i965/skl: Use 1 register for uniform pull constant payload

When under dispatch_width=16 the previous code would allocate 2 registers for
the payload when only one is needed. This manifested itself through bugs on SKL
which needs to mess with this instruction.

Ken though this might impact shader-db, but apparently it doesn't

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89118
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88999
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Tested-by: Timo Aaltonen <timo.aaltonen@canonical.com>

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index a2a5234b0e9ab9600fff85a999802ba475578f0e..9e1676e628cc5f5119c1a93139d2e7f77902b26c 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -3063,7 +3063,7 @@ fs_visitor::lower_uniform_pull_constant_loads()
          assert(const_offset_reg.file == IMM &&
                 const_offset_reg.type == BRW_REGISTER_TYPE_UD);
          const_offset_reg.fixed_hw_reg.dw1.ud /= 4;
-         fs_reg payload = vgrf(glsl_type::uint_type);
+         fs_reg payload = fs_reg(GRF, alloc.allocate(1));
 
          /* We have to use a message header on Skylake to get SIMD4x2 mode.
           * Reserve space for the register.