i965/gs/gen6: Maximum allowed size of SEND messages is 15 (4 bits)

Comit d48ac9306619 addressed this for VS, but we forgot to do the same for
URB writes generated by the gen6 GS.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp b/src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp
index def21d80b2453ae90d03d2ef09030515555d7afb..59a765591033bf91f4bb85f93ebd17f401c436b7 100644 (file)
--- a/src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp
@@ -273,6 +273,18 @@ gen6_gs_visitor::emit_urb_write_header(int mrf)
    emit(GS_OPCODE_SET_DWORD_2, dst_reg(MRF, mrf), flags_data);
 }
 
+static int
+align_interleaved_urb_mlen(int mlen)
+{
+   /* URB data written (does not include the message header reg) must
+    * be a multiple of 256 bits, or 2 VS registers.  See vol5c.5,
+    * section 5.4.3.2.2: URB_INTERLEAVED.
+    */
+   if ((mlen % 2) != 1)
+      mlen++;
+   return mlen;
+}
+
 void
 gen6_gs_visitor::emit_urb_write_opcode(bool complete, int base_mrf,
                                        int last_mrf, int urb_offset)
@@ -299,14 +311,7 @@ gen6_gs_visitor::emit_urb_write_opcode(bool complete, int base_mrf,
    }
 
    inst->base_mrf = base_mrf;
-   /* URB data written (does not include the message header reg) must
-    * be a multiple of 256 bits, or 2 VS registers.  See vol5c.5,
-    * section 5.4.3.2.2: URB_INTERLEAVED.
-    */
-   int mlen = last_mrf - base_mrf;
-   if ((mlen % 2) != 1)
-      mlen++;
-   inst->mlen = mlen;
+   inst->mlen = align_interleaved_urb_mlen(last_mrf - base_mrf);
    inst->offset = urb_offset;
 }
 
@@ -339,9 +344,9 @@ gen6_gs_visitor::emit_thread_end()
 
    /* In the process of generating our URB write message contents, we
     * may need to unspill a register or load from an array.  Those
-    * reads would use MRFs 14-15.
+    * reads would use MRFs 21..23
     */
-   int max_usable_mrf = 13;
+   int max_usable_mrf = FIRST_SPILL_MRF(devinfo->gen);
 
    /* Issue the FF_SYNC message and obtain the initial VUE handle. */
    emit(CMP(dst_null_d(), this->vertex_count, 0u, BRW_CONDITIONAL_G));
@@ -416,9 +421,10 @@ gen6_gs_visitor::emit_thread_end()
                         this->vertex_output_offset, 1u));
 
                /* If this was max_usable_mrf, we can't fit anything more into
-                * this URB WRITE.
+                * this URB WRITE. Same if we reached the max. message length.
                 */
-               if (mrf > max_usable_mrf) {
+               if (mrf > max_usable_mrf ||
+                   align_interleaved_urb_mlen(mrf - base_mrf + 1) > BRW_MAX_MSG_LENGTH) {
                   slot++;
                   break;
                }