Mesa (master): i965/fs: Properly patch special values during VGRF compaction.

[Kenneth Graunke]

Module: Mesa
Branch: master
Commit: 5cea0273414bd5897c318b4d632b08ce8080a2fe
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=5cea0273414bd5897c318b4d632b08ce8080a2fe

Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Wed Nov 14 20:50:05 2012 -0800

i965/fs: Properly patch special values during VGRF compaction.

In addition to registers used by instructions, fs_visitor maintains
direct references to certain "special" values used for inputs/outputs.

When I added VGRF compaction, I overlooked these, believing that these
direct references weren't used once instructions were generated.  That
was wrong.  For example, pixel_x/y are used in virtual_grf_interferes(),
which is called by optimization passes and register allocation.

This patch treats all of them as used and patches them after compacting.
While it's not strictly necessary to patch all of them (as some aren't
used after emitting code), it seems safer to simply fix them all.

Fixes oglconform's textureswizzle/advanced.shader.targets, piglit's
glsl-fs-lots-of-tex, and glean's texCombine on pre-Gen6 hardware.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=56790
Reviewed-by: Eric Anholt <eric at anholt.net>

---

 src/mesa/drivers/dri/i965/brw_fs.cpp |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index f25fd16..2cd3ffe 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1130,6 +1130,27 @@ fs_visitor::compact_virtual_grfs()
       }
    }
 
+   /* In addition to registers used in instructions, fs_visitor keeps
+    * direct references to certain special values which must be patched:
+    */
+   fs_reg *special[] = {
+      &frag_depth, &pixel_x, &pixel_y, &pixel_w, &wpos_w, &dual_src_output,
+      &outputs[0], &outputs[1], &outputs[2], &outputs[3],
+      &outputs[4], &outputs[5], &outputs[6], &outputs[7],
+      &delta_x[0], &delta_x[1], &delta_x[2],
+      &delta_x[3], &delta_x[4], &delta_x[5],
+      &delta_y[0], &delta_y[1], &delta_y[2],
+      &delta_y[3], &delta_y[4], &delta_y[5],
+   };
+   STATIC_ASSERT(BRW_WM_BARYCENTRIC_INTERP_MODE_COUNT == 6);
+   STATIC_ASSERT(BRW_MAX_DRAW_BUFFERS == 8);
+
+   /* Treat all special values as used, to be conservative */
+   for (unsigned i = 0; i < ARRAY_SIZE(special); i++) {
+      if (special[i]->file == GRF)
+	 remap_table[special[i]->reg] = 0;
+   }
+
    /* Compact the GRF arrays. */
    int new_index = 0;
    for (int i = 0; i < this->virtual_grf_count; i++) {
@@ -1158,6 +1179,12 @@ fs_visitor::compact_virtual_grfs()
             inst->src[i].reg = remap_table[inst->src[i].reg];
       }
    }
+
+   /* Patch all the references to special values */
+   for (unsigned i = 0; i < ARRAY_SIZE(special); i++) {
+      if (special[i]->file == GRF && remap_table[special[i]->reg] != -1)
+	 special[i]->reg = remap_table[special[i]->reg];
+   }
 }
 
 bool