Mesa (8.0): r300/compiler: Clear loop registers in vertex shaders w/o loops

[Tom Stellard]

Module: Mesa
Branch: 8.0
Commit: 649a8952dfd9bc3d81330a9350eb96ce587f3c3e
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=649a8952dfd9bc3d81330a9350eb96ce587f3c3e

Author: Tom Stellard <thomas.stellard at amd.com>
Date:   Thu Apr 12 22:07:40 2012 -0400

r300/compiler: Clear loop registers in vertex shaders w/o loops

The loop registers weren't being cleared, so any shader that was
executed after a shader containing loops was at risk of having a loop
randomly inserted into it.

This fixes over one hundred piglit tests, although these test
only failed during full piglit runs and would pass if
run individually.  The exact number of piglit tests that this patch
fixes will vary depending on the version of piglit and the order the
tests are run.

(cherry-picked from commit 4a269a8dc0170c75ff22af3910786228727ea41e)

---

 src/gallium/drivers/r300/r300_emit.c  |   24 +++++++++++-------------
 src/gallium/drivers/r300/r300_state.c |    5 ++---
 2 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/src/gallium/drivers/r300/r300_emit.c b/src/gallium/drivers/r300/r300_emit.c
index 3897e99..e4afe78 100644
--- a/src/gallium/drivers/r300/r300_emit.c
+++ b/src/gallium/drivers/r300/r300_emit.c
@@ -1030,20 +1030,18 @@ void r300_emit_vs_state(struct r300_context* r300, unsigned size, void* state)
             R300_PVS_VF_MAX_VTX_NUM(12) |
             (r300screen->caps.is_r500 ? R500_TCL_STATE_OPTIMIZATION : 0));
 
-    /* Emit flow control instructions. */
-    if (code->num_fc_ops) {
-
-        OUT_CS_REG(R300_VAP_PVS_FLOW_CNTL_OPC, code->fc_ops);
-        if (r300screen->caps.is_r500) {
-            OUT_CS_REG_SEQ(R500_VAP_PVS_FLOW_CNTL_ADDRS_LW_0, code->num_fc_ops * 2);
-            OUT_CS_TABLE(code->fc_op_addrs.r500, code->num_fc_ops * 2);
-        } else {
-            OUT_CS_REG_SEQ(R300_VAP_PVS_FLOW_CNTL_ADDRS_0, code->num_fc_ops);
-            OUT_CS_TABLE(code->fc_op_addrs.r300, code->num_fc_ops);
-        }
-        OUT_CS_REG_SEQ(R300_VAP_PVS_FLOW_CNTL_LOOP_INDEX_0, code->num_fc_ops);
-        OUT_CS_TABLE(code->fc_loop_index, code->num_fc_ops);
+    /* Emit flow control instructions.  Even if there are no fc instructions,
+     * we still need to write the registers to make sure they are cleared. */
+    OUT_CS_REG(R300_VAP_PVS_FLOW_CNTL_OPC, code->fc_ops);
+    if (r300screen->caps.is_r500) {
+        OUT_CS_REG_SEQ(R500_VAP_PVS_FLOW_CNTL_ADDRS_LW_0, R300_VS_MAX_FC_OPS * 2);
+        OUT_CS_TABLE(code->fc_op_addrs.r500, R300_VS_MAX_FC_OPS * 2);
+    } else {
+        OUT_CS_REG_SEQ(R300_VAP_PVS_FLOW_CNTL_ADDRS_0, R300_VS_MAX_FC_OPS);
+        OUT_CS_TABLE(code->fc_op_addrs.r300, R300_VS_MAX_FC_OPS);
     }
+    OUT_CS_REG_SEQ(R300_VAP_PVS_FLOW_CNTL_LOOP_INDEX_0, R300_VS_MAX_FC_OPS);
+    OUT_CS_TABLE(code->fc_loop_index, R300_VS_MAX_FC_OPS);
 
     END_CS;
 }
diff --git a/src/gallium/drivers/r300/r300_state.c b/src/gallium/drivers/r300/r300_state.c
index c43352a..8a656e6 100644
--- a/src/gallium/drivers/r300/r300_state.c
+++ b/src/gallium/drivers/r300/r300_state.c
@@ -1802,9 +1802,8 @@ static void r300_bind_vs_state(struct pipe_context* pipe, void* shader)
     if (r300->screen->caps.has_tcl) {
         unsigned fc_op_dwords = r300->screen->caps.is_r500 ? 3 : 2;
         r300_mark_atom_dirty(r300, &r300->vs_state);
-        r300->vs_state.size =
-                vs->code.length + 9 +
-        (vs->code.num_fc_ops ? vs->code.num_fc_ops * fc_op_dwords + 4 : 0);
+        r300->vs_state.size = vs->code.length + 9 +
+			(R300_VS_MAX_FC_OPS * fc_op_dwords + 4);
 
         r300_mark_atom_dirty(r300, &r300->vs_constants);
         r300->vs_constants.size =