i965/gen8: Change the winsys MSAA blits from blorp to meta.

This gets us equivalent code paths on BDW and pre-BDW, except for stencil
(where we don't have MSAA stencil resolve code yet)

Improves MSAA-forced citybench by 7.94496% +/- 2.38429% (n=16).  Reduces
DRI2 MSAA glxgears performance by -12.3559% +/- 1.52845% (n=9).

v2: Move the new meta code to brw_meta_updownsample.c, name it
    brw_meta_updownsample(), add a comment about
    intel_rb_storage_first_mt_slice(), and rename that function and move
    the RB generation into it (review ideas by Ken).
v3: Fix 2 src vs dst pasteos in previous change.
v4: Skip this path pre-gen8 for now, until we can analyze the glxgears
    performance delta some more.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

4 files changed, 152 insertions, 8 deletions

diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
index 1649369e9e..dfb88e281e 100644
--- a/src/mesa/drivers/dri/i965/Makefile.sources
+++ b/src/mesa/drivers/dri/i965/Makefile.sources
@@ -74,6 +74,7 @@ i965_FILES = \
 	brw_interpolation_map.c \
 	brw_lower_texture_gradients.cpp \
 	brw_lower_unnormalized_offset.cpp \
+	brw_meta_updownsample.c \
 	brw_misc_state.c \
 	brw_object_purgeable.c \
 	brw_performance_monitor.c \
diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index 32fc38be56..04af5d04d3 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -1484,6 +1484,12 @@ GLboolean brwCreateContext(gl_api api,
 /*======================================================================
  * brw_misc_state.c
  */
+void brw_meta_updownsample(struct brw_context *brw,
+                           struct intel_mipmap_tree *src,
+                           struct intel_mipmap_tree *dst);
+/*======================================================================
+ * brw_misc_state.c
+ */
 void brw_get_depthstencil_tile_masks(struct intel_mipmap_tree *depth_mt,
                                      uint32_t depth_level,
                                      uint32_t depth_layer,
diff --git a/src/mesa/drivers/dri/i965/brw_meta_updownsample.c b/src/mesa/drivers/dri/i965/brw_meta_updownsample.c
new file mode 100644
index 0000000000..de25bf4f7a
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_meta_updownsample.c
@@ -0,0 +1,132 @@
+/*
+ * Copyright © 2014 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "brw_context.h"
+#include "intel_batchbuffer.h"
+#include "intel_fbo.h"
+
+#include "main/blit.h"
+#include "main/buffers.h"
+#include "main/fbobject.h"
+
+#include "drivers/common/meta.h"
+
+/**
+ * @file brw_meta_updownsample.c
+ *
+ * Implements upsampling and downsampling of miptrees for window system
+ * framebuffers.
+ */
+
+/**
+ * Creates a new named renderbuffer that wraps the first slice
+ * of an existing miptree.
+ *
+ * Clobbers the current renderbuffer binding (ctx->CurrentRenderbuffer).
+ */
+static GLuint
+brw_get_rb_for_first_slice(struct brw_context *brw, struct intel_mipmap_tree *mt)
+{
+   struct gl_context *ctx = &brw->ctx;
+   GLuint rbo;
+   struct gl_renderbuffer *rb;
+   struct intel_renderbuffer *irb;
+
+   /* This turns the GenRenderbuffers name into an actual struct
+    * intel_renderbuffer.
+    */
+   _mesa_GenRenderbuffers(1, &rbo);
+   _mesa_BindRenderbuffer(GL_RENDERBUFFER, rbo);
+
+   rb = ctx->CurrentRenderbuffer;
+   irb = intel_renderbuffer(rb);
+
+   rb->Format = mt->format;
+   rb->_BaseFormat = _mesa_base_fbo_format(ctx, mt->format);
+
+   rb->NumSamples = mt->num_samples;
+   rb->Width = mt->logical_width0;
+   rb->Height = mt->logical_height0;
+
+   intel_miptree_reference(&irb->mt, mt);
+
+   return rbo;
+}
+
+/**
+ * Implementation of up or downsampling for window-system MSAA miptrees.
+ */
+void
+brw_meta_updownsample(struct brw_context *brw,
+                      struct intel_mipmap_tree *src_mt,
+                      struct intel_mipmap_tree *dst_mt)
+{
+   struct gl_context *ctx = &brw->ctx;
+   GLuint fbos[2], src_rbo, dst_rbo, src_fbo, dst_fbo;
+   GLenum drawbuffer;
+   GLbitfield attachment, blit_bit;
+
+   if (_mesa_get_format_base_format(src_mt->format) == GL_DEPTH_COMPONENT ||
+       _mesa_get_format_base_format(src_mt->format) == GL_DEPTH_STENCIL) {
+      attachment = GL_DEPTH_ATTACHMENT;
+      drawbuffer = GL_NONE;
+      blit_bit = GL_DEPTH_BUFFER_BIT;
+   } else {
+      attachment = GL_COLOR_ATTACHMENT0;
+      drawbuffer = GL_COLOR_ATTACHMENT0;
+      blit_bit = GL_COLOR_BUFFER_BIT;
+   }
+
+   intel_batchbuffer_emit_mi_flush(brw);
+
+   _mesa_meta_begin(ctx, MESA_META_ALL);
+   _mesa_GenFramebuffers(2, fbos);
+   src_rbo = brw_get_rb_for_first_slice(brw, src_mt);
+   dst_rbo = brw_get_rb_for_first_slice(brw, dst_mt);
+   src_fbo = fbos[0];
+   dst_fbo = fbos[1];
+
+   _mesa_BindFramebuffer(GL_READ_FRAMEBUFFER, src_fbo);
+   _mesa_FramebufferRenderbuffer(GL_READ_FRAMEBUFFER, attachment,
+                                 GL_RENDERBUFFER, src_rbo);
+   _mesa_ReadBuffer(drawbuffer);
+
+   _mesa_BindFramebuffer(GL_DRAW_FRAMEBUFFER, dst_fbo);
+   _mesa_FramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, attachment,
+                                 GL_RENDERBUFFER, dst_rbo);
+   _mesa_DrawBuffer(drawbuffer);
+
+   _mesa_BlitFramebuffer(0, 0,
+                         src_mt->logical_width0, src_mt->logical_height0,
+                         0, 0,
+                         dst_mt->logical_width0, dst_mt->logical_height0,
+                         blit_bit, GL_NEAREST);
+
+   _mesa_DeleteRenderbuffers(1, &src_rbo);
+   _mesa_DeleteRenderbuffers(1, &dst_rbo);
+   _mesa_DeleteFramebuffers(2, fbos);
+
+   _mesa_meta_end(ctx);
+
+   intel_batchbuffer_emit_mi_flush(brw);
+}
diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index 10a1bbc7fe..9c5623c264 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -41,6 +41,7 @@
 #include "brw_context.h"
 
 #include "main/enums.h"
+#include "main/fbobject.h"
 #include "main/formats.h"
 #include "main/glformats.h"
 #include "main/texcompress_etc.h"
@@ -1555,14 +1556,18 @@ intel_miptree_updownsample(struct brw_context *brw,
                            struct intel_mipmap_tree *src,
                            struct intel_mipmap_tree *dst)
 {
-   brw_blorp_blit_miptrees(brw,
-                           src, 0 /* level */, 0 /* layer */,
-                           dst, 0 /* level */, 0 /* layer */,
-                           0, 0,
-                           src->logical_width0, src->logical_height0,
-                           0, 0,
-                           dst->logical_width0, dst->logical_height0,
-                           GL_NEAREST, false, false /*mirror x, y*/);
+   if (brw->gen < 8 || src->format == MESA_FORMAT_S_UINT8) {
+      brw_blorp_blit_miptrees(brw,
+                              src, 0 /* level */, 0 /* layer */,
+                              dst, 0 /* level */, 0 /* layer */,
+                              0, 0,
+                              src->logical_width0, src->logical_height0,
+                              0, 0,
+                              dst->logical_width0, dst->logical_height0,
+                              GL_NEAREST, false, false /*mirror x, y*/);
+   } else {
+      brw_meta_updownsample(brw, src, dst);
+   }
 
    if (src->stencil_mt) {
       brw_blorp_blit_miptrees(brw,