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538 lines
23 KiB
C++
538 lines
23 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/check/thunk.h"
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#include <utility>
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#include "toolchain/base/kind_switch.h"
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#include "toolchain/check/call.h"
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#include "toolchain/check/convert.h"
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#include "toolchain/check/cpp/operators.h"
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#include "toolchain/check/deferred_definition_worklist.h"
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#include "toolchain/check/diagnostic_helpers.h"
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#include "toolchain/check/function.h"
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#include "toolchain/check/generic.h"
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#include "toolchain/check/inst.h"
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#include "toolchain/check/member_access.h"
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#include "toolchain/check/name_ref.h"
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#include "toolchain/check/pattern.h"
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#include "toolchain/check/pattern_match.h"
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#include "toolchain/check/pointer_dereference.h"
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#include "toolchain/check/return.h"
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#include "toolchain/check/type.h"
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#include "toolchain/diagnostics/diagnostic.h"
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#include "toolchain/sem_ir/function.h"
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#include "toolchain/sem_ir/generic.h"
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#include "toolchain/sem_ir/ids.h"
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#include "toolchain/sem_ir/inst.h"
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#include "toolchain/sem_ir/pattern.h"
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#include "toolchain/sem_ir/typed_insts.h"
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namespace Carbon::Check {
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// Adds a pattern instruction for a thunk, copying the location from an existing
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// instruction.
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static auto RebuildPatternInst(Context& context, SemIR::InstId orig_inst_id,
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SemIR::Inst new_inst) -> SemIR::InstId {
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// Ensure we built the same kind of instruction. In particular, this ensures
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// that the location of the old instruction can be reused for the new one.
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CARBON_CHECK(context.insts().Get(orig_inst_id).kind() == new_inst.kind(),
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"Rebuilt pattern with the wrong kind: {0} -> {1}",
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context.insts().Get(orig_inst_id), new_inst);
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return AddInst(context,
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SemIR::LocIdAndInst::RuntimeVerified(
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context.sem_ir(), SemIR::LocId(orig_inst_id), new_inst));
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}
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// Wrapper to allow the type to be specified as a template argument for API
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// consistency with `AddInst`.
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template <typename InstT>
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static auto RebuildPatternInst(Context& context, SemIR::InstId orig_inst_id,
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InstT new_inst) -> SemIR::InstId {
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return RebuildPatternInst(context, orig_inst_id, SemIR::Inst(new_inst));
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}
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// Makes a copy of the given binding pattern, with its type adjusted to be
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// `new_pattern_type_id`.
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static auto CloneBindingPattern(Context& context, SemIR::InstId pattern_id,
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SemIR::AnyBindingPattern pattern,
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SemIR::TypeId new_pattern_type_id)
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-> SemIR::InstId {
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auto entity_name = context.entity_names().Get(pattern.entity_name_id);
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CARBON_CHECK((pattern.kind == SemIR::SymbolicBindingPattern::Kind) ==
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entity_name.bind_index().has_value());
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CARBON_CHECK(pattern.kind != SemIR::FormBindingPattern::Kind);
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// Get the transformed type of the binding.
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if (new_pattern_type_id == SemIR::ErrorInst::TypeId) {
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return SemIR::ErrorInst::InstId;
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}
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pattern.type_id = new_pattern_type_id;
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auto phase = BindingPhase::Runtime;
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if (pattern.kind == SemIR::SymbolicBindingPattern::Kind) {
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phase = entity_name.is_template ? BindingPhase::Template
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: BindingPhase::Symbolic;
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}
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pattern.entity_name_id = AddBindingEntityName(context, entity_name.name_id,
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/*form_id=*/SemIR::InstId::None,
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entity_name.is_unused, phase);
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if (pattern.kind == SemIR::WrapperBindingPattern::Kind) {
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auto subpattern = context.insts().GetAs<SemIR::AnyLeafParamPattern>(
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pattern.subpattern_id);
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if (subpattern.kind == SemIR::FormParamPattern::Kind) {
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context.TODO(pattern_id, "Support for cloning form bindings");
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return SemIR::ErrorInst::InstId;
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}
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pattern.subpattern_id = RebuildPatternInst<SemIR::AnyLeafParamPattern>(
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context, pattern.subpattern_id,
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{.kind = subpattern.kind,
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.type_id = new_pattern_type_id,
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.pretty_name_id = entity_name.name_id});
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}
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// Rebuild the binding pattern.
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return AddBindingPattern(context, SemIR::LocId(pattern_id),
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SemIR::ExprRegionId::None, pattern)
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.pattern_id;
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}
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// Makes a copy of the given pattern instruction, substituting values from a
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// specific as needed. The resulting pattern behaves like a newly-created
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// pattern, so is suitable for running `CalleePatternMatch` against.
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static auto ClonePattern(Context& context, SemIR::SpecificId specific_id,
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SemIR::InstId pattern_id) -> SemIR::InstId {
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if (!pattern_id.has_value()) {
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return SemIR::InstId::None;
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}
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auto get_type = [&](SemIR::InstId inst_id) -> SemIR::TypeId {
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return SemIR::GetTypeOfInstInSpecific(context.sem_ir(), specific_id,
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inst_id);
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};
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auto pattern = context.insts().Get(pattern_id);
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// Decompose the pattern. The forms we allow for patterns in a function
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// parameter list are currently fairly restrictive.
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// Optional var parameter pattern.
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auto [var_param, var_param_id] = context.insts().TryUnwrap(
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pattern, pattern_id, &SemIR::VarParamPattern::subpattern_id);
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// Finally, either a binding pattern or a return slot pattern.
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auto new_pattern_id = SemIR::InstId::None;
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if (auto binding = pattern.TryAs<SemIR::AnyBindingPattern>()) {
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new_pattern_id = CloneBindingPattern(context, pattern_id, *binding,
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get_type(pattern_id));
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} else if (auto return_slot = pattern.TryAs<SemIR::ReturnSlotPattern>()) {
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auto new_subpattern_id = SemIR::InstId::None;
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auto subpattern = context.insts().Get(return_slot->subpattern_id);
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CARBON_KIND_SWITCH(subpattern) {
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case SemIR::OutParamPattern::Kind:
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case SemIR::RefReturnPattern::Kind:
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case SemIR::ValueReturnPattern::Kind:
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// These are leaf insts, so we can reuse their contents after updating
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// the type.
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subpattern.SetType(get_type(return_slot->subpattern_id));
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new_subpattern_id =
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RebuildPatternInst(context, return_slot->subpattern_id, subpattern);
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break;
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case SemIR::ErrorInst::Kind:
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subpattern.SetType(SemIR::ErrorInst::TypeId);
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new_subpattern_id = SemIR::ErrorInst::InstId;
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break;
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default:
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CARBON_FATAL("Unexpected kind for return slot subpattern {0}",
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subpattern);
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}
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new_pattern_id = RebuildPatternInst<SemIR::ReturnSlotPattern>(
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context, pattern_id,
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{.type_id = get_type(pattern_id),
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.subpattern_id = new_subpattern_id,
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.type_inst_id = SemIR::TypeInstId::None});
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} else {
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CARBON_CHECK(pattern.Is<SemIR::ErrorInst>(),
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"Unexpected pattern {0} in function signature", pattern);
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return SemIR::ErrorInst::InstId;
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}
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// Rebuild parameter.
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if (var_param && new_pattern_id != SemIR::ErrorInst::InstId) {
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new_pattern_id = RebuildPatternInst<SemIR::VarParamPattern>(
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context, var_param_id,
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{.type_id = get_type(var_param_id), .subpattern_id = new_pattern_id});
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}
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return new_pattern_id;
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}
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static auto ClonePatternBlock(Context& context, SemIR::SpecificId specific_id,
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SemIR::InstBlockId inst_block_id)
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-> SemIR::InstBlockId {
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if (!inst_block_id.has_value()) {
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return SemIR::InstBlockId::None;
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}
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return context.inst_blocks().Transform(
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inst_block_id, [&](SemIR::InstId inst_id) {
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return ClonePattern(context, specific_id, inst_id);
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});
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}
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static auto CloneInstId(Context& context, SemIR::SpecificId specific_id,
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SemIR::InstId inst_id) -> SemIR::InstId {
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if (!inst_id.has_value()) {
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return SemIR::InstId::None;
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}
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return GetOrAddInst<SemIR::SpecificConstant>(
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context, SemIR::LocId(inst_id),
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{.type_id = SemIR::TypeType::TypeId,
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.inst_id = inst_id,
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.specific_id = specific_id});
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}
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static auto CloneTypeInstId(Context& context, SemIR::SpecificId specific_id,
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SemIR::TypeInstId inst_id) -> SemIR::TypeInstId {
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if (!inst_id.has_value()) {
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return SemIR::TypeInstId::None;
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}
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return context.types().GetAsTypeInstId(
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CloneInstId(context, specific_id, inst_id));
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}
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static auto CloneFunctionDecl(Context& context, SemIR::LocId loc_id,
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SemIR::FunctionId signature_id,
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SemIR::SpecificId signature_specific_id,
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SemIR::FunctionId callee_id)
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-> std::pair<SemIR::FunctionId, SemIR::InstId> {
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StartGenericDecl(context);
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const auto& signature = context.functions().Get(signature_id);
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// Clone the signature.
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context.pattern_block_stack().Push();
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auto implicit_param_patterns_id = ClonePatternBlock(
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context, signature_specific_id, signature.implicit_param_patterns_id);
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auto param_patterns_id = ClonePatternBlock(context, signature_specific_id,
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signature.param_patterns_id);
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auto return_pattern_id =
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ClonePattern(context, signature_specific_id, signature.return_pattern_id);
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auto return_type_inst_id = CloneTypeInstId(context, signature_specific_id,
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signature.return_type_inst_id);
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auto return_form_inst_id = CloneInstId(context, signature_specific_id,
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signature.return_form_inst_id);
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auto self_param_id = FindSelfPattern(context, implicit_param_patterns_id);
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auto pattern_block_id = context.pattern_block_stack().Pop();
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// Perform callee-side pattern matching to rebuild the parameter list.
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context.inst_block_stack().Push();
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auto match_results = CalleePatternMatch(context, implicit_param_patterns_id,
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param_patterns_id, return_pattern_id);
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auto decl_block_id = context.inst_block_stack().Pop();
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// Create the `FunctionDecl` instruction.
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auto& callee = context.functions().Get(callee_id);
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auto [decl_id, function_id] = MakeFunctionDecl(
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context, loc_id, decl_block_id, /*build_generic=*/true,
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/*is_definition=*/true,
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SemIR::Function{
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{
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.name_id = signature.name_id,
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.parent_scope_id = callee.parent_scope_id,
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// Set by `MakeFunctionDecl`.
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.generic_id = SemIR::GenericId::None,
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.first_param_node_id = signature.first_param_node_id,
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.last_param_node_id = signature.last_param_node_id,
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.pattern_block_id = pattern_block_id,
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.implicit_param_patterns_id = implicit_param_patterns_id,
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.param_patterns_id = param_patterns_id,
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.is_extern = false,
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.extern_library_id = SemIR::LibraryNameId::None,
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.non_owning_decl_id = SemIR::InstId::None,
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// Set by `MakeFunctionDecl`.
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.first_owning_decl_id = SemIR::InstId::None,
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},
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{
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.call_param_patterns_id = match_results.call_param_patterns_id,
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.call_params_id = match_results.call_params_id,
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.call_param_ranges = match_results.param_ranges,
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.return_type_inst_id = return_type_inst_id,
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.return_form_inst_id = return_form_inst_id,
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.return_pattern_id = return_pattern_id,
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.virtual_modifier = callee.virtual_modifier,
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.virtual_index = callee.virtual_index,
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.evaluation_mode = signature.evaluation_mode,
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.self_param_id = self_param_id,
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}});
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context.inst_block_stack().AddInstId(decl_id);
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return {function_id, decl_id};
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}
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static auto HasDeclaredReturnType(Context& context,
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SemIR::FunctionId function_id) -> bool {
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return context.functions().Get(function_id).return_type_inst_id.has_value();
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}
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auto PerformThunkCall(Context& context, SemIR::LocId loc_id,
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SemIR::FunctionId function_id,
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llvm::ArrayRef<SemIR::InstId> param_pattern_ids,
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llvm::ArrayRef<SemIR::InstId> call_arg_ids,
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SemIR::InstId callee_id) -> SemIR::InstId {
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auto& function = context.functions().Get(function_id);
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auto [args_vec, ignored_call_args] = ThunkPatternMatch(
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context, function.self_param_id, param_pattern_ids, call_arg_ids);
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llvm::ArrayRef<SemIR::InstId> args = args_vec;
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// If we have a self parameter, form `self.<callee_id>` if needed.
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// When calling a C++ constructor to implement `Copy`, or calling a C++
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// non-method operator to implement a Carbon operator, the interface has a
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// `self` parameter but C++ models that parameter as an explicit argument
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// instead, so add the `self` to the argument list instead in that case.
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if (function.self_param_id.has_value() &&
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!IsCppConstructorOrNonMethodOperator(context, callee_id)) {
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callee_id = PerformCompoundMemberAccess(context, loc_id,
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args.consume_front(), callee_id);
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}
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return PerformCall(context, loc_id, callee_id, args);
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}
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// Build a call to a function that forwards the arguments of the enclosing
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// function, for use when constructing a thunk.
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static auto BuildThunkCall(Context& context, SemIR::FunctionId function_id,
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SemIR::InstId callee_id,
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llvm::ArrayRef<SemIR::InstId> param_pattern_ids,
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llvm::ArrayRef<SemIR::InstId> call_arg_ids)
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-> SemIR::InstId {
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auto& function = context.functions().Get(function_id);
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// Build a `NameRef` naming the callee, and a `SpecificConstant` if needed.
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auto loc_id = SemIR::LocId(callee_id);
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auto callee_type = context.types().GetAs<SemIR::FunctionType>(
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context.insts().Get(callee_id).type_id());
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callee_id = BuildNameRef(context, loc_id, function.name_id, callee_id,
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callee_type.specific_id);
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return PerformThunkCall(context, loc_id, function_id, param_pattern_ids,
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call_arg_ids, callee_id);
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}
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static auto StartThunkFunctionDefinition(Context& context,
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SemIR::FunctionId function_id,
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SemIR::InstId thunk_id,
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SemIR::InstId callee_id) {
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// The check below produces diagnostics referring to the signature, so also
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// note the callee.
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Diagnostics::AnnotationScope annot_scope(
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&context.emitter(), [&](DiagnosticBuilder& builder) {
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CARBON_DIAGNOSTIC(ThunkCallee, Note,
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"while building thunk calling this function");
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builder.Note(callee_id, ThunkCallee);
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});
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StartFunctionDefinition(context, thunk_id, function_id);
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}
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// Given a declaration of a thunk and the function that it should call, build
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// the thunk body.
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static auto BuildThunkDefinition(Context& context,
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SemIR::FunctionId signature_id,
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SemIR::FunctionId function_id,
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SemIR::InstId thunk_id,
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SemIR::InstId callee_id) -> void {
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// TODO: Improve the diagnostics produced here. Specifically, it would likely
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// be better for the primary error message to be that we tried to produce a
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// thunk because of a type mismatch, but couldn't, with notes explaining
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// why, rather than the primary error message being whatever went wrong
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// building the thunk.
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StartThunkFunctionDefinition(context, function_id, thunk_id, callee_id);
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// The checks below produce diagnostics pointing at the callee, so also note
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// the signature.
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Diagnostics::AnnotationScope annot_scope(
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&context.emitter(), [&](DiagnosticBuilder& builder) {
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CARBON_DIAGNOSTIC(
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ThunkSignature, Note,
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"while building thunk to match the signature of this function");
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builder.Note(context.functions().Get(signature_id).first_owning_decl_id,
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ThunkSignature);
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});
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const auto& function = context.functions().Get(function_id);
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llvm::ArrayRef<SemIR::InstId> param_pattern_ids;
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if (function.param_patterns_id.has_value()) {
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param_pattern_ids = context.inst_blocks().Get(function.param_patterns_id);
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}
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auto call_param_ids = context.inst_blocks().Get(function.call_params_id);
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auto call_id = BuildThunkCall(context, function_id, callee_id,
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param_pattern_ids, call_param_ids);
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if (HasDeclaredReturnType(context, function_id)) {
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BuildReturnWithExpr(context, SemIR::LocId(callee_id), call_id);
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} else {
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DiscardExpr(context, call_id);
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BuildReturnWithNoExpr(context, SemIR::LocId(callee_id));
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}
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FinishFunctionDefinition(context, function_id);
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}
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auto BuildThunkDefinitionForExport(Context& context,
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SemIR::FunctionId thunk_function_id,
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SemIR::FunctionId callee_function_id,
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SemIR::InstId thunk_id,
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SemIR::InstId callee_id) -> void {
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auto& thunk_function = context.functions().Get(thunk_function_id);
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auto& callee_function = context.functions().Get(callee_function_id);
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StartThunkFunctionDefinition(context, thunk_function_id, thunk_id, callee_id);
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const bool thunk_has_return_param =
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callee_function.return_type_inst_id != SemIR::TypeInstId::None;
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llvm::ArrayRef<SemIR::InstId> param_pattern_ids;
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if (thunk_function.param_patterns_id.has_value()) {
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param_pattern_ids =
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context.inst_blocks().Get(thunk_function.param_patterns_id);
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}
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llvm::SmallVector<SemIR::InstId> call_param_ids(
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context.inst_blocks().Get(thunk_function.call_params_id));
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if (thunk_has_return_param) {
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param_pattern_ids = param_pattern_ids.drop_back();
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call_param_ids.pop_back();
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}
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auto callee_param_ids =
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context.inst_blocks().Get(callee_function.call_param_patterns_id);
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// If any explicit parameters of the callee are `ref` parameters,
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// modify the corresponding call arguments to be `ref` tagged.
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for (auto index = thunk_function.call_param_ranges.explicit_begin().index;
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index < thunk_function.call_param_ranges.explicit_end().index; index++) {
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if (context.insts().Is<SemIR::RefParamPattern>(callee_param_ids[index])) {
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auto& call_param_id = call_param_ids[index];
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auto type = context.insts().Get(call_param_id).type_id();
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SemIR::LocId loc_id(thunk_id);
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call_param_id =
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AddInst(context, SemIR::LocIdAndInst::RuntimeVerified(
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context.sem_ir(), SemIR::LocId(call_param_id),
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SemIR::RefTagExpr{
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.type_id = type,
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|
.expr_id = call_param_id,
|
|
}));
|
|
}
|
|
}
|
|
|
|
auto call_id = BuildThunkCall(context, thunk_function_id, callee_id,
|
|
param_pattern_ids, call_param_ids);
|
|
if (thunk_has_return_param) {
|
|
auto out_param_id =
|
|
context.inst_blocks().Get(thunk_function.call_params_id).back();
|
|
|
|
SemIR::LocId loc_id(out_param_id);
|
|
auto init_id =
|
|
Initialize(context, loc_id, out_param_id, call_id, /*for_return=*/true);
|
|
AddInst(context, loc_id,
|
|
SemIR::Assign{
|
|
.lhs_id = out_param_id,
|
|
.rhs_id = init_id,
|
|
});
|
|
} else {
|
|
DiscardExpr(context, call_id);
|
|
}
|
|
|
|
BuildReturnWithNoExpr(context, SemIR::LocId(callee_id));
|
|
|
|
FinishFunctionDefinition(context, thunk_function_id);
|
|
}
|
|
|
|
auto BuildThunkDefinition(Context& context,
|
|
DeferredDefinitionWorklist::DefineThunk&& task)
|
|
-> void {
|
|
context.scope_stack().Restore(std::move(task.scope));
|
|
|
|
BuildThunkDefinition(context, task.info.signature_id, task.info.function_id,
|
|
task.info.decl_id, task.info.callee_id);
|
|
|
|
context.scope_stack().Pop();
|
|
}
|
|
|
|
auto BuildThunk(Context& context, SemIR::FunctionId signature_id,
|
|
SemIR::SpecificId signature_specific_id,
|
|
SemIR::InstId callee_id, bool defer_definition)
|
|
-> SemIR::InstId {
|
|
auto callee = SemIR::GetCalleeAsFunction(context.sem_ir(), callee_id);
|
|
|
|
// Check whether we can use the given function without a thunk.
|
|
// TODO: For virtual functions, we want different rules for checking `self`.
|
|
// TODO: This is too strict; for example, we should not compare parameter
|
|
// names here.
|
|
if (context.functions().Get(callee.function_id).special_function_kind !=
|
|
SemIR::Function::SpecialFunctionKind::HasCppThunk &&
|
|
CheckFunctionTypeMatches(
|
|
context, context.functions().Get(callee.function_id),
|
|
context.functions().Get(signature_id), signature_specific_id,
|
|
/*check_syntax=*/false, /*check_self=*/true, /*diagnose=*/false)) {
|
|
return callee_id;
|
|
}
|
|
|
|
// From P3763:
|
|
// If the function in the interface does not have a return type, the
|
|
// program is invalid if the function in the impl specifies a return type.
|
|
//
|
|
// Call into the redeclaration checking logic to produce a suitable error.
|
|
//
|
|
// TODO: Consider a different rule: always use an explicit return type for the
|
|
// thunk, and always convert the result of the wrapped call to the return type
|
|
// of the thunk.
|
|
if (!HasDeclaredReturnType(context, signature_id) &&
|
|
HasDeclaredReturnType(context, callee.function_id) &&
|
|
context.functions().Get(callee.function_id).name_id !=
|
|
SemIR::NameId::CppOperator) {
|
|
bool success = CheckFunctionReturnTypeMatches(
|
|
context, context.functions().Get(callee.function_id),
|
|
context.functions().Get(signature_id), signature_specific_id);
|
|
CARBON_CHECK(!success, "Return type unexpectedly matches");
|
|
return SemIR::ErrorInst::InstId;
|
|
}
|
|
|
|
// Create a scope for the function's parameters and generic parameters.
|
|
context.scope_stack().PushForDeclName();
|
|
|
|
// We can't use the function directly. Build a thunk.
|
|
// TODO: Check for and diagnose obvious reasons why this will fail, such as
|
|
// arity mismatch, before trying to build the thunk.
|
|
auto [function_id, thunk_id] =
|
|
CloneFunctionDecl(context, SemIR::LocId(callee_id), signature_id,
|
|
signature_specific_id, callee.function_id);
|
|
|
|
// Track that this function is a thunk.
|
|
context.functions().Get(function_id).SetThunk(callee_id);
|
|
|
|
if (defer_definition) {
|
|
// Register the thunk to be defined when we reach the end of the enclosing
|
|
// deferred definition scope, for example an `impl` or `class` definition,
|
|
// as if the thunk's body were written inline in this location.
|
|
context.deferred_definition_worklist().SuspendThunkAndPush(
|
|
context, {
|
|
.signature_id = signature_id,
|
|
.function_id = function_id,
|
|
.decl_id = thunk_id,
|
|
.callee_id = callee_id,
|
|
});
|
|
} else {
|
|
BuildThunkDefinition(context, signature_id, function_id, thunk_id,
|
|
callee_id);
|
|
context.scope_stack().Pop();
|
|
}
|
|
|
|
return thunk_id;
|
|
}
|
|
|
|
} // namespace Carbon::Check
|