[Mesa-stable] [PATCH 10.6] i965/fs: Handle MRF destinations in lower_integer_multiplication().

[Matt Turner]

The lowered code reads from the destination, which isn't possible from
message registers.

Fixes the following dEQP tests on SNB:

    dEQP-GLES3.functional.shaders.precision.int.highp_mul_fragment
    dEQP-GLES3.functional.shaders.precision.int.mediump_mul_fragment
    dEQP-GLES3.functional.shaders.precision.int.lowp_mul_fragment

Cc: "10.6 11.0" <mesa-stable at lists.freedesktop.org>
Tested-by:  Mark Janes <mark.a.janes at intel.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>
(cherry picked from commit 9390cb84593bda516e8c1521c87a08475574d1be)
---
Emil, this is the 10.6 backport for the above mentioned commit.

 src/mesa/drivers/dri/i965/brw_fs.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index d99c79b..07a6bfa 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -3607,7 +3607,8 @@ fs_visitor::lower_integer_multiplication()
           * schedule multi-component multiplications much better.
           */
 
-         if (inst->conditional_mod && inst->dst.is_null()) {
+         fs_reg orig_dst = inst->dst;
+         if (orig_dst.is_null() || orig_dst.file == MRF) {
             inst->dst = fs_reg(GRF, alloc.allocate(dispatch_width / 8),
                                inst->dst.type, dispatch_width);
          }
@@ -3673,9 +3674,8 @@ fs_visitor::lower_integer_multiplication()
 
          insert(ADD(dst, low, high));
 
-         if (inst->conditional_mod) {
-            fs_reg null(retype(brw_null_reg(), inst->dst.type));
-            fs_inst *mov = MOV(null, inst->dst);
+         if (inst->conditional_mod || orig_dst.file == MRF) {
+            fs_inst *mov = MOV(orig_dst, inst->dst);
             mov->conditional_mod = inst->conditional_mod;
             insert(mov);
          }
-- 
2.4.6