1 /**************************************************************************
3 * Copyright 2009 VMware, Inc.
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
26 **************************************************************************/
29 #include "util/u_memory.h"
30 #include "util/u_math.h"
31 #include "util/u_cpu_detect.h"
32 #include "util/u_surface.h"
34 #include "lp_scene_queue.h"
39 #include "lp_rast_priv.h"
40 #include "lp_tile_soa.h"
41 #include "gallivm/lp_bld_debug.h"
45 /* Begin rasterizing a scene:
48 lp_rast_begin( struct lp_rasterizer
*rast
,
49 struct lp_scene
*scene
)
51 const struct pipe_framebuffer_state
*fb
= &scene
->fb
;
52 boolean write_color
= fb
->nr_cbufs
!= 0;
53 boolean write_zstencil
= fb
->zsbuf
!= NULL
;
56 rast
->curr_scene
= scene
;
58 LP_DBG(DEBUG_RAST
, "%s\n", __FUNCTION__
);
60 rast
->state
.nr_cbufs
= scene
->fb
.nr_cbufs
;
61 rast
->state
.write_zstencil
= write_zstencil
;
62 rast
->state
.write_color
= write_color
;
64 for (i
= 0; i
< rast
->state
.nr_cbufs
; i
++) {
65 struct pipe_surface
*cbuf
= scene
->fb
.cbufs
[i
];
66 rast
->cbuf
[i
].map
= scene
->cbuf_map
[i
];
67 rast
->cbuf
[i
].format
= cbuf
->texture
->format
;
68 rast
->cbuf
[i
].width
= cbuf
->width
;
69 rast
->cbuf
[i
].height
= cbuf
->height
;
70 rast
->cbuf
[i
].stride
= llvmpipe_texture_stride(cbuf
->texture
, cbuf
->level
);
74 struct pipe_surface
*zsbuf
= scene
->fb
.zsbuf
;
75 rast
->zsbuf
.map
= scene
->zsbuf_map
;
76 rast
->zsbuf
.stride
= llvmpipe_texture_stride(zsbuf
->texture
, zsbuf
->level
);
77 rast
->zsbuf
.blocksize
=
78 util_format_get_blocksize(zsbuf
->texture
->format
);
81 lp_scene_bin_iter_begin( scene
);
88 lp_rast_end( struct lp_rasterizer
*rast
)
92 lp_scene_reset( rast
->curr_scene
);
94 for (i
= 0; i
< rast
->state
.nr_cbufs
; i
++)
95 rast
->cbuf
[i
].map
= NULL
;
97 rast
->zsbuf
.map
= NULL
;
98 rast
->curr_scene
= NULL
;
102 * Begining rasterization of a tile.
103 * \param x window X position of the tile, in pixels
104 * \param y window Y position of the tile, in pixels
107 lp_rast_start_tile(struct lp_rasterizer_task
*task
,
108 unsigned x
, unsigned y
)
110 LP_DBG(DEBUG_RAST
, "%s %d,%d\n", __FUNCTION__
, x
, y
);
118 * Clear the rasterizer's current color tile.
119 * This is a bin command called during bin processing.
122 lp_rast_clear_color(struct lp_rasterizer_task
*task
,
123 const union lp_rast_cmd_arg arg
)
125 struct lp_rasterizer
*rast
= task
->rast
;
126 const uint8_t *clear_color
= arg
.clear_color
;
127 uint8_t **color_tile
= task
->tile
.color
;
130 LP_DBG(DEBUG_RAST
, "%s 0x%x,0x%x,0x%x,0x%x\n", __FUNCTION__
,
136 if (clear_color
[0] == clear_color
[1] &&
137 clear_color
[1] == clear_color
[2] &&
138 clear_color
[2] == clear_color
[3]) {
139 /* clear to grayscale value {x, x, x, x} */
140 for (i
= 0; i
< rast
->state
.nr_cbufs
; i
++) {
141 memset(color_tile
[i
], clear_color
[0], TILE_SIZE
* TILE_SIZE
* 4);
146 * Note: if the swizzled tile layout changes (see TILE_PIXEL) this code
147 * will need to change. It'll be pretty obvious when clearing no longer
150 const unsigned chunk
= TILE_SIZE
/ 4;
151 for (i
= 0; i
< rast
->state
.nr_cbufs
; i
++) {
152 uint8_t *c
= color_tile
[i
];
154 for (j
= 0; j
< 4 * TILE_SIZE
; j
++) {
155 memset(c
, clear_color
[0], chunk
);
157 memset(c
, clear_color
[1], chunk
);
159 memset(c
, clear_color
[2], chunk
);
161 memset(c
, clear_color
[3], chunk
);
164 assert(c
- color_tile
[i
] == TILE_SIZE
* TILE_SIZE
* 4);
168 LP_COUNT(nr_color_tile_clear
);
173 * Clear the rasterizer's current z/stencil tile.
174 * This is a bin command called during bin processing.
177 lp_rast_clear_zstencil(struct lp_rasterizer_task
*task
,
178 const union lp_rast_cmd_arg arg
)
180 struct lp_rasterizer
*rast
= task
->rast
;
181 const unsigned tile_x
= task
->x
;
182 const unsigned tile_y
= task
->y
;
183 const unsigned height
= TILE_SIZE
/ TILE_VECTOR_HEIGHT
;
184 const unsigned width
= TILE_SIZE
* TILE_VECTOR_HEIGHT
;
185 unsigned block_size
= rast
->zsbuf
.blocksize
;
187 unsigned dst_stride
= rast
->zsbuf
.stride
* TILE_VECTOR_HEIGHT
;
190 LP_DBG(DEBUG_RAST
, "%s 0x%x\n", __FUNCTION__
, arg
.clear_zstencil
);
192 /*assert(rast->zsbuf.map);*/
193 if (!rast
->zsbuf
.map
)
196 LP_DBG(DEBUG_RAST
, "%s\n", __FUNCTION__
);
199 * Clear the aera of the swizzled depth/depth buffer matching this tile, in
200 * stripes of TILE_VECTOR_HEIGHT x TILE_SIZE at a time.
202 * The swizzled depth format is such that the depths for
203 * TILE_VECTOR_HEIGHT x TILE_VECTOR_WIDTH pixels have consecutive offsets.
206 dst
= lp_rast_depth_pointer(rast
, tile_x
, tile_y
);
208 switch (block_size
) {
210 memset(dst
, (uint8_t) arg
.clear_zstencil
, height
* width
);
213 for (i
= 0; i
< height
; i
++) {
214 uint16_t *row
= (uint16_t *)dst
;
215 for (j
= 0; j
< width
; j
++)
216 *row
++ = (uint16_t) arg
.clear_zstencil
;
221 for (i
= 0; i
< height
; i
++) {
222 uint32_t *row
= (uint32_t *)dst
;
223 for (j
= 0; j
< width
; j
++)
224 *row
++ = arg
.clear_zstencil
;
236 * Load tile color from the framebuffer surface.
237 * This is a bin command called during bin processing.
240 lp_rast_load_color(struct lp_rasterizer_task
*task
,
241 const union lp_rast_cmd_arg arg
)
243 struct lp_rasterizer
*rast
= task
->rast
;
244 const unsigned x
= task
->x
, y
= task
->y
;
247 LP_DBG(DEBUG_RAST
, "%s at %u, %u\n", __FUNCTION__
, x
, y
);
249 for (i
= 0; i
< rast
->state
.nr_cbufs
; i
++) {
250 if (x
>= rast
->cbuf
[i
].width
|| y
>= rast
->cbuf
[i
].height
)
253 lp_tile_read_4ub(rast
->cbuf
[i
].format
,
256 rast
->cbuf
[i
].stride
,
258 TILE_SIZE
, TILE_SIZE
);
260 LP_COUNT(nr_color_tile_load
);
266 lp_rast_set_state(struct lp_rasterizer_task
*task
,
267 const union lp_rast_cmd_arg arg
)
269 const struct lp_rast_state
*state
= arg
.set_state
;
271 LP_DBG(DEBUG_RAST
, "%s %p\n", __FUNCTION__
, (void *) state
);
273 /* just set the current state pointer for this rasterizer */
274 task
->current_state
= state
;
280 * Run the shader on all blocks in a tile. This is used when a tile is
281 * completely contained inside a triangle.
282 * This is a bin command called during bin processing.
285 lp_rast_shade_tile(struct lp_rasterizer_task
*task
,
286 const union lp_rast_cmd_arg arg
)
288 struct lp_rasterizer
*rast
= task
->rast
;
289 const struct lp_rast_state
*state
= task
->current_state
;
290 struct lp_rast_tile
*tile
= &task
->tile
;
291 const struct lp_rast_shader_inputs
*inputs
= arg
.shade_tile
;
292 const unsigned tile_x
= task
->x
, tile_y
= task
->y
;
295 LP_DBG(DEBUG_RAST
, "%s\n", __FUNCTION__
);
297 /* render the whole 64x64 tile in 4x4 chunks */
298 for (y
= 0; y
< TILE_SIZE
; y
+= 4){
299 for (x
= 0; x
< TILE_SIZE
; x
+= 4) {
300 uint8_t *color
[PIPE_MAX_COLOR_BUFS
];
302 unsigned block_offset
, i
;
304 /* offset of the 16x16 pixel block within the tile */
305 block_offset
= ((y
/ 4) * (16 * 16) + (x
/ 4) * 16);
308 for (i
= 0; i
< rast
->state
.nr_cbufs
; i
++)
309 color
[i
] = tile
->color
[i
] + 4 * block_offset
;
312 depth
= lp_rast_depth_pointer(rast
, tile_x
+ x
, tile_y
+ y
);
315 state
->jit_function
[RAST_WHOLE
]( &state
->jit_context
,
316 tile_x
+ x
, tile_y
+ y
,
323 INT_MIN
, INT_MIN
, INT_MIN
,
331 * Compute shading for a 4x4 block of pixels.
332 * This is a bin command called during bin processing.
334 void lp_rast_shade_quads( struct lp_rasterizer_task
*task
,
335 const struct lp_rast_shader_inputs
*inputs
,
336 unsigned x
, unsigned y
,
337 int32_t c1
, int32_t c2
, int32_t c3
)
339 const struct lp_rast_state
*state
= task
->current_state
;
340 struct lp_rasterizer
*rast
= task
->rast
;
341 struct lp_rast_tile
*tile
= &task
->tile
;
342 uint8_t *color
[PIPE_MAX_COLOR_BUFS
];
351 assert(x
% TILE_VECTOR_WIDTH
== 0);
352 assert(y
% TILE_VECTOR_HEIGHT
== 0);
354 assert((x
% 4) == 0);
355 assert((y
% 4) == 0);
360 /* offset of the 16x16 pixel block within the tile */
361 block_offset
= ((iy
/ 4) * (16 * 16) + (ix
/ 4) * 16);
364 for (i
= 0; i
< rast
->state
.nr_cbufs
; i
++)
365 color
[i
] = tile
->color
[i
] + 4 * block_offset
;
368 depth
= lp_rast_depth_pointer(rast
, x
, y
);
371 assert(lp_check_alignment(tile
->color
[0], 16));
372 assert(lp_check_alignment(state
->jit_context
.blend_color
, 16));
374 assert(lp_check_alignment(inputs
->step
[0], 16));
375 assert(lp_check_alignment(inputs
->step
[1], 16));
376 assert(lp_check_alignment(inputs
->step
[2], 16));
379 state
->jit_function
[RAST_EDGE_TEST
]( &state
->jit_context
,
395 * Set top row and left column of the tile's pixels to white. For debugging.
398 outline_tile(uint8_t *tile
)
400 const uint8_t val
= 0xff;
403 for (i
= 0; i
< TILE_SIZE
; i
++) {
404 TILE_PIXEL(tile
, i
, 0, 0) = val
;
405 TILE_PIXEL(tile
, i
, 0, 1) = val
;
406 TILE_PIXEL(tile
, i
, 0, 2) = val
;
407 TILE_PIXEL(tile
, i
, 0, 3) = val
;
409 TILE_PIXEL(tile
, 0, i
, 0) = val
;
410 TILE_PIXEL(tile
, 0, i
, 1) = val
;
411 TILE_PIXEL(tile
, 0, i
, 2) = val
;
412 TILE_PIXEL(tile
, 0, i
, 3) = val
;
418 * Draw grid of gray lines at 16-pixel intervals across the tile to
419 * show the sub-tile boundaries. For debugging.
422 outline_subtiles(uint8_t *tile
)
424 const uint8_t val
= 0x80;
425 const unsigned step
= 16;
428 for (i
= 0; i
< TILE_SIZE
; i
+= step
) {
429 for (j
= 0; j
< TILE_SIZE
; j
++) {
430 TILE_PIXEL(tile
, i
, j
, 0) = val
;
431 TILE_PIXEL(tile
, i
, j
, 1) = val
;
432 TILE_PIXEL(tile
, i
, j
, 2) = val
;
433 TILE_PIXEL(tile
, i
, j
, 3) = val
;
435 TILE_PIXEL(tile
, j
, i
, 0) = val
;
436 TILE_PIXEL(tile
, j
, i
, 1) = val
;
437 TILE_PIXEL(tile
, j
, i
, 2) = val
;
438 TILE_PIXEL(tile
, j
, i
, 3) = val
;
448 * Write the rasterizer's color tile to the framebuffer.
451 lp_rast_store_color(struct lp_rasterizer_task
*task
)
453 struct lp_rasterizer
*rast
= task
->rast
;
454 const unsigned x
= task
->x
, y
= task
->y
;
457 for (i
= 0; i
< rast
->state
.nr_cbufs
; i
++) {
458 if (x
>= rast
->cbuf
[i
].width
)
461 if (y
>= rast
->cbuf
[i
].height
)
464 LP_DBG(DEBUG_RAST
, "%s [%u] %d,%d\n", __FUNCTION__
,
465 task
->thread_index
, x
, y
);
467 if (LP_DEBUG
& DEBUG_SHOW_SUBTILES
)
468 outline_subtiles(task
->tile
.color
[i
]);
469 else if (LP_DEBUG
& DEBUG_SHOW_TILES
)
470 outline_tile(task
->tile
.color
[i
]);
472 lp_tile_write_4ub(rast
->cbuf
[i
].format
,
475 rast
->cbuf
[i
].stride
,
477 TILE_SIZE
, TILE_SIZE
);
479 LP_COUNT(nr_color_tile_store
);
486 * Signal on a fence. This is called during bin execution/rasterization.
490 lp_rast_fence(struct lp_rasterizer_task
*task
,
491 const union lp_rast_cmd_arg arg
)
493 struct lp_fence
*fence
= arg
.fence
;
494 lp_fence_signal(fence
);
501 * Rasterize commands for a single bin.
502 * \param x, y position of the bin's tile in the framebuffer
503 * Must be called between lp_rast_begin() and lp_rast_end().
507 rasterize_bin(struct lp_rasterizer_task
*task
,
508 const struct cmd_bin
*bin
,
511 const struct cmd_block_list
*commands
= &bin
->commands
;
512 struct cmd_block
*block
;
515 lp_rast_start_tile( task
, x
* TILE_SIZE
, y
* TILE_SIZE
);
517 /* simply execute each of the commands in the block list */
518 for (block
= commands
->head
; block
; block
= block
->next
) {
519 for (k
= 0; k
< block
->count
; k
++) {
520 block
->cmd
[k
]( task
, block
->arg
[k
] );
524 /* Write the rasterizer's tiles to the framebuffer.
526 if (task
->rast
->state
.write_color
)
527 lp_rast_store_color(task
);
529 /* Free data for this bin.
531 lp_scene_bin_reset( task
->rast
->curr_scene
, x
, y
);
535 #define RAST(x) { lp_rast_##x, #x }
544 RAST(clear_zstencil
),
552 debug_bin( const struct cmd_bin
*bin
)
554 const struct cmd_block
*head
= bin
->commands
.head
;
557 for (i
= 0; i
< head
->count
; i
++) {
558 debug_printf("%d: ", i
);
559 for (j
= 0; j
< Elements(cmd_names
); j
++) {
560 if (head
->cmd
[i
] == cmd_names
[j
].cmd
) {
561 debug_printf("%s\n", cmd_names
[j
].name
);
565 if (j
== Elements(cmd_names
))
566 debug_printf("...other\n");
571 /* An empty bin is one that just loads the contents of the tile and
572 * stores them again unchanged. This typically happens when bins have
573 * been flushed for some reason in the middle of a frame, or when
574 * incremental updates are being made to a render target.
576 * Try to avoid doing pointless work in this case.
579 is_empty_bin( const struct cmd_bin
*bin
)
581 const struct cmd_block
*head
= bin
->commands
.head
;
587 /* We emit at most two load-tile commands at the start of the first
588 * command block. In addition we seem to emit a couple of
589 * set-state commands even in empty bins.
591 * As a heuristic, if a bin has more than 4 commands, consider it
594 if (head
->next
!= NULL
||
599 for (i
= 0; i
< head
->count
; i
++)
600 if (head
->cmd
[i
] != lp_rast_load_color
&&
601 head
->cmd
[i
] != lp_rast_set_state
) {
611 * Rasterize/execute all bins within a scene.
615 rasterize_scene(struct lp_rasterizer_task
*task
,
616 struct lp_scene
*scene
)
618 /* loop over scene bins, rasterize each */
622 for (i
= 0; i
< scene
->tiles_x
; i
++) {
623 for (j
= 0; j
< scene
->tiles_y
; j
++) {
624 struct cmd_bin
*bin
= lp_scene_get_bin(scene
, i
, j
);
625 rasterize_bin(task
, bin
, i
, j
);
635 while ((bin
= lp_scene_bin_iter_next(scene
, &x
, &y
))) {
636 if (!is_empty_bin( bin
))
637 rasterize_bin(task
, bin
, x
, y
);
645 * Called by setup module when it has something for us to render.
648 lp_rast_queue_scene( struct lp_rasterizer
*rast
,
649 struct lp_scene
*scene
)
651 LP_DBG(DEBUG_SETUP
, "%s\n", __FUNCTION__
);
653 if (rast
->num_threads
== 0) {
656 lp_rast_begin( rast
, scene
);
658 rasterize_scene( &rast
->tasks
[0], scene
);
660 lp_scene_reset( scene
);
661 rast
->curr_scene
= NULL
;
664 /* threaded rendering! */
667 lp_scene_enqueue( rast
->full_scenes
, scene
);
669 /* signal the threads that there's work to do */
670 for (i
= 0; i
< rast
->num_threads
; i
++) {
671 pipe_semaphore_signal(&rast
->tasks
[i
].work_ready
);
675 LP_DBG(DEBUG_SETUP
, "%s done \n", __FUNCTION__
);
680 lp_rast_finish( struct lp_rasterizer
*rast
)
682 if (rast
->num_threads
== 0) {
688 /* wait for work to complete */
689 for (i
= 0; i
< rast
->num_threads
; i
++) {
690 pipe_semaphore_wait(&rast
->tasks
[i
].work_done
);
697 * This is the thread's main entrypoint.
698 * It's a simple loop:
701 * 3. signal that we're done
703 static PIPE_THREAD_ROUTINE( thread_func
, init_data
)
705 struct lp_rasterizer_task
*task
= (struct lp_rasterizer_task
*) init_data
;
706 struct lp_rasterizer
*rast
= task
->rast
;
707 boolean debug
= false;
712 debug_printf("thread %d waiting for work\n", task
->thread_index
);
713 pipe_semaphore_wait(&task
->work_ready
);
718 if (task
->thread_index
== 0) {
720 * - get next scene to rasterize
721 * - map the framebuffer surfaces
724 lp_scene_dequeue( rast
->full_scenes
, TRUE
) );
727 /* Wait for all threads to get here so that threads[1+] don't
728 * get a null rast->curr_scene pointer.
730 pipe_barrier_wait( &rast
->barrier
);
734 debug_printf("thread %d doing work\n", task
->thread_index
);
736 rasterize_scene(task
,
739 /* wait for all threads to finish with this scene */
740 pipe_barrier_wait( &rast
->barrier
);
742 /* XXX: shouldn't be necessary:
744 if (task
->thread_index
== 0) {
748 /* signal done with work */
750 debug_printf("thread %d done working\n", task
->thread_index
);
752 pipe_semaphore_signal(&task
->work_done
);
760 * Initialize semaphores and spawn the threads.
763 create_rast_threads(struct lp_rasterizer
*rast
)
767 #ifdef PIPE_OS_WINDOWS
768 /* Multithreading not supported on windows until conditions and barriers are
769 * properly implemented. */
770 rast
->num_threads
= 0;
772 #ifdef PIPE_OS_EMBEDDED
773 rast
->num_threads
= 0;
775 rast
->num_threads
= util_cpu_caps
.nr_cpus
;
777 rast
->num_threads
= debug_get_num_option("LP_NUM_THREADS", rast
->num_threads
);
778 rast
->num_threads
= MIN2(rast
->num_threads
, MAX_THREADS
);
781 /* NOTE: if num_threads is zero, we won't use any threads */
782 for (i
= 0; i
< rast
->num_threads
; i
++) {
783 pipe_semaphore_init(&rast
->tasks
[i
].work_ready
, 0);
784 pipe_semaphore_init(&rast
->tasks
[i
].work_done
, 0);
785 rast
->threads
[i
] = pipe_thread_create(thread_func
,
786 (void *) &rast
->tasks
[i
]);
793 * Create new lp_rasterizer.
794 * \param empty the queue to put empty scenes on after we've finished
797 struct lp_rasterizer
*
798 lp_rast_create( void )
800 struct lp_rasterizer
*rast
;
803 rast
= CALLOC_STRUCT(lp_rasterizer
);
807 rast
->full_scenes
= lp_scene_queue_create();
809 for (i
= 0; i
< Elements(rast
->tasks
); i
++) {
810 struct lp_rasterizer_task
*task
= &rast
->tasks
[i
];
812 for (cbuf
= 0; cbuf
< PIPE_MAX_COLOR_BUFS
; cbuf
++ )
813 task
->tile
.color
[cbuf
] = align_malloc(TILE_SIZE
* TILE_SIZE
* 4, 16);
816 task
->thread_index
= i
;
819 create_rast_threads(rast
);
821 /* for synchronizing rasterization threads */
822 pipe_barrier_init( &rast
->barrier
, rast
->num_threads
);
830 void lp_rast_destroy( struct lp_rasterizer
*rast
)
834 for (i
= 0; i
< Elements(rast
->tasks
); i
++) {
835 for (cbuf
= 0; cbuf
< PIPE_MAX_COLOR_BUFS
; cbuf
++ )
836 align_free(rast
->tasks
[i
].tile
.color
[cbuf
]);
839 /* Set exit_flag and signal each thread's work_ready semaphore.
840 * Each thread will be woken up, notice that the exit_flag is set and
841 * break out of its main loop. The thread will then exit.
843 rast
->exit_flag
= TRUE
;
844 for (i
= 0; i
< rast
->num_threads
; i
++) {
845 pipe_semaphore_signal(&rast
->tasks
[i
].work_ready
);
848 /* Wait for threads to terminate before cleaning up per-thread data */
849 for (i
= 0; i
< rast
->num_threads
; i
++) {
850 pipe_thread_wait(rast
->threads
[i
]);
853 /* Clean up per-thread data */
854 for (i
= 0; i
< rast
->num_threads
; i
++) {
855 pipe_semaphore_destroy(&rast
->tasks
[i
].work_ready
);
856 pipe_semaphore_destroy(&rast
->tasks
[i
].work_done
);
859 /* for synchronizing rasterization threads */
860 pipe_barrier_destroy( &rast
->barrier
);
866 /** Return number of rasterization threads */
868 lp_rast_get_num_threads( struct lp_rasterizer
*rast
)
870 return rast
->num_threads
;