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.

NOTE: This is a candidate for the stable branches.

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;
 }

src/gallium/drivers/r300/r300_state.c

@@ -1796,9 +1796,8 @@ 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 =