diff options
Diffstat (limited to 'src/gallium')
| -rw-r--r-- | src/gallium/drivers/r600/evergreen_compute.c | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/src/gallium/drivers/r600/evergreen_compute.c b/src/gallium/drivers/r600/evergreen_compute.c index eaffb7513ec..3ec9d9bb453 100644 --- a/src/gallium/drivers/r600/evergreen_compute.c +++ b/src/gallium/drivers/r600/evergreen_compute.c @@ -188,20 +188,6 @@ static void evergreen_bind_compute_state(struct pipe_context *ctx_, void *state) r600_inval_shader_cache(ctx); - /* We can't always determine the - * number of iterations in a loop before it's executed, - * so we just need to set up the loop counter to give us the maximum - * number of iterations possible. Currently, loops in shader code - * ignore the loop counter and use a break instruction to exit the - * loop at the correct time. - */ - evergreen_set_loop_const(ctx->cs_shader, - 0, /* index */ - 0xFFF, /* Maximum value of the loop counter (i.e. when the loop - * counter reaches this value, the program will break - * out of the loop. */ - 0x0, /* Starting value of the loop counter. */ - 0x1); /* Amount to increment the loop counter each iteration. */ } /* The kernel parameters are stored a vtx buffer (ID=0), besides the explicit @@ -674,6 +660,22 @@ void evergreen_init_atom_start_compute_cs(struct r600_context *ctx) | S_0286E8_TGID_ENA | S_0286E8_DISABLE_INDEX_PACK) ; + + /* The LOOP_CONST registers are an optimizations for loops that allows + * you to store the initial counter, increment value, and maximum + * counter value in a register so that hardware can calculate the + * correct number of iterations for the loop, so that you don't need + * to have the loop counter in your shader code. We don't currently use + * this optimization, so we must keep track of the counter in the + * shader and use a break instruction to exit loops. However, the + * hardware will still uses this register to determine when to exit a + * loop, so we need to initialize the counter to 0, set the increment + * value to 1 and the maximum counter value to the 4095 (0xfff) which + * is the maximum value allowed. This gives us a maximum of 4096 + * iterations for our loops, but hopefully our break instruction will + * execute before some time before the 4096th iteration. + */ + eg_store_loop_const(cb, R_03A200_SQ_LOOP_CONST_0 + (160 * 4), 0x1000FFF); } void evergreen_init_compute_state_functions(struct r600_context *ctx) |