[Mesa-dev] [PATCH v2 1/3] i965/fs: fix indirect load DF uniforms on BSW/BXT

[Samuel Iglesias Gonsálvez]

The lowered BSW/BXT indirect move instructions had incorrect
source types, which luckily wasn't causing incorrect assembly to be
generated due to the bug fixed in the next patch, but would have
confused the remaining back-end IR infrastructure due to the mismatch
between the IR source types and the emitted machine code.

v2:
- Improve commit log (Curro)
- Fix read_size (Curro)
- Fix DF uniform array detection in assign_constant_locations() when
  it is acceded with 32-bit MOV_INDIRECTs in BSW/BXT.

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Cc: "17.0" <mesa-stable at lists.freedesktop.org>
---
 src/mesa/drivers/dri/i965/brw_fs.cpp     | 11 ++++++++-
 src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 41 ++++++++++++++++----------------
 2 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index c348bc7138d..93ab84b5845 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1944,10 +1944,19 @@ fs_visitor::assign_constant_locations()
             unsigned last = constant_nr + (inst->src[2].ud / 4) - 1;
             assert(last < uniforms);
 
+            bool supports_64bit_indirects =
+               !devinfo->is_cherryview && !devinfo->is_broxton;
+            /* Detect if this is as a result 64-bit MOV INDIRECT. In case
+             * of BSW/BXT, we substitute each DF MOV INDIRECT by two 32-bit MOV
+             * INDIRECT.
+             */
+            bool mov_indirect_64bit = (type_sz(inst->src[i].type) == 8) ||
+               (!supports_64bit_indirects && inst->dst.type == BRW_REGISTER_TYPE_UD &&
+                inst->src[0].type == BRW_REGISTER_TYPE_UD && inst->dst.stride == 2);
             for (unsigned j = constant_nr; j < last; j++) {
                is_live[j] = true;
                contiguous[j] = true;
-               if (type_sz(inst->src[i].type) == 8) {
+               if (mov_indirect_64bit) {
                   is_live_64bit[j] = true;
                }
             }
diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
index 991c20fad62..4aaf84964e9 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
@@ -3878,31 +3878,30 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr
          unsigned read_size = instr->const_index[1] -
             (instr->num_components - 1) * type_sz(dest.type);
 
-         fs_reg indirect_chv_high_32bit;
-         bool is_chv_bxt_64bit =
-            (devinfo->is_cherryview || devinfo->is_broxton) &&
-            type_sz(dest.type) == 8;
-         if (is_chv_bxt_64bit) {
-            indirect_chv_high_32bit = vgrf(glsl_type::uint_type);
-            /* Calculate indirect address to read high 32 bits */
-            bld.ADD(indirect_chv_high_32bit, indirect, brw_imm_ud(4));
-         }
+         bool supports_64bit_indirects =
+            !devinfo->is_cherryview && !devinfo->is_broxton;
 
-         for (unsigned j = 0; j < instr->num_components; j++) {
-            if (!is_chv_bxt_64bit) {
+         if (type_sz(dest.type) != 8 || supports_64bit_indirects) {
+            for (unsigned j = 0; j < instr->num_components; j++) {
                bld.emit(SHADER_OPCODE_MOV_INDIRECT,
                         offset(dest, bld, j), offset(src, bld, j),
                         indirect, brw_imm_ud(read_size));
-            } else {
-               bld.emit(SHADER_OPCODE_MOV_INDIRECT,
-                        subscript(offset(dest, bld, j), BRW_REGISTER_TYPE_UD, 0),
-                        offset(src, bld, j),
-                        indirect, brw_imm_ud(read_size));
-
-               bld.emit(SHADER_OPCODE_MOV_INDIRECT,
-                        subscript(offset(dest, bld, j), BRW_REGISTER_TYPE_UD, 1),
-                        offset(src, bld, j),
-                        indirect_chv_high_32bit, brw_imm_ud(read_size));
+            }
+         } else {
+            const unsigned num_mov_indirects =
+               type_sz(dest.type) / type_sz(BRW_REGISTER_TYPE_UD);
+            /* We read a little bit less per MOV INDIRECT, as they are now
+             * 32-bits ones instead of 64-bit. Fix read_size then.
+             */
+            const unsigned read_size_32bit = read_size -
+                (num_mov_indirects - 1) * type_sz(BRW_REGISTER_TYPE_UD);
+            for (unsigned j = 0; j < instr->num_components; j++) {
+               for (unsigned i = 0; i < num_mov_indirects; i++) {
+                  bld.emit(SHADER_OPCODE_MOV_INDIRECT,
+                           subscript(offset(dest, bld, j), BRW_REGISTER_TYPE_UD, i),
+                           subscript(offset(src, bld, j), BRW_REGISTER_TYPE_UD, i),
+                           indirect, brw_imm_ud(read_size_32bit));
+               }
             }
          }
       }
-- 
2.11.0