X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Fgallium%2Fdrivers%2Fr300%2Fr300_state_derived.c;h=6af49888b9e32ac57ccddc915997ecc8eb984573;hb=b5e256c76dea2182c82af2a4f66224735701d55a;hp=cd969d633bcc92bf728f8f854f72be3a87081d23;hpb=cc8a537c57a62a196106b592e510e4c93bd1826e;p=mesa.git

diff --git a/src/gallium/drivers/r300/r300_state_derived.c b/src/gallium/drivers/r300/r300_state_derived.c
index cd969d633bc..6af49888b9e 100644
--- a/src/gallium/drivers/r300/r300_state_derived.c
+++ b/src/gallium/drivers/r300/r300_state_derived.c
@@ -462,6 +462,29 @@ static void r300_update_derived_shader_state(struct r300_context* r300)
     r300->dirty_state |= R300_NEW_RS_BLOCK;
 }
 
+static boolean r300_dsa_writes_depth_stencil(struct r300_dsa_state* dsa)
+{
+    /* We are interested only in the cases when a new depth or stencil value
+     * can be written and changed. */
+
+    /* We might optionally check for [Z func: never] and inspect the stencil
+     * state in a similar fashion, but it's not terribly important. */
+    return (dsa->z_buffer_control & R300_Z_WRITE_ENABLE) ||
+           (dsa->stencil_ref_mask & R300_STENCILWRITEMASK_MASK) ||
+           ((dsa->z_buffer_control & R500_STENCIL_REFMASK_FRONT_BACK) &&
+            (dsa->stencil_ref_bf & R300_STENCILWRITEMASK_MASK));
+}
+
+static boolean r300_dsa_alpha_test_enabled(struct r300_dsa_state* dsa)
+{
+    /* We are interested only in the cases when alpha testing can kill
+     * a fragment. */
+    uint32_t af = dsa->alpha_function;
+
+    return (af & R300_FG_ALPHA_FUNC_ENABLE) &&
+           (af & R300_FG_ALPHA_FUNC_ALWAYS) != R300_FG_ALPHA_FUNC_ALWAYS;
+}
+
 static void r300_update_ztop(struct r300_context* r300)
 {
     r300->ztop_state.z_buffer_top = R300_ZTOP_ENABLE;
@@ -478,19 +501,25 @@ static void r300_update_ztop(struct r300_context* r300)
      * The docs claim that for the first three cases, if no ZS writes happen,
      * then ZTOP can be used.
      *
+     * (3) will never apply since we do not support chroma-keyed operations.
+     * (4) will need to be re-examined (and this comment updated) if/when
+     * Hyper-Z becomes supported.
+     *
      * Additionally, the following conditions require disabled ZTOP:
-     * ~) Depth writes in fragment shader
-     * ~) Outstanding occlusion queries
+     * 5) Depth writes in fragment shader
+     * 6) Outstanding occlusion queries
      *
      * ~C.
      */
-    if (r300->dsa_state->alpha_function) {
-        r300->ztop_state.z_buffer_top = R300_ZTOP_DISABLE;
-    } else if (r300->fs->info.uses_kill) {
+
+    /* ZS writes */
+    if (r300_dsa_writes_depth_stencil(r300->dsa_state) &&
+           (r300_dsa_alpha_test_enabled(r300->dsa_state) ||   /* (1) */
+            r300->fs->info.uses_kill)) {                      /* (2) */
         r300->ztop_state.z_buffer_top = R300_ZTOP_DISABLE;
-    } else if (r300_fragment_shader_writes_depth(r300->fs)) {
+    } else if (r300_fragment_shader_writes_depth(r300->fs)) { /* (5) */
         r300->ztop_state.z_buffer_top = R300_ZTOP_DISABLE;
-    } else if (r300->query_current) {
+    } else if (r300->query_current) {                         /* (6) */
         r300->ztop_state.z_buffer_top = R300_ZTOP_DISABLE;
     }
 }