Mesa (master): vc4: Prevent copy propagating out the MOVs from r4.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 93cac2637ba5a7cd5c79a0e74b87298fae807135
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=93cac2637ba5a7cd5c79a0e74b87298fae807135

Author: Eric Anholt <eric at anholt.net>
Date:   Thu Oct  9 16:36:45 2014 +0200

vc4: Prevent copy propagating out the MOVs from r4.

Copy propagating these might result in reading the r4 after some other
instruction has written r4.  Just prevent all copy propagation of this for
now.

Fixes bad rendering with upcoming indirect register access support, where
the copy propagation was consistently happening across another read.

---

 src/gallium/drivers/vc4/vc4_opt_copy_propagation.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/vc4/vc4_opt_copy_propagation.c b/src/gallium/drivers/vc4/vc4_opt_copy_propagation.c
index 0cffb28..9cf1352 100644
--- a/src/gallium/drivers/vc4/vc4_opt_copy_propagation.c
+++ b/src/gallium/drivers/vc4/vc4_opt_copy_propagation.c
@@ -41,10 +41,14 @@ qir_opt_copy_propagation(struct vc4_compile *c)
         struct simple_node *node;
         bool debug = false;
         struct qreg *movs = calloc(c->num_temps, sizeof(struct qreg));
+        struct qinst **defs = calloc(c->num_temps, sizeof(struct qreg));
 
         foreach(node, &c->instructions) {
                 struct qinst *inst = (struct qinst *)node;
 
+                if (inst->dst.file == QFILE_TEMP)
+                        defs[inst->dst.index] = inst;
+
                 /* A single instruction can only read one uniform value.  (It
                  * could maybe read the same uniform value in two operands,
                  * but that doesn't seem important to do).
@@ -81,10 +85,16 @@ qir_opt_copy_propagation(struct vc4_compile *c)
                         }
                 }
 
-                if (inst->op == QOP_MOV && inst->dst.file == QFILE_TEMP)
+                if (inst->op == QOP_MOV &&
+                    inst->dst.file == QFILE_TEMP &&
+                    (inst->src[0].file != QFILE_TEMP ||
+                     (defs[inst->src[0].index]->op != QOP_TEX_RESULT &&
+                      defs[inst->dst.index]->op != QOP_TLB_COLOR_READ))) {
                         movs[inst->dst.index] = inst->src[0];
+                }
         }
 
         free(movs);
+        free(defs);
         return progress;
 }