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-rw-r--r--src/intel/compiler/brw_fs_nir.cpp25
1 files changed, 23 insertions, 2 deletions
diff --git a/src/intel/compiler/brw_fs_nir.cpp b/src/intel/compiler/brw_fs_nir.cpp
index 38d0d357e82..ca3707db90f 100644
--- a/src/intel/compiler/brw_fs_nir.cpp
+++ b/src/intel/compiler/brw_fs_nir.cpp
@@ -1395,10 +1395,31 @@ fs_visitor::nir_emit_alu(const fs_builder &bld, nir_alu_instr *instr)
case nir_op_extract_u8:
case nir_op_extract_i8: {
- const brw_reg_type type = brw_int_type(1, instr->op == nir_op_extract_i8);
nir_const_value *byte = nir_src_as_const_value(instr->src[1].src);
assert(byte != NULL);
- bld.MOV(result, subscript(op[0], type, byte->u32[0]));
+
+ /* The PRMs say:
+ *
+ * BDW+
+ * There is no direct conversion from B/UB to Q/UQ or Q/UQ to B/UB.
+ * Use two instructions and a word or DWord intermediate integer type.
+ */
+ if (nir_dest_bit_size(instr->dest.dest) == 64) {
+ const brw_reg_type type = brw_int_type(2, instr->op == nir_op_extract_i8);
+
+ if (instr->op == nir_op_extract_i8) {
+ /* If we need to sign extend, extract to a word first */
+ fs_reg w_temp = bld.vgrf(BRW_REGISTER_TYPE_W);
+ bld.MOV(w_temp, subscript(op[0], type, byte->u32[0]));
+ bld.MOV(result, w_temp);
+ } else {
+ /* Otherwise use an AND with 0xff and a word type */
+ bld.AND(result, subscript(op[0], type, byte->u32[0] / 2), brw_imm_uw(0xff));
+ }
+ } else {
+ const brw_reg_type type = brw_int_type(1, instr->op == nir_op_extract_i8);
+ bld.MOV(result, subscript(op[0], type, byte->u32[0]));
+ }
break;
}