src/abi/returning.rs

   1 use crate::abi::pass_mode::*;
   2 use crate::prelude::*;
   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
  31                 .insert(RETURN_PLACE, CPlace::for_addr(ret_param, ret_layout));
  32
  33             Single(ret_param)
  34         }
  35     };
  36
  37     #[cfg(debug_assertions)]
  38     crate::abi::comments::add_arg_comment(
  39         fx,
  40         "ret",
  41         RETURN_PLACE,
  42         None,
  43         ret_param,
  44         output_pass_mode,
  45         ret_layout.ty,
  46     );
  47 }
  48
  49 pub fn codegen_with_call_return_arg<'tcx, B: Backend, T>(
  50     fx: &mut FunctionCx<'_, 'tcx, B>,
  51     fn_sig: FnSig<'tcx>,
  52     ret_place: Option<CPlace<'tcx>>,
  53     f: impl FnOnce(&mut FunctionCx<'_, 'tcx, B>, Option<Value>) -> (Inst, T),
  54 ) -> (Inst, T) {
  55     let ret_layout = fx.layout_of(fn_sig.output());
  56
  57     let output_pass_mode = get_pass_mode(fx.tcx, ret_layout);
  58     let return_ptr = match output_pass_mode {
  59         PassMode::NoPass => None,
  60         PassMode::ByRef => match ret_place {
  61             Some(ret_place) => Some(ret_place.to_addr(fx)),
  62             None => Some(fx.bcx.ins().iconst(fx.pointer_type, 43)),
  63         },
  64         PassMode::ByVal(_) | PassMode::ByValPair(_, _) => None,
  65     };
  66
  67     let (call_inst, meta) = f(fx, return_ptr);
  68
  69     match output_pass_mode {
  70         PassMode::NoPass => {}
  71         PassMode::ByVal(_) => {
  72             if let Some(ret_place) = ret_place {
  73                 let ret_val = fx.bcx.inst_results(call_inst)[0];
  74                 ret_place.write_cvalue(fx, CValue::by_val(ret_val, ret_layout));
  75             }
  76         }
  77         PassMode::ByValPair(_, _) => {
  78             if let Some(ret_place) = ret_place {
  79                 let ret_val_a = fx.bcx.inst_results(call_inst)[0];
  80                 let ret_val_b = fx.bcx.inst_results(call_inst)[1];
  81                 ret_place.write_cvalue(fx, CValue::by_val_pair(ret_val_a, ret_val_b, ret_layout));
  82             }
  83         }
  84         PassMode::ByRef => {}
  85     }
  86
  87     (call_inst, meta)
  88 }
  89
  90 pub fn codegen_return(fx: &mut FunctionCx<impl Backend>) {
  91     match get_pass_mode(fx.tcx, fx.return_layout()) {
  92         PassMode::NoPass | PassMode::ByRef => {
  93             fx.bcx.ins().return_(&[]);
  94         }
  95         PassMode::ByVal(_) => {
  96             let place = fx.get_local_place(RETURN_PLACE);
  97             let ret_val = place.to_cvalue(fx).load_scalar(fx);
  98             fx.bcx.ins().return_(&[ret_val]);
  99         }
 100         PassMode::ByValPair(_, _) => {
 101             let place = fx.get_local_place(RETURN_PLACE);
 102             let (ret_val_a, ret_val_b) = place.to_cvalue(fx).load_scalar_pair(fx);
 103             fx.bcx.ins().return_(&[ret_val_a, ret_val_b]);
 104         }
 105     }
 106 }