drm/radeon: refactor register check loop

After this patch the register check loop does the same thing as before, except that now gcc does better job optimizing it: it now sees that end_reg was already checked against PACKET3_SET_CONTEXT_REG_END and can optimize REG_SAFE_BM_SIZE comparison out of evergreen_is_safe_reg() as (PACKET3_SET_CONTEXT_REG_END >> 7) < REG_SAFE_BM_SIZE. Reviewed-by: Dave Airlie <[email protected]> Signed-off-by: Grazvydas Ignotas <[email protected]> Signed-off-by: Alex Deucher <[email protected]>
voxadam · Oct 2, 2015 · 7874d39 · 7874d39
1 parent e5b69da
commit 7874d39
Showing 1 changed file with 4 additions and 6 deletions.
diff --git a/drivers/gpu/drm/radeon/evergreen_cs.c b/drivers/gpu/drm/radeon/evergreen_cs.c
@@ -2299,11 +2299,10 @@ static int evergreen_packet3_check(struct radeon_cs_parser *p,
 			DRM_ERROR("bad PACKET3_SET_CONFIG_REG\n");
 			return -EINVAL;
 		}
-		for (i = 0; i < pkt->count; i++) {
-			reg = start_reg + (4 * i);
+		for (reg = start_reg, idx++; reg <= end_reg; reg += 4, idx++) {
 			if (evergreen_is_safe_reg(p, reg))
 				continue;
-			r = evergreen_cs_handle_reg(p, reg, idx + 1 + i);
+			r = evergreen_cs_handle_reg(p, reg, idx);
 			if (r)
 				return r;
 		}
@@ -2317,11 +2316,10 @@ static int evergreen_packet3_check(struct radeon_cs_parser *p,
 			DRM_ERROR("bad PACKET3_SET_CONTEXT_REG\n");
 			return -EINVAL;
 		}
-		for (i = 0; i < pkt->count; i++) {
-			reg = start_reg + (4 * i);
+		for (reg = start_reg, idx++; reg <= end_reg; reg += 4, idx++) {
 			if (evergreen_is_safe_reg(p, reg))
 				continue;
-			r = evergreen_cs_handle_reg(p, reg, idx + 1 + i);
+			r = evergreen_cs_handle_reg(p, reg, idx);
 			if (r)
 				return r;
 		}