intel/fs: Use a strided MOV instead of a conversion for load_* destinations

In many cases, the compiler can just copy-prop the strided MOV whereas
the conversion is a bit trickier.  This cuts 5% of the instructions off
of one particular Vulkan CTS test which does lots of load_ssbo.

Reviewed-by: Matt Turner <mattst88@gmail.com>

diff --git a/src/intel/compiler/brw_fs_nir.cpp b/src/intel/compiler/brw_fs_nir.cpp
index aeebaaeb62ccc99926dd01c0e2ae840b7db3b245..e5a927431c4e01f28a7b3118b3c6cda85429699a 100644 (file)
--- a/src/intel/compiler/brw_fs_nir.cpp
+++ b/src/intel/compiler/brw_fs_nir.cpp
@@ -4018,7 +4018,7 @@ fs_visitor::nir_emit_cs_intrinsic(const fs_builder &bld,
          fs_reg read_result = bld.vgrf(BRW_REGISTER_TYPE_UD);
          bld.emit(SHADER_OPCODE_BYTE_SCATTERED_READ_LOGICAL,
                   read_result, srcs, SURFACE_LOGICAL_NUM_SRCS);
-         bld.MOV(dest, read_result);
+         bld.MOV(dest, subscript(read_result, dest.type, 0));
       }
       break;
    }
@@ -4644,15 +4644,13 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr
          const unsigned bit_size = nir_dest_bit_size(instr->dest);
          assert(bit_size <= 32);
          assert(nir_dest_num_components(instr->dest) == 1);
-         brw_reg_type data_type =
-            brw_reg_type_from_bit_size(bit_size, BRW_REGISTER_TYPE_UD);
          fs_reg tmp = bld.vgrf(BRW_REGISTER_TYPE_UD);
          bld.emit(SHADER_OPCODE_A64_BYTE_SCATTERED_READ_LOGICAL,
                   tmp,
                   get_nir_src(instr->src[0]), /* Address */
                   fs_reg(), /* No source data */
                   brw_imm_ud(bit_size));
-         bld.MOV(retype(dest, data_type), tmp);
+         bld.MOV(dest, subscript(tmp, dest.type, 0));
       }
       break;
    }
@@ -4755,7 +4753,7 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr
          fs_reg read_result = bld.vgrf(BRW_REGISTER_TYPE_UD);
          bld.emit(SHADER_OPCODE_BYTE_SCATTERED_READ_LOGICAL,
                   read_result, srcs, SURFACE_LOGICAL_NUM_SRCS);
-         bld.MOV(dest, read_result);
+         bld.MOV(dest, subscript(read_result, dest.type, 0));
       }
       break;
    }