i965/fs: Enable rounding mode on f2f16 ops

By default we don't set the rounding mode. We only set
round-to-near-even or round-to-zero mode if explicitly set from nir.

v2: Use a single SHADER_OPCODE_RND_MODE opcode taking an immediate
    with the rounding mode (Curro)

v3: Use new helper brw_rnd_mode_from_nir_op  (Jason Ekstrand)

Signed-off-by: Jose Maria Casanova Crespo <jmcasanova@igalia.com>
Signed-off-by: Alejandro Piñeiro <apinheiro@igalia.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

diff --git a/src/intel/compiler/brw_fs_nir.cpp b/src/intel/compiler/brw_fs_nir.cpp
index ddc0c6d..d6ab286 100644 (file)
--- a/src/intel/compiler/brw_fs_nir.cpp
+++ b/src/intel/compiler/brw_fs_nir.cpp
@@ -621,6 +621,18 @@ emit_find_msb_using_lzd(const fs_builder &bld,
    inst->src[0].negate = true;
 }
 
+static brw_rnd_mode
+brw_rnd_mode_from_nir_op (const nir_op op) {
+   switch (op) {
+   case nir_op_f2f16_rtz:
+      return BRW_RND_MODE_RTZ;
+   case nir_op_f2f16_rtne:
+      return BRW_RND_MODE_RTNE;
+   default:
+      unreachable("Operation doesn't support rounding mode");
+   }
+}
+
 void
 fs_visitor::nir_emit_alu(const fs_builder &bld, nir_alu_instr *instr)
 {
@@ -724,6 +736,12 @@ fs_visitor::nir_emit_alu(const fs_builder &bld, nir_alu_instr *instr)
       inst->saturate = instr->dest.saturate;
       break;
 
+   case nir_op_f2f16_rtne:
+   case nir_op_f2f16_rtz:
+      bld.emit(SHADER_OPCODE_RND_MODE, bld.null_reg_ud(),
+               brw_imm_d(brw_rnd_mode_from_nir_op(instr->op)));
+      /* fallthrough */
+
       /* In theory, it would be better to use BRW_OPCODE_F32TO16. Depending
        * on the HW gen, it is a special hw opcode or just a MOV, and
        * brw_F32TO16 (at brw_eu_emit) would do the work to chose.