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Implement a short-circuit case for Clang types in GetNumChildren(). #3651

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Merged
merged 1 commit into from
Dec 10, 2021
Merged

Implement a short-circuit case for Clang types in GetNumChildren(). #3651

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42 changes: 27 additions & 15 deletions lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwiftTypeRef.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2462,21 +2462,33 @@ TypeSystemSwiftTypeRef::GetNumChildren(opaque_compiler_type_t type,
LLDB_SCOPED_TIMER();
FALLBACK(GetNumChildren,
(ReconstructType(type), omit_empty_base_classes, exe_ctx));
if (exe_ctx)
if (auto *exe_scope = exe_ctx->GetBestExecutionContextScope())
if (auto *runtime =
SwiftLanguageRuntime::Get(exe_scope->CalculateProcess()))
if (auto num_children =
runtime->GetNumChildren(GetCanonicalType(type), nullptr))
// Use a lambda to intercept and unwrap the `Optional` return value.
// Optional<uint32_t> uses more lax equivalency function.
return [&]() -> llvm::Optional<uint32_t> {
auto impl = [&]() { return num_children; };
VALIDATE_AND_RETURN(
impl, GetNumChildren, type,
(ReconstructType(type), omit_empty_base_classes, exe_ctx),
(ReconstructType(type), omit_empty_base_classes, exe_ctx));
}().getValueOr(0);

auto impl = [&]() -> llvm::Optional<uint32_t> {
if (exe_ctx)
if (auto *exe_scope = exe_ctx->GetBestExecutionContextScope())
if (auto *runtime =
SwiftLanguageRuntime::Get(exe_scope->CalculateProcess()))
return runtime->GetNumChildren(GetCanonicalType(type), nullptr);

if (CompilerType clang_type = GetAsClangTypeOrNull(type)) {
bool is_signed;
// Clang-imported enum types always have one child in Swift.
if (clang_type.IsEnumerationType(is_signed))
return 1;
return clang_type.GetNumChildren(omit_empty_base_classes, exe_ctx);
}
return {};
};
if (llvm::Optional<uint32_t> num_children = impl())
// Use a lambda to intercept and unwrap the `Optional` return value.
// Optional<uint32_t> uses more lax equivalency function.
return [&]() -> llvm::Optional<uint32_t> {
auto impl = [&]() { return num_children; };
VALIDATE_AND_RETURN(
impl, GetNumChildren, type,
(ReconstructType(type), omit_empty_base_classes, exe_ctx),
(ReconstructType(type), omit_empty_base_classes, exe_ctx));
}().getValueOr(0);

LLDB_LOGF(GetLogIfAllCategoriesSet(LIBLLDB_LOG_TYPES),
"Using SwiftASTContext::GetNumChildren fallback for type %s",
Expand Down