+/* Sets the destination channels to 1.0 or 0.0 according to glFrontFacing. */
+static void emit_frontfacing(struct brw_wm_compile *c,
+ struct prog_instruction *inst)
+{
+ struct brw_compile *p = &c->func;
+ struct brw_reg r1_6ud = retype(brw_vec1_grf(1, 6), BRW_REGISTER_TYPE_UD);
+ struct brw_reg dst;
+ GLuint mask = inst->DstReg.WriteMask;
+ int i;
+
+ for (i = 0; i < 4; i++) {
+ if (mask & (1<<i)) {
+ dst = get_dst_reg(c, inst, i, 1);
+ brw_MOV(p, dst, brw_imm_f(0.0));
+ }
+ }
+
+ /* bit 31 is "primitive is back face", so checking < (1 << 31) gives
+ * us front face
+ */
+ brw_CMP(p, brw_null_reg(), BRW_CONDITIONAL_L, r1_6ud, brw_imm_ud(1 << 31));
+ for (i = 0; i < 4; i++) {
+ if (mask & (1<<i)) {
+ dst = get_dst_reg(c, inst, i, 1);
+ brw_MOV(p, dst, brw_imm_f(1.0));
+ }
+ }
+ brw_set_predicate_control_flag_value(p, 0xff);
+}
+