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improve PassMode docs #115654

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merged 4 commits into from
Sep 17, 2023
Merged

improve PassMode docs #115654

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7740476
explain PassMode::Cast
RalfJung Sep 7, 2023
89139d4
clarify PassMode::Indirect as well
RalfJung Sep 8, 2023
29a4b7b
fix gcc, cranelift build
RalfJung Sep 9, 2023
3ee65c2
cannot have Direct for unsized types
RalfJung Sep 15, 2023
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22 changes: 11 additions & 11 deletions compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -100,11 +100,11 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
}
_ => unreachable!("{:?}", self.layout.abi),
},
PassMode::Cast(ref cast, pad_i32) => {
PassMode::Cast { ref cast, pad_i32 } => {
assert!(!pad_i32, "padding support not yet implemented");
cast_target_to_abi_params(cast)
}
PassMode::Indirect { attrs, extra_attrs: None, on_stack } => {
PassMode::Indirect { attrs, meta_attrs: None, on_stack } => {
if on_stack {
// Abi requires aligning struct size to pointer size
let size = self.layout.size.align_to(tcx.data_layout.pointer_align.abi);
Expand All @@ -117,11 +117,11 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
smallvec![apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), attrs)]
}
}
PassMode::Indirect { attrs, extra_attrs: Some(extra_attrs), on_stack } => {
PassMode::Indirect { attrs, meta_attrs: Some(meta_attrs), on_stack } => {
assert!(!on_stack);
smallvec![
apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), attrs),
apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), extra_attrs),
apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), meta_attrs),
]
}
}
Expand All @@ -148,14 +148,14 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
}
_ => unreachable!("{:?}", self.layout.abi),
},
PassMode::Cast(ref cast, _) => {
PassMode::Cast { ref cast, .. } => {
(None, cast_target_to_abi_params(cast).into_iter().collect())
}
PassMode::Indirect { attrs: _, extra_attrs: None, on_stack } => {
PassMode::Indirect { attrs: _, meta_attrs: None, on_stack } => {
assert!(!on_stack);
(Some(AbiParam::special(pointer_ty(tcx), ArgumentPurpose::StructReturn)), vec![])
}
PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
unreachable!("unsized return value")
}
}
Expand Down Expand Up @@ -229,7 +229,7 @@ pub(super) fn adjust_arg_for_abi<'tcx>(
let (a, b) = arg.load_scalar_pair(fx);
smallvec![a, b]
}
PassMode::Cast(ref cast, _) => to_casted_value(fx, arg, cast),
PassMode::Cast { ref cast, .. } => to_casted_value(fx, arg, cast),
PassMode::Indirect { .. } => {
if is_owned {
match arg.force_stack(fx) {
Expand Down Expand Up @@ -287,14 +287,14 @@ pub(super) fn cvalue_for_param<'tcx>(
assert_eq!(block_params.len(), 2, "{:?}", block_params);
Some(CValue::by_val_pair(block_params[0], block_params[1], arg_abi.layout))
}
PassMode::Cast(ref cast, _) => {
PassMode::Cast { ref cast, .. } => {
Some(from_casted_value(fx, &block_params, arg_abi.layout, cast))
}
PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: None, on_stack: _ } => {
assert_eq!(block_params.len(), 1, "{:?}", block_params);
Some(CValue::by_ref(Pointer::new(block_params[0]), arg_abi.layout))
}
PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
assert_eq!(block_params.len(), 2, "{:?}", block_params);
Some(CValue::by_ref_unsized(
Pointer::new(block_params[0]),
Expand Down
24 changes: 12 additions & 12 deletions compiler/rustc_codegen_cranelift/src/abi/returning.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ pub(super) fn codegen_return_param<'tcx>(
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 | PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast(..) => {
PassMode::Ignore | PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast { .. } => {
let is_ssa =
ssa_analyzed[RETURN_PLACE].is_ssa(fx, fx.fn_abi.as_ref().unwrap().ret.layout.ty);
(
Expand All @@ -26,15 +26,15 @@ pub(super) fn codegen_return_param<'tcx>(
smallvec![],
)
}
PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: None, on_stack: _ } => {
let ret_param = block_params_iter.next().unwrap();
assert_eq!(fx.bcx.func.dfg.value_type(ret_param), fx.pointer_type);
(
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: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
unreachable!("unsized return value")
}
};
Expand Down Expand Up @@ -62,7 +62,7 @@ pub(super) fn codegen_with_call_return_arg<'tcx>(
) {
let (ret_temp_place, return_ptr) = match ret_arg_abi.mode {
PassMode::Ignore => (None, None),
PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: None, on_stack: _ } => {
if let Some(ret_ptr) = ret_place.try_to_ptr() {
// This is an optimization to prevent unnecessary copies of the return value when
// the return place is already a memory place as opposed to a register.
Expand All @@ -73,10 +73,10 @@ pub(super) fn codegen_with_call_return_arg<'tcx>(
(Some(place), Some(place.to_ptr().get_addr(fx)))
}
}
PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
unreachable!("unsized return value")
}
PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast(..) => (None, None),
PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast { .. } => (None, None),
};

let call_inst = f(fx, return_ptr);
Expand All @@ -93,21 +93,21 @@ pub(super) fn codegen_with_call_return_arg<'tcx>(
ret_place
.write_cvalue(fx, CValue::by_val_pair(ret_val_a, ret_val_b, ret_arg_abi.layout));
}
PassMode::Cast(ref cast, _) => {
PassMode::Cast { ref cast, .. } => {
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::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: None, on_stack: _ } => {
if let Some(ret_temp_place) = ret_temp_place {
// If ret_temp_place is None, it is not necessary to copy the return value.
let ret_temp_value = ret_temp_place.to_cvalue(fx);
ret_place.write_cvalue(fx, ret_temp_value);
}
}
PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
unreachable!("unsized return value")
}
}
Expand All @@ -116,10 +116,10 @@ pub(super) fn codegen_with_call_return_arg<'tcx>(
/// 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: _ } => {
PassMode::Ignore | PassMode::Indirect { attrs: _, meta_attrs: None, on_stack: _ } => {
fx.bcx.ins().return_(&[]);
}
PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
unreachable!("unsized return value")
}
PassMode::Direct(_) => {
Expand All @@ -132,7 +132,7 @@ pub(crate) fn codegen_return(fx: &mut FunctionCx<'_, '_, '_>) {
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(ref cast, _) => {
PassMode::Cast { ref 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);
Expand Down
10 changes: 5 additions & 5 deletions compiler/rustc_codegen_gcc/src/abi.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -113,7 +113,7 @@ impl<'gcc, 'tcx> FnAbiGccExt<'gcc, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
match self.ret.mode {
PassMode::Ignore => cx.type_void(),
PassMode::Direct(_) | PassMode::Pair(..) => self.ret.layout.immediate_gcc_type(cx),
PassMode::Cast(ref cast, _) => cast.gcc_type(cx),
PassMode::Cast { ref cast, .. } => cast.gcc_type(cx),
PassMode::Indirect { .. } => {
argument_tys.push(cx.type_ptr_to(self.ret.memory_ty(cx)));
cx.type_void()
Expand All @@ -129,21 +129,21 @@ impl<'gcc, 'tcx> FnAbiGccExt<'gcc, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
argument_tys.push(arg.layout.scalar_pair_element_gcc_type(cx, 1));
continue;
}
PassMode::Indirect { extra_attrs: Some(_), .. } => {
PassMode::Indirect { meta_attrs: Some(_), .. } => {
unimplemented!();
}
PassMode::Cast(ref cast, pad_i32) => {
PassMode::Cast { ref cast, pad_i32 } => {
// add padding
if pad_i32 {
argument_tys.push(Reg::i32().gcc_type(cx));
}
cast.gcc_type(cx)
}
PassMode::Indirect { extra_attrs: None, on_stack: true, .. } => {
PassMode::Indirect { meta_attrs: None, on_stack: true, .. } => {
on_stack_param_indices.insert(argument_tys.len());
arg.memory_ty(cx)
},
PassMode::Indirect { extra_attrs: None, on_stack: false, .. } => cx.type_ptr_to(arg.memory_ty(cx)),
PassMode::Indirect { meta_attrs: None, on_stack: false, .. } => cx.type_ptr_to(arg.memory_ty(cx)),
};
argument_tys.push(arg_ty);
}
Expand Down
10 changes: 5 additions & 5 deletions compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -144,7 +144,7 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
sym::volatile_load | sym::unaligned_volatile_load => {
let tp_ty = fn_args.type_at(0);
let mut ptr = args[0].immediate();
if let PassMode::Cast(ty, _) = &fn_abi.ret.mode {
if let PassMode::Cast { cast: ty, .. } = &fn_abi.ret.mode {
ptr = self.pointercast(ptr, self.type_ptr_to(ty.gcc_type(self)));
}
let load = self.volatile_load(ptr.get_type(), ptr);
Expand Down Expand Up @@ -353,7 +353,7 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
};

if !fn_abi.ret.is_ignore() {
if let PassMode::Cast(ty, _) = &fn_abi.ret.mode {
if let PassMode::Cast { cast: ty, .. } = &fn_abi.ret.mode {
let ptr_llty = self.type_ptr_to(ty.gcc_type(self));
let ptr = self.pointercast(result.llval, ptr_llty);
self.store(llval, ptr, result.align);
Expand Down Expand Up @@ -449,7 +449,7 @@ impl<'gcc, 'tcx> ArgAbiExt<'gcc, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
else if self.is_unsized_indirect() {
bug!("unsized `ArgAbi` must be handled through `store_fn_arg`");
}
else if let PassMode::Cast(ref cast, _) = self.mode {
else if let PassMode::Cast { ref cast, .. } = self.mode {
// FIXME(eddyb): Figure out when the simpler Store is safe, clang
// uses it for i16 -> {i8, i8}, but not for i24 -> {i8, i8, i8}.
let can_store_through_cast_ptr = false;
Expand Down Expand Up @@ -511,10 +511,10 @@ impl<'gcc, 'tcx> ArgAbiExt<'gcc, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
PassMode::Pair(..) => {
OperandValue::Pair(next(), next()).store(bx, dst);
},
PassMode::Indirect { extra_attrs: Some(_), .. } => {
PassMode::Indirect { meta_attrs: Some(_), .. } => {
OperandValue::Ref(next(), Some(next()), self.layout.align.abi).store(bx, dst);
},
PassMode::Direct(_) | PassMode::Indirect { extra_attrs: None, .. } | PassMode::Cast(..) => {
PassMode::Direct(_) | PassMode::Indirect { meta_attrs: None, .. } | PassMode::Cast { .. } => {
let next_arg = next();
self.store(bx, next_arg, dst);
},
Expand Down
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