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//===-- Coroutines.cpp ----------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "Coroutines.h"
#include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Symbol/VariableList.h"
using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::formatters;
static lldb::addr_t GetCoroFramePtrFromHandle(ValueObjectSP valobj_sp) {
if (!valobj_sp)
return LLDB_INVALID_ADDRESS;
// We expect a single pointer in the `coroutine_handle` class.
// We don't care about its name.
if (valobj_sp->GetNumChildrenIgnoringErrors() != 1)
return LLDB_INVALID_ADDRESS;
ValueObjectSP ptr_sp(valobj_sp->GetChildAtIndex(0));
if (!ptr_sp)
return LLDB_INVALID_ADDRESS;
if (!ptr_sp->GetCompilerType().IsPointerType())
return LLDB_INVALID_ADDRESS;
auto [frame_ptr_addr, addr_type] = ptr_sp->GetPointerValue();
if (!frame_ptr_addr || frame_ptr_addr == LLDB_INVALID_ADDRESS)
return LLDB_INVALID_ADDRESS;
lldbassert(addr_type == AddressType::eAddressTypeLoad);
if (addr_type != AddressType::eAddressTypeLoad)
return LLDB_INVALID_ADDRESS;
return frame_ptr_addr;
}
static Function *ExtractDestroyFunction(lldb::TargetSP target_sp,
lldb::addr_t frame_ptr_addr) {
lldb::ProcessSP process_sp = target_sp->GetProcessSP();
auto ptr_size = process_sp->GetAddressByteSize();
Status error;
auto destroy_func_ptr_addr = frame_ptr_addr + ptr_size;
lldb::addr_t destroy_func_addr =
process_sp->ReadPointerFromMemory(destroy_func_ptr_addr, error);
if (error.Fail())
return nullptr;
Address destroy_func_address;
if (!target_sp->ResolveLoadAddress(destroy_func_addr, destroy_func_address))
return nullptr;
return destroy_func_address.CalculateSymbolContextFunction();
}
// clang generates aritifical `__promise` and `__coro_frame` variables inside
// the destroy function. Look for those variables and extract their type.
static CompilerType InferArtificialCoroType(Function *destroy_func,
ConstString var_name) {
if (!destroy_func)
return {};
Block &block = destroy_func->GetBlock(true);
auto variable_list = block.GetBlockVariableList(true);
auto var = variable_list->FindVariable(var_name);
if (!var)
return {};
if (!var->IsArtificial())
return {};
Type *promise_type = var->GetType();
if (!promise_type)
return {};
return promise_type->GetForwardCompilerType();
}
bool lldb_private::formatters::StdlibCoroutineHandleSummaryProvider(
ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
lldb::addr_t frame_ptr_addr =
GetCoroFramePtrFromHandle(valobj.GetNonSyntheticValue());
if (frame_ptr_addr == LLDB_INVALID_ADDRESS)
return false;
if (frame_ptr_addr == 0) {
stream << "nullptr";
} else {
stream.Printf("coro frame = 0x%" PRIx64, frame_ptr_addr);
}
return true;
}
lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEnd::
StdlibCoroutineHandleSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
: SyntheticChildrenFrontEnd(*valobj_sp) {
if (valobj_sp)
Update();
}
lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEnd::
~StdlibCoroutineHandleSyntheticFrontEnd() = default;
llvm::Expected<uint32_t> lldb_private::formatters::
StdlibCoroutineHandleSyntheticFrontEnd::CalculateNumChildren() {
return m_children.size();
}
lldb::ValueObjectSP lldb_private::formatters::
StdlibCoroutineHandleSyntheticFrontEnd::GetChildAtIndex(uint32_t idx) {
return idx < m_children.size() ? m_children[idx] : lldb::ValueObjectSP();
}
lldb::ChildCacheState
lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEnd::Update() {
m_children.clear();
ValueObjectSP valobj_sp = m_backend.GetNonSyntheticValue();
if (!valobj_sp)
return lldb::ChildCacheState::eRefetch;
lldb::addr_t frame_ptr_addr = GetCoroFramePtrFromHandle(valobj_sp);
if (frame_ptr_addr == 0 || frame_ptr_addr == LLDB_INVALID_ADDRESS)
return lldb::ChildCacheState::eRefetch;
lldb::TargetSP target_sp = m_backend.GetTargetSP();
auto &exe_ctx = m_backend.GetExecutionContextRef();
lldb::ProcessSP process_sp = target_sp->GetProcessSP();
auto ptr_size = process_sp->GetAddressByteSize();
auto ast_ctx = valobj_sp->GetCompilerType().GetTypeSystem<TypeSystemClang>();
if (!ast_ctx)
return lldb::ChildCacheState::eRefetch;
// Determine the coroutine frame type and the promise type. Fall back
// to `void`, since even the pointer itself might be useful, even if the
// type inference failed.
Function *destroy_func = ExtractDestroyFunction(target_sp, frame_ptr_addr);
CompilerType void_type = ast_ctx->GetBasicType(lldb::eBasicTypeVoid);
CompilerType promise_type;
if (CompilerType template_arg =
valobj_sp->GetCompilerType().GetTypeTemplateArgument(0))
promise_type = std::move(template_arg);
if (promise_type.IsVoidType()) {
// Try to infer the promise_type if it was type-erased
if (destroy_func) {
if (CompilerType inferred_type =
InferArtificialCoroType(destroy_func, ConstString("__promise"))) {
promise_type = inferred_type;
}
}
}
CompilerType coro_frame_type =
InferArtificialCoroType(destroy_func, ConstString("__coro_frame"));
if (!coro_frame_type)
coro_frame_type = void_type;
// Create the `resume` and `destroy` children.
std::array<CompilerType, 1> args{coro_frame_type};
CompilerType coro_func_type = ast_ctx->CreateFunctionType(
/*result_type=*/void_type, args,
/*is_variadic=*/false, /*qualifiers=*/0);
CompilerType coro_func_ptr_type = coro_func_type.GetPointerType();
ValueObjectSP resume_ptr_sp = CreateValueObjectFromAddress(
"resume", frame_ptr_addr + 0 * ptr_size, exe_ctx, coro_func_ptr_type);
assert(resume_ptr_sp);
m_children.push_back(std::move(resume_ptr_sp));
ValueObjectSP destroy_ptr_sp = CreateValueObjectFromAddress(
"destroy", frame_ptr_addr + 1 * ptr_size, exe_ctx, coro_func_ptr_type);
assert(destroy_ptr_sp);
m_children.push_back(std::move(destroy_ptr_sp));
// Add promise and coro_frame
// Add the `promise` and `coro_frame` member. We intentionally add them as
// pointer types instead of a value type, and don't automatically dereference
// those pointers. We do so to avoid potential very deep recursion in case
// there is a cycle formed between `std::coroutine_handle`s and their
// promises.
ValueObjectSP promise_ptr_sp = CreateValueObjectFromAddress(
"promise", frame_ptr_addr + 2 * ptr_size, exe_ctx,
promise_type.GetPointerType(), /*do_deref=*/false);
m_children.push_back(std::move(promise_ptr_sp));
ValueObjectSP coroframe_ptr_sp = CreateValueObjectFromAddress(
"coro_frame", frame_ptr_addr, exe_ctx, coro_frame_type.GetPointerType(),
/*do_deref=*/false);
m_children.push_back(std::move(coroframe_ptr_sp));
return lldb::ChildCacheState::eRefetch;
}
llvm::Expected<size_t>
StdlibCoroutineHandleSyntheticFrontEnd::GetIndexOfChildWithName(
ConstString name) {
for (const auto &[idx, child_sp] : llvm::enumerate(m_children)) {
if (child_sp->GetName() == name)
return idx;
}
return llvm::createStringError("Type has no child named '%s'",
name.AsCString());
}
SyntheticChildrenFrontEnd *
lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEndCreator(
CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
return (valobj_sp ? new StdlibCoroutineHandleSyntheticFrontEnd(valobj_sp)
: nullptr);
}
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