Files
carbon-lang/toolchain/check/full_pattern_stack.cpp
T
Geoff Romer 1a3966d2c4 Build VarStorage insts more efficiently. (#7422)
Instead of traversing the entire pattern block looking for
`VarPattern`s, we keep track of them on creation, and then build
`VarStorage`s directly from that list.

This also gets rid of the global `var_storage_map`, and instead keep
that information narrowly scoped to each full-pattern, and consume it in
a single linear traversal instead of with random-access lookups. To
enable that, this fixes a parse bug where nested `var` patterns were
getting diagnosed but not marked as errors.
2026-06-26 22:26:13 +00:00

59 lines
2.3 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 "toolchain/check/full_pattern_stack.h"
#include "toolchain/check/context.h"
#include "toolchain/check/pattern.h"
namespace Carbon::Check {
auto FullPatternStack::StartPatternInitializer() -> void {
CARBON_CHECK(kind_stack_.back() == Kind::ClassScopeVarDecl ||
kind_stack_.back() == Kind::NameBindingDecl);
for (auto& [name_id, inst_id] : bind_name_stack_.PeekArray()) {
CARBON_CHECK(
inst_id == SemIR::InstId::InitTombstone,
"stashing the lookup result would overwrite an existing stash {0}",
inst_id);
auto& lookup_result = lookup_->Get(name_id);
if (!lookup_result.empty()) {
// Temporarily overwrite the result of name lookup for this binding to be
// `InitTombstone`, so that references to it in the initializer are
// diagnosed as errors. The original result of name lookup is stashed in
// `bind_name_stack_` so we can restore it later.
//
// TODO: find a way to preserve location information, so that we can
// provide good diagnostics for a redeclaration of `name_id` in
// the initializer, if that becomes possible.
std::swap(lookup_result.back().inst_id, inst_id);
}
}
}
auto FullPatternStack::EndPatternInitializer() -> void {
for (auto& [name_id, inst_id] : bind_name_stack_.PeekArray()) {
auto& lookup_result = lookup_->Get(name_id);
if (!lookup_result.empty()) {
// Restore the original result of name lookup for this binding.
std::swap(lookup_result.back().inst_id, inst_id);
}
CARBON_CHECK(inst_id == SemIR::InstId::InitTombstone,
"name_id resolved to a non-tombstone value {0} during "
"initializer handling",
inst_id);
}
}
auto FullPatternStack::BuildLocalVarStorage(Context& context,
bool is_returned_var) -> void {
for (auto& var_info : var_pattern_stack_.PeekArray()) {
var_info.storage_id =
GetOrAddVarStorage(context, var_info.pattern_id, is_returned_var);
}
next_var_index_stack_.back() = 0;
}
} // namespace Carbon::Check