2 * Mesa 3-D graphics library
5 * Copyright (C) 2009 VMware, Inc. All Rights Reserved.
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * VMWARE BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
21 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
27 #include "main/glheader.h"
28 #include "main/context.h"
29 #include "main/macros.h"
31 #include "prog_instruction.h"
32 #include "prog_optimize.h"
33 #include "prog_print.h"
36 #define MAX_LOOP_NESTING 50
37 /* MAX_PROGRAM_TEMPS is a low number (256), and we want to be able to
38 * register allocate many temporary values into that small number of
39 * temps. So allow large temporary indices coming into the register
42 #define REG_ALLOCATE_MAX_PROGRAM_TEMPS ((1 << INST_INDEX_BITS) - 1)
44 static GLboolean dbg = GL_FALSE;
49 * Returns the mask of channels (bitmask of WRITEMASK_X,Y,Z,W) which
50 * are read from the given src in this instruction, We also provide
51 * one optional masks which may mask other components in the dst
55 get_src_arg_mask(const struct prog_instruction *inst,
56 GLuint arg, GLuint dst_mask)
58 GLuint read_mask, channel_mask;
61 ASSERT(arg < _mesa_num_inst_src_regs(inst->Opcode));
63 /* Form the dst register, find the written channels */
64 if (inst->CondUpdate) {
65 channel_mask = WRITEMASK_XYZW;
68 switch (inst->Opcode) {
88 channel_mask = inst->DstReg.WriteMask & dst_mask;
97 channel_mask = WRITEMASK_X;
100 channel_mask = WRITEMASK_XY;
104 channel_mask = WRITEMASK_XYZ;
107 channel_mask = WRITEMASK_XYZW;
112 /* Now, given the src swizzle and the written channels, find which
113 * components are actually read
116 for (comp = 0; comp < 4; ++comp) {
117 const GLuint coord = GET_SWZ(inst->SrcReg[arg].Swizzle, comp);
119 if (channel_mask & (1 << comp) && coord <= SWIZZLE_W)
120 read_mask |= 1 << coord;
128 * For a MOV instruction, compute a write mask when src register also has
132 get_dst_mask_for_mov(const struct prog_instruction *mov, GLuint src_mask)
134 const GLuint mask = mov->DstReg.WriteMask;
136 GLuint updated_mask = 0x0;
138 ASSERT(mov->Opcode == OPCODE_MOV);
140 for (comp = 0; comp < 4; ++comp) {
142 if ((mask & (1 << comp)) == 0)
144 src_comp = GET_SWZ(mov->SrcReg[0].Swizzle, comp);
145 if ((src_mask & (1 << src_comp)) == 0)
147 updated_mask |= 1 << comp;
155 * Ensure that the swizzle is regular. That is, all of the swizzle
156 * terms are SWIZZLE_X,Y,Z,W and not SWIZZLE_ZERO or SWIZZLE_ONE.
159 is_swizzle_regular(GLuint swz)
161 return GET_SWZ(swz,0) <= SWIZZLE_W &&
162 GET_SWZ(swz,1) <= SWIZZLE_W &&
163 GET_SWZ(swz,2) <= SWIZZLE_W &&
164 GET_SWZ(swz,3) <= SWIZZLE_W;
169 * In 'prog' remove instruction[i] if removeFlags[i] == TRUE.
170 * \return number of instructions removed
173 remove_instructions(struct gl_program *prog, const GLboolean *removeFlags)
175 GLint i, removeEnd = 0, removeCount = 0;
176 GLuint totalRemoved = 0;
179 for (i = prog->NumInstructions - 1; i >= 0; i--) {
180 if (removeFlags[i]) {
182 if (removeCount == 0) {
183 /* begin a run of instructions to remove */
188 /* extend the run of instructions to remove */
193 /* don't remove this instruction, but check if the preceeding
194 * instructions are to be removed.
196 if (removeCount > 0) {
197 GLint removeStart = removeEnd - removeCount + 1;
198 _mesa_delete_instructions(prog, removeStart, removeCount);
199 removeStart = removeCount = 0; /* reset removal info */
203 /* Finish removing if the first instruction was to be removed. */
204 if (removeCount > 0) {
205 GLint removeStart = removeEnd - removeCount + 1;
206 _mesa_delete_instructions(prog, removeStart, removeCount);
213 * Remap register indexes according to map.
214 * \param prog the program to search/replace
215 * \param file the type of register file to search/replace
216 * \param map maps old register indexes to new indexes
219 replace_regs(struct gl_program *prog, gl_register_file file, const GLint map[])
223 for (i = 0; i < prog->NumInstructions; i++) {
224 struct prog_instruction *inst = prog->Instructions + i;
225 const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
227 for (j = 0; j < numSrc; j++) {
228 if (inst->SrcReg[j].File == file) {
229 GLuint index = inst->SrcReg[j].Index;
230 ASSERT(map[index] >= 0);
231 inst->SrcReg[j].Index = map[index];
234 if (inst->DstReg.File == file) {
235 const GLuint index = inst->DstReg.Index;
236 ASSERT(map[index] >= 0);
237 inst->DstReg.Index = map[index];
244 * Remove dead instructions from the given program.
245 * This is very primitive for now. Basically look for temp registers
246 * that are written to but never read. Remove any instructions that
247 * write to such registers. Be careful with condition code setters.
250 _mesa_remove_dead_code_global(struct gl_program *prog)
252 GLboolean tempRead[REG_ALLOCATE_MAX_PROGRAM_TEMPS][4];
253 GLboolean *removeInst; /* per-instruction removal flag */
254 GLuint i, rem = 0, comp;
256 memset(tempRead, 0, sizeof(tempRead));
259 printf("Optimize: Begin dead code removal\n");
260 /*_mesa_print_program(prog);*/
264 calloc(1, prog->NumInstructions * sizeof(GLboolean));
266 /* Determine which temps are read and written */
267 for (i = 0; i < prog->NumInstructions; i++) {
268 const struct prog_instruction *inst = prog->Instructions + i;
269 const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
273 for (j = 0; j < numSrc; j++) {
274 if (inst->SrcReg[j].File == PROGRAM_TEMPORARY) {
275 const GLuint index = inst->SrcReg[j].Index;
277 ASSERT(index < REG_ALLOCATE_MAX_PROGRAM_TEMPS);
278 read_mask = get_src_arg_mask(inst, j, NO_MASK);
280 if (inst->SrcReg[j].RelAddr) {
282 printf("abort remove dead code (indirect temp)\n");
286 for (comp = 0; comp < 4; comp++) {
287 const GLuint swz = GET_SWZ(inst->SrcReg[j].Swizzle, comp);
289 if ((read_mask & (1 << swz)) == 0)
291 if (swz <= SWIZZLE_W)
292 tempRead[index][swz] = GL_TRUE;
298 if (inst->DstReg.File == PROGRAM_TEMPORARY) {
299 const GLuint index = inst->DstReg.Index;
300 ASSERT(index < REG_ALLOCATE_MAX_PROGRAM_TEMPS);
302 if (inst->DstReg.RelAddr) {
304 printf("abort remove dead code (indirect temp)\n");
308 if (inst->CondUpdate) {
309 /* If we're writing to this register and setting condition
310 * codes we cannot remove the instruction. Prevent removal
311 * by setting the 'read' flag.
313 tempRead[index][0] = GL_TRUE;
314 tempRead[index][1] = GL_TRUE;
315 tempRead[index][2] = GL_TRUE;
316 tempRead[index][3] = GL_TRUE;
321 /* find instructions that write to dead registers, flag for removal */
322 for (i = 0; i < prog->NumInstructions; i++) {
323 struct prog_instruction *inst = prog->Instructions + i;
324 const GLuint numDst = _mesa_num_inst_dst_regs(inst->Opcode);
326 if (numDst != 0 && inst->DstReg.File == PROGRAM_TEMPORARY) {
327 GLint chan, index = inst->DstReg.Index;
329 for (chan = 0; chan < 4; chan++) {
330 if (!tempRead[index][chan] &&
331 inst->DstReg.WriteMask & (1 << chan)) {
333 printf("Remove writemask on %u.%c\n", i,
334 chan == 3 ? 'w' : 'x' + chan);
336 inst->DstReg.WriteMask &= ~(1 << chan);
341 if (inst->DstReg.WriteMask == 0) {
342 /* If we cleared all writes, the instruction can be removed. */
344 printf("Remove instruction %u: \n", i);
345 removeInst[i] = GL_TRUE;
350 /* now remove the instructions which aren't needed */
351 rem = remove_instructions(prog, removeInst);
354 printf("Optimize: End dead code removal.\n");
355 printf(" %u channel writes removed\n", rem);
356 printf(" %u instructions removed\n", rem);
357 /*_mesa_print_program(prog);*/
376 * Scan forward in program from 'start' for the next occurances of TEMP[index].
377 * We look if an instruction reads the component given by the masks and if they
379 * Return READ, WRITE, FLOW or END to indicate the next usage or an indicator
380 * that we can't look further.
383 find_next_use(const struct gl_program *prog,
390 for (i = start; i < prog->NumInstructions; i++) {
391 const struct prog_instruction *inst = prog->Instructions + i;
392 switch (inst->Opcode) {
408 const GLuint numSrc = _mesa_num_inst_src_regs(inst->Opcode);
410 for (j = 0; j < numSrc; j++) {
411 if (inst->SrcReg[j].RelAddr ||
412 (inst->SrcReg[j].File == PROGRAM_TEMPORARY &&
413 inst->SrcReg[j].Index == index &&
414 (get_src_arg_mask(inst,j,NO_MASK) & mask)))
417 if (_mesa_num_inst_dst_regs(inst->Opcode) == 1 &&
418 inst->DstReg.File == PROGRAM_TEMPORARY &&
419 inst->DstReg.Index == index) {
420 mask &= ~inst->DstReg.WriteMask;
432 * Is the given instruction opcode a flow-control opcode?
433 * XXX maybe move this into prog_instruction.[ch]
436 _mesa_is_flow_control_opcode(enum prog_opcode opcode)
458 * Test if the given instruction is a simple MOV (no conditional updating,
459 * not relative addressing, no negation/abs, etc).
462 can_downward_mov_be_modifed(const struct prog_instruction *mov)
465 mov->Opcode == OPCODE_MOV &&
466 mov->CondUpdate == GL_FALSE &&
467 mov->SrcReg[0].RelAddr == 0 &&
468 mov->SrcReg[0].Negate == 0 &&
469 mov->SrcReg[0].Abs == 0 &&
470 mov->SrcReg[0].HasIndex2 == 0 &&
471 mov->SrcReg[0].RelAddr2 == 0 &&
472 mov->DstReg.RelAddr == 0 &&
473 mov->DstReg.CondMask == COND_TR;
478 can_upward_mov_be_modifed(const struct prog_instruction *mov)
481 can_downward_mov_be_modifed(mov) &&
482 mov->DstReg.File == PROGRAM_TEMPORARY &&
483 mov->SaturateMode == SATURATE_OFF;
488 * Try to remove use of extraneous MOV instructions, to free them up for dead
492 _mesa_remove_extra_move_use(struct gl_program *prog)
497 printf("Optimize: Begin remove extra move use\n");
498 _mesa_print_program(prog);
502 * Look for sequences such as this:
505 * FOO tmpY, tmpX, arg1;
509 * FOO tmpY, arg0, arg1;
512 for (i = 0; i + 1 < prog->NumInstructions; i++) {
513 const struct prog_instruction *mov = prog->Instructions + i;
514 GLuint dst_mask, src_mask;
515 if (can_upward_mov_be_modifed(mov) == GL_FALSE)
518 /* Scanning the code, we maintain the components which are still active in
521 dst_mask = mov->DstReg.WriteMask;
522 src_mask = get_src_arg_mask(mov, 0, NO_MASK);
524 /* Walk through remaining instructions until the or src reg gets
525 * rewritten or we get into some flow-control, eliminating the use of
528 for (j = i + 1; j < prog->NumInstructions; j++) {
529 struct prog_instruction *inst2 = prog->Instructions + j;
532 if (_mesa_is_flow_control_opcode(inst2->Opcode))
535 /* First rewrite this instruction's args if appropriate. */
536 for (arg = 0; arg < _mesa_num_inst_src_regs(inst2->Opcode); arg++) {
537 GLuint comp, read_mask;
539 if (inst2->SrcReg[arg].File != mov->DstReg.File ||
540 inst2->SrcReg[arg].Index != mov->DstReg.Index ||
541 inst2->SrcReg[arg].RelAddr ||
542 inst2->SrcReg[arg].Abs)
544 read_mask = get_src_arg_mask(inst2, arg, NO_MASK);
546 /* Adjust the swizzles of inst2 to point at MOV's source if ALL the
547 * components read still come from the mov instructions
549 if (is_swizzle_regular(inst2->SrcReg[arg].Swizzle) &&
550 (read_mask & dst_mask) == read_mask) {
551 for (comp = 0; comp < 4; comp++) {
552 const GLuint inst2_swz =
553 GET_SWZ(inst2->SrcReg[arg].Swizzle, comp);
554 const GLuint s = GET_SWZ(mov->SrcReg[0].Swizzle, inst2_swz);
555 inst2->SrcReg[arg].Swizzle &= ~(7 << (3 * comp));
556 inst2->SrcReg[arg].Swizzle |= s << (3 * comp);
557 inst2->SrcReg[arg].Negate ^= (((mov->SrcReg[0].Negate >>
558 inst2_swz) & 0x1) << comp);
560 inst2->SrcReg[arg].File = mov->SrcReg[0].File;
561 inst2->SrcReg[arg].Index = mov->SrcReg[0].Index;
565 /* The source of MOV is written. This potentially deactivates some
566 * components from the src and dst of the MOV instruction
568 if (inst2->DstReg.File == mov->DstReg.File &&
569 (inst2->DstReg.RelAddr ||
570 inst2->DstReg.Index == mov->DstReg.Index)) {
571 dst_mask &= ~inst2->DstReg.WriteMask;
572 src_mask = get_src_arg_mask(mov, 0, dst_mask);
575 /* Idem when the destination of mov is written */
576 if (inst2->DstReg.File == mov->SrcReg[0].File &&
577 (inst2->DstReg.RelAddr ||
578 inst2->DstReg.Index == mov->SrcReg[0].Index)) {
579 src_mask &= ~inst2->DstReg.WriteMask;
580 dst_mask &= get_dst_mask_for_mov(mov, src_mask);
588 printf("Optimize: End remove extra move use.\n");
589 /*_mesa_print_program(prog);*/
595 * Complements dead_code_global. Try to remove code in block of code by
596 * carefully monitoring the swizzles. Both functions should be merged into one
597 * with a proper control flow graph
600 _mesa_remove_dead_code_local(struct gl_program *prog)
602 GLboolean *removeInst;
603 GLuint i, arg, rem = 0;
606 calloc(1, prog->NumInstructions * sizeof(GLboolean));
608 for (i = 0; i < prog->NumInstructions; i++) {
609 const struct prog_instruction *inst = prog->Instructions + i;
610 const GLuint index = inst->DstReg.Index;
611 const GLuint mask = inst->DstReg.WriteMask;
614 /* We must deactivate the pass as soon as some indirection is used */
615 if (inst->DstReg.RelAddr)
617 for (arg = 0; arg < _mesa_num_inst_src_regs(inst->Opcode); arg++)
618 if (inst->SrcReg[arg].RelAddr)
621 if (_mesa_is_flow_control_opcode(inst->Opcode) ||
622 _mesa_num_inst_dst_regs(inst->Opcode) == 0 ||
623 inst->DstReg.File != PROGRAM_TEMPORARY ||
624 inst->DstReg.RelAddr)
627 use = find_next_use(prog, i+1, index, mask);
628 if (use == WRITE || use == END)
629 removeInst[i] = GL_TRUE;
632 rem = remove_instructions(prog, removeInst);
641 * Try to inject the destination of mov as the destination of inst and recompute
642 * the swizzles operators for the sources of inst if required. Return GL_TRUE
643 * of the substitution was possible, GL_FALSE otherwise
646 _mesa_merge_mov_into_inst(struct prog_instruction *inst,
647 const struct prog_instruction *mov)
649 /* Indirection table which associates destination and source components for
650 * the mov instruction
652 const GLuint mask = get_src_arg_mask(mov, 0, NO_MASK);
654 /* Some components are not written by inst. We cannot remove the mov */
655 if (mask != (inst->DstReg.WriteMask & mask))
658 inst->SaturateMode |= mov->SaturateMode;
660 /* Depending on the instruction, we may need to recompute the swizzles.
661 * Also, some other instructions (like TEX) are not linear. We will only
662 * consider completely active sources and destinations
664 switch (inst->Opcode) {
666 /* Carstesian instructions: we compute the swizzle */
676 GLuint dst_to_src_comp[4] = {0,0,0,0};
677 GLuint dst_comp, arg;
678 for (dst_comp = 0; dst_comp < 4; ++dst_comp) {
679 if (mov->DstReg.WriteMask & (1 << dst_comp)) {
680 const GLuint src_comp = GET_SWZ(mov->SrcReg[0].Swizzle, dst_comp);
681 ASSERT(src_comp < 4);
682 dst_to_src_comp[dst_comp] = src_comp;
686 /* Patch each source of the instruction */
687 for (arg = 0; arg < _mesa_num_inst_src_regs(inst->Opcode); arg++) {
688 const GLuint arg_swz = inst->SrcReg[arg].Swizzle;
689 inst->SrcReg[arg].Swizzle = 0;
691 /* Reset each active component of the swizzle */
692 for (dst_comp = 0; dst_comp < 4; ++dst_comp) {
693 GLuint src_comp, arg_comp;
694 if ((mov->DstReg.WriteMask & (1 << dst_comp)) == 0)
696 src_comp = dst_to_src_comp[dst_comp];
697 ASSERT(src_comp < 4);
698 arg_comp = GET_SWZ(arg_swz, src_comp);
699 ASSERT(arg_comp < 4);
700 inst->SrcReg[arg].Swizzle |= arg_comp << (3*dst_comp);
703 inst->DstReg = mov->DstReg;
707 /* Dot products and scalar instructions: we only change the destination */
718 inst->DstReg = mov->DstReg;
721 /* All other instructions require fully active components with no swizzle */
723 if (mov->SrcReg[0].Swizzle != SWIZZLE_XYZW ||
724 inst->DstReg.WriteMask != WRITEMASK_XYZW)
726 inst->DstReg = mov->DstReg;
733 * Try to remove extraneous MOV instructions from the given program.
736 _mesa_remove_extra_moves(struct gl_program *prog)
738 GLboolean *removeInst; /* per-instruction removal flag */
739 GLuint i, rem = 0, nesting = 0;
742 printf("Optimize: Begin remove extra moves\n");
743 _mesa_print_program(prog);
747 calloc(1, prog->NumInstructions * sizeof(GLboolean));
750 * Look for sequences such as this:
751 * FOO tmpX, arg0, arg1;
754 * FOO tmpY, arg0, arg1;
757 for (i = 0; i < prog->NumInstructions; i++) {
758 const struct prog_instruction *mov = prog->Instructions + i;
760 switch (mov->Opcode) {
773 can_downward_mov_be_modifed(mov) &&
774 mov->SrcReg[0].File == PROGRAM_TEMPORARY &&
778 /* see if this MOV can be removed */
779 const GLuint id = mov->SrcReg[0].Index;
780 struct prog_instruction *prevInst;
783 /* get pointer to previous instruction */
785 while (prevI > 0 && removeInst[prevI])
787 prevInst = prog->Instructions + prevI;
789 if (prevInst->DstReg.File == PROGRAM_TEMPORARY &&
790 prevInst->DstReg.Index == id &&
791 prevInst->DstReg.RelAddr == 0 &&
792 prevInst->DstReg.CondMask == COND_TR) {
794 const GLuint dst_mask = prevInst->DstReg.WriteMask;
795 enum inst_use next_use = find_next_use(prog, i+1, id, dst_mask);
797 if (next_use == WRITE || next_use == END) {
798 /* OK, we can safely remove this MOV instruction.
800 * prevI: FOO tempIndex, x, y;
801 * i: MOV z, tempIndex;
803 * prevI: FOO z, x, y;
805 if (_mesa_merge_mov_into_inst(prevInst, mov)) {
806 removeInst[i] = GL_TRUE;
808 printf("Remove MOV at %u\n", i);
809 printf("new prev inst %u: ", prevI);
810 _mesa_print_instruction(prevInst);
822 /* now remove the instructions which aren't needed */
823 rem = remove_instructions(prog, removeInst);
828 printf("Optimize: End remove extra moves. %u instructions removed\n", rem);
829 /*_mesa_print_program(prog);*/
836 /** A live register interval */
839 GLuint Reg; /** The temporary register index */
840 GLuint Start, End; /** Start/end instruction numbers */
844 /** A list of register intervals */
848 struct interval Intervals[REG_ALLOCATE_MAX_PROGRAM_TEMPS];
853 append_interval(struct interval_list *list, const struct interval *inv)
855 list->Intervals[list->Num++] = *inv;
859 /** Insert interval inv into list, sorted by interval end */
861 insert_interval_by_end(struct interval_list *list, const struct interval *inv)
863 /* XXX we could do a binary search insertion here since list is sorted */
864 GLint i = list->Num - 1;
865 while (i >= 0 && list->Intervals[i].End > inv->End) {
866 list->Intervals[i + 1] = list->Intervals[i];
869 list->Intervals[i + 1] = *inv;
875 for (i = 0; i + 1 < list->Num; i++) {
876 ASSERT(list->Intervals[i].End <= list->Intervals[i + 1].End);
883 /** Remove the given interval from the interval list */
885 remove_interval(struct interval_list *list, const struct interval *inv)
887 /* XXX we could binary search since list is sorted */
889 for (k = 0; k < list->Num; k++) {
890 if (list->Intervals[k].Reg == inv->Reg) {
891 /* found, remove it */
892 ASSERT(list->Intervals[k].Start == inv->Start);
893 ASSERT(list->Intervals[k].End == inv->End);
894 while (k < list->Num - 1) {
895 list->Intervals[k] = list->Intervals[k + 1];
905 /** called by qsort() */
907 compare_start(const void *a, const void *b)
909 const struct interval *ia = (const struct interval *) a;
910 const struct interval *ib = (const struct interval *) b;
911 if (ia->Start < ib->Start)
913 else if (ia->Start > ib->Start)
920 /** sort the interval list according to interval starts */
922 sort_interval_list_by_start(struct interval_list *list)
924 qsort(list->Intervals, list->Num, sizeof(struct interval), compare_start);
928 for (i = 0; i + 1 < list->Num; i++) {
929 ASSERT(list->Intervals[i].Start <= list->Intervals[i + 1].Start);
937 GLuint Start, End; /**< Start, end instructions of loop */
941 * Update the intermediate interval info for register 'index' and
945 update_interval(GLint intBegin[], GLint intEnd[],
946 struct loop_info *loopStack, GLuint loopStackDepth,
947 GLuint index, GLuint ic)
953 /* If the register is used in a loop, extend its lifetime through the end
954 * of the outermost loop that doesn't contain its definition.
956 for (i = 0; i < loopStackDepth; i++) {
957 if (intBegin[index] < loopStack[i].Start) {
958 end = loopStack[i].End;
963 /* Variables that are live at the end of a loop will also be live at the
964 * beginning, so an instruction inside of a loop should have its live
965 * interval begin at the start of the outermost loop.
967 if (loopStackDepth > 0 && ic > loopStack[0].Start && ic < loopStack[0].End) {
968 begin = loopStack[0].Start;
971 ASSERT(index < REG_ALLOCATE_MAX_PROGRAM_TEMPS);
972 if (intBegin[index] == -1) {
973 ASSERT(intEnd[index] == -1);
974 intBegin[index] = begin;
984 * Find first/last instruction that references each temporary register.
987 _mesa_find_temp_intervals(const struct prog_instruction *instructions,
988 GLuint numInstructions,
989 GLint intBegin[REG_ALLOCATE_MAX_PROGRAM_TEMPS],
990 GLint intEnd[REG_ALLOCATE_MAX_PROGRAM_TEMPS])
992 struct loop_info loopStack[MAX_LOOP_NESTING];
993 GLuint loopStackDepth = 0;
996 for (i = 0; i < REG_ALLOCATE_MAX_PROGRAM_TEMPS; i++){
997 intBegin[i] = intEnd[i] = -1;
1000 /* Scan instructions looking for temporary registers */
1001 for (i = 0; i < numInstructions; i++) {
1002 const struct prog_instruction *inst = instructions + i;
1003 if (inst->Opcode == OPCODE_BGNLOOP) {
1004 loopStack[loopStackDepth].Start = i;
1005 loopStack[loopStackDepth].End = inst->BranchTarget;
1008 else if (inst->Opcode == OPCODE_ENDLOOP) {
1011 else if (inst->Opcode == OPCODE_CAL) {
1015 const GLuint numSrc = 3;/*_mesa_num_inst_src_regs(inst->Opcode);*/
1017 for (j = 0; j < numSrc; j++) {
1018 if (inst->SrcReg[j].File == PROGRAM_TEMPORARY) {
1019 const GLuint index = inst->SrcReg[j].Index;
1020 if (inst->SrcReg[j].RelAddr)
1022 update_interval(intBegin, intEnd, loopStack, loopStackDepth,
1026 if (inst->DstReg.File == PROGRAM_TEMPORARY) {
1027 const GLuint index = inst->DstReg.Index;
1028 if (inst->DstReg.RelAddr)
1030 update_interval(intBegin, intEnd, loopStack, loopStackDepth,
1041 * Find the live intervals for each temporary register in the program.
1042 * For register R, the interval [A,B] indicates that R is referenced
1043 * from instruction A through instruction B.
1044 * Special consideration is needed for loops and subroutines.
1045 * \return GL_TRUE if success, GL_FALSE if we cannot proceed for some reason
1048 find_live_intervals(struct gl_program *prog,
1049 struct interval_list *liveIntervals)
1051 GLint intBegin[REG_ALLOCATE_MAX_PROGRAM_TEMPS];
1052 GLint intEnd[REG_ALLOCATE_MAX_PROGRAM_TEMPS];
1056 * Note: we'll return GL_FALSE below if we find relative indexing
1057 * into the TEMP register file. We can't handle that yet.
1058 * We also give up on subroutines for now.
1062 printf("Optimize: Begin find intervals\n");
1065 /* build intermediate arrays */
1066 if (!_mesa_find_temp_intervals(prog->Instructions, prog->NumInstructions,
1070 /* Build live intervals list from intermediate arrays */
1071 liveIntervals->Num = 0;
1072 for (i = 0; i < REG_ALLOCATE_MAX_PROGRAM_TEMPS; i++) {
1073 if (intBegin[i] >= 0) {
1074 struct interval inv;
1076 inv.Start = intBegin[i];
1077 inv.End = intEnd[i];
1078 append_interval(liveIntervals, &inv);
1082 /* Sort the list according to interval starts */
1083 sort_interval_list_by_start(liveIntervals);
1086 /* print interval info */
1087 for (i = 0; i < liveIntervals->Num; i++) {
1088 const struct interval *inv = liveIntervals->Intervals + i;
1089 printf("Reg[%d] live [%d, %d]:",
1090 inv->Reg, inv->Start, inv->End);
1093 for (j = 0; j < inv->Start; j++)
1095 for (j = inv->Start; j <= inv->End; j++)
1106 /** Scan the array of used register flags to find free entry */
1108 alloc_register(GLboolean usedRegs[REG_ALLOCATE_MAX_PROGRAM_TEMPS])
1111 for (k = 0; k < REG_ALLOCATE_MAX_PROGRAM_TEMPS; k++) {
1113 usedRegs[k] = GL_TRUE;
1122 * This function implements "Linear Scan Register Allocation" to reduce
1123 * the number of temporary registers used by the program.
1125 * We compute the "live interval" for all temporary registers then
1126 * examine the overlap of the intervals to allocate new registers.
1127 * Basically, if two intervals do not overlap, they can use the same register.
1130 _mesa_reallocate_registers(struct gl_program *prog)
1132 struct interval_list liveIntervals;
1133 GLint registerMap[REG_ALLOCATE_MAX_PROGRAM_TEMPS];
1134 GLboolean usedRegs[REG_ALLOCATE_MAX_PROGRAM_TEMPS];
1139 printf("Optimize: Begin live-interval register reallocation\n");
1140 _mesa_print_program(prog);
1143 for (i = 0; i < REG_ALLOCATE_MAX_PROGRAM_TEMPS; i++){
1144 registerMap[i] = -1;
1145 usedRegs[i] = GL_FALSE;
1148 if (!find_live_intervals(prog, &liveIntervals)) {
1150 printf("Aborting register reallocation\n");
1155 struct interval_list activeIntervals;
1156 activeIntervals.Num = 0;
1158 /* loop over live intervals, allocating a new register for each */
1159 for (i = 0; i < liveIntervals.Num; i++) {
1160 const struct interval *live = liveIntervals.Intervals + i;
1163 printf("Consider register %u\n", live->Reg);
1165 /* Expire old intervals. Intervals which have ended with respect
1166 * to the live interval can have their remapped registers freed.
1170 for (j = 0; j < (GLint) activeIntervals.Num; j++) {
1171 const struct interval *inv = activeIntervals.Intervals + j;
1172 if (inv->End >= live->Start) {
1173 /* Stop now. Since the activeInterval list is sorted
1174 * we know we don't have to go further.
1179 /* Interval 'inv' has expired */
1180 const GLint regNew = registerMap[inv->Reg];
1181 ASSERT(regNew >= 0);
1184 printf(" expire interval for reg %u\n", inv->Reg);
1186 /* remove interval j from active list */
1187 remove_interval(&activeIntervals, inv);
1188 j--; /* counter-act j++ in for-loop above */
1190 /* return register regNew to the free pool */
1192 printf(" free reg %d\n", regNew);
1193 ASSERT(usedRegs[regNew] == GL_TRUE);
1194 usedRegs[regNew] = GL_FALSE;
1199 /* find a free register for this live interval */
1201 const GLint k = alloc_register(usedRegs);
1203 /* out of registers, give up */
1206 registerMap[live->Reg] = k;
1207 maxTemp = MAX2(maxTemp, k);
1209 printf(" remap register %u -> %d\n", live->Reg, k);
1212 /* Insert this live interval into the active list which is sorted
1213 * by increasing end points.
1215 insert_interval_by_end(&activeIntervals, live);
1219 if (maxTemp + 1 < (GLint) liveIntervals.Num) {
1220 /* OK, we've reduced the number of registers needed.
1221 * Scan the program and replace all the old temporary register
1222 * indexes with the new indexes.
1224 replace_regs(prog, PROGRAM_TEMPORARY, registerMap);
1226 prog->NumTemporaries = maxTemp + 1;
1230 printf("Optimize: End live-interval register reallocation\n");
1231 printf("Num temp regs before: %u after: %u\n",
1232 liveIntervals.Num, maxTemp + 1);
1233 _mesa_print_program(prog);
1240 print_it(struct gl_context *ctx, struct gl_program *program, const char *txt) {
1241 fprintf(stderr, "%s (%u inst):\n", txt, program->NumInstructions);
1242 _mesa_print_program(program);
1243 _mesa_print_program_parameters(ctx, program);
1244 fprintf(stderr, "\n\n");
1249 * This pass replaces CMP T0, T1 T2 T0 with MOV T0, T2 when the CMP
1250 * instruction is the first instruction to write to register T0. The are
1251 * several lowering passes done in GLSL IR (e.g. branches and
1252 * relative addressing) that create a large number of conditional assignments
1253 * that ir_to_mesa converts to CMP instructions like the one mentioned above.
1255 * Here is why this conversion is safe:
1256 * CMP T0, T1 T2 T0 can be expanded to:
1262 * If (T1 < 0.0) evaluates to true then our replacement MOV T0, T2 is the same
1263 * as the original program. If (T1 < 0.0) evaluates to false, executing
1264 * MOV T0, T0 will store a garbage value in T0 since T0 is uninitialized.
1265 * Therefore, it doesn't matter that we are replacing MOV T0, T0 with MOV T0, T2
1266 * because any instruction that was going to read from T0 after this was going
1267 * to read a garbage value anyway.
1270 _mesa_simplify_cmp(struct gl_program * program)
1272 GLuint tempWrites[REG_ALLOCATE_MAX_PROGRAM_TEMPS];
1273 GLuint outputWrites[MAX_PROGRAM_OUTPUTS];
1277 printf("Optimize: Begin reads without writes\n");
1278 _mesa_print_program(program);
1281 for (i = 0; i < REG_ALLOCATE_MAX_PROGRAM_TEMPS; i++) {
1285 for (i = 0; i < MAX_PROGRAM_OUTPUTS; i++) {
1286 outputWrites[i] = 0;
1289 for (i = 0; i < program->NumInstructions; i++) {
1290 struct prog_instruction *inst = program->Instructions + i;
1291 GLuint prevWriteMask;
1293 /* Give up if we encounter relative addressing or flow control. */
1294 if (_mesa_is_flow_control_opcode(inst->Opcode) || inst->DstReg.RelAddr) {
1298 if (inst->DstReg.File == PROGRAM_OUTPUT) {
1299 assert(inst->DstReg.Index < MAX_PROGRAM_OUTPUTS);
1300 prevWriteMask = outputWrites[inst->DstReg.Index];
1301 outputWrites[inst->DstReg.Index] |= inst->DstReg.WriteMask;
1302 } else if (inst->DstReg.File == PROGRAM_TEMPORARY) {
1303 assert(inst->DstReg.Index < REG_ALLOCATE_MAX_PROGRAM_TEMPS);
1304 prevWriteMask = tempWrites[inst->DstReg.Index];
1305 tempWrites[inst->DstReg.Index] |= inst->DstReg.WriteMask;
1307 /* No other register type can be a destination register. */
1311 /* For a CMP to be considered a conditional write, the destination
1312 * register and source register two must be the same. */
1313 if (inst->Opcode == OPCODE_CMP
1314 && !(inst->DstReg.WriteMask & prevWriteMask)
1315 && inst->SrcReg[2].File == inst->DstReg.File
1316 && inst->SrcReg[2].Index == inst->DstReg.Index
1317 && inst->DstReg.WriteMask == get_src_arg_mask(inst, 2, NO_MASK)) {
1319 inst->Opcode = OPCODE_MOV;
1320 inst->SrcReg[0] = inst->SrcReg[1];
1322 /* Unused operands are expected to have the file set to
1323 * PROGRAM_UNDEFINED. This is how _mesa_init_instructions initializes
1324 * all of the sources.
1326 inst->SrcReg[1].File = PROGRAM_UNDEFINED;
1327 inst->SrcReg[1].Swizzle = SWIZZLE_NOOP;
1328 inst->SrcReg[2].File = PROGRAM_UNDEFINED;
1329 inst->SrcReg[2].Swizzle = SWIZZLE_NOOP;
1333 printf("Optimize: End reads without writes\n");
1334 _mesa_print_program(program);
1339 * Apply optimizations to the given program to eliminate unnecessary
1340 * instructions, temp regs, etc.
1343 _mesa_optimize_program(struct gl_context *ctx, struct gl_program *program)
1345 GLboolean any_change;
1347 _mesa_simplify_cmp(program);
1348 /* Stop when no modifications were output */
1350 any_change = GL_FALSE;
1351 _mesa_remove_extra_move_use(program);
1352 if (_mesa_remove_dead_code_global(program))
1353 any_change = GL_TRUE;
1354 if (_mesa_remove_extra_moves(program))
1355 any_change = GL_TRUE;
1356 if (_mesa_remove_dead_code_local(program))
1357 any_change = GL_TRUE;
1359 any_change = _mesa_constant_fold(program) || any_change;
1360 _mesa_reallocate_registers(program);
1361 } while (any_change);