[Mesa-dev] [PATCH 1/2] i965/vec4: Add and use byte-MOV instruction for unpack 4x8.

[Matt Turner]

Previously we were using a B/UB source in an Align16 instruction, which
is illegal. It for some reason works on all platforms, except Broadwell.

Cc: "10.5" <mesa-stable at lists.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=86811
---
I know! Another instruction for MOV! Sorry!

 src/mesa/drivers/dri/i965/brw_defines.h          |  1 +
 src/mesa/drivers/dri/i965/brw_vec4_generator.cpp | 16 ++++++++++++++++
 src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp   |  4 ++--
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
index a597d6b..17c27dd 100644
--- a/src/mesa/drivers/dri/i965/brw_defines.h
+++ b/src/mesa/drivers/dri/i965/brw_defines.h
@@ -911,6 +911,7 @@ enum opcode {
 
    SHADER_OPCODE_URB_WRITE_SIMD8,
 
+   VEC4_OPCODE_MOV_BYTES,
    VEC4_OPCODE_PACK_BYTES,
    VEC4_OPCODE_UNPACK_UNIFORM,
 
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp b/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
index e38e6ea..85a92ee 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
@@ -1513,6 +1513,22 @@ vec4_generator::generate_code(const cfg_t *cfg)
          generate_unpack_flags(inst, dst);
          break;
 
+      case VEC4_OPCODE_MOV_BYTES: {
+         /* Moves the low byte from each channel, using an Align1 access mode
+          * and a <4,1,0> source region.
+          */
+         assert(src[0].type == BRW_REGISTER_TYPE_UB ||
+                src[0].type == BRW_REGISTER_TYPE_B);
+
+         brw_set_default_access_mode(p, BRW_ALIGN_1);
+         src[0].vstride = BRW_VERTICAL_STRIDE_4;
+         src[0].width = BRW_WIDTH_1;
+         src[0].hstride = BRW_HORIZONTAL_STRIDE_0;
+         brw_MOV(p, dst, src[0]);
+         brw_set_default_access_mode(p, BRW_ALIGN_16);
+         break;
+      }
+
       case VEC4_OPCODE_PACK_BYTES: {
          /* Is effectively:
           *
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index 5638105..f15c66a 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -489,7 +489,7 @@ vec4_visitor::emit_unpack_unorm_4x8(const dst_reg &dst, src_reg src0)
 
    shifted.type = BRW_REGISTER_TYPE_UB;
    dst_reg f(this, glsl_type::vec4_type);
-   emit(MOV(f, src_reg(shifted)));
+   emit(VEC4_OPCODE_MOV_BYTES, f, src_reg(shifted));
 
    emit(MUL(dst, src_reg(f), src_reg(1.0f / 255.0f)));
 }
@@ -511,7 +511,7 @@ vec4_visitor::emit_unpack_snorm_4x8(const dst_reg &dst, src_reg src0)
 
    shifted.type = BRW_REGISTER_TYPE_B;
    dst_reg f(this, glsl_type::vec4_type);
-   emit(MOV(f, src_reg(shifted)));
+   emit(VEC4_OPCODE_MOV_BYTES, f, src_reg(shifted));
 
    dst_reg scaled(this, glsl_type::vec4_type);
    emit(MUL(scaled, src_reg(f), src_reg(1.0f / 127.0f)));
-- 
2.0.5