---
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 eaffb75..3ec9d9b 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)
--
1.7.7.6
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