i965: Fix clears of layered framebuffers with mismatched layer counts.

Previously, Mesa enforced the following rule (from
ARB_geometry_shader4's list of criteria for framebuffer completeness):

  * If any framebuffer attachment is layered, all attachments must have
    the same layer count.  For three-dimensional textures, the layer count
    is the depth of the attached volume.  For cube map textures, the layer
    count is always six.  For one- and two-dimensional array textures, the
    layer count is simply the number of layers in the array texture.
    { FRAMEBUFFER_INCOMPLETE_LAYER_COUNT_ARB }

However, when ARB_geometry_shader4 was adopted into GL 3.2, this rule
was dropped; GL 3.2 permits different attachments to have different
layer counts.  This patch brings Mesa in line with GL 3.2.

In order to ensure that layered clears properly clear all layers, we
now have to keep track of the maximum number of layers in a layered
framebuffer.

Fixes the following piglit tests in spec/!OpenGL 3.2/layered-rendering:
- clear-color-all-types 1d_array mipmapped
- clear-color-all-types 1d_array single_level
- clear-color-mismatched-layer-count
- framebuffer-layer-count-mismatch

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>

src/mesa/drivers/common/meta.c

@@ -2407,9 +2407,9 @@ _mesa_meta_glsl_Clear(struct gl_context *ctx, GLbitfield buffers)
 		       GL_DYNAMIC_DRAW_ARB);
 
    /* draw quad(s) */
-   if (fb->NumLayers > 0) {
+   if (fb->MaxNumLayers > 0) {
       unsigned layer;
-      for (layer = 0; layer < fb->NumLayers; layer++) {
+      for (layer = 0; layer < fb->MaxNumLayers; layer++) {
          if (fb->_IntegerColor)
             _mesa_Uniform1i(clear->IntegerLayerLocation, layer);
          else

src/mesa/drivers/dri/i965/brw_blorp_clear.cpp

@@ -573,14 +573,14 @@ brw_blorp_clear_color(struct brw_context *brw, struct gl_framebuffer *fb,
       if (rb == NULL)
          continue;
 
-      if (fb->NumLayers > 0) {
+      if (fb->MaxNumLayers > 0) {
          unsigned layer_multiplier =
             (irb->mt->msaa_layout == INTEL_MSAA_LAYOUT_UMS ||
              irb->mt->msaa_layout == INTEL_MSAA_LAYOUT_CMS) ?
             irb->mt->num_samples : 1;
-         assert(fb->NumLayers * layer_multiplier ==
-                irb->mt->level[irb->mt_level].depth);
-         for (unsigned layer = 0; layer < fb->NumLayers; layer++) {
+         unsigned num_layers =
+            irb->mt->level[irb->mt_level].depth / layer_multiplier;
+         for (unsigned layer = 0; layer < num_layers; layer++) {
             if (!do_single_blorp_clear(brw, fb, rb, buf, partial_clear,
                                        layer * layer_multiplier)) {
                return false;

src/mesa/drivers/dri/i965/brw_clear.c

@@ -181,9 +181,9 @@ brw_fast_clear_depth(struct gl_context *ctx)
     */
    intel_batchbuffer_emit_mi_flush(brw);
 
-   if (fb->NumLayers > 0) {
-      assert(fb->NumLayers == depth_irb->mt->level[depth_irb->mt_level].depth);
-      for (unsigned layer = 0; layer < fb->NumLayers; layer++) {
+   if (fb->MaxNumLayers > 0) {
+      unsigned num_layers = depth_irb->mt->level[depth_irb->mt_level].depth;
+      for (unsigned layer = 0; layer < num_layers; layer++) {
          intel_hiz_exec(brw, mt, depth_irb->mt_level, layer,
                         GEN6_HIZ_OP_DEPTH_CLEAR);
       }

src/mesa/drivers/dri/i965/brw_wm_surface_state.c

@@ -700,7 +700,7 @@ brw_update_renderbuffer_surfaces(struct brw_context *brw)
       for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
 	 if (intel_renderbuffer(ctx->DrawBuffer->_ColorDrawBuffers[i])) {
 	    brw->vtbl.update_renderbuffer_surface(brw, ctx->DrawBuffer->_ColorDrawBuffers[i],
-                                                  ctx->DrawBuffer->NumLayers > 0, i);
+                                                  ctx->DrawBuffer->MaxNumLayers > 0, i);
 	 } else {
 	    brw->vtbl.update_null_renderbuffer_surface(brw, i);
 	 }

src/mesa/drivers/dri/i965/gen6_clip_state.c

@@ -121,7 +121,7 @@ upload_clip_state(struct brw_context *brw)
 	     dw2);
    OUT_BATCH(U_FIXED(0.125, 3) << GEN6_CLIP_MIN_POINT_WIDTH_SHIFT |
              U_FIXED(255.875, 3) << GEN6_CLIP_MAX_POINT_WIDTH_SHIFT |
-             (fb->NumLayers > 0 ? 0 : GEN6_CLIP_FORCE_ZERO_RTAINDEX));
+             (fb->MaxNumLayers > 0 ? 0 : GEN6_CLIP_FORCE_ZERO_RTAINDEX));
    ADVANCE_BATCH();
 }
 

src/mesa/drivers/dri/i965/gen7_misc_state.c

@@ -81,7 +81,7 @@ gen7_emit_depth_stencil_hiz(struct brw_context *brw,
       break;
    }
 
-   if (fb->NumLayers > 0 || !irb) {
+   if (fb->MaxNumLayers > 0 || !irb) {
       min_array_element = 0;
    } else if (irb->mt->num_samples > 1) {
       /* Convert physical layer to logical layer. */

src/mesa/main/fbobject.c

@@ -877,8 +877,10 @@ _mesa_test_framebuffer_completeness(struct gl_context *ctx,
    GLint fixedSampleLocations = -1;
    GLint i;
    GLuint j;
-   bool layer_info_valid = false; /* Covers layer_count and layer_tex_target */
-   GLuint layer_count = 0, att_layer_count;
+   /* Covers max_layer_count, is_layered, and layer_tex_target */
+   bool layer_info_valid = false;
+   GLuint max_layer_count = 0, att_layer_count;
+   bool is_layered;
    GLenum layer_tex_target = 0;
 
    assert(_mesa_is_user_fbo(fb));
@@ -1064,26 +1066,24 @@ _mesa_test_framebuffer_completeness(struct gl_context *ctx,
          att_layer_count = 0;
       }
       if (!layer_info_valid) {
-         layer_count = att_layer_count;
+         is_layered = att->Layered;
+         max_layer_count = att_layer_count;
          layer_tex_target = att_tex_target;
          layer_info_valid = true;
-      } else if (layer_count > 0 && layer_tex_target != att_tex_target) {
+      } else if (max_layer_count > 0 && layer_tex_target != att_tex_target) {
          fb->_Status = GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS;
          fbo_incomplete(ctx, "layered framebuffer has mismatched targets", i);
          return;
-      } else if (layer_count != att_layer_count) {
-         if (layer_count == 0 || att_layer_count == 0) {
-            fb->_Status = GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS;
-            fbo_incomplete(ctx, "framebuffer attachment layer mode is inconsistent", i);
-         } else {
-            fb->_Status = GL_FRAMEBUFFER_INCOMPLETE_LAYER_COUNT_ARB;
-            fbo_incomplete(ctx, "framebuffer attachment layer count is inconsistent", i);
-         }
+      } else if (is_layered != att->Layered) {
+         fb->_Status = GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS;
+         fbo_incomplete(ctx, "framebuffer attachment layer mode is inconsistent", i);
          return;
+      } else if (att_layer_count > max_layer_count) {
+         max_layer_count = att_layer_count;
       }
    }
 
-   fb->NumLayers = layer_count;
+   fb->MaxNumLayers = max_layer_count;
 
    if (_mesa_is_desktop_gl(ctx) && !ctx->Extensions.ARB_ES2_compatibility) {
       /* Check that all DrawBuffers are present */

src/mesa/main/mtypes.h

@@ -3008,12 +3008,11 @@ struct gl_framebuffer
    struct gl_renderbuffer *_ColorReadBuffer;
 
    /**
-    * The number of layers in the framebuffer, or 0 if the framebuffer is not
-    * layered.  For cube maps, this value is 6.  For cube map arrays, this
-    * value is the "depth" value passed to TexImage3D (always a multiple of
-    * 6).
+    * The maximum number of layers in the framebuffer, or 0 if the framebuffer
+    * is not layered.  For cube maps and cube map arrays, each cube face
+    * counts as a layer.
     */
-   GLuint NumLayers;
+   GLuint MaxNumLayers;
 
    /** Delete this framebuffer */
    void (*Delete)(struct gl_framebuffer *fb);