+//! Return value handling
+
use crate::prelude::*;
-use crate::abi::pass_mode::*;
-pub fn codegen_return_param(
- fx: &mut FunctionCx<impl Backend>,
- ssa_analyzed: &HashMap<Local, crate::analyze::Flags>,
- start_ebb: Ebb,
-) {
- let ret_layout = fx.return_layout();
- let output_pass_mode = get_pass_mode(fx.tcx, fx.return_layout());
+use rustc_middle::ty::layout::FnAbiExt;
+use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode};
+use smallvec::{smallvec, SmallVec};
- let ret_param = match output_pass_mode {
- PassMode::NoPass => {
- fx.local_map
- .insert(RETURN_PLACE, CPlace::no_place(ret_layout));
- Empty
- }
- PassMode::ByVal(_) | PassMode::ByValPair(_, _) => {
- let is_ssa = !ssa_analyzed
- .get(&RETURN_PLACE)
- .unwrap()
- .contains(crate::analyze::Flags::NOT_SSA);
+/// Can the given type be returned into an ssa var or does it need to be returned on the stack.
+pub(crate) fn can_return_to_ssa_var<'tcx>(
+ fx: &FunctionCx<'_, '_, 'tcx>,
+ func: &mir::Operand<'tcx>,
+ args: &[mir::Operand<'tcx>],
+) -> bool {
+ let fn_ty = fx.monomorphize(func.ty(fx.mir, fx.tcx));
+ let fn_sig =
+ fx.tcx.normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), fn_ty.fn_sig(fx.tcx));
- super::local_place(fx, RETURN_PLACE, ret_layout, is_ssa);
+ // Handle special calls like instrinsics and empty drop glue.
+ let instance = if let ty::FnDef(def_id, substs) = *fn_ty.kind() {
+ let instance = ty::Instance::resolve(fx.tcx, ty::ParamEnv::reveal_all(), def_id, substs)
+ .unwrap()
+ .unwrap()
+ .polymorphize(fx.tcx);
- Empty
+ match instance.def {
+ InstanceDef::Intrinsic(_) | InstanceDef::DropGlue(_, _) => {
+ return true;
+ }
+ _ => Some(instance),
}
- PassMode::ByRef => {
- let ret_param = fx.bcx.append_ebb_param(start_ebb, fx.pointer_type);
- fx.local_map.insert(
- RETURN_PLACE,
- CPlace::for_addr(ret_param, ret_layout),
- );
+ } else {
+ None
+ };
- Single(ret_param)
+ let extra_args = &args[fn_sig.inputs().len()..];
+ let extra_args = extra_args
+ .iter()
+ .map(|op_arg| fx.monomorphize(op_arg.ty(fx.mir, fx.tcx)))
+ .collect::<Vec<_>>();
+ let fn_abi = if let Some(instance) = instance {
+ FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), instance, &extra_args)
+ } else {
+ FnAbi::of_fn_ptr(&RevealAllLayoutCx(fx.tcx), fn_ty.fn_sig(fx.tcx), &extra_args)
+ };
+ match fn_abi.ret.mode {
+ PassMode::Ignore | PassMode::Direct(_) | PassMode::Pair(_, _) => true,
+ // FIXME Make it possible to return Cast and Indirect to an ssa var.
+ PassMode::Cast(_) | PassMode::Indirect { .. } => false,
+ }
+}
+
+/// Return a place where the return value of the current function can be written to. If necessary
+/// this adds an extra parameter pointing to where the return value needs to be stored.
+pub(super) fn codegen_return_param<'tcx>(
+ fx: &mut FunctionCx<'_, '_, 'tcx>,
+ ssa_analyzed: &rustc_index::vec::IndexVec<Local, crate::analyze::SsaKind>,
+ block_params_iter: &mut impl Iterator<Item = Value>,
+) -> CPlace<'tcx> {
+ let (ret_place, ret_param): (_, SmallVec<[_; 2]>) = match fx.fn_abi.as_ref().unwrap().ret.mode {
+ PassMode::Ignore => (CPlace::no_place(fx.fn_abi.as_ref().unwrap().ret.layout), smallvec![]),
+ PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast(_) => {
+ let is_ssa = ssa_analyzed[RETURN_PLACE] == crate::analyze::SsaKind::Ssa;
+ (
+ super::make_local_place(
+ fx,
+ RETURN_PLACE,
+ fx.fn_abi.as_ref().unwrap().ret.layout,
+ is_ssa,
+ ),
+ smallvec![],
+ )
+ }
+ PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
+ let ret_param = block_params_iter.next().unwrap();
+ assert_eq!(fx.bcx.func.dfg.value_type(ret_param), pointer_ty(fx.tcx));
+ (
+ CPlace::for_ptr(Pointer::new(ret_param), fx.fn_abi.as_ref().unwrap().ret.layout),
+ smallvec![ret_param],
+ )
+ }
+ PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
+ unreachable!("unsized return value")
}
};
- #[cfg(debug_assertions)]
- {
- super::add_arg_comment(
- fx,
- "ret",
- RETURN_PLACE,
- None,
- ret_param,
- output_pass_mode,
- ssa_analyzed[&RETURN_PLACE],
- ret_layout.ty,
- );
- }
+ crate::abi::comments::add_arg_comment(
+ fx,
+ "ret",
+ Some(RETURN_PLACE),
+ None,
+ &ret_param,
+ fx.fn_abi.as_ref().unwrap().ret.mode,
+ fx.fn_abi.as_ref().unwrap().ret.layout,
+ );
+
+ ret_place
}
-pub fn codegen_with_call_return_arg<'tcx, B: Backend, T>(
- fx: &mut FunctionCx<'_, 'tcx, B>,
- fn_sig: FnSig<'tcx>,
+/// Invokes the closure with if necessary a value representing the return pointer. When the closure
+/// returns the call return value(s) if any are written to the correct place.
+pub(super) fn codegen_with_call_return_arg<'tcx, T>(
+ fx: &mut FunctionCx<'_, '_, 'tcx>,
+ ret_arg_abi: &ArgAbi<'tcx, Ty<'tcx>>,
ret_place: Option<CPlace<'tcx>>,
- f: impl FnOnce(&mut FunctionCx<'_, 'tcx, B>, Option<Value>) -> (Inst, T),
+ f: impl FnOnce(&mut FunctionCx<'_, '_, 'tcx>, Option<Value>) -> (Inst, T),
) -> (Inst, T) {
- let ret_layout = fx.layout_of(fn_sig.output());
-
- let output_pass_mode = get_pass_mode(fx.tcx, ret_layout);
- let return_ptr = match output_pass_mode {
- PassMode::NoPass => None,
- PassMode::ByRef => match ret_place {
- Some(ret_place) => Some(ret_place.to_addr(fx)),
- None => Some(fx.bcx.ins().iconst(fx.pointer_type, 43)),
+ let return_ptr = match ret_arg_abi.mode {
+ PassMode::Ignore => None,
+ PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => match ret_place {
+ Some(ret_place) => Some(ret_place.to_ptr().get_addr(fx)),
+ None => Some(fx.bcx.ins().iconst(fx.pointer_type, 43)), // FIXME allocate temp stack slot
},
- PassMode::ByVal(_) | PassMode::ByValPair(_, _) => None,
+ PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
+ unreachable!("unsized return value")
+ }
+ PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast(_) => None,
};
let (call_inst, meta) = f(fx, return_ptr);
- match output_pass_mode {
- PassMode::NoPass => {}
- PassMode::ByVal(_) => {
+ match ret_arg_abi.mode {
+ PassMode::Ignore => {}
+ PassMode::Direct(_) => {
if let Some(ret_place) = ret_place {
let ret_val = fx.bcx.inst_results(call_inst)[0];
- ret_place.write_cvalue(fx, CValue::by_val(ret_val, ret_layout));
+ ret_place.write_cvalue(fx, CValue::by_val(ret_val, ret_arg_abi.layout));
}
}
- PassMode::ByValPair(_, _) => {
+ PassMode::Pair(_, _) => {
if let Some(ret_place) = ret_place {
let ret_val_a = fx.bcx.inst_results(call_inst)[0];
let ret_val_b = fx.bcx.inst_results(call_inst)[1];
- ret_place.write_cvalue(fx, CValue::by_val_pair(ret_val_a, ret_val_b, ret_layout));
+ ret_place.write_cvalue(
+ fx,
+ CValue::by_val_pair(ret_val_a, ret_val_b, ret_arg_abi.layout),
+ );
+ }
+ }
+ PassMode::Cast(cast) => {
+ if let Some(ret_place) = ret_place {
+ let results = fx
+ .bcx
+ .inst_results(call_inst)
+ .iter()
+ .copied()
+ .collect::<SmallVec<[Value; 2]>>();
+ let result =
+ super::pass_mode::from_casted_value(fx, &results, ret_place.layout(), cast);
+ ret_place.write_cvalue(fx, result);
}
}
- PassMode::ByRef => {}
+ PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {}
+ PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
+ unreachable!("unsized return value")
+ }
}
(call_inst, meta)
}
-pub fn codegen_return(fx: &mut FunctionCx<impl Backend>) {
- match get_pass_mode(fx.tcx, fx.return_layout()) {
- PassMode::NoPass | PassMode::ByRef => {
+/// Codegen a return instruction with the right return value(s) if any.
+pub(crate) fn codegen_return(fx: &mut FunctionCx<'_, '_, '_>) {
+ match fx.fn_abi.as_ref().unwrap().ret.mode {
+ PassMode::Ignore | PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
fx.bcx.ins().return_(&[]);
}
- PassMode::ByVal(_) => {
+ PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
+ unreachable!("unsized return value")
+ }
+ PassMode::Direct(_) => {
let place = fx.get_local_place(RETURN_PLACE);
let ret_val = place.to_cvalue(fx).load_scalar(fx);
fx.bcx.ins().return_(&[ret_val]);
}
- PassMode::ByValPair(_, _) => {
+ PassMode::Pair(_, _) => {
let place = fx.get_local_place(RETURN_PLACE);
let (ret_val_a, ret_val_b) = place.to_cvalue(fx).load_scalar_pair(fx);
fx.bcx.ins().return_(&[ret_val_a, ret_val_b]);
}
+ PassMode::Cast(cast) => {
+ let place = fx.get_local_place(RETURN_PLACE);
+ let ret_val = place.to_cvalue(fx);
+ let ret_vals = super::pass_mode::to_casted_value(fx, ret_val, cast);
+ fx.bcx.ins().return_(&ret_vals);
+ }
}
}
projects / rust.git / blobdiff