Files
carbon-lang/toolchain/lower/handle_aggregates.cpp
T
Jon Ross-PerkinsandRichard Smith 76ed3c73cb Promote FunctionType to a standard instruction. (#3931)
This removes the builtin FunctionType, replacing it with a FunctionType
instruction. The constant for a FunctionDecl is now a StructValue with
type of FunctionType.

Note this means a function declaration produces _both_ a type, and a
value of the type. This has some consequences in terms of circularity,
and makes the importing of function declarations a little more complex.

It'll get particularly peculiar for imports because of the behavior of
the reference, but that's a known issue due to other things such as
`alias`. The impact will hopefully be contained to
ResolvePrevInstForMerge (and ImportRefs).

To note a small formatting change in diagnostics:

```
-  // CHECK:STDERR: fail_member_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated <function> in Interface>` is not callable.
+  // CHECK:STDERR: fail_member_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated F in Interface>` is not callable.

-  // CHECK:STDERR: fail_todo_facet_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated <function> in Interface>` is not callable.
+  // CHECK:STDERR: fail_todo_facet_lookup.carbon:[[@LINE+4]]:3: ERROR: Value of type `<associated F in Interface>` is not callable.
```

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2024-05-03 15:18:04 +00:00

276 lines
11 KiB
C++

// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Value.h"
#include "toolchain/lower/function_context.h"
#include "toolchain/sem_ir/inst.h"
#include "toolchain/sem_ir/typed_insts.h"
namespace Carbon::Lower {
auto HandleClassDecl(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/,
SemIR::ClassDecl /*inst*/) -> void {
// No action to perform.
}
// Extracts an element of an aggregate, such as a struct, tuple, or class, by
// index. Depending on the expression category and value representation of the
// aggregate input, this will either produce a value or a reference.
static auto GetAggregateElement(FunctionContext& context,
SemIR::InstId aggr_inst_id,
SemIR::ElementIndex idx,
SemIR::TypeId result_type_id, llvm::Twine name)
-> llvm::Value* {
auto aggr_inst = context.sem_ir().insts().Get(aggr_inst_id);
auto* aggr_value = context.GetValue(aggr_inst_id);
switch (SemIR::GetExprCategory(context.sem_ir(), aggr_inst_id)) {
case SemIR::ExprCategory::Error:
case SemIR::ExprCategory::NotExpr:
case SemIR::ExprCategory::Initializing:
case SemIR::ExprCategory::Mixed:
CARBON_FATAL() << "Unexpected expression category for aggregate access";
case SemIR::ExprCategory::Value: {
auto value_rep =
SemIR::GetValueRepr(context.sem_ir(), aggr_inst.type_id());
CARBON_CHECK(value_rep.aggregate_kind != SemIR::ValueRepr::NotAggregate)
<< "aggregate type should have aggregate value representation";
switch (value_rep.kind) {
case SemIR::ValueRepr::Unknown:
CARBON_FATAL() << "Lowering access to incomplete aggregate type";
case SemIR::ValueRepr::None:
return aggr_value;
case SemIR::ValueRepr::Copy:
// We are holding the values of the aggregate directly, elementwise.
return context.builder().CreateExtractValue(aggr_value, idx.index,
name);
case SemIR::ValueRepr::Pointer: {
// The value representation is a pointer to an aggregate that we want
// to index into.
auto pointee_type_id =
context.sem_ir().GetPointeeType(value_rep.type_id);
auto* value_type = context.GetType(pointee_type_id);
auto* elem_ptr = context.builder().CreateStructGEP(
value_type, aggr_value, idx.index, name);
if (!value_rep.elements_are_values()) {
// `elem_ptr` points to an object representation, which is our
// result.
return elem_ptr;
}
// `elem_ptr` points to a value representation. Load it.
auto result_value_type_id =
SemIR::GetValueRepr(context.sem_ir(), result_type_id).type_id;
return context.builder().CreateLoad(
context.GetType(result_value_type_id), elem_ptr, name + ".load");
}
case SemIR::ValueRepr::Custom:
CARBON_FATAL()
<< "Aggregate should never have custom value representation";
}
}
case SemIR::ExprCategory::DurableRef:
case SemIR::ExprCategory::EphemeralRef: {
// Just locate the aggregate element.
auto* aggr_type = context.GetType(aggr_inst.type_id());
return context.builder().CreateStructGEP(aggr_type, aggr_value, idx.index,
name);
}
}
}
static auto GetStructFieldName(FunctionContext& context,
SemIR::TypeId struct_type_id,
SemIR::ElementIndex index) -> llvm::StringRef {
auto fields = context.sem_ir().inst_blocks().Get(
context.sem_ir()
.types()
.GetAs<SemIR::StructType>(struct_type_id)
.fields_id);
auto field = context.sem_ir().insts().GetAs<SemIR::StructTypeField>(
fields[index.index]);
return context.sem_ir().names().GetIRBaseName(field.name_id);
}
auto HandleClassElementAccess(FunctionContext& context, SemIR::InstId inst_id,
SemIR::ClassElementAccess inst) -> void {
// Find the class that we're performing access into.
auto class_type_id = context.sem_ir().insts().Get(inst.base_id).type_id();
auto class_id =
context.sem_ir().types().GetAs<SemIR::ClassType>(class_type_id).class_id;
const auto& class_info = context.sem_ir().classes().Get(class_id);
// Translate the class field access into a struct access on the object
// representation.
context.SetLocal(
inst_id,
GetAggregateElement(
context, inst.base_id, inst.index, inst.type_id,
GetStructFieldName(context, class_info.object_repr_id, inst.index)));
}
static auto EmitAggregateInitializer(FunctionContext& context,
SemIR::TypeId type_id,
SemIR::InstBlockId refs_id,
llvm::Twine name) -> llvm::Value* {
auto* llvm_type = context.GetType(type_id);
switch (SemIR::GetInitRepr(context.sem_ir(), type_id).kind) {
case SemIR::InitRepr::None:
case SemIR::InitRepr::InPlace:
// TODO: Add a helper to poison a value slot.
return llvm::PoisonValue::get(llvm_type);
case SemIR::InitRepr::ByCopy: {
auto refs = context.sem_ir().inst_blocks().Get(refs_id);
CARBON_CHECK(refs.size() == 1)
<< "Unexpected size for aggregate with by-copy value representation";
// TODO: Remove the LLVM StructType wrapper in this case, so we don't
// need this `insert_value` wrapping.
return context.builder().CreateInsertValue(
llvm::PoisonValue::get(llvm_type), context.GetValue(refs[0]), {0},
name);
}
}
}
auto HandleClassInit(FunctionContext& context, SemIR::InstId inst_id,
SemIR::ClassInit inst) -> void {
context.SetLocal(
inst_id, EmitAggregateInitializer(context, inst.type_id, inst.elements_id,
"class.init"));
}
auto HandleStructAccess(FunctionContext& context, SemIR::InstId inst_id,
SemIR::StructAccess inst) -> void {
auto struct_type_id = context.sem_ir().insts().Get(inst.struct_id).type_id();
context.SetLocal(
inst_id, GetAggregateElement(
context, inst.struct_id, inst.index, inst.type_id,
GetStructFieldName(context, struct_type_id, inst.index)));
}
auto HandleStructLiteral(FunctionContext& /*context*/,
SemIR::InstId /*inst_id*/,
SemIR::StructLiteral /*inst*/) -> void {
// A StructLiteral should always be converted to a StructInit or StructValue
// if its value is needed.
}
// Emits the value representation for a struct or tuple whose elements are the
// contents of `refs_id`.
auto EmitAggregateValueRepr(FunctionContext& context, SemIR::TypeId type_id,
SemIR::InstBlockId refs_id) -> llvm::Value* {
auto value_rep = SemIR::GetValueRepr(context.sem_ir(), type_id);
switch (value_rep.kind) {
case SemIR::ValueRepr::Unknown:
CARBON_FATAL() << "Incomplete aggregate type in lowering";
case SemIR::ValueRepr::None:
// TODO: Add a helper to get a "no value representation" value.
return llvm::PoisonValue::get(context.GetType(value_rep.type_id));
case SemIR::ValueRepr::Copy: {
auto refs = context.sem_ir().inst_blocks().Get(refs_id);
CARBON_CHECK(refs.size() == 1)
<< "Unexpected size for aggregate with by-copy value representation";
// TODO: Remove the LLVM StructType wrapper in this case, so we don't
// need this `insert_value` wrapping.
return context.builder().CreateInsertValue(
llvm::PoisonValue::get(context.GetType(value_rep.type_id)),
context.GetValue(refs[0]), {0});
}
case SemIR::ValueRepr::Pointer: {
auto pointee_type_id = context.sem_ir().GetPointeeType(value_rep.type_id);
auto* llvm_value_rep_type = context.GetType(pointee_type_id);
// Write the value representation to a local alloca so we can produce a
// pointer to it as the value representation of the struct or tuple.
auto* alloca = context.builder().CreateAlloca(llvm_value_rep_type);
for (auto [i, ref] :
llvm::enumerate(context.sem_ir().inst_blocks().Get(refs_id))) {
context.builder().CreateStore(
context.GetValue(ref),
context.builder().CreateStructGEP(llvm_value_rep_type, alloca, i));
}
return alloca;
}
case SemIR::ValueRepr::Custom:
CARBON_FATAL()
<< "Aggregate should never have custom value representation";
}
}
auto HandleStructInit(FunctionContext& context, SemIR::InstId inst_id,
SemIR::StructInit inst) -> void {
context.SetLocal(
inst_id, EmitAggregateInitializer(context, inst.type_id, inst.elements_id,
"struct.init"));
}
auto HandleStructValue(FunctionContext& context, SemIR::InstId inst_id,
SemIR::StructValue inst) -> void {
if (auto fn_type = context.sem_ir().types().TryGetAs<SemIR::FunctionType>(
inst.type_id)) {
context.SetLocal(inst_id, context.GetFunction(fn_type->function_id));
return;
}
context.SetLocal(
inst_id, EmitAggregateValueRepr(context, inst.type_id, inst.elements_id));
}
auto HandleStructTypeField(FunctionContext& /*context*/,
SemIR::InstId /*inst_id*/,
SemIR::StructTypeField /*inst*/) -> void {
// No action to take.
}
auto HandleTupleAccess(FunctionContext& context, SemIR::InstId inst_id,
SemIR::TupleAccess inst) -> void {
context.SetLocal(inst_id,
GetAggregateElement(context, inst.tuple_id, inst.index,
inst.type_id, "tuple.elem"));
}
auto HandleTupleIndex(FunctionContext& context, SemIR::InstId inst_id,
SemIR::TupleIndex inst) -> void {
auto index_inst =
context.sem_ir().insts().GetAs<SemIR::IntLiteral>(inst.index_id);
auto index = context.sem_ir().ints().Get(index_inst.int_id).getZExtValue();
context.SetLocal(inst_id, GetAggregateElement(context, inst.tuple_id,
SemIR::ElementIndex(index),
inst.type_id, "tuple.index"));
}
auto HandleTupleLiteral(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/,
SemIR::TupleLiteral /*inst*/) -> void {
// A TupleLiteral should always be converted to a TupleInit or TupleValue if
// its value is needed.
}
auto HandleTupleInit(FunctionContext& context, SemIR::InstId inst_id,
SemIR::TupleInit inst) -> void {
context.SetLocal(
inst_id, EmitAggregateInitializer(context, inst.type_id, inst.elements_id,
"tuple.init"));
}
auto HandleTupleValue(FunctionContext& context, SemIR::InstId inst_id,
SemIR::TupleValue inst) -> void {
context.SetLocal(
inst_id, EmitAggregateValueRepr(context, inst.type_id, inst.elements_id));
}
} // namespace Carbon::Lower