mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-10-04 19:11:11 +01:00
Richard Smith
71aa4a45be
Add a `NameId` that is effectively just a wrapper around a `StringId`, with some additional predefined values for names that don't correspond to strings, such as the name of `self` or the function's return slot.
292 lines
12 KiB
C++
292 lines
12 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 "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Value.h"
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#include "toolchain/lower/function_context.h"
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#include "toolchain/sem_ir/inst.h"
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#include "toolchain/sem_ir/inst_kind.h"
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namespace Carbon::Lower {
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auto HandleClassDeclaration(FunctionContext& /*context*/,
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SemIR::InstId /*inst_id*/,
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SemIR::ClassDeclaration /*inst*/) -> void {
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// No action to perform.
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}
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// Extracts an element of an aggregate, such as a struct, tuple, or class, by
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// index. Depending on the expression category and value representation of the
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// aggregate input, this will either produce a value or a reference.
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static auto GetAggregateElement(FunctionContext& context,
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SemIR::InstId aggr_inst_id,
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SemIR::MemberIndex idx,
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SemIR::TypeId result_type_id, llvm::Twine name)
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-> llvm::Value* {
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auto aggr_inst = context.sem_ir().insts().Get(aggr_inst_id);
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auto* aggr_value = context.GetLocal(aggr_inst_id);
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switch (SemIR::GetExpressionCategory(context.sem_ir(), aggr_inst_id)) {
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case SemIR::ExpressionCategory::Error:
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case SemIR::ExpressionCategory::NotExpression:
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case SemIR::ExpressionCategory::Initializing:
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case SemIR::ExpressionCategory::Mixed:
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CARBON_FATAL() << "Unexpected expression category for aggregate access";
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case SemIR::ExpressionCategory::Value: {
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auto value_rep =
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SemIR::GetValueRepresentation(context.sem_ir(), aggr_inst.type_id());
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CARBON_CHECK(value_rep.aggregate_kind !=
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SemIR::ValueRepresentation::NotAggregate)
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<< "aggregate type should have aggregate value representation";
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switch (value_rep.kind) {
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case SemIR::ValueRepresentation::Unknown:
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CARBON_FATAL() << "Lowering access to incomplete aggregate type";
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case SemIR::ValueRepresentation::None:
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return aggr_value;
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case SemIR::ValueRepresentation::Copy:
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// We are holding the values of the aggregate directly, elementwise.
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return context.builder().CreateExtractValue(aggr_value, idx.index,
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name);
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case SemIR::ValueRepresentation::Pointer: {
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// The value representation is a pointer to an aggregate that we want
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// to index into.
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auto pointee_type_id =
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context.sem_ir().GetPointeeType(value_rep.type_id);
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auto* value_type = context.GetType(pointee_type_id);
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auto* elem_ptr = context.builder().CreateStructGEP(
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value_type, aggr_value, idx.index, name);
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if (!value_rep.elements_are_values()) {
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// `elem_ptr` points to an object representation, which is our
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// result.
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return elem_ptr;
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}
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// `elem_ptr` points to a value representation. Load it.
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auto result_value_type_id =
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SemIR::GetValueRepresentation(context.sem_ir(), result_type_id)
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.type_id;
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return context.builder().CreateLoad(
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context.GetType(result_value_type_id), elem_ptr, name + ".load");
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}
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case SemIR::ValueRepresentation::Custom:
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CARBON_FATAL()
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<< "Aggregate should never have custom value representation";
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}
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}
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case SemIR::ExpressionCategory::DurableReference:
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case SemIR::ExpressionCategory::EphemeralReference: {
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// Just locate the aggregate element.
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auto* aggr_type = context.GetType(aggr_inst.type_id());
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return context.builder().CreateStructGEP(aggr_type, aggr_value, idx.index,
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name);
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}
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}
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}
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static auto GetStructFieldName(FunctionContext& context,
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SemIR::TypeId struct_type_id,
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SemIR::MemberIndex index) -> llvm::StringRef {
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auto fields = context.sem_ir().inst_blocks().Get(
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context.sem_ir()
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.insts()
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.GetAs<SemIR::StructType>(
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context.sem_ir().types().Get(struct_type_id).inst_id)
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.fields_id);
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auto field = context.sem_ir().insts().GetAs<SemIR::StructTypeField>(
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fields[index.index]);
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return context.sem_ir().names().GetIRBaseName(field.name_id);
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}
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auto HandleClassFieldAccess(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::ClassFieldAccess inst) -> void {
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// Find the class that we're performing access into.
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auto class_type_id = context.sem_ir().insts().Get(inst.base_id).type_id();
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auto class_id =
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context.sem_ir()
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.insts()
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.GetAs<SemIR::ClassType>(
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context.sem_ir().GetTypeAllowBuiltinTypes(class_type_id))
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.class_id;
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auto& class_info = context.sem_ir().classes().Get(class_id);
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// Translate the class field access into a struct access on the object
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// representation.
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context.SetLocal(
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inst_id,
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GetAggregateElement(
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context, inst.base_id, inst.index, inst.type_id,
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GetStructFieldName(context, class_info.object_representation_id,
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inst.index)));
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}
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static auto EmitAggregateInitializer(FunctionContext& context,
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SemIR::TypeId type_id,
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SemIR::InstBlockId refs_id,
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llvm::Twine name) -> llvm::Value* {
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auto* llvm_type = context.GetType(type_id);
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switch (
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SemIR::GetInitializingRepresentation(context.sem_ir(), type_id).kind) {
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case SemIR::InitializingRepresentation::None:
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case SemIR::InitializingRepresentation::InPlace:
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// TODO: Add a helper to poison a value slot.
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return llvm::PoisonValue::get(llvm_type);
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case SemIR::InitializingRepresentation::ByCopy: {
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auto refs = context.sem_ir().inst_blocks().Get(refs_id);
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CARBON_CHECK(refs.size() == 1)
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<< "Unexpected size for aggregate with by-copy value representation";
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// TODO: Remove the LLVM StructType wrapper in this case, so we don't
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// need this `insert_value` wrapping.
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return context.builder().CreateInsertValue(
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llvm::PoisonValue::get(llvm_type), context.GetLocal(refs[0]), {0},
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name);
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}
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}
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}
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auto HandleClassInit(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::ClassInit inst) -> void {
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context.SetLocal(
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inst_id, EmitAggregateInitializer(context, inst.type_id, inst.elements_id,
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"class.init"));
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}
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auto HandleField(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/,
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SemIR::Field /*inst*/) -> void {
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// No action to perform.
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}
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auto HandleStructAccess(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::StructAccess inst) -> void {
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auto struct_type_id = context.sem_ir().insts().Get(inst.struct_id).type_id();
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context.SetLocal(
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inst_id, GetAggregateElement(
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context, inst.struct_id, inst.index, inst.type_id,
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GetStructFieldName(context, struct_type_id, inst.index)));
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}
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auto HandleStructLiteral(FunctionContext& /*context*/,
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SemIR::InstId /*inst_id*/,
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SemIR::StructLiteral /*inst*/) -> void {
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// A StructLiteral should always be converted to a StructInit or StructValue
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// if its value is needed.
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}
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// Emits the value representation for a struct or tuple whose elements are the
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// contents of `refs_id`.
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auto EmitAggregateValueRepresentation(FunctionContext& context,
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SemIR::TypeId type_id,
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SemIR::InstBlockId refs_id,
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llvm::Twine name) -> llvm::Value* {
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auto value_rep = SemIR::GetValueRepresentation(context.sem_ir(), type_id);
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switch (value_rep.kind) {
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case SemIR::ValueRepresentation::Unknown:
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CARBON_FATAL() << "Incomplete aggregate type in lowering";
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case SemIR::ValueRepresentation::None:
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// TODO: Add a helper to get a "no value representation" value.
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return llvm::PoisonValue::get(context.GetType(value_rep.type_id));
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case SemIR::ValueRepresentation::Copy: {
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auto refs = context.sem_ir().inst_blocks().Get(refs_id);
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CARBON_CHECK(refs.size() == 1)
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<< "Unexpected size for aggregate with by-copy value representation";
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// TODO: Remove the LLVM StructType wrapper in this case, so we don't
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// need this `insert_value` wrapping.
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return context.builder().CreateInsertValue(
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llvm::PoisonValue::get(context.GetType(value_rep.type_id)),
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context.GetLocal(refs[0]), {0});
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}
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case SemIR::ValueRepresentation::Pointer: {
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auto pointee_type_id = context.sem_ir().GetPointeeType(value_rep.type_id);
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auto* llvm_value_rep_type = context.GetType(pointee_type_id);
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// Write the value representation to a local alloca so we can produce a
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// pointer to it as the value representation of the struct or tuple.
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auto* alloca =
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context.builder().CreateAlloca(llvm_value_rep_type,
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/*ArraySize=*/nullptr, name);
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for (auto [i, ref] :
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llvm::enumerate(context.sem_ir().inst_blocks().Get(refs_id))) {
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context.builder().CreateStore(
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context.GetLocal(ref),
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context.builder().CreateStructGEP(llvm_value_rep_type, alloca, i));
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}
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return alloca;
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}
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case SemIR::ValueRepresentation::Custom:
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CARBON_FATAL()
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<< "Aggregate should never have custom value representation";
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}
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}
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auto HandleStructInit(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::StructInit inst) -> void {
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context.SetLocal(
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inst_id, EmitAggregateInitializer(context, inst.type_id, inst.elements_id,
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"struct.init"));
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}
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auto HandleStructValue(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::StructValue inst) -> void {
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context.SetLocal(
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inst_id, EmitAggregateValueRepresentation(context, inst.type_id,
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inst.elements_id, "struct"));
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}
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auto HandleStructTypeField(FunctionContext& /*context*/,
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SemIR::InstId /*inst_id*/,
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SemIR::StructTypeField /*inst*/) -> void {
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// No action to take.
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}
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auto HandleTupleAccess(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::TupleAccess inst) -> void {
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context.SetLocal(inst_id,
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GetAggregateElement(context, inst.tuple_id, inst.index,
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inst.type_id, "tuple.elem"));
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}
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auto HandleTupleIndex(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::TupleIndex inst) -> void {
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auto index_inst =
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context.sem_ir().insts().GetAs<SemIR::IntegerLiteral>(inst.index_id);
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auto index =
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context.sem_ir().integers().Get(index_inst.integer_id).getZExtValue();
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context.SetLocal(inst_id, GetAggregateElement(context, inst.tuple_id,
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SemIR::MemberIndex(index),
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inst.type_id, "tuple.index"));
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}
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auto HandleTupleLiteral(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/,
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SemIR::TupleLiteral /*inst*/) -> void {
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// A TupleLiteral should always be converted to a TupleInit or TupleValue if
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// its value is needed.
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}
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auto HandleTupleInit(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::TupleInit inst) -> void {
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context.SetLocal(
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inst_id, EmitAggregateInitializer(context, inst.type_id, inst.elements_id,
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"tuple.init"));
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}
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auto HandleTupleValue(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::TupleValue inst) -> void {
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context.SetLocal(inst_id,
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EmitAggregateValueRepresentation(context, inst.type_id,
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inst.elements_id, "tuple"));
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}
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} // namespace Carbon::Lower
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