mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Geoff Romer
4c9049346d
See [here](https://docs.google.com/document/d/1rWcueFwIfZox6GKVGxiUG4cBzjrZ6djXiIDGyJDtrE4/edit?tab=t.0) for the design doc. This also removes the default value of the `result_type_inst_id` parameter of `HandleAction`, moves it before the action in the parameter list, and documents it. This solves two problems: - The default made it easy to forget, leading to unnecessary `TypeOfInst` instructions. - When it was present, putting it after the fairly "bulky" action argument tended to make the callsite harder to read.
236 lines
8.6 KiB
C++
236 lines
8.6 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/sem_ir/expr_info.h"
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#include <concepts>
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#include "common/check.h"
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#include "toolchain/base/kind_switch.h"
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#include "toolchain/sem_ir/ids.h"
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#include "toolchain/sem_ir/inst_kind.h"
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#include "toolchain/sem_ir/typed_insts.h"
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namespace Carbon::SemIR {
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// Returns the InstId represented by an instruction operand.
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static auto AsAnyInstId(Inst::ArgAndKind arg) -> InstId {
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if (auto inst_id = arg.TryAs<SemIR::InstId>()) {
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return *inst_id;
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}
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return arg.As<SemIR::AbsoluteInstId>();
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}
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static auto GetExprCategoryImpl(const File* ir, InstId inst_id)
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-> ExprCategory {
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// The overall expression category if the current instruction is a value
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// expression.
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ExprCategory value_category = ExprCategory::Value;
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while (true) {
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auto untyped_inst = ir->insts().Get(inst_id);
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auto category_from_kind = untyped_inst.kind().expr_category();
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// If this instruction kind has a fixed category, return it.
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if (auto fixed_category = category_from_kind.TryAsFixedCategory()) {
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return *fixed_category == ExprCategory::Value ? value_category
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: *fixed_category;
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}
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// Handle any special cases that use
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// ComputedExprCategory::DependsOnOperands.
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auto handle_special_case =
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[&]<typename TypedInstT>(
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TypedInstT inst) -> std::optional<ExprCategory> {
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if constexpr (std::same_as<TypedInstT, ClassElementAccess>) {
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inst_id = inst.base_id;
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// A value of class type is a pointer to an object representation.
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// Therefore, if the base is a value, the result is an ephemeral
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// reference.
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value_category = ExprCategory::EphemeralRef;
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return std::nullopt;
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} else if constexpr (std::same_as<TypedInstT, ImportRefLoaded> ||
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std::same_as<TypedInstT, ImportRefUnloaded>) {
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auto import_ir_inst = ir->import_ir_insts().Get(inst.import_ir_inst_id);
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ir = ir->import_irs().Get(import_ir_inst.ir_id()).sem_ir;
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inst_id = import_ir_inst.inst_id();
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return std::nullopt;
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} else if constexpr (std::same_as<TypedInstT, Call>) {
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auto callee = GetCallee(*ir, inst.callee_id);
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CARBON_KIND_SWITCH(callee) {
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case CARBON_KIND(SemIR::CalleeError _): {
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return ExprCategory::Error;
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}
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case CARBON_KIND(SemIR::CalleeFunction callee_function): {
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const auto& function =
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ir->functions().Get(callee_function.function_id);
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auto return_form_id = function.GetDeclaredReturnForm(
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*ir, callee_function.resolved_specific_id);
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if (!return_form_id.has_value()) {
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// Treat as equivalent to `-> ()`.
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return ExprCategory::ReprInitializing;
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}
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auto return_form = ir->insts().Get(return_form_id);
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CARBON_KIND_SWITCH(return_form) {
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case CARBON_KIND(InitForm _):
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return ExprCategory::ReprInitializing;
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case CARBON_KIND(RefForm _):
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return ExprCategory::DurableRef;
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case CARBON_KIND(ValueForm _):
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return ExprCategory::Value;
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case CARBON_KIND(ErrorInst _):
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return ExprCategory::Error;
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default:
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CARBON_FATAL("Unexpected inst kind: {0}", return_form);
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}
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}
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case CARBON_KIND(SemIR::CalleeNonFunction _): {
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return ExprCategory::NotExpr;
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}
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case CARBON_KIND(SemIR::CalleeCppOverloadSet _): {
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// TODO: support `ref` returns from C++.
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return ExprCategory::ReprInitializing;
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}
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}
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} else {
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static_assert(
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TypedInstT::Kind.expr_category().TryAsComputedCategory() !=
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ComputedExprCategory::DependsOnOperands,
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"Missing expression category computation for type");
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}
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CARBON_FATAL("Unreachable");
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};
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// If the category depends on the operands of the instruction, determine it.
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// Usually this means the category is the same as the category of an
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// operand.
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switch (*category_from_kind.TryAsComputedCategory()) {
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case ComputedExprCategory::ValueIfHasType: {
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return untyped_inst.kind().has_type() ? value_category
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: ExprCategory::NotExpr;
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}
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case ComputedExprCategory::SameAsFirstOperand: {
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inst_id = AsAnyInstId(untyped_inst.arg0_and_kind());
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break;
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}
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case ComputedExprCategory::SameAsSecondOperand: {
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inst_id = AsAnyInstId(untyped_inst.arg1_and_kind());
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break;
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}
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case ComputedExprCategory::DependsOnOperands: {
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switch (untyped_inst.kind()) {
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#define CARBON_SEM_IR_INST_KIND(TypedInstT) \
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case TypedInstT::Kind: { \
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auto category = handle_special_case(untyped_inst.As<TypedInstT>()); \
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if (category.has_value()) { \
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return *category; \
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} \
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break; \
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}
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#include "toolchain/sem_ir/inst_kind.def"
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}
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}
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}
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}
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}
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auto GetExprCategory(const File& file, InstId inst_id) -> ExprCategory {
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return GetExprCategoryImpl(&file, inst_id);
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}
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auto FindStorageArgForInitializer(const File& sem_ir, InstId init_id,
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bool allow_transitive) -> InstId {
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while (true) {
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Inst init_untyped = sem_ir.insts().Get(init_id);
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CARBON_KIND_SWITCH(init_untyped) {
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case CARBON_KIND(AsCompatible init): {
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if (!allow_transitive) {
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return InstId::None;
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}
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init_id = init.source_id;
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continue;
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}
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case CARBON_KIND(Converted init): {
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if (!allow_transitive) {
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return InstId::None;
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}
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init_id = init.result_id;
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continue;
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}
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case CARBON_KIND(UpdateInit init): {
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if (!allow_transitive) {
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return InstId::None;
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}
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init_id = init.base_init_id;
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continue;
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}
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case CARBON_KIND(ArrayInit init): {
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return init.dest_id;
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}
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case CARBON_KIND(ClassInit init): {
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return init.dest_id;
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}
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case CARBON_KIND(StructInit init): {
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return init.dest_id;
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}
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case CARBON_KIND(TupleInit init): {
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return init.dest_id;
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}
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case CARBON_KIND(InPlaceInit init): {
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return init.dest_id;
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}
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case CARBON_KIND(MarkInPlaceInit init): {
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return init.dest_id;
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}
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case CARBON_KIND(Call call): {
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auto callee_function = GetCalleeAsFunction(sem_ir, call.callee_id);
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const auto& function =
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sem_ir.functions().Get(callee_function.function_id);
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if (!function.return_form_inst_id.has_value()) {
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return InstId::None;
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}
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auto return_form_constant_id = GetConstantValueInSpecific(
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sem_ir, callee_function.resolved_specific_id,
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function.return_form_inst_id);
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auto return_form = sem_ir.insts().Get(
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sem_ir.constant_values().GetInstId(return_form_constant_id));
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CARBON_KIND_SWITCH(return_form) {
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case CARBON_KIND(InitForm init_form): {
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auto type_id = sem_ir.types().GetTypeIdForTypeInstId(
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init_form.type_component_inst_id);
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if (!InitRepr::ForType(sem_ir, type_id).MightBeInPlace()) {
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return InstId::None;
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}
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if (!call.args_id.has_value()) {
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// Argument initialization failed, so we have no return slot.
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return InstId::None;
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}
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CARBON_CHECK(function.call_param_ranges.return_size() == 1,
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"Unexpected number of output parameters on function");
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return sem_ir.inst_blocks().Get(
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call.args_id)[function.call_param_ranges.return_begin().index];
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}
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case CARBON_KIND(RefForm _): {
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return InstId::None;
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}
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default:
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CARBON_FATAL("Unexpected inst kind: {0}", return_form);
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}
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}
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case CARBON_KIND(ErrorInst _): {
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return InstId::None;
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}
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default:
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CARBON_FATAL("Initialization from unexpected inst {0}", init_untyped);
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}
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}
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}
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} // namespace Carbon::SemIR
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