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b138c90c9e4c4f84fa6cfeaf27792d3b5160d715
carbon-lang/toolchain/check/context.cpp
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Richard Smith b138c90c9e Use constant evaluation to determine the identity of types. (#3617) 
Remove the type canonicalization mechanism and instead rely on constant
canonicalization to deduplicate types.

Rename the `Canonicalize*Type` functions to reflect that they're no
longer performing canonicalization. Switch code that creates types due
to semantic checking, rather than due to source syntax, to directly
create type constants through evaluation rather than creating an
instruction and evaluating it to produce a separate constant
representation.

The mapping from `const (const T)` that was previously performed by type
canonicalization is now implemented in expression evaluation instead.

The value `<error>` is now treated as a constant value, with a special
property that an instruction involving `<error>` that could possibly be
constant evaluates to `<error>`. This helps avoid producing follow-on
errors when an error occurs as a subexpression of an expression, such as
a type, that is intended to be constant.
2024-01-19 00:47:37 +00:00

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// 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 "toolchain/check/context.h"
#include <string>
#include <utility>
#include "common/check.h"
#include "common/vlog.h"
#include "llvm/ADT/Sequence.h"
#include "toolchain/check/decl_name_stack.h"
#include "toolchain/check/eval.h"
#include "toolchain/check/inst_block_stack.h"
#include "toolchain/lex/tokenized_buffer.h"
#include "toolchain/parse/node_kind.h"
#include "toolchain/sem_ir/file.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/inst.h"
#include "toolchain/sem_ir/inst_kind.h"
#include "toolchain/sem_ir/typed_insts.h"
#include "toolchain/sem_ir/value_stores.h"
namespace Carbon::Check {
Context::Context(const Lex::TokenizedBuffer& tokens, DiagnosticEmitter& emitter,
const Parse::Tree& parse_tree, SemIR::File& sem_ir,
llvm::raw_ostream* vlog_stream)
: tokens_(&tokens),
emitter_(&emitter),
parse_tree_(&parse_tree),
sem_ir_(&sem_ir),
vlog_stream_(vlog_stream),
node_stack_(parse_tree, vlog_stream),
inst_block_stack_("inst_block_stack_", sem_ir, vlog_stream),
params_or_args_stack_("params_or_args_stack_", sem_ir, vlog_stream),
args_type_info_stack_("args_type_info_stack_", sem_ir, vlog_stream),
decl_name_stack_(this),
lexical_lookup_(sem_ir_->identifiers()) {
// Map the builtin `<error>` and `type` type constants to their corresponding
// special `TypeId` values.
type_ids_for_type_constants_.insert(
{SemIR::ConstantId::ForTemplateConstant(SemIR::InstId::BuiltinError),
SemIR::TypeId::Error});
type_ids_for_type_constants_.insert(
{SemIR::ConstantId::ForTemplateConstant(SemIR::InstId::BuiltinTypeType),
SemIR::TypeId::TypeType});
}
auto Context::TODO(Parse::NodeId parse_node, std::string label) -> bool {
CARBON_DIAGNOSTIC(SemanticsTodo, Error, "Semantics TODO: `{0}`.",
std::string);
emitter_->Emit(parse_node, SemanticsTodo, std::move(label));
return false;
}
auto Context::VerifyOnFinish() -> void {
// Information in all the various context objects should be cleaned up as
// various pieces of context go out of scope. At this point, nothing should
// remain.
// node_stack_ will still contain top-level entities.
CARBON_CHECK(scope_stack_.empty()) << scope_stack_.size();
CARBON_CHECK(inst_block_stack_.empty()) << inst_block_stack_.size();
CARBON_CHECK(params_or_args_stack_.empty()) << params_or_args_stack_.size();
}
auto Context::AddInstInNoBlock(SemIR::ParseNodeAndInst parse_node_and_inst)
-> SemIR::InstId {
auto inst_id = sem_ir().insts().AddInNoBlock(parse_node_and_inst);
CARBON_VLOG() << "AddInst: " << parse_node_and_inst.inst << "\n";
auto const_id = TryEvalInst(*this, inst_id, parse_node_and_inst.inst);
if (const_id.is_constant()) {
CARBON_VLOG() << "Constant: " << parse_node_and_inst.inst << " -> "
<< const_id.inst_id() << "\n";
constant_values().Set(inst_id, const_id);
}
return inst_id;
}
auto Context::AddInst(SemIR::ParseNodeAndInst parse_node_and_inst)
-> SemIR::InstId {
auto inst_id = AddInstInNoBlock(parse_node_and_inst);
inst_block_stack_.AddInstId(inst_id);
return inst_id;
}
auto Context::AddPlaceholderInstInNoBlock(
SemIR::ParseNodeAndInst parse_node_and_inst) -> SemIR::InstId {
auto inst_id = sem_ir().insts().AddInNoBlock(parse_node_and_inst);
CARBON_VLOG() << "AddPlaceholderInst: " << parse_node_and_inst.inst << "\n";
return inst_id;
}
auto Context::AddPlaceholderInst(SemIR::ParseNodeAndInst parse_node_and_inst)
-> SemIR::InstId {
auto inst_id = AddPlaceholderInstInNoBlock(parse_node_and_inst);
inst_block_stack_.AddInstId(inst_id);
return inst_id;
}
auto Context::AddConstant(SemIR::Inst inst, bool is_symbolic)
-> SemIR::ConstantId {
auto [inst_id, added] = constants().GetOrAdd(inst);
auto const_id = is_symbolic ? SemIR::ConstantId::ForSymbolicConstant(inst_id)
: SemIR::ConstantId::ForTemplateConstant(inst_id);
if (added) {
// TODO: Should `ConstantStore` do this for us?
constant_values().Set(inst_id, const_id);
}
CARBON_VLOG() << "AddConstantInst: " << inst << "\n";
return const_id;
}
auto Context::AddInstAndPush(SemIR::ParseNodeAndInst parse_node_and_inst)
-> void {
auto inst_id = AddInst(parse_node_and_inst);
node_stack_.Push(parse_node_and_inst.parse_node, inst_id);
}
auto Context::ReplaceInstBeforeConstantUse(
SemIR::InstId inst_id, SemIR::ParseNodeAndInst parse_node_and_inst)
-> void {
sem_ir().insts().Set(inst_id, parse_node_and_inst);
CARBON_VLOG() << "ReplaceInst: " << inst_id << " -> "
<< parse_node_and_inst.inst << "\n";
// Redo evaluation. This is only safe to do if this instruction has not
// already been used as a constant, which is the caller's responsibility to
// ensure.
auto const_id = TryEvalInst(*this, inst_id, parse_node_and_inst.inst);
if (const_id.is_constant()) {
CARBON_VLOG() << "Constant: " << parse_node_and_inst.inst << " -> "
<< const_id.inst_id() << "\n";
}
constant_values().Set(inst_id, const_id);
}
auto Context::DiagnoseDuplicateName(SemIR::InstId dup_def_id,
SemIR::InstId prev_def_id) -> void {
CARBON_DIAGNOSTIC(NameDeclDuplicate, Error,
"Duplicate name being declared in the same scope.");
CARBON_DIAGNOSTIC(NameDeclPrevious, Note,
"Name is previously declared here.");
emitter_->Build(dup_def_id, NameDeclDuplicate)
.Note(prev_def_id, NameDeclPrevious)
.Emit();
}
auto Context::DiagnoseNameNotFound(Parse::NodeId parse_node,
SemIR::NameId name_id) -> void {
CARBON_DIAGNOSTIC(NameNotFound, Error, "Name `{0}` not found.", std::string);
emitter_->Emit(parse_node, NameNotFound, names().GetFormatted(name_id).str());
}
auto Context::NoteIncompleteClass(SemIR::ClassId class_id,
DiagnosticBuilder& builder) -> void {
CARBON_DIAGNOSTIC(ClassForwardDeclaredHere, Note,
"Class was forward declared here.");
CARBON_DIAGNOSTIC(ClassIncompleteWithinDefinition, Note,
"Class is incomplete within its definition.");
const auto& class_info = classes().Get(class_id);
CARBON_CHECK(!class_info.is_defined()) << "Class is not incomplete";
if (class_info.definition_id.is_valid()) {
builder.Note(class_info.definition_id, ClassIncompleteWithinDefinition);
} else {
builder.Note(class_info.decl_id, ClassForwardDeclaredHere);
}
}
auto Context::AddPackageImports(Parse::NodeId import_node,
IdentifierId package_id,
llvm::ArrayRef<const SemIR::File*> sem_irs,
bool has_load_error) -> void {
CARBON_CHECK(has_load_error || !sem_irs.empty())
<< "There should be either a load error or at least one IR.";
auto name_id = SemIR::NameId::ForIdentifier(package_id);
SemIR::CrossRefIRId first_id(cross_ref_irs().size());
for (const auto* sem_ir : sem_irs) {
cross_ref_irs().Add(sem_ir);
}
if (has_load_error) {
cross_ref_irs().Add(nullptr);
}
SemIR::CrossRefIRId last_id(cross_ref_irs().size() - 1);
auto type_id = GetBuiltinType(SemIR::BuiltinKind::NamespaceType);
auto inst_id =
AddInst({import_node, SemIR::Import{.type_id = type_id,
.first_cross_ref_ir_id = first_id,
.last_cross_ref_ir_id = last_id}});
// Add the import to lookup. Should always succeed because imports will be
// uniquely named.
AddNameToLookup(name_id, inst_id);
// Add a name for formatted output. This isn't used in name lookup in order
// to reduce indirection, but it's separate from the Import because it
// otherwise fits in an Inst.
auto bind_name_id = bind_names().Add(
{.name_id = name_id, .enclosing_scope_id = SemIR::NameScopeId::Package});
AddInst({import_node, SemIR::BindName{.type_id = type_id,
.bind_name_id = bind_name_id,
.value_id = inst_id}});
}
auto Context::AddNameToLookup(SemIR::NameId name_id, SemIR::InstId target_id)
-> void {
if (current_scope().names.insert(name_id).second) {
// TODO: Reject if we previously performed a failed lookup for this name in
// this scope or a scope nested within it.
auto& lexical_results = lexical_lookup_.Get(name_id);
CARBON_CHECK(lexical_results.empty() ||
lexical_results.back().scope_index < current_scope_index())
<< "Failed to clean up after scope nested within the current scope";
lexical_results.push_back(
{.inst_id = target_id, .scope_index = current_scope_index()});
} else {
DiagnoseDuplicateName(target_id,
lexical_lookup_.Get(name_id).back().inst_id);
}
}
auto Context::ResolveIfLazyImportRef(SemIR::InstId inst_id) -> void {
auto inst = insts().Get(inst_id);
auto lazy_inst = inst.TryAs<SemIR::LazyImportRef>();
if (!lazy_inst) {
return;
}
const SemIR::File& import_ir = *cross_ref_irs().Get(lazy_inst->ir_id);
auto import_inst = import_ir.insts().Get(lazy_inst->inst_id);
switch (import_inst.kind()) {
case SemIR::InstKind::FunctionDecl: {
// TODO: Fill this in better.
auto function_id =
functions().Add({.name_id = SemIR::NameId::Invalid,
.enclosing_scope_id = SemIR::NameScopeId::Invalid,
.decl_id = inst_id,
.implicit_param_refs_id = SemIR::InstBlockId::Empty,
.param_refs_id = SemIR::InstBlockId::Empty,
.return_type_id = SemIR::TypeId::Invalid,
.return_slot_id = SemIR::InstId::Invalid});
ReplaceInstBeforeConstantUse(
inst_id,
// TODO: For diagnostic purposes, we should provide some form of
// location for the function.
{Parse::NodeId::Invalid,
SemIR::FunctionDecl{GetBuiltinType(SemIR::BuiltinKind::FunctionType),
function_id}});
constant_values().Set(inst_id,
SemIR::ConstantId::ForTemplateConstant(inst_id));
break;
}
default:
// TODO: We need more type support. For now we inject an arbitrary
// invalid node that's unrelated to the underlying value. The TODO
// diagnostic is used since this section shouldn't typically be able to
// error.
TODO(Parse::NodeId::Invalid,
(llvm::Twine("TODO: support ") + import_inst.kind().name()).str());
ReplaceInstBeforeConstantUse(
inst_id, {Parse::NodeId::Invalid,
SemIR::VarStorage{SemIR::TypeId::Error,
SemIR::NameId::PackageNamespace}});
break;
}
}
auto Context::LookupNameInDecl(Parse::NodeId /*parse_node*/,
SemIR::NameId name_id,
SemIR::NameScopeId scope_id) -> SemIR::InstId {
if (!scope_id.is_valid()) {
// Look for a name in the current scope only. There are two cases where the
// name would be in an outer scope:
//
// - The name is the sole component of the declared name:
//
// class A;
// fn F() {
// class A;
// }
//
// In this case, the inner A is not the same class as the outer A, so
// lookup should not find the outer A.
//
// - The name is a qualifier of some larger declared name:
//
// class A { class B; }
// fn F() {
// class A.B {}
// }
//
// In this case, we're not in the correct scope to define a member of
// class A, so we should reject, and we achieve this by not finding the
// name A from the outer scope.
auto& lexical_results = lexical_lookup_.Get(name_id);
if (!lexical_results.empty()) {
auto result = lexical_results.back();
if (result.scope_index == current_scope_index()) {
ResolveIfLazyImportRef(result.inst_id);
return result.inst_id;
}
}
return SemIR::InstId::Invalid;
} else {
// We do not look into `extend`ed scopes here. A qualified name in a
// declaration must specify the exact scope in which the name was originally
// introduced:
//
// base class A { fn F(); }
// class B { extend base: A; }
//
// // Error, no `F` in `B`.
// fn B.F() {}
return LookupNameInExactScope(name_id, name_scopes().Get(scope_id));
}
}
auto Context::LookupUnqualifiedName(Parse::NodeId parse_node,
SemIR::NameId name_id) -> SemIR::InstId {
// TODO: Check for shadowed lookup results.
// Find the results from enclosing lexical scopes. These will be combined with
// results from non-lexical scopes such as namespaces and classes.
llvm::ArrayRef<LexicalLookup::Result> lexical_results =
lexical_lookup_.Get(name_id);
// Walk the non-lexical scopes and perform lookups into each of them.
for (auto [index, name_scope_id] : llvm::reverse(non_lexical_scope_stack_)) {
// If the innermost lexical result is within this non-lexical scope, then
// it shadows all further non-lexical results and we're done.
if (!lexical_results.empty() &&
lexical_results.back().scope_index > index) {
auto inst_id = lexical_results.back().inst_id;
ResolveIfLazyImportRef(inst_id);
return inst_id;
}
if (auto non_lexical_result =
LookupQualifiedName(parse_node, name_id, name_scope_id,
/*required=*/false);
non_lexical_result.is_valid()) {
return non_lexical_result;
}
}
if (!lexical_results.empty()) {
auto inst_id = lexical_results.back().inst_id;
ResolveIfLazyImportRef(inst_id);
return inst_id;
}
// We didn't find anything at all.
if (!lexical_lookup_has_load_error_) {
DiagnoseNameNotFound(parse_node, name_id);
}
return SemIR::InstId::BuiltinError;
}
auto Context::LookupNameInExactScope(SemIR::NameId name_id,
const SemIR::NameScope& scope)
-> SemIR::InstId {
if (auto it = scope.names.find(name_id); it != scope.names.end()) {
ResolveIfLazyImportRef(it->second);
return it->second;
}
return SemIR::InstId::Invalid;
}
auto Context::LookupQualifiedName(Parse::NodeId parse_node,
SemIR::NameId name_id,
SemIR::NameScopeId scope_id, bool required)
-> SemIR::InstId {
llvm::SmallVector<SemIR::NameScopeId> scope_ids = {scope_id};
auto result_id = SemIR::InstId::Invalid;
bool has_error = false;
// Walk this scope and, if nothing is found here, the scopes it extends.
while (!scope_ids.empty()) {
const auto& scope = name_scopes().Get(scope_ids.pop_back_val());
has_error |= scope.has_error;
auto scope_result_id = LookupNameInExactScope(name_id, scope);
if (!scope_result_id.is_valid()) {
// Nothing found in this scope: also look in its extended scopes.
auto extended = llvm::reverse(scope.extended_scopes);
scope_ids.append(extended.begin(), extended.end());
continue;
}
// If this is our second lookup result, diagnose an ambiguity.
if (result_id.is_valid()) {
// TODO: This is currently not reachable because the only scope that can
// extend is a class scope, and it can only extend a single base class.
// Add test coverage once this is possible.
CARBON_DIAGNOSTIC(
NameAmbiguousDueToExtend, Error,
"Ambiguous use of name `{0}` found in multiple extended scopes.",
std::string);
emitter_->Emit(parse_node, NameAmbiguousDueToExtend,
names().GetFormatted(name_id).str());
// TODO: Add notes pointing to the scopes.
return SemIR::InstId::BuiltinError;
}
result_id = scope_result_id;
}
if (required && !result_id.is_valid()) {
if (!has_error) {
DiagnoseNameNotFound(parse_node, name_id);
}
return SemIR::InstId::BuiltinError;
}
return result_id;
}
auto Context::PushScope(SemIR::InstId scope_inst_id,
SemIR::NameScopeId scope_id,
bool lexical_lookup_has_load_error) -> void {
scope_stack_.push_back(
{.index = next_scope_index_,
.scope_inst_id = scope_inst_id,
.scope_id = scope_id,
.prev_lexical_lookup_has_load_error = lexical_lookup_has_load_error_});
if (scope_id.is_valid()) {
non_lexical_scope_stack_.push_back({next_scope_index_, scope_id});
}
lexical_lookup_has_load_error_ |= lexical_lookup_has_load_error;
// TODO: Handle this case more gracefully.
CARBON_CHECK(next_scope_index_.index != std::numeric_limits<int32_t>::max())
<< "Ran out of scopes";
++next_scope_index_.index;
}
auto Context::PopScope() -> void {
auto scope = scope_stack_.pop_back_val();
lexical_lookup_has_load_error_ = scope.prev_lexical_lookup_has_load_error;
for (const auto& str_id : scope.names) {
auto& lexical_results = lexical_lookup_.Get(str_id);
CARBON_CHECK(lexical_results.back().scope_index == scope.index)
<< "Inconsistent scope index for name " << names().GetFormatted(str_id);
lexical_results.pop_back();
}
if (scope.scope_id.is_valid()) {
CARBON_CHECK(non_lexical_scope_stack_.back().first == scope.index);
non_lexical_scope_stack_.pop_back();
}
if (scope.has_returned_var) {
CARBON_CHECK(!return_scope_stack_.empty());
CARBON_CHECK(return_scope_stack_.back().returned_var.is_valid());
return_scope_stack_.back().returned_var = SemIR::InstId::Invalid;
}
}
auto Context::PopToScope(ScopeIndex index) -> void {
while (current_scope_index() > index) {
PopScope();
}
CARBON_CHECK(current_scope_index() == index)
<< "Scope index " << index << " does not enclose the current scope "
<< current_scope_index();
}
auto Context::SetReturnedVarOrGetExisting(SemIR::InstId inst_id)
-> SemIR::InstId {
CARBON_CHECK(!return_scope_stack_.empty()) << "`returned var` in no function";
auto& returned_var = return_scope_stack_.back().returned_var;
if (returned_var.is_valid()) {
return returned_var;
}
returned_var = inst_id;
CARBON_CHECK(!current_scope().has_returned_var)
<< "Scope has returned var but none is set";
if (inst_id.is_valid()) {
current_scope().has_returned_var = true;
}
return SemIR::InstId::Invalid;
}
template <typename BranchNode, typename... Args>
static auto AddDominatedBlockAndBranchImpl(Context& context,
Parse::NodeId parse_node,
Args... args) -> SemIR::InstBlockId {
if (!context.inst_block_stack().is_current_block_reachable()) {
return SemIR::InstBlockId::Unreachable;
}
auto block_id = context.inst_blocks().AddDefaultValue();
context.AddInst({parse_node, BranchNode{block_id, args...}});
return block_id;
}
auto Context::AddDominatedBlockAndBranch(Parse::NodeId parse_node)
-> SemIR::InstBlockId {
return AddDominatedBlockAndBranchImpl<SemIR::Branch>(*this, parse_node);
}
auto Context::AddDominatedBlockAndBranchWithArg(Parse::NodeId parse_node,
SemIR::InstId arg_id)
-> SemIR::InstBlockId {
return AddDominatedBlockAndBranchImpl<SemIR::BranchWithArg>(*this, parse_node,
arg_id);
}
auto Context::AddDominatedBlockAndBranchIf(Parse::NodeId parse_node,
SemIR::InstId cond_id)
-> SemIR::InstBlockId {
return AddDominatedBlockAndBranchImpl<SemIR::BranchIf>(*this, parse_node,
cond_id);
}
auto Context::AddConvergenceBlockAndPush(Parse::NodeId parse_node,
int num_blocks) -> void {
CARBON_CHECK(num_blocks >= 2) << "no convergence";
SemIR::InstBlockId new_block_id = SemIR::InstBlockId::Unreachable;
for ([[maybe_unused]] auto _ : llvm::seq(num_blocks)) {
if (inst_block_stack().is_current_block_reachable()) {
if (new_block_id == SemIR::InstBlockId::Unreachable) {
new_block_id = inst_blocks().AddDefaultValue();
}
AddInst({parse_node, SemIR::Branch{new_block_id}});
}
inst_block_stack().Pop();
}
inst_block_stack().Push(new_block_id);
}
auto Context::AddConvergenceBlockWithArgAndPush(
Parse::NodeId parse_node, std::initializer_list<SemIR::InstId> block_args)
-> SemIR::InstId {
CARBON_CHECK(block_args.size() >= 2) << "no convergence";
SemIR::InstBlockId new_block_id = SemIR::InstBlockId::Unreachable;
for (auto arg_id : block_args) {
if (inst_block_stack().is_current_block_reachable()) {
if (new_block_id == SemIR::InstBlockId::Unreachable) {
new_block_id = inst_blocks().AddDefaultValue();
}
AddInst({parse_node, SemIR::BranchWithArg{new_block_id, arg_id}});
}
inst_block_stack().Pop();
}
inst_block_stack().Push(new_block_id);
// Acquire the result value.
SemIR::TypeId result_type_id = insts().Get(*block_args.begin()).type_id();
return AddInst({parse_node, SemIR::BlockArg{result_type_id, new_block_id}});
}
// Add the current code block to the enclosing function.
auto Context::AddCurrentCodeBlockToFunction(Parse::NodeId parse_node) -> void {
CARBON_CHECK(!inst_block_stack().empty()) << "no current code block";
if (return_scope_stack().empty()) {
CARBON_CHECK(parse_node.is_valid())
<< "No current function, but parse_node not provided";
TODO(parse_node,
"Control flow expressions are currently only supported inside "
"functions.");
return;
}
if (!inst_block_stack().is_current_block_reachable()) {
// Don't include unreachable blocks in the function.
return;
}
auto function_id =
insts()
.GetAs<SemIR::FunctionDecl>(return_scope_stack().back().decl_id)
.function_id;
functions()
.Get(function_id)
.body_block_ids.push_back(inst_block_stack().PeekOrAdd());
}
auto Context::is_current_position_reachable() -> bool {
if (!inst_block_stack().is_current_block_reachable()) {
return false;
}
// Our current position is at the end of a reachable block. That position is
// reachable unless the previous instruction is a terminator instruction.
auto block_contents = inst_block_stack().PeekCurrentBlockContents();
if (block_contents.empty()) {
return true;
}
const auto& last_inst = insts().Get(block_contents.back());
return last_inst.kind().terminator_kind() !=
SemIR::TerminatorKind::Terminator;
}
auto Context::ParamOrArgStart() -> void { params_or_args_stack_.Push(); }
auto Context::ParamOrArgComma() -> void {
ParamOrArgSave(node_stack_.PopExpr());
}
auto Context::ParamOrArgEndNoPop(Parse::NodeKind start_kind) -> void {
if (!node_stack_.PeekIs(start_kind)) {
ParamOrArgSave(node_stack_.PopExpr());
}
}
auto Context::ParamOrArgPop() -> SemIR::InstBlockId {
return params_or_args_stack_.Pop();
}
auto Context::ParamOrArgEnd(Parse::NodeKind start_kind) -> SemIR::InstBlockId {
ParamOrArgEndNoPop(start_kind);
return ParamOrArgPop();
}
namespace {
// Worklist-based type completion mechanism.
//
// When attempting to complete a type, we may find other types that also need to
// be completed: types nested within that type, and the value representation of
// the type. In order to complete a type without recursing arbitrarily deeply,
// we use a worklist of tasks:
//
// - An `AddNestedIncompleteTypes` step adds a task for all incomplete types
// nested within a type to the work list.
// - A `BuildValueRepr` step computes the value representation for a
// type, once all of its nested types are complete, and marks the type as
// complete.
class TypeCompleter {
public:
TypeCompleter(
Context& context,
std::optional<llvm::function_ref<auto()->Context::DiagnosticBuilder>>
diagnoser)
: context_(context), diagnoser_(diagnoser) {}
// Attempts to complete the given type. Returns true if it is now complete,
// false if it could not be completed.
auto Complete(SemIR::TypeId type_id) -> bool {
Push(type_id);
while (!work_list_.empty()) {
if (!ProcessStep()) {
return false;
}
}
return true;
}
private:
// Adds `type_id` to the work list, if it's not already complete.
auto Push(SemIR::TypeId type_id) -> void {
if (!context_.types().IsComplete(type_id)) {
work_list_.push_back({type_id, Phase::AddNestedIncompleteTypes});
}
}
// Runs the next step.
auto ProcessStep() -> bool {
auto [type_id, phase] = work_list_.back();
// We might have enqueued the same type more than once. Just skip the
// type if it's already complete.
if (context_.types().IsComplete(type_id)) {
work_list_.pop_back();
return true;
}
auto inst_id = context_.types().GetInstId(type_id);
auto inst = context_.insts().Get(inst_id);
auto old_work_list_size = work_list_.size();
switch (phase) {
case Phase::AddNestedIncompleteTypes:
if (!AddNestedIncompleteTypes(inst)) {
return false;
}
CARBON_CHECK(work_list_.size() >= old_work_list_size)
<< "AddNestedIncompleteTypes should not remove work items";
work_list_[old_work_list_size - 1].phase = Phase::BuildValueRepr;
break;
case Phase::BuildValueRepr: {
auto value_rep = BuildValueRepr(type_id, inst);
context_.sem_ir().CompleteType(type_id, value_rep);
CARBON_CHECK(old_work_list_size == work_list_.size())
<< "BuildValueRepr should not change work items";
work_list_.pop_back();
// Also complete the value representation type, if necessary. This
// should never fail: the value representation shouldn't require any
// additional nested types to be complete.
if (!context_.types().IsComplete(value_rep.type_id)) {
work_list_.push_back({value_rep.type_id, Phase::BuildValueRepr});
}
// For a pointer representation, the pointee also needs to be complete.
if (value_rep.kind == SemIR::ValueRepr::Pointer) {
auto pointee_type_id =
context_.sem_ir().GetPointeeType(value_rep.type_id);
if (!context_.types().IsComplete(pointee_type_id)) {
work_list_.push_back({pointee_type_id, Phase::BuildValueRepr});
}
}
break;
}
}
return true;
}
// Adds any types nested within `type_inst` that need to be complete for
// `type_inst` to be complete to our work list.
auto AddNestedIncompleteTypes(SemIR::Inst type_inst) -> bool {
switch (type_inst.kind()) {
case SemIR::ArrayType::Kind:
Push(type_inst.As<SemIR::ArrayType>().element_type_id);
break;
case SemIR::StructType::Kind:
for (auto field_id : context_.inst_blocks().Get(
type_inst.As<SemIR::StructType>().fields_id)) {
Push(context_.insts()
.GetAs<SemIR::StructTypeField>(field_id)
.field_type_id);
}
break;
case SemIR::TupleType::Kind:
for (auto element_type_id : context_.type_blocks().Get(
type_inst.As<SemIR::TupleType>().elements_id)) {
Push(element_type_id);
}
break;
case SemIR::ClassType::Kind: {
auto class_type = type_inst.As<SemIR::ClassType>();
auto& class_info = context_.classes().Get(class_type.class_id);
if (!class_info.is_defined()) {
if (diagnoser_) {
auto builder = (*diagnoser_)();
context_.NoteIncompleteClass(class_type.class_id, builder);
builder.Emit();
}
return false;
}
Push(class_info.object_repr_id);
break;
}
case SemIR::ConstType::Kind:
Push(type_inst.As<SemIR::ConstType>().inner_id);
break;
default:
break;
}
return true;
}
// Makes an empty value representation, which is used for types that have no
// state, such as empty structs and tuples.
auto MakeEmptyValueRepr() const -> SemIR::ValueRepr {
return {.kind = SemIR::ValueRepr::None,
.type_id = context_.GetTupleType({})};
}
// Makes a value representation that uses pass-by-copy, copying the given
// type.
auto MakeCopyValueRepr(SemIR::TypeId rep_id,
SemIR::ValueRepr::AggregateKind aggregate_kind =
SemIR::ValueRepr::NotAggregate) const
-> SemIR::ValueRepr {
return {.kind = SemIR::ValueRepr::Copy,
.aggregate_kind = aggregate_kind,
.type_id = rep_id};
}
// Makes a value representation that uses pass-by-address with the given
// pointee type.
auto MakePointerValueRepr(SemIR::TypeId pointee_id,
SemIR::ValueRepr::AggregateKind aggregate_kind =
SemIR::ValueRepr::NotAggregate) const
-> SemIR::ValueRepr {
// TODO: Should we add `const` qualification to `pointee_id`?
return {.kind = SemIR::ValueRepr::Pointer,
.aggregate_kind = aggregate_kind,
.type_id = context_.GetPointerType(pointee_id)};
}
// Gets the value representation of a nested type, which should already be
// complete.
auto GetNestedValueRepr(SemIR::TypeId nested_type_id) const {
CARBON_CHECK(context_.types().IsComplete(nested_type_id))
<< "Nested type should already be complete";
auto value_rep = context_.types().GetValueRepr(nested_type_id);
CARBON_CHECK(value_rep.kind != SemIR::ValueRepr::Unknown)
<< "Complete type should have a value representation";
return value_rep;
};
auto BuildCrossRefValueRepr(SemIR::TypeId type_id, SemIR::CrossRef xref) const
-> SemIR::ValueRepr {
auto xref_inst =
context_.cross_ref_irs().Get(xref.ir_id)->insts().Get(xref.inst_id);
// The canonical description of a type should only have cross-references
// for entities owned by another File, such as builtins, which are owned
// by the prelude, and named entities like classes and interfaces, which
// we don't support yet.
CARBON_CHECK(xref_inst.kind() == SemIR::Builtin::Kind)
<< "TODO: Handle other kinds of inst cross-references";
// clang warns on unhandled enum values; clang-tidy is incorrect here.
// NOLINTNEXTLINE(bugprone-switch-missing-default-case)
switch (xref_inst.As<SemIR::Builtin>().builtin_kind) {
case SemIR::BuiltinKind::TypeType:
case SemIR::BuiltinKind::Error:
case SemIR::BuiltinKind::Invalid:
case SemIR::BuiltinKind::BoolType:
case SemIR::BuiltinKind::IntType:
case SemIR::BuiltinKind::FloatType:
case SemIR::BuiltinKind::NamespaceType:
case SemIR::BuiltinKind::FunctionType:
case SemIR::BuiltinKind::BoundMethodType:
return MakeCopyValueRepr(type_id);
case SemIR::BuiltinKind::StringType:
// TODO: Decide on string value semantics. This should probably be a
// custom value representation carrying a pointer and size or
// similar.
return MakePointerValueRepr(type_id);
}
llvm_unreachable("All builtin kinds were handled above");
}
auto BuildStructOrTupleValueRepr(std::size_t num_elements,
SemIR::TypeId elementwise_rep,
bool same_as_object_rep) const
-> SemIR::ValueRepr {
SemIR::ValueRepr::AggregateKind aggregate_kind =
same_as_object_rep ? SemIR::ValueRepr::ValueAndObjectAggregate
: SemIR::ValueRepr::ValueAggregate;
if (num_elements == 1) {
// The value representation for a struct or tuple with a single element
// is a struct or tuple containing the value representation of the
// element.
// TODO: Consider doing the same whenever `elementwise_rep` is
// sufficiently small.
return MakeCopyValueRepr(elementwise_rep, aggregate_kind);
}
// For a struct or tuple with multiple fields, we use a pointer
// to the elementwise value representation.
return MakePointerValueRepr(elementwise_rep, aggregate_kind);
}
auto BuildStructTypeValueRepr(SemIR::TypeId type_id,
SemIR::StructType struct_type) const
-> SemIR::ValueRepr {
// TODO: Share more code with tuples.
auto fields = context_.inst_blocks().Get(struct_type.fields_id);
if (fields.empty()) {
return MakeEmptyValueRepr();
}
// Find the value representation for each field, and construct a struct
// of value representations.
llvm::SmallVector<SemIR::InstId> value_rep_fields;
value_rep_fields.reserve(fields.size());
bool same_as_object_rep = true;
for (auto field_id : fields) {
auto field = context_.insts().GetAs<SemIR::StructTypeField>(field_id);
auto field_value_rep = GetNestedValueRepr(field.field_type_id);
if (field_value_rep.type_id != field.field_type_id) {
same_as_object_rep = false;
field.field_type_id = field_value_rep.type_id;
// TODO: Use `TryEvalInst` to form this value.
field_id = context_
.AddConstant(field, context_.constant_values()
.Get(context_.types().GetInstId(
field.field_type_id))
.is_symbolic())
.inst_id();
}
value_rep_fields.push_back(field_id);
}
auto value_rep = same_as_object_rep
? type_id
: context_.GetStructType(
context_.inst_blocks().Add(value_rep_fields));
return BuildStructOrTupleValueRepr(fields.size(), value_rep,
same_as_object_rep);
}
auto BuildTupleTypeValueRepr(SemIR::TypeId type_id,
SemIR::TupleType tuple_type) const
-> SemIR::ValueRepr {
// TODO: Share more code with structs.
auto elements = context_.type_blocks().Get(tuple_type.elements_id);
if (elements.empty()) {
return MakeEmptyValueRepr();
}
// Find the value representation for each element, and construct a tuple
// of value representations.
llvm::SmallVector<SemIR::TypeId> value_rep_elements;
value_rep_elements.reserve(elements.size());
bool same_as_object_rep = true;
for (auto element_type_id : elements) {
auto element_value_rep = GetNestedValueRepr(element_type_id);
if (element_value_rep.type_id != element_type_id) {
same_as_object_rep = false;
}
value_rep_elements.push_back(element_value_rep.type_id);
}
auto value_rep = same_as_object_rep
? type_id
: context_.GetTupleType(value_rep_elements);
return BuildStructOrTupleValueRepr(elements.size(), value_rep,
same_as_object_rep);
}
// Builds and returns the value representation for the given type. All nested
// types, as found by AddNestedIncompleteTypes, are known to be complete.
auto BuildValueRepr(SemIR::TypeId type_id, SemIR::Inst inst) const
-> SemIR::ValueRepr {
// TODO: This can emit new SemIR instructions. Consider emitting them into a
// dedicated file-scope instruction block where possible, or somewhere else
// that better reflects the definition of the type, rather than wherever the
// type happens to first be required to be complete.
// clang warns on unhandled enum values; clang-tidy is incorrect here.
// NOLINTNEXTLINE(bugprone-switch-missing-default-case)
switch (inst.kind()) {
case SemIR::AddrOf::Kind:
case SemIR::AddrPattern::Kind:
case SemIR::ArrayIndex::Kind:
case SemIR::ArrayInit::Kind:
case SemIR::Assign::Kind:
case SemIR::BaseDecl::Kind:
case SemIR::BindName::Kind:
case SemIR::BindValue::Kind:
case SemIR::BlockArg::Kind:
case SemIR::BoolLiteral::Kind:
case SemIR::BoundMethod::Kind:
case SemIR::Branch::Kind:
case SemIR::BranchIf::Kind:
case SemIR::BranchWithArg::Kind:
case SemIR::Call::Kind:
case SemIR::ClassDecl::Kind:
case SemIR::ClassElementAccess::Kind:
case SemIR::ClassInit::Kind:
case SemIR::Converted::Kind:
case SemIR::Deref::Kind:
case SemIR::FieldDecl::Kind:
case SemIR::FunctionDecl::Kind:
case SemIR::Import::Kind:
case SemIR::InitializeFrom::Kind:
case SemIR::InterfaceDecl::Kind:
case SemIR::IntLiteral::Kind:
case SemIR::LazyImportRef::Kind:
case SemIR::NameRef::Kind:
case SemIR::Namespace::Kind:
case SemIR::Param::Kind:
case SemIR::RealLiteral::Kind:
case SemIR::Return::Kind:
case SemIR::ReturnExpr::Kind:
case SemIR::SpliceBlock::Kind:
case SemIR::StringLiteral::Kind:
case SemIR::StructAccess::Kind:
case SemIR::StructTypeField::Kind:
case SemIR::StructLiteral::Kind:
case SemIR::StructInit::Kind:
case SemIR::StructValue::Kind:
case SemIR::Temporary::Kind:
case SemIR::TemporaryStorage::Kind:
case SemIR::TupleAccess::Kind:
case SemIR::TupleIndex::Kind:
case SemIR::TupleLiteral::Kind:
case SemIR::TupleInit::Kind:
case SemIR::TupleValue::Kind:
case SemIR::UnaryOperatorNot::Kind:
case SemIR::ValueAsRef::Kind:
case SemIR::ValueOfInitializer::Kind:
case SemIR::VarStorage::Kind:
CARBON_FATAL() << "Type refers to non-type inst " << inst;
case SemIR::CrossRef::Kind:
return BuildCrossRefValueRepr(type_id, inst.As<SemIR::CrossRef>());
case SemIR::ArrayType::Kind: {
// For arrays, it's convenient to always use a pointer representation,
// even when the array has zero or one element, in order to support
// indexing.
return MakePointerValueRepr(type_id, SemIR::ValueRepr::ObjectAggregate);
}
case SemIR::StructType::Kind:
return BuildStructTypeValueRepr(type_id, inst.As<SemIR::StructType>());
case SemIR::TupleType::Kind:
return BuildTupleTypeValueRepr(type_id, inst.As<SemIR::TupleType>());
case SemIR::ClassType::Kind:
// The value representation for a class is a pointer to the object
// representation.
// TODO: Support customized value representations for classes.
// TODO: Pick a better value representation when possible.
return MakePointerValueRepr(
context_.classes()
.Get(inst.As<SemIR::ClassType>().class_id)
.object_repr_id,
SemIR::ValueRepr::ObjectAggregate);
case SemIR::Builtin::Kind:
CARBON_FATAL() << "Builtins should be named as cross-references";
case SemIR::BindSymbolicName::Kind:
case SemIR::PointerType::Kind:
case SemIR::UnboundElementType::Kind:
return MakeCopyValueRepr(type_id);
case SemIR::ConstType::Kind:
// The value representation of `const T` is the same as that of `T`.
// Objects are not modifiable through their value representations.
return GetNestedValueRepr(inst.As<SemIR::ConstType>().inner_id);
}
}
enum class Phase : int8_t {
// The next step is to add nested types to the list of types to complete.
AddNestedIncompleteTypes,
// The next step is to build the value representation for the type.
BuildValueRepr,
};
struct WorkItem {
SemIR::TypeId type_id;
Phase phase;
};
Context& context_;
llvm::SmallVector<WorkItem> work_list_;
std::optional<llvm::function_ref<auto()->Context::DiagnosticBuilder>>
diagnoser_;
};
} // namespace
auto Context::TryToCompleteType(
SemIR::TypeId type_id,
std::optional<llvm::function_ref<auto()->DiagnosticBuilder>> diagnoser)
-> bool {
return TypeCompleter(*this, diagnoser).Complete(type_id);
}
auto Context::GetTypeIdForTypeConstant(SemIR::ConstantId constant_id)
-> SemIR::TypeId {
CARBON_CHECK(constant_id.is_constant()) << "Canonicalizing non-constant type";
auto [it, added] = type_ids_for_type_constants_.insert(
{constant_id, SemIR::TypeId::Invalid});
if (added) {
// TODO: Store the full `constant_id` on the TypeInfo.
it->second = types().Add({.inst_id = constant_id.inst_id()});
}
return it->second;
}
template <typename InstT, typename... EachArgT>
static auto GetTypeImpl(Context& context, EachArgT... each_arg)
-> SemIR::TypeId {
// TODO: Remove inst_id parameter from TryEvalInst.
return context.GetTypeIdForTypeConstant(
TryEvalInst(context, SemIR::InstId::Invalid,
InstT{SemIR::TypeId::TypeType, each_arg...}));
}
auto Context::GetStructType(SemIR::InstBlockId refs_id) -> SemIR::TypeId {
return GetTypeImpl<SemIR::StructType>(*this, refs_id);
}
auto Context::GetTupleType(llvm::ArrayRef<SemIR::TypeId> type_ids)
-> SemIR::TypeId {
// TODO: Deduplicate the type block here. Currently requesting the same tuple
// type more than once will create multiple type blocks, all but one of which
// is unused.
return GetTypeImpl<SemIR::TupleType>(*this, type_blocks().Add(type_ids));
}
auto Context::GetBuiltinType(SemIR::BuiltinKind kind) -> SemIR::TypeId {
CARBON_CHECK(kind != SemIR::BuiltinKind::Invalid);
auto type_id = GetTypeIdForTypeConstant(
constant_values().Get(SemIR::InstId::ForBuiltin(kind)));
// To keep client code simpler, complete builtin types before returning them.
bool complete = TryToCompleteType(type_id);
CARBON_CHECK(complete) << "Failed to complete builtin type";
return type_id;
}
auto Context::GetClassType(SemIR::ClassId class_id) -> SemIR::TypeId {
return GetTypeImpl<SemIR::ClassType>(*this, class_id);
}
auto Context::GetPointerType(SemIR::TypeId pointee_type_id) -> SemIR::TypeId {
return GetTypeImpl<SemIR::PointerType>(*this, pointee_type_id);
}
auto Context::GetUnboundElementType(SemIR::TypeId class_type_id,
SemIR::TypeId element_type_id)
-> SemIR::TypeId {
return GetTypeImpl<SemIR::UnboundElementType>(*this, class_type_id,
element_type_id);
}
auto Context::GetUnqualifiedType(SemIR::TypeId type_id) -> SemIR::TypeId {
if (auto const_type = types().TryGetAs<SemIR::ConstType>(type_id)) {
return const_type->inner_id;
}
return type_id;
}
auto Context::PrintForStackDump(llvm::raw_ostream& output) const -> void {
node_stack_.PrintForStackDump(output);
inst_block_stack_.PrintForStackDump(output);
params_or_args_stack_.PrintForStackDump(output);
args_type_info_stack_.PrintForStackDump(output);
}
} // namespace Carbon::Check
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