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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->GetNumChildren() != 1)
return LLDB_INVALID_ADDRESS;
ValueObjectSP ptr_sp(valobj_sp->GetChildAtIndex(0, true));
if (!ptr_sp)
return LLDB_INVALID_ADDRESS;
if (!ptr_sp->GetCompilerType().IsPointerType())
return LLDB_INVALID_ADDRESS;
AddressType addr_type;
lldb::addr_t frame_ptr_addr = ptr_sp->GetPointerValue(&addr_type);
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();
}
static CompilerType InferPromiseType(Function &destroy_func) {
Block &block = destroy_func.GetBlock(true);
auto variable_list = block.GetBlockVariableList(true);
// clang generates an artificial `__promise` variable inside the
// `destroy` function. Look for it.
auto promise_var = variable_list->FindVariable(ConstString("__promise"));
if (!promise_var)
return {};
if (!promise_var->IsArtificial())
return {};
Type *promise_type = promise_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;
size_t lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEnd::
CalculateNumChildren() {
if (!m_resume_ptr_sp || !m_destroy_ptr_sp)
return 0;
return m_promise_ptr_sp ? 3 : 2;
}
lldb::ValueObjectSP lldb_private::formatters::
StdlibCoroutineHandleSyntheticFrontEnd::GetChildAtIndex(size_t idx) {
switch (idx) {
case 0:
return m_resume_ptr_sp;
case 1:
return m_destroy_ptr_sp;
case 2:
return m_promise_ptr_sp;
}
return lldb::ValueObjectSP();
}
bool lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEnd::
Update() {
m_resume_ptr_sp.reset();
m_destroy_ptr_sp.reset();
m_promise_ptr_sp.reset();
ValueObjectSP valobj_sp = m_backend.GetNonSyntheticValue();
if (!valobj_sp)
return false;
lldb::addr_t frame_ptr_addr = GetCoroFramePtrFromHandle(valobj_sp);
if (frame_ptr_addr == 0 || frame_ptr_addr == LLDB_INVALID_ADDRESS)
return false;
auto ts = valobj_sp->GetCompilerType().GetTypeSystem();
auto ast_ctx = ts.dyn_cast_or_null<TypeSystemClang>();
if (!ast_ctx)
return false;
// Create the `resume` and `destroy` children.
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();
CompilerType void_type = ast_ctx->GetBasicType(lldb::eBasicTypeVoid);
CompilerType coro_func_type = ast_ctx->CreateFunctionType(
/*result_type=*/void_type, /*args=*/&void_type, /*num_args=*/1,
/*is_variadic=*/false, /*qualifiers=*/0);
CompilerType coro_func_ptr_type = coro_func_type.GetPointerType();
m_resume_ptr_sp = CreateValueObjectFromAddress(
"resume", frame_ptr_addr + 0 * ptr_size, exe_ctx, coro_func_ptr_type);
lldbassert(m_resume_ptr_sp);
m_destroy_ptr_sp = CreateValueObjectFromAddress(
"destroy", frame_ptr_addr + 1 * ptr_size, exe_ctx, coro_func_ptr_type);
lldbassert(m_destroy_ptr_sp);
// Get the `promise_type` from the template argument
CompilerType promise_type(
valobj_sp->GetCompilerType().GetTypeTemplateArgument(0));
if (!promise_type)
return false;
// Try to infer the promise_type if it was type-erased
if (promise_type.IsVoidType()) {
if (Function *destroy_func =
ExtractDestroyFunction(target_sp, frame_ptr_addr)) {
if (CompilerType inferred_type = InferPromiseType(*destroy_func)) {
promise_type = inferred_type;
}
}
}
// If we don't know the promise type, we don't display the `promise` member.
// `CreateValueObjectFromAddress` below would fail for `void` types.
if (promise_type.IsVoidType()) {
return false;
}
// Add the `promise` member. We intentionally add `promise` as a pointer type
// instead of a value type, and don't automatically dereference this pointer.
// We do so to avoid potential very deep recursion in case there is a cycle
// formed between `std::coroutine_handle`s and their promises.
lldb::ValueObjectSP promise = CreateValueObjectFromAddress(
"promise", frame_ptr_addr + 2 * ptr_size, exe_ctx, promise_type);
Status error;
lldb::ValueObjectSP promisePtr = promise->AddressOf(error);
if (error.Success())
m_promise_ptr_sp = promisePtr->Clone(ConstString("promise"));
return false;
}
bool lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEnd::
MightHaveChildren() {
return true;
}
size_t StdlibCoroutineHandleSyntheticFrontEnd::GetIndexOfChildWithName(
ConstString name) {
if (!m_resume_ptr_sp || !m_destroy_ptr_sp)
return UINT32_MAX;
if (name == ConstString("resume"))
return 0;
if (name == ConstString("destroy"))
return 1;
if (name == ConstString("promise_ptr") && m_promise_ptr_sp)
return 2;
return UINT32_MAX;
}
SyntheticChildrenFrontEnd *
lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEndCreator(
CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
return (valobj_sp ? new StdlibCoroutineHandleSyntheticFrontEnd(valobj_sp)
: nullptr);
}
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