Mesa (master): vc4: Eliminate unused texture instructions.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 40748cf8d9b9f4d72bcfb9872d891c1705a81b8d
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=40748cf8d9b9f4d72bcfb9872d891c1705a81b8d

Author: Eric Anholt <eric at anholt.net>
Date:   Thu Oct  9 14:42:14 2014 +0200

vc4: Eliminate unused texture instructions.

---

 src/gallium/drivers/vc4/vc4_opt_dead_code.c |   22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/vc4/vc4_opt_dead_code.c b/src/gallium/drivers/vc4/vc4_opt_dead_code.c
index 0c273ff..f08818a 100644
--- a/src/gallium/drivers/vc4/vc4_opt_dead_code.c
+++ b/src/gallium/drivers/vc4/vc4_opt_dead_code.c
@@ -52,6 +52,8 @@ qir_opt_dead_code(struct vc4_compile *c)
         bool progress = false;
         bool *used = calloc(c->num_temps, sizeof(bool));
         bool sf_used = false;
+        /* Whether we're eliminating texture setup currently. */
+        bool dce_tex = false;
 
         struct simple_node *node, *t;
         for (node = c->instructions.prev, t = node->prev;
@@ -61,7 +63,13 @@ qir_opt_dead_code(struct vc4_compile *c)
 
                 if (inst->dst.file == QFILE_TEMP &&
                     !used[inst->dst.index] &&
-                    !qir_has_side_effects(inst)) {
+                    (!qir_has_side_effects(inst) ||
+                     inst->op == QOP_TEX_RESULT)) {
+                        if (inst->op == QOP_TEX_RESULT) {
+                                dce_tex = true;
+                                c->num_texture_samples--;
+                        }
+
                         dce(c, inst);
                         progress = true;
                         continue;
@@ -78,6 +86,18 @@ qir_opt_dead_code(struct vc4_compile *c)
                         sf_used = false;
                 }
 
+                if (inst->op == QOP_TEX_RESULT)
+                        dce_tex = false;
+
+                if (dce_tex && (inst->op == QOP_TEX_S ||
+                                inst->op == QOP_TEX_T ||
+                                inst->op == QOP_TEX_R ||
+                                inst->op == QOP_TEX_B)) {
+                        dce(c, inst);
+                        progress = true;
+                        continue;
+                }
+
                 for (int i = 0; i < qir_get_op_nsrc(inst->op); i++) {
                         if (inst->src[i].file == QFILE_TEMP)
                                 used[inst->src[i].index] = true;