       if (!rstr_in) CeedCallBackend(CeedElemRestrictionReferenceCopy(elem_rstr, &rstr_in));
661       CeedCheck(rstr_in == elem_rstr, ceed, CEED_ERROR_BACKEND, "Backend does not implement multi-field non-composite operator diagonal assembly");
662       CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
663       CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
664       if (!basis_in) CeedCallBackend(CeedBasisReferenceCopy(basis, &basis_in));
665       CeedCheck(basis_in == basis, ceed, CEED_ERROR_BACKEND, "Backend does not implement operator diagonal assembly with multiple active bases");
666       CeedCallBackend(CeedBasisDestroy(&basis));
667       CeedCallBackend(CeedBasisGetDimension(basis_in, &dim));
668       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
669       switch (eval_mode) {
670         case CEED_EVAL_NONE:
671         case CEED_EVAL_INTERP:
672           CeedCallBackend(CeedRealloc(num_eval_mode_in + 1, &eval_mode_in));
673           eval_mode_in[num_eval_mode_in] = eval_mode;
674           num_eval_mode_in += 1;
675           break;
676         case CEED_EVAL_GRAD:
677           CeedCallBackend(CeedRealloc(num_eval_mode_in + dim, &eval_mode_in));
678           for (CeedInt d = 0; d < dim; d++) eval_mode_in[num_eval_mode_in + d] = eval_mode;
679           num_eval_mode_in += dim;
680           break;
681         case CEED_EVAL_WEIGHT:
682         case CEED_EVAL_DIV:
683         case CEED_EVAL_CURL:
684           break;  // Caught by QF Assembly
685       }
686     }
687     CeedCallBackend(CeedVectorDestroy(&vec));
688   }
689   CeedCallBackend(CeedElemRestrictionDestroy(&rstr_in));
690 
691   // Determine active output basis
692   CeedCallBackend(CeedOperatorGetFields(op, NULL, NULL, NULL, &op_fields));
693   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, NULL, NULL, &qf_fields));
694   for (CeedInt i = 0; i < num_output_fields; i++) {
695     CeedVector vec;
696 
697     CeedCallBackend(CeedOperatorFieldGetVector(op_fields[i], &vec));
698     if (vec == CEED_VECTOR_ACTIVE) {
699       CeedEvalMode        eval_mode;
700       CeedElemRestriction elem_rstr;
701       CeedBasis           basis;
702 
703       CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_fields[i], &elem_rstr));
704       if (!rstr_out) CeedCallBackend(CeedElemRestrictionReferenceCopy(elem_rstr, &rstr_out));
705       CeedCheck(rstr_out == elem_rstr, ceed, CEED_ERROR_BACKEND, "Backend does not implement multi-field non-composite operator diagonal assembly");
706       CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
707       CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
708       if (!basis_out) CeedCallBackend(CeedBasisReferenceCopy(basis, &basis_out));
709       CeedCheck(basis_out == basis, ceed, CEED_ERROR_BACKEND, "Backend does not implement operator diagonal assembly with multiple active bases");
710       CeedCallBackend(CeedBasisDestroy(&basis));
711       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
712       switch (eval_mode) {
713         case CEED_EVAL_NONE:
714         case CEED_EVAL_INTERP:
715           CeedCallBackend(CeedRealloc(num_eval_mode_out + 1, &eval_mode_out));
716           eval_mode_out[num_eval_mode_out] = eval_mode;
717           num_eval_mode_out += 1;
718           break;
719         case CEED_EVAL_GRAD:
720           CeedCallBackend(CeedRealloc(num_eval_mode_out + dim, &eval_mode_out));
721           for (CeedInt d = 0; d < dim; d++) eval_mode_out[num_eval_mode_out + d] = eval_mode;
722           num_eval_mode_out += dim;
723           break;
724         case CEED_EVAL_WEIGHT:
725         case CEED_EVAL_DIV:
726         case CEED_EVAL_CURL:
727           break;  // Caught by QF Assembly
728       }
729     }
730     CeedCallBackend(CeedVectorDestroy(&vec));
731   }
732 
733   // Operator data struct
734   CeedCallBackend(CeedOperatorGetData(op, &impl));
735   CeedCallBackend(CeedGetData(ceed, &sycl_data));
736   CeedCallBackend(CeedCalloc(1, &impl->diag));
737   CeedOperatorDiag_Sycl *diag = impl->diag;
738 
739   CeedCallBackend(CeedBasisReferenceCopy(basis_in, &diag->basis_in));
740   CeedCallBackend(CeedBasisReferenceCopy(basis_out, &diag->basis_out));
741   diag->h_eval_mode_in    = eval_mode_in;
742   diag->h_eval_mode_out   = eval_mode_out;
743   diag->num_eval_mode_in  = num_eval_mode_in;
744   diag->num_eval_mode_out = num_eval_mode_out;
745 
746   // Kernel parameters
747   CeedInt num_nodes, num_qpts;
748   CeedCallBackend(CeedBasisGetNumNodes(basis_in, &num_nodes));
749   CeedCallBackend(CeedBasisGetNumQuadraturePoints(basis_in, &num_qpts));
750   CeedCallBackend(CeedBasisGetNumComponents(basis_in, &num_comp));
751   diag->num_nodes = num_nodes;
752   diag->num_qpts  = num_qpts;
753   diag->num_comp  = num_comp;
754 
755   // Basis matrices
756   const CeedInt     i_len = num_qpts * num_nodes;
757   const CeedInt     g_len = num_qpts * num_nodes * dim;
758   const CeedScalar *interp_in, *interp_out, *grad_in, *grad_out;
759 
760   // CEED_EVAL_NONE
761   CeedScalar *identity      = NULL;
762   bool        has_eval_none = false;
763   for (CeedInt i = 0; i < num_eval_mode_in; i++) has_eval_none = has_eval_none || (eval_mode_in[i] == CEED_EVAL_NONE);
764   for (CeedInt i = 0; i < num_eval_mode_out; i++) has_eval_none = has_eval_none || (eval_mode_out[i] == CEED_EVAL_NONE);
765 
766   std::vector<sycl::event> e;
767 
768   if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
769 
770   std::vector<sycl::event> copy_events;
771 
772   if (has_eval_none) {
773     CeedCallBackend(CeedCalloc(num_qpts * num_nodes, &identity));
774     for (CeedSize i = 0; i < (num_nodes < num_qpts ? num_nodes : num_qpts); i++) identity[i * num_nodes + i] = 1.0;
775     CeedCallSycl(ceed, diag->d_identity = sycl::malloc_device<CeedScalar>(i_len, sycl_data->sycl_device, sycl_data->sycl_context));
776     sycl::event identity_copy = sycl_data->sycl_queue.copy<CeedScalar>(identity, diag->d_identity, i_len, e);
777     copy_events.push_back(identity_copy);
778   }
779 
780   // CEED_EVAL_INTERP
781   CeedCallBackend(CeedBasisGetInterp(basis_in, &interp_in));
782   CeedCallSycl(ceed, diag->d_interp_in = sycl::malloc_device<CeedScalar>(i_len, sycl_data->sycl_device, sycl_data->sycl_context));
783   sycl::event interp_in_copy = sycl_data->sycl_queue.copy<CeedScalar>(interp_in, diag->d_interp_in, i_len, e);
784   copy_events.push_back(interp_in_copy);
785 
786   CeedCallBackend(CeedBasisGetInterp(basis_out, &interp_out));
787   CeedCallSycl(ceed, diag->d_interp_out = sycl::malloc_device<CeedScalar>(i_len, sycl_data->sycl_device, sycl_data->sycl_context));
788   sycl::event interp_out_copy = sycl_data->sycl_queue.copy<CeedScalar>(interp_out, diag->d_interp_out, i_len, e);
789   copy_events.push_back(interp_out_copy);
790 
791   // CEED_EVAL_GRAD
792   CeedCallBackend(CeedBasisGetGrad(basis_in, &grad_in));
793   CeedCallSycl(ceed, diag->d_grad_in = sycl::malloc_device<CeedScalar>(g_len, sycl_data->sycl_device, sycl_data->sycl_context));
794   sycl::event grad_in_copy = sycl_data->sycl_queue.copy<CeedScalar>(grad_in, diag->d_grad_in, g_len, e);
795   copy_events.push_back(grad_in_copy);
796 
797   CeedCallBackend(CeedBasisGetGrad(basis_out, &grad_out));
798   CeedCallSycl(ceed, diag->d_grad_out = sycl::malloc_device<CeedScalar>(g_len, sycl_data->sycl_device, sycl_data->sycl_context));
799   sycl::event grad_out_copy = sycl_data->sycl_queue.copy<CeedScalar>(grad_out, diag->d_grad_out, g_len, e);
800   copy_events.push_back(grad_out_copy);
801 
802   // Arrays of  eval_modes
803   CeedCallSycl(ceed, diag->d_eval_mode_in = sycl::malloc_device<CeedEvalMode>(num_eval_mode_in, sycl_data->sycl_device, sycl_data->sycl_context));
804   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);
805   copy_events.push_back(eval_mode_in_copy);
806 
807   CeedCallSycl(ceed, diag->d_eval_mode_out = sycl::malloc_device<CeedEvalMode>(num_eval_mode_out, sycl_data->sycl_device, sycl_data->sycl_context));
808   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);
809   copy_events.push_back(eval_mode_out_copy);
810 
811   // Restriction
812   CeedCallBackend(CeedElemRestrictionReferenceCopy(rstr_out, &diag->diag_rstr));
813   CeedCallBackend(CeedElemRestrictionDestroy(&rstr_out));
814 
815   // Cleanup
816   CeedCallBackend(CeedDestroy(&ceed));
817   CeedCallBackend(CeedBasisDestroy(&basis_in));
818   CeedCallBackend(CeedBasisDestroy(&basis_out));
819 
820   // Wait for all copies to complete and handle exceptions
821   CeedCallSycl(ceed, sycl::event::wait_and_throw(copy_events));
822   return CEED_ERROR_SUCCESS;
823 }
824 
825 //------------------------------------------------------------------------------
826 //  Kernel for diagonal assembly
827 //------------------------------------------------------------------------------
828 static int CeedOperatorLinearDiagonal_Sycl(sycl::queue &sycl_queue, const bool is_point_block, const CeedInt num_elem,
829                                            const CeedOperatorDiag_Sycl *diag, const CeedScalar *assembled_qf_array, CeedScalar *elem_diag_array) {
830   const CeedSize      num_nodes         = diag->num_nodes;
831   const CeedSize      num_qpts          = diag->num_qpts;
832   const CeedSize      num_comp          = diag->num_comp;
833   const CeedSize      num_eval_mode_in  = diag->num_eval_mode_in;
834   const CeedSize      num_eval_mode_out = diag->num_eval_mode_out;
835   const CeedScalar   *identity          = diag->d_identity;
836   const CeedScalar   *interp_in         = diag->d_interp_in;
837   const CeedScalar   *grad_in           = diag->d_grad_in;
838   const CeedScalar   *interp_out        = diag->d_interp_out;
839   const CeedScalar   *grad_out          = diag->d_grad_out;
840   const CeedEvalMode *eval_mode_in      = diag->d_eval_mode_in;
841   const CeedEvalMode *eval_mode_out     = diag->d_eval_mode_out;
842 
843   sycl::range<1> kernel_range(num_elem * num_nodes);
844 
845   std::vector<sycl::event> e;
846 
847   if (!sycl_queue.is_in_order()) e = {sycl_queue.ext_oneapi_submit_barrier()};
848 
849   sycl_queue.parallel_for<CeedOperatorSyclLinearDiagonal>(kernel_range, e, [=](sycl::id<1> idx) {
850     const CeedInt tid = idx % num_nodes;
851     const CeedInt e   = idx / num_nodes;
852 
853     // Compute the diagonal of B^T D B
854     // Each element
855     CeedInt d_out = -1;
856     // Each basis eval mode pair
857     for (CeedSize e_out = 0; e_out < num_eval_mode_out; e_out++) {
858       const CeedScalar *bt = NULL;
859 
860       if (eval_mode_out[e_out] == CEED_EVAL_GRAD) ++d_out;
861       CeedOperatorGetBasisPointer_Sycl(&bt, eval_mode_out[e_out], identity, interp_out, &grad_out[d_out * num_qpts * num_nodes]);
862       CeedInt d_in = -1;
863 
864       for (CeedSize e_in = 0; e_in < num_eval_mode_in; e_in++) {
865         const CeedScalar *b = NULL;
866 
867         if (eval_mode_in[e_in] == CEED_EVAL_GRAD) ++d_in;
868         CeedOperatorGetBasisPointer_Sycl(&b, eval_mode_in[e_in], identity, interp_in, &grad_in[d_in * num_qpts * num_nodes]);
869         // Each component
870         for (CeedSize comp_out = 0; comp_out < num_comp; comp_out++) {
871           // Each qpoint/node pair
872           if (is_point_block) {
873             // Point Block Diagonal
874             for (CeedInt comp_in = 0; comp_in < num_comp; comp_in++) {
875               CeedScalar e_value = 0.0;
876 
877               for (CeedSize q = 0; q < num_qpts; q++) {
878                 const CeedScalar qf_value =
879                     assembled_qf_array[((((e_in * num_comp + comp_in) * num_eval_mode_out + e_out) * num_comp + comp_out) * num_elem + e) * num_qpts +
880                                        q];
881 
882                 e_value += bt[q * num_nodes + tid] * qf_value * b[q * num_nodes + tid];
883               }
884               elem_diag_array[((comp_out * num_comp + comp_in) * num_elem + e) * num_nodes + tid] += e_value;
885             }
886           } else {
887             // Diagonal Only
888             CeedScalar e_value = 0.0;
889 
890             for (CeedSize q = 0; q < num_qpts; q++) {
891               const CeedScalar qf_value =
892                   assembled_qf_array[((((e_in * num_comp + comp_out) * num_eval_mode_out + e_out) * num_comp + comp_out) * num_elem + e) * num_qpts +
893                                      q];
894               e_value += bt[q * num_nodes + tid] * qf_value * b[q * num_nodes + tid];
895             }
896             elem_diag_array[(comp_out * num_elem + e) * num_nodes + tid] += e_value;
897           }
898         }
899       }
900     }
901   });
902   return CEED_ERROR_SUCCESS;
903 }
904 
905 //------------------------------------------------------------------------------
906 // Assemble diagonal common code
907 //------------------------------------------------------------------------------
908 static inline int CeedOperatorAssembleDiagonalCore_Sycl(CeedOperator op, CeedVector assembled, CeedRequest *request, const bool is_point_block) {
909   Ceed               ceed;
910   Ceed_Sycl         *sycl_data;
911   CeedInt            num_elem;
912   CeedScalar        *elem_diag_array;
913   const CeedScalar  *assembled_qf_array;
914   CeedVector         assembled_qf = NULL;
915   CeedOperator_Sycl *impl;
916 
917   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
918   CeedCallBackend(CeedGetData(ceed, &sycl_data));
919   CeedCallBackend(CeedDestroy(&ceed));
920   CeedCallBackend(CeedOperatorGetData(op, &impl));
921 
922   // Assemble QFunction
923   {
924     CeedElemRestriction elem_rstr = NULL;
925 
926     CeedCallBackend(CeedOperatorLinearAssembleQFunctionBuildOrUpdate(op, &assembled_qf, &elem_rstr, request));
927     CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
928   }
929 
930   // Setup
931   if (!impl->diag) {
932     CeedCallBackend(CeedOperatorAssembleDiagonalSetup_Sycl(op));
933   }
934   CeedOperatorDiag_Sycl *diag = impl->diag;
935 
936   assert(diag != NULL);
937 
938   // Restriction
939   if (is_point_block && !diag->point_block_diag_rstr) {
940     CeedCallBackend(CeedOperatorCreateActivePointBlockRestriction(diag->diag_rstr, &diag->point_block_diag_rstr));
941   }
942   CeedElemRestriction diag_rstr = is_point_block ? diag->point_block_diag_rstr : diag->diag_rstr;
943 
944   // Create diagonal vector
945   CeedVector elem_diag = is_point_block ? diag->point_block_elem_diag : diag->elem_diag;
946 
947   if (!elem_diag) {
948     CeedCallBackend(CeedElemRestrictionCreateVector(diag_rstr, NULL, &elem_diag));
949     if (is_point_block) diag->point_block_elem_diag = elem_diag;
950     else diag->elem_diag = elem_diag;
951   }
952   CeedCallBackend(CeedVectorSetValue(elem_diag, 0.0));
953 
954   // Assemble element operator diagonals
955   CeedCallBackend(CeedVectorGetArray(elem_diag, CEED_MEM_DEVICE, &elem_diag_array));
956   CeedCallBackend(CeedVectorGetArrayRead(assembled_qf, CEED_MEM_DEVICE, &assembled_qf_array));
957   CeedCallBackend(CeedElemRestrictionGetNumElements(diag_rstr, &num_elem));
958 
959   // Compute the diagonal of B^T D B
960   CeedCallBackend(CeedOperatorLinearDiagonal_Sycl(sycl_data->sycl_queue, is_point_block, num_elem, diag, assembled_qf_array, elem_diag_array));
961 
962   // Wait for queue to complete and handle exceptions
963   sycl_data->sycl_queue.wait_and_throw();
964 
965   // Restore arrays
966   CeedCallBackend(CeedVectorRestoreArray(elem_diag, &elem_diag_array));
967   CeedCallBackend(CeedVectorRestoreArrayRead(assembled_qf, &assembled_qf_array));
968 
969   // Assemble local operator diagonal
970   CeedCallBackend(CeedElemRestrictionApply(diag_rstr, CEED_TRANSPOSE, elem_diag, assembled, request));
971 
972   // Cleanup
973   CeedCallBackend(CeedVectorDestroy(&assembled_qf));
974   return CEED_ERROR_SUCCESS;
975 }
976 
977 //------------------------------------------------------------------------------
978 // Assemble Linear Diagonal
979 //------------------------------------------------------------------------------
980 static int CeedOperatorLinearAssembleAddDiagonal_Sycl(CeedOperator op, CeedVector assembled, CeedRequest *request) {
981   CeedCallBackend(CeedOperatorAssembleDiagonalCore_Sycl(op, assembled, request, false));
982   return CEED_ERROR_SUCCESS;
983 }
984 
985 //------------------------------------------------------------------------------
986 // Assemble Linear Point Block Diagonal
987 //------------------------------------------------------------------------------
988 static int CeedOperatorLinearAssembleAddPointBlockDiagonal_Sycl(CeedOperator op, CeedVector assembled, CeedRequest *request) {
989   CeedCallBackend(CeedOperatorAssembleDiagonalCore_Sycl(op, assembled, request, true));
990   return CEED_ERROR_SUCCESS;
991 }
992 
993 //------------------------------------------------------------------------------
994 // Single operator assembly setup
995 //------------------------------------------------------------------------------
996 static int CeedSingleOperatorAssembleSetup_Sycl(CeedOperator op) {
997   Ceed    ceed;
998   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,
999                                                num_B_out_mats_to_load = 0, size_B_out = 0, num_qpts = 0, elem_size = 0, num_elem, num_comp,
1000                                                mat_start = 0;
1001   CeedEvalMode       *eval_mode_in = NULL, *eval_mode_out = NULL;
1002   const CeedScalar   *interp_in, *grad_in;
1003   CeedElemRestriction rstr_in = NULL, rstr_out = NULL;
1004   CeedBasis           basis_in = NULL, basis_out = NULL;
1005   CeedQFunctionField *qf_fields;
1006   CeedQFunction       qf;
1007   CeedOperatorField  *input_fields, *output_fields;
1008   CeedOperator_Sycl  *impl;
1009 
1010   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
1011   CeedCallBackend(CeedOperatorGetData(op, &impl));
1012 
1013   // Get input and output fields
1014   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &input_fields, &num_output_fields, &output_fields));
1015 
1016   // Determine active input basis eval mode
1017   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
1018   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_fields, NULL, NULL));
1019   // Note that the kernel will treat each dimension of a gradient action separately;
1020   // i.e., when an active input has a CEED_EVAL_GRAD mode, num_ eval_mode_in will increment by dim.
1021   // 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,
1022   // so num_B_in_mats_to_load will be incremented by 1.
1023   for (CeedInt i = 0; i < num_input_fields; i++) {
1024     CeedVector vec;
1025 
1026     CeedCallBackend(CeedOperatorFieldGetVector(input_fields[i], &vec));
1027     if (vec == CEED_VECTOR_ACTIVE) {
1028       CeedEvalMode        eval_mode;
1029       CeedElemRestriction elem_rstr;
1030       CeedBasis           basis;
1031 
1032       CeedCallBackend(CeedOperatorFieldGetElemRestriction(input_fields[i], &elem_rstr));
1033       if (!rstr_in) CeedCallBackend(CeedElemRestrictionReferenceCopy(elem_rstr, &rstr_in));
1034       CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
1035       CeedCallBackend(CeedElemRestrictionGetElementSize(rstr_in, &elem_size));
1036       CeedCallBackend(CeedOperatorFieldGetBasis(input_fields[i], &basis));
1037       if (!basis_in) CeedCallBackend(CeedBasisReferenceCopy(basis, &basis_in));
1038       CeedCheck(basis_in == basis, ceed, CEED_ERROR_BACKEND, "Backend does not implement operator assembly with multiple active bases");
1039       CeedCallBackend(CeedBasisDestroy(&basis));
1040       CeedCallBackend(CeedBasisGetDimension(basis_in, &dim));
1041       CeedCallBackend(CeedBasisGetNumQuadraturePoints(basis_in, &num_qpts));
1042       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
1043       if (eval_mode != CEED_EVAL_NONE) {
1044         CeedCallBackend(CeedRealloc(num_B_in_mats_to_load + 1, &eval_mode_in));
1045         eval_mode_in[num_B_in_mats_to_load] = eval_mode;
1046         num_B_in_mats_to_load += 1;
1047         if (eval_mode == CEED_EVAL_GRAD) {
1048           num_eval_mode_in += dim;
1049           size_B_in += dim * elem_size * num_qpts;
1050         } else {
1051           num_eval_mode_in += 1;
1052           size_B_in += elem_size * num_qpts;
1053         }
1054       }
1055     }
1056     CeedCallBackend(CeedVectorDestroy(&vec));
1057   }
1058 
1059   // Determine active output basis; basis_out and rstr_out only used if same as input, TODO
1060   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, NULL, NULL, &qf_fields));
1061   for (CeedInt i = 0; i < num_output_fields; i++) {
1062     CeedVector vec;
1063 
1064     CeedCallBackend(CeedOperatorFieldGetVector(output_fields[i], &vec));
1065     if (vec == CEED_VECTOR_ACTIVE) {
1066       CeedEvalMode        eval_mode;
1067       CeedElemRestriction elem_rstr;
1068       CeedBasis           basis;
1069 
1070       CeedCallBackend(CeedOperatorFieldGetElemRestriction(output_fields[i], &elem_rstr));
1071       if (!rstr_out) CeedCallBackend(CeedElemRestrictionReferenceCopy(elem_rstr, &rstr_out));
1072       CeedCheck(rstr_out == rstr_in, ceed, CEED_ERROR_BACKEND, "Backend does not implement multi-field non-composite operator assembly");
1073       CeedCallBackend(CeedElemRestrictionDestroy(&elem_rstr));
1074       CeedCallBackend(CeedOperatorFieldGetBasis(output_fields[i], &basis));
1075       if (!basis_out) CeedCallBackend(CeedBasisReferenceCopy(basis, &basis_out));
1076       CeedCheck(basis_out == basis, ceed, CEED_ERROR_BACKEND, "Backend does not implement operator assembly with multiple active bases");
1077       CeedCallBackend(CeedBasisDestroy(&basis));
1078       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
1079       if (eval_mode != CEED_EVAL_NONE) {
1080         CeedCallBackend(CeedRealloc(num_B_out_mats_to_load + 1, &eval_mode_out));
1081         eval_mode_out[num_B_out_mats_to_load] = eval_mode;
1082         num_B_out_mats_to_load += 1;
1083         if (eval_mode == CEED_EVAL_GRAD) {
1084           num_eval_mode_out += dim;
1085           size_B_out += dim * elem_size * num_qpts;
1086         } else {
1087           num_eval_mode_out += 1;
1088           size_B_out += elem_size * num_qpts;
1089         }
1090       }
1091     }
1092     CeedCallBackend(CeedVectorDestroy(&vec));
1093   }
1094   CeedCheck(num_eval_mode_in > 0 && num_eval_mode_out > 0, ceed, CEED_ERROR_UNSUPPORTED, "Cannot assemble operator without inputs/outputs");
1095 
1096   CeedCallBackend(CeedElemRestrictionGetNumElements(rstr_in, &num_elem));
1097   CeedCallBackend(CeedElemRestrictionGetNumComponents(rstr_in, &num_comp));
1098 
1099   CeedCallBackend(CeedCalloc(1, &impl->asmb));
1100   CeedOperatorAssemble_Sycl *asmb = impl->asmb;
1101   asmb->num_elem                  = num_elem;
1102 
1103   Ceed_Sycl *sycl_data;
1104   CeedCallBackend(CeedGetData(ceed, &sycl_data));
1105 
1106   // Kernel setup
1107   int elems_per_block     = 1;
1108   asmb->elems_per_block   = elems_per_block;
1109   asmb->block_size_x      = elem_size;
1110   asmb->block_size_y      = elem_size;
1111   asmb->num_eval_mode_in  = num_eval_mode_in;
1112   asmb->num_eval_mode_out = num_eval_mode_out;
1113   asmb->num_qpts          = num_qpts;
1114   asmb->num_nodes         = elem_size;
1115   asmb->block_size        = elem_size * elem_size * elems_per_block;
1116   asmb->num_comp          = num_comp;
1117 
1118   // Build 'full' B matrices (not 1D arrays used for tensor-product matrices
1119   CeedCallBackend(CeedBasisGetInterp(basis_in, &interp_in));
1120   CeedCallBackend(CeedBasisGetGrad(basis_in, &grad_in));
1121 
1122   // Load into B_in, in order that they will be used in eval_mode
1123   CeedCallSycl(ceed, asmb->d_B_in = sycl::malloc_device<CeedScalar>(size_B_in, sycl_data->sycl_device, sycl_data->sycl_context));
1124   for (int i = 0; i < num_B_in_mats_to_load; i++) {
1125     CeedEvalMode eval_mode = eval_mode_in[i];
1126 
1127     if (eval_mode == CEED_EVAL_INTERP) {
1128       std::vector<sycl::event> e;
1129 
1130       if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
1131       sycl_data->sycl_queue.copy<CeedScalar>(interp_in, &asmb->d_B_in[mat_start], elem_size * num_qpts, e);
1132       mat_start += elem_size * num_qpts;
1133     } else if (eval_mode == CEED_EVAL_GRAD) {
1134       std::vector<sycl::event> e;
1135 
1136       if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
1137       sycl_data->sycl_queue.copy<CeedScalar>(grad_in, &asmb->d_B_in[mat_start], dim * elem_size * num_qpts, e);
1138       mat_start += dim * elem_size * num_qpts;
1139     }
1140   }
1141 
1142   const CeedScalar *interp_out, *grad_out;
1143   // Note that this function currently assumes 1 basis, so this should always be true
1144   // for now
1145   if (basis_out == basis_in) {
1146     interp_out = interp_in;
1147     grad_out   = grad_in;
1148   } else {
1149     CeedCallBackend(CeedBasisGetInterp(basis_out, &interp_out));
1150     CeedCallBackend(CeedBasisGetGrad(basis_out, &grad_out));
1151   }
1152 
1153   // Load into B_out, in order that they will be used in eval_mode
1154   mat_start = 0;
1155   CeedCallSycl(ceed, asmb->d_B_out = sycl::malloc_device<CeedScalar>(size_B_out, sycl_data->sycl_device, sycl_data->sycl_context));
1156   for (int i = 0; i < num_B_out_mats_to_load; i++) {
1157     CeedEvalMode eval_mode = eval_mode_out[i];
1158 
1159     if (eval_mode == CEED_EVAL_INTERP) {
1160       std::vector<sycl::event> e;
1161 
1162       if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
1163       sycl_data->sycl_queue.copy<CeedScalar>(interp_out, &asmb->d_B_out[mat_start], elem_size * num_qpts, e);
1164       mat_start += elem_size * num_qpts;
1165     } else if (eval_mode == CEED_EVAL_GRAD) {
1166       std::vector<sycl::event> e;
1167 
1168       if (!sycl_data->sycl_queue.is_in_order()) e = {sycl_data->sycl_queue.ext_oneapi_submit_barrier()};
1169       sycl_data->sycl_queue.copy<CeedScalar>(grad_out, &asmb->d_B_out[mat_start], dim * elem_size * num_qpts, e);
1170       mat_start += dim * elem_size * num_qpts;
1171     }
1172   }
1173   CeedCallBackend(CeedDestroy(&ceed));
1174   CeedCallBackend(CeedElemRestrictionDestroy(&rstr_in));
1175   CeedCallBackend(CeedElemRestrictionDestroy(&rstr_out));
1176   CeedCallBackend(CeedBasisDestroy(&basis_in));
1177   CeedCallBackend(CeedBasisDestroy(&basis_out));
1178   return CEED_ERROR_SUCCESS;
1179 }
1180 
1181 //------------------------------------------------------------------------------
1182 // Matrix assembly kernel for low-order elements (3D thread block)
1183 //------------------------------------------------------------------------------
1184 static int CeedOperatorLinearAssemble_Sycl(sycl::queue &sycl_queue, const CeedOperator_Sycl *impl, const CeedScalar *qf_array,
1185                                            CeedScalar *values_array) {
1186   // This kernels assumes B_in and B_out have the same number of quadrature points and basis points.
1187   // TODO: expand to more general cases
1188   CeedOperatorAssemble_Sycl *asmb              = impl->asmb;
1189   const CeedInt              num_elem          = asmb->num_elem;
1190   const CeedSize             num_nodes         = asmb->num_nodes;
1191   const CeedSize             num_comp          = asmb->num_comp;
1192   const CeedSize             num_qpts          = asmb->num_qpts;
1193   const CeedSize             num_eval_mode_in  = asmb->num_eval_mode_in;
1194   const CeedSize             num_eval_mode_out = asmb->num_eval_mode_out;
1195 
1196   // Strides for final output ordering, determined by the reference (inference) implementation of the symbolic assembly, slowest --> fastest: element,
1197   // comp_in, comp_out, node_row, node_col
1198   const CeedSize comp_out_stride = num_nodes * num_nodes;
1199   const CeedSize comp_in_stride  = comp_out_stride * num_comp;
1200   const CeedSize e_stride        = comp_in_stride * num_comp;
1201   // Strides for QF array, slowest --> fastest:  eval_mode_in, comp_in,  eval_mode_out, comp_out, elem, qpt
1202   const CeedSize q_e_stride             = num_qpts;
1203   const CeedSize q_comp_out_stride      = num_elem * q_e_stride;
1204   const CeedSize q_eval_mode_out_stride = q_comp_out_stride * num_comp;
1205   const CeedSize q_comp_in_stride       = q_eval_mode_out_stride * num_eval_mode_out;
1206   const CeedSize q_eval_mode_in_stride  = q_comp_in_stride * num_comp;
1207 
1208   CeedScalar *B_in, *B_out;
1209   B_in                       = asmb->d_B_in;
1210   B_out                      = asmb->d_B_out;
1211   const CeedInt block_size_x = asmb->block_size_x;
1212   const CeedInt block_size_y = asmb->block_size_y;
1213 
1214   sycl::range<3> kernel_range(num_elem, block_size_y, block_size_x);
1215 
1216   std::vector<sycl::event> e;
1217 
1218   if (!sycl_queue.is_in_order()) e = {sycl_queue.ext_oneapi_submit_barrier()};
1219   sycl_queue.parallel_for<CeedOperatorSyclLinearAssemble>(kernel_range, e, [=](sycl::id<3> idx) {
1220     const int e = idx.get(0);  // Element index
1221     const int l = idx.get(1);  // The output column index of each B^TDB operation
1222     const int i = idx.get(2);  // The output row index of each B^TDB operation
1223                                // such that we have (Bout^T)_ij D_jk Bin_kl = C_il
1224     for (CeedSize comp_in = 0; comp_in < num_comp; comp_in++) {
1225       for (CeedSize comp_out = 0; comp_out < num_comp; comp_out++) {
1226         CeedScalar result        = 0.0;
1227         CeedSize   qf_index_comp = q_comp_in_stride * comp_in + q_comp_out_stride * comp_out + q_e_stride * e;
1228 
1229         for (CeedSize eval_mode_in = 0; eval_mode_in < num_eval_mode_in; eval_mode_in++) {
1230           CeedSize b_in_index = eval_mode_in * num_qpts * num_nodes;
1231 
1232           for (CeedSize eval_mode_out = 0; eval_mode_out < num_eval_mode_out; eval_mode_out++) {
1233             CeedSize b_out_index = eval_mode_out * num_qpts * num_nodes;
1234             CeedSize qf_index    = qf_index_comp + q_eval_mode_out_stride * eval_mode_out + q_eval_mode_in_stride * eval_mode_in;
1235 
1236             // Perform the B^T D B operation for this 'chunk' of D (the qf_array)
1237             for (CeedSize j = 0; j < num_qpts; j++) {
1238               result += B_out[b_out_index + j * num_nodes + i] * qf_array[qf_index + j] * B_in[b_in_index + j * num_nodes + l];
1239             }
1240           }  // end of  eval_mode_out
1241         }  // end of  eval_mode_in
1242         CeedSize val_index = comp_in_stride * comp_in + comp_out_stride * comp_out + e_stride * e + num_nodes * i + l;
1243 
1244         values_array[val_index] = result;
1245       }  // end of out component
1246     }  // end of in component
1247   });
1248   return CEED_ERROR_SUCCESS;
1249 }
1250 
1251 //------------------------------------------------------------------------------
1252 // Fallback kernel for larger orders (1D thread block)
1253 //------------------------------------------------------------------------------
1254 /*
1255 static int CeedOperatorLinearAssembleFallback_Sycl(sycl::queue &sycl_queue, const CeedOperator_Sycl *impl, const CeedScalar *qf_array,
1256                                                    CeedScalar *values_array) {
1257   // This kernel assumes B_in and B_out have the same number of quadrature points and basis points.
1258   // TODO: expand to more general cases
1259   CeedOperatorAssemble_Sycl *asmb        = impl->asmb;
1260   const CeedInt              num_elem       = asmb->num_elem;
1261   const CeedInt              num_nodes      = asmb->num_nodes;
1262   const CeedInt              num_comp       = asmb->num_comp;
1263   const CeedInt              num_qpts       = asmb->num_qpts;
1264   const CeedInt              num_eval_mode_in  = asmb->num_eval_mode_in;
1265   const CeedInt              num_eval_mode_out = asmb->num_eval_mode_out;
1266 
1267   // Strides for final output ordering, determined by the reference (interface) implementation of the symbolic assembly, slowest --> fastest: elememt,
1268   // comp_in, comp_out, node_row, node_col
1269   const CeedInt comp_out_stride = num_nodes * num_nodes;
1270   const CeedInt comp_in_stride  = comp_out_stride * num_comp;
1271   const CeedInt e_stride        = comp_in_stride * num_comp;
1272   // Strides for QF array, slowest --> fastest:  eval_mode_in, comp_in,  eval_mode_out, comp_out, elem, qpt
1273   const CeedInt q_e_stride         = num_qpts;
1274   const CeedInt q_comp_out_stride  = num_elem * q_e_stride;
1275   const CeedInt q_eval_mode_out_stride = q_comp_out_stride * num_comp;
1276   const CeedInt q_comp_in_stride   = q_eval_mode_out_stride * num_eval_mode_out;
1277   const CeedInt q_eval_mode_in_stride  = q_comp_in_stride * num_comp;
1278 
1279   CeedScalar *B_in, *B_out;
1280   B_in                        = asmb->d_B_in;
1281   B_out                       = asmb->d_B_out;
1282   const CeedInt elems_per_block = asmb->elems_per_block;
1283   const CeedInt block_size_x  = asmb->block_size_x;
1284   const CeedInt block_size_y  = asmb->block_size_y;  // This will be 1 for the fallback kernel
1285 
1286   const CeedInt     grid = num_elem / elems_per_block + ((num_elem / elems_per_block * elems_per_block < num_elem) ? 1 : 0);
1287   sycl::range<3>    local_range(block_size_x, block_size_y, elems_per_block);
1288   sycl::range<3>    global_range(grid * block_size_x, block_size_y, elems_per_block);
1289   sycl::nd_range<3> kernel_range(global_range, local_range);
1290 
1291   sycl_queue.parallel_for<CeedOperatorSyclLinearAssembleFallback>(kernel_range, [=](sycl::nd_item<3> work_item) {
1292     const CeedInt blockIdx  = work_item.get_group(0);
1293     const CeedInt gridDimx  = work_item.get_group_range(0);
1294     const CeedInt threadIdx = work_item.get_local_id(0);
1295     const CeedInt threadIdz = work_item.get_local_id(2);
1296     const CeedInt blockDimz = work_item.get_local_range(2);
1297 
1298     const int l = threadIdx;  // The output column index of each B^TDB operation
1299                               // such that we have (Bout^T)_ij D_jk Bin_kl = C_il
1300     for (CeedInt e = blockIdx * blockDimz + threadIdz; e < num_elem; e += gridDimx * blockDimz) {
1301       for (CeedInt comp_in = 0; comp_in < num_comp; comp_in++) {
1302         for (CeedInt comp_out = 0; comp_out < num_comp; comp_out++) {
1303           for (CeedInt i = 0; i < num_nodes; i++) {
1304             CeedScalar result        = 0.0;
1305             CeedInt    qf_index_comp = q_comp_in_stride * comp_in + q_comp_out_stride * comp_out + q_e_stride * e;
1306             for (CeedInt  eval_mode_in = 0;  eval_mode_in < num_eval_mode_in;  eval_mode_in++) {
1307               CeedInt b_in_index =  eval_mode_in * num_qpts * num_nodes;
1308               for (CeedInt  eval_mode_out = 0;  eval_mode_out < num_eval_mode_out;  eval_mode_out++) {
1309                 CeedInt b_out_index =  eval_mode_out * num_qpts * num_nodes;
1310                 CeedInt qf_index    = qf_index_comp + q_eval_mode_out_stride *  eval_mode_out + q_eval_mode_in_stride *  eval_mode_in;
1311                 // Perform the B^T D B operation for this 'chunk' of D (the qf_array)
1312                 for (CeedInt j = 0; j < num_qpts; j++) {
1313                   result += B_out[b_out_index + j * num_nodes + i] * qf_array[qf_index + j] * B_in[b_in_index + j * num_nodes + l];
1314                 }
1315               }  // end of  eval_mode_out
1316             }    // end of  eval_mode_in
1317             CeedInt val_index       = comp_in_stride * comp_in + comp_out_stride * comp_out + e_stride * e + num_nodes * i + l;
1318             values_array[val_index] = result;
1319           }  // end of loop over element node index, i
1320         }    // end of out component
1321       }      // end of in component
1322     }        // end of element loop
1323   });
1324   return CEED_ERROR_SUCCESS;
1325 }*/
1326 
1327 //------------------------------------------------------------------------------
1328 // Assemble matrix data for COO matrix of assembled operator.
1329 // The sparsity pattern is set by CeedOperatorLinearAssembleSymbolic.
1330 //
1331 // Note that this (and other assembly routines) currently assume only one active
1332 // input restriction/basis per operator (could have multiple basis eval modes).
1333 // TODO: allow multiple active input restrictions/basis objects
1334 //------------------------------------------------------------------------------
1335 static int CeedSingleOperatorAssemble_Sycl(CeedOperator op, CeedInt offset, CeedVector values) {
1336   Ceed                ceed;
1337   Ceed_Sycl          *sycl_data;
1338   CeedScalar         *values_array;
1339   const CeedScalar   *qf_array;
1340   CeedVector          assembled_qf = NULL;
1341   CeedElemRestriction rstr_q       = NULL;
1342   CeedOperator_Sycl  *impl;
1343 
1344   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
1345   CeedCallBackend(CeedGetData(ceed, &sycl_data));
1346   CeedCallBackend(CeedDestroy(&ceed));
1347   CeedCallBackend(CeedOperatorGetData(op, &impl));
1348 
1349   // Setup
1350   if (!impl->asmb) {
1351     CeedCallBackend(CeedSingleOperatorAssembleSetup_Sycl(op));
1352     assert(impl->asmb != NULL);
1353   }
1354 
1355   // Assemble QFunction
1356   CeedCallBackend(CeedOperatorLinearAssembleQFunctionBuildOrUpdate(op, &assembled_qf, &rstr_q, CEED_REQUEST_IMMEDIATE));
1357   CeedCallBackend(CeedElemRestrictionDestroy(&rstr_q));
1358   CeedCallBackend(CeedVectorGetArrayWrite(values, CEED_MEM_DEVICE, &values_array));
1359   values_array += offset;
1360   CeedCallBackend(CeedVectorGetArrayRead(assembled_qf, CEED_MEM_DEVICE, &qf_array));
1361 
1362   // Compute B^T D B
1363   CeedCallBackend(CeedOperatorLinearAssemble_Sycl(sycl_data->sycl_queue, impl, qf_array, values_array));
1364 
1365   // Wait for kernels to be completed
1366   // Kris: Review if this is necessary -- enqueing an async barrier may be sufficient
1367   sycl_data->sycl_queue.wait_and_throw();
1368 
1369   // Restore arrays
1370   CeedCallBackend(CeedVectorRestoreArray(values, &values_array));
1371   CeedCallBackend(CeedVectorRestoreArrayRead(assembled_qf, &qf_array));
1372 
1373   // Cleanup
1374   CeedCallBackend(CeedVectorDestroy(&assembled_qf));
1375   return CEED_ERROR_SUCCESS;
1376 }
1377 
1378 //------------------------------------------------------------------------------
1379 // Create operator
1380 //------------------------------------------------------------------------------
1381 int CeedOperatorCreate_Sycl(CeedOperator op) {
1382   Ceed               ceed;
1383   CeedOperator_Sycl *impl;
1384 
1385   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
1386 
1387   CeedCallBackend(CeedCalloc(1, &impl));
1388   CeedCallBackend(CeedOperatorSetData(op, impl));
1389 
1390   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleQFunction", CeedOperatorLinearAssembleQFunction_Sycl));
1391   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleQFunctionUpdate", CeedOperatorLinearAssembleQFunctionUpdate_Sycl));
1392   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleAddDiagonal", CeedOperatorLinearAssembleAddDiagonal_Sycl));
1393   CeedCallBackend(
1394       CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleAddPointBlockDiagonal", CeedOperatorLinearAssembleAddPointBlockDiagonal_Sycl));
1395   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "LinearAssembleSingle", CeedSingleOperatorAssemble_Sycl));
1396   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "ApplyAdd", CeedOperatorApplyAdd_Sycl));
1397   CeedCallBackend(CeedSetBackendFunctionCpp(ceed, "Operator", op, "Destroy", CeedOperatorDestroy_Sycl));
1398   CeedCallBackend(CeedDestroy(&ceed));
1399   return CEED_ERROR_SUCCESS;
1400 }
1401 
1402 //------------------------------------------------------------------------------
1403