src/abi/returning.rs

   1 use crate::prelude::*;
   2 use crate::abi::pass_mode::*;
   3
   4 pub fn codegen_return_param(
   5     fx: &mut FunctionCx<impl Backend>,
   6     ssa_analyzed: &HashMap<Local, crate::analyze::Flags>,
   7     start_ebb: Ebb,
   8 ) {
   9     let ret_layout = fx.return_layout();
  10     let output_pass_mode = get_pass_mode(fx.tcx, fx.return_layout());
  11
  12     let ret_param = match output_pass_mode {
  13         PassMode::NoPass => {
  14             fx.local_map
  15                 .insert(RETURN_PLACE, CPlace::no_place(ret_layout));
  16             Empty
  17         }
  18         PassMode::ByVal(_) | PassMode::ByValPair(_, _) => {
  19             let is_ssa = !ssa_analyzed
  20                 .get(&RETURN_PLACE)
  21                 .unwrap()
  22                 .contains(crate::analyze::Flags::NOT_SSA);
  23
  24             super::local_place(fx, RETURN_PLACE, ret_layout, is_ssa);
  25
  26             Empty
  27         }
  28         PassMode::ByRef => {
  29             let ret_param = fx.bcx.append_ebb_param(start_ebb, fx.pointer_type);
  30             fx.local_map.insert(
  31                 RETURN_PLACE,
  32                 CPlace::for_addr(ret_param, ret_layout),
  33             );
  34
  35             Single(ret_param)
  36         }
  37     };
  38
  39     #[cfg(debug_assertions)]
  40     crate::abi::comments::add_arg_comment(
  41         fx,
  42         "ret",
  43         RETURN_PLACE,
  44         None,
  45         ret_param,
  46         output_pass_mode,
  47         ret_layout.ty,
  48     );
  49 }
  50
  51 pub fn codegen_with_call_return_arg<'tcx, B: Backend, T>(
  52     fx: &mut FunctionCx<'_, 'tcx, B>,
  53     fn_sig: FnSig<'tcx>,
  54     ret_place: Option<CPlace<'tcx>>,
  55     f: impl FnOnce(&mut FunctionCx<'_, 'tcx, B>, Option<Value>) -> (Inst, T),
  56 ) -> (Inst, T) {
  57     let ret_layout = fx.layout_of(fn_sig.output());
  58
  59     let output_pass_mode = get_pass_mode(fx.tcx, ret_layout);
  60     let return_ptr = match output_pass_mode {
  61         PassMode::NoPass => None,
  62         PassMode::ByRef => match ret_place {
  63             Some(ret_place) => Some(ret_place.to_addr(fx)),
  64             None => Some(fx.bcx.ins().iconst(fx.pointer_type, 43)),
  65         },
  66         PassMode::ByVal(_) | PassMode::ByValPair(_, _) => None,
  67     };
  68
  69     let (call_inst, meta) = f(fx, return_ptr);
  70
  71     match output_pass_mode {
  72         PassMode::NoPass => {}
  73         PassMode::ByVal(_) => {
  74             if let Some(ret_place) = ret_place {
  75                 let ret_val = fx.bcx.inst_results(call_inst)[0];
  76                 ret_place.write_cvalue(fx, CValue::by_val(ret_val, ret_layout));
  77             }
  78         }
  79         PassMode::ByValPair(_, _) => {
  80             if let Some(ret_place) = ret_place {
  81                 let ret_val_a = fx.bcx.inst_results(call_inst)[0];
  82                 let ret_val_b = fx.bcx.inst_results(call_inst)[1];
  83                 ret_place.write_cvalue(fx, CValue::by_val_pair(ret_val_a, ret_val_b, ret_layout));
  84             }
  85         }
  86         PassMode::ByRef => {}
  87     }
  88
  89     (call_inst, meta)
  90 }
  91
  92 pub fn codegen_return(fx: &mut FunctionCx<impl Backend>) {
  93     match get_pass_mode(fx.tcx, fx.return_layout()) {
  94         PassMode::NoPass | PassMode::ByRef => {
  95             fx.bcx.ins().return_(&[]);
  96         }
  97         PassMode::ByVal(_) => {
  98             let place = fx.get_local_place(RETURN_PLACE);
  99             let ret_val = place.to_cvalue(fx).load_scalar(fx);
 100             fx.bcx.ins().return_(&[ret_val]);
 101         }
 102         PassMode::ByValPair(_, _) => {
 103             let place = fx.get_local_place(RETURN_PLACE);
 104             let (ret_val_a, ret_val_b) = place.to_cvalue(fx).load_scalar_pair(fx);
 105             fx.bcx.ins().return_(&[ret_val_a, ret_val_b]);
 106         }
 107     }
 108 }