i965/vs: Properly clear cur_value when propagating direct copies.

Consider the following code:

MOV A.x, B.x
MOV B.x, C.x

After the first line, cur_value[A][0] == B, indicating that A.x's
current value came from register B.

When processing the second line, we update cur_value[B][0] to C.
However, for drect copies, we fail to reset cur_value[A][0] to NULL.
This is necessary because the value of A is no longer the value of B.

Fixes Counter-Strike: Source in Wine (where the menu rendered completely
black in DX9 mode), completely white textures in Civilization V, and the
new Piglit test glsl-vs-copy-propagation-1.shader_test.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=42032
Tested-by: Matt Turner <mattst88@gmail.com>
Tested-by: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
index 95aa30614b155c8c239e3031b6055b9ec2091273..08d8f5b7034f302487a70f10c970c34ddc5fe1df 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
@@ -297,30 +297,26 @@ vec4_visitor::opt_copy_propagation()
       }
 
       /* Track available source registers. */
-      if (is_direct_copy(inst)) {
-        int reg = virtual_grf_reg_map[inst->dst.reg] + inst->dst.reg_offset;
-        for (int i = 0; i < 4; i++) {
-           if (inst->dst.writemask & (1 << i)) {
-              cur_value[reg][i] = &inst->src[0];
-           }
+      const int reg = virtual_grf_reg_map[inst->dst.reg] + inst->dst.reg_offset;
+
+      /* Update our destination's current channel values.  For a direct copy,
+       * the value is the newly propagated source.  Otherwise, we don't know
+       * the new value, so clear it.
+       */
+      bool direct_copy = is_direct_copy(inst);
+      for (int i = 0; i < 4; i++) {
+        if (inst->dst.writemask & (1 << i)) {
+           cur_value[reg][i] = direct_copy ? &inst->src[0] : NULL;
         }
-        continue;
       }
 
-      /* For any updated channels, clear tracking of them as a source
-       * or destination.
+      /* Clear the records for any registers whose current value came from
+       * our destination's updated channels, as the two are no longer equal.
        */
       if (inst->dst.file == GRF) {
         if (inst->dst.reladdr)
            memset(cur_value, 0, sizeof(cur_value));
         else {
-           int reg = virtual_grf_reg_map[inst->dst.reg] + inst->dst.reg_offset;
-
-           for (int i = 0; i < 4; i++) {
-              if (inst->dst.writemask & (1 << i))
-                 cur_value[reg][i] = NULL;
-           }
-
            for (int i = 0; i < virtual_grf_reg_count; i++) {
               for (int j = 0; j < 4; j++) {
                  if (inst->dst.writemask & (1 << j) &&