From: Eric Anholt <eric@anholt.net>
Date: Thu, 9 Oct 2014 14:36:45 +0000 (+0200)
Subject: vc4: Prevent copy propagating out the MOVs from r4.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=93cac2637ba5a7cd5c79a0e74b87298fae807135;p=mesa.git

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.
---

diff --git a/src/gallium/drivers/vc4/vc4_opt_copy_propagation.c b/src/gallium/drivers/vc4/vc4_opt_copy_propagation.c
index 0cffb284e44..9cf1352514c 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;
 }