[Lldb-commits] [lldb] [LLDB] Add formatters for MSVC STL std::vector (PR #147538)

[via lldb-commits]

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@@ -0,0 +1,295 @@
+//===-- MsvcStlVector.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 "MsvcStl.h"
+
+#include "lldb/DataFormatters/FormattersHelpers.h"
+#include "lldb/DataFormatters/TypeSynthetic.h"
+
+using namespace lldb;
+
+namespace lldb_private {
+namespace formatters {
+
+class MsvcStlVectorSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  MsvcStlVectorSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
+
+  llvm::Expected<uint32_t> CalculateNumChildren() override;
+
+  lldb::ValueObjectSP GetChildAtIndex(uint32_t idx) override;
+
+  lldb::ChildCacheState Update() override;
+
+  llvm::Expected<size_t> GetIndexOfChildWithName(ConstString name) override;
+
+private:
+  ValueObject *m_start = nullptr;
+  ValueObject *m_finish = nullptr;
+  CompilerType m_element_type;
+  uint32_t m_element_size = 0;
+};
+
+class MsvcStlVectorBoolSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  MsvcStlVectorBoolSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
+
+  llvm::Expected<uint32_t> CalculateNumChildren() override;
+
+  lldb::ValueObjectSP GetChildAtIndex(uint32_t idx) override;
+
+  lldb::ChildCacheState Update() override;
+
+  llvm::Expected<size_t> GetIndexOfChildWithName(ConstString name) override;
+
+private:
+  CompilerType m_bool_type;
+  ExecutionContextRef m_exe_ctx_ref;
+  uint64_t m_count = 0;
+  uint64_t m_element_bit_size = 0;
+  lldb::addr_t m_base_data_address = 0;
+  std::map<size_t, lldb::ValueObjectSP> m_children;
+};
+
+} // namespace formatters
+} // namespace lldb_private
+
+lldb_private::formatters::MsvcStlVectorSyntheticFrontEnd::
+    MsvcStlVectorSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
+    : SyntheticChildrenFrontEnd(*valobj_sp), m_element_type() {
+  if (valobj_sp)
+    Update();
+}
+
+llvm::Expected<uint32_t> lldb_private::formatters::
+    MsvcStlVectorSyntheticFrontEnd::CalculateNumChildren() {
+  if (!m_start || !m_finish)
+    return llvm::createStringError(
+        "Failed to determine start/end of vector data.");
+
+  uint64_t start_val = m_start->GetValueAsUnsigned(0);
+  uint64_t finish_val = m_finish->GetValueAsUnsigned(0);
+
+  // A default-initialized empty vector.
+  if (start_val == 0 && finish_val == 0)
+    return 0;
+
+  if (start_val == 0)
+    return llvm::createStringError("Invalid value for start of vector.");
+
+  if (finish_val == 0)
+    return llvm::createStringError("Invalid value for end of vector.");
+
+  if (start_val > finish_val)
+    return llvm::createStringError(
+        "Start of vector data begins after end pointer.");
+
+  size_t num_children = (finish_val - start_val);
+  if (num_children % m_element_size)
+    return llvm::createStringError("Size not multiple of element size.");
+
+  return num_children / m_element_size;
+}
+
+lldb::ValueObjectSP
+lldb_private::formatters::MsvcStlVectorSyntheticFrontEnd::GetChildAtIndex(
+    uint32_t idx) {
+  if (!m_start || !m_finish)
+    return lldb::ValueObjectSP();
+
+  uint64_t offset = idx * m_element_size;
+  offset = offset + m_start->GetValueAsUnsigned(0);
+  StreamString name;
+  name.Printf("[%" PRIu64 "]", (uint64_t)idx);
+  return CreateValueObjectFromAddress(name.GetString(), offset,
+                                      m_backend.GetExecutionContextRef(),
+                                      m_element_type);
+}
+
+lldb::ChildCacheState
+lldb_private::formatters::MsvcStlVectorSyntheticFrontEnd::Update() {
+  m_start = m_finish = nullptr;
+  ValueObjectSP data_sp(m_backend.GetChildAtNamePath({"_Mypair", "_Myval2"}));
+
+  if (!data_sp)
+    return lldb::ChildCacheState::eRefetch;
+
+  m_start = data_sp->GetChildMemberWithName("_Myfirst").get();
+  m_finish = data_sp->GetChildMemberWithName("_Mylast").get();
+  if (!m_start || !m_finish)
+    return lldb::ChildCacheState::eRefetch;
+
+  m_element_type = m_start->GetCompilerType().GetPointeeType();
+  llvm::Expected<uint64_t> size_or_err = m_element_type.GetByteSize(nullptr);
+  if (size_or_err)
+    m_element_size = *size_or_err;
+  else
+    LLDB_LOG_ERRORV(GetLog(LLDBLog::DataFormatters), size_or_err.takeError(),
+                    "{0}");
+
+  return lldb::ChildCacheState::eRefetch;
+}
+
+llvm::Expected<size_t> lldb_private::formatters::
+    MsvcStlVectorSyntheticFrontEnd::GetIndexOfChildWithName(ConstString name) {
+  if (!m_start || !m_finish)
+    return llvm::createStringError("Type has no child named '%s'",
+                                   name.AsCString());
+  auto optional_idx = ExtractIndexFromString(name.GetCString());
+  if (!optional_idx) {
+    return llvm::createStringError("Type has no child named '%s'",
+                                   name.AsCString());
+  }
+  return *optional_idx;
+}
+
+lldb_private::formatters::MsvcStlVectorBoolSyntheticFrontEnd::
+    MsvcStlVectorBoolSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
+    : SyntheticChildrenFrontEnd(*valobj_sp), m_bool_type(), m_exe_ctx_ref(),
+      m_children() {
+  if (valobj_sp) {
+    Update();
+    m_bool_type =
+        valobj_sp->GetCompilerType().GetBasicTypeFromAST(lldb::eBasicTypeBool);
+  }
+}
+
+llvm::Expected<uint32_t> lldb_private::formatters::
+    MsvcStlVectorBoolSyntheticFrontEnd::CalculateNumChildren() {
+  return m_count;
+}
+
+lldb::ValueObjectSP
+lldb_private::formatters::MsvcStlVectorBoolSyntheticFrontEnd::GetChildAtIndex(
+    uint32_t idx) {
+  auto iter = m_children.find(idx), end = m_children.end();
+  if (iter != end)
+    return iter->second;
+  if (idx >= m_count)
+    return {};
+  if (m_base_data_address == 0 || m_count == 0)
+    return {};
+  if (!m_bool_type)
+    return {};
+
+  // The vector<bool> is represented as a sequence of `int`s.
+  // The size of an `int` is in `m_element_bit_size` (most often 32b).
+  // To access the element at index `i`:
+  // (bool)((data_address[i / bit_size] >> (i % bit_size)) & 1)
+
+  // int *byte_location = &data_address[i / bit_size]
+  size_t byte_idx = (idx / m_element_bit_size) * (m_element_bit_size / 8);
+  lldb::addr_t byte_location = m_base_data_address + byte_idx;
+
+  ProcessSP process_sp(m_exe_ctx_ref.GetProcessSP());
+  if (!process_sp)
+    return {};
+  Status err;
+  Scalar scalar;
+  size_t bytes_read = process_sp->ReadScalarIntegerFromMemory(
+      byte_location, m_element_bit_size / 8, false, scalar, err);
+  if (err.Fail() || bytes_read == 0 || !scalar.IsValid())
+    return {};
+
+  size_t bit_index = idx % m_element_bit_size;
+  bool bit_set = scalar.GetAPSInt()[bit_index];
+  std::optional<uint64_t> size =
+      llvm::expectedToOptional(m_bool_type.GetByteSize(nullptr));
+  if (!size)
+    return {};
+  WritableDataBufferSP buffer_sp(new DataBufferHeap(*size, 0));
+  if (bit_set && buffer_sp && buffer_sp->GetBytes()) {
+    // regardless of endianness, anything non-zero is true
+    *(buffer_sp->GetBytes()) = 1;
+  }
+  StreamString name;
+  name.Printf("[%" PRIu64 "]", (uint64_t)idx);
+  ValueObjectSP retval_sp(CreateValueObjectFromData(
+      name.GetString(),
+      DataExtractor(buffer_sp, process_sp->GetByteOrder(),
+                    process_sp->GetAddressByteSize()),
+      m_exe_ctx_ref, m_bool_type));
+  if (retval_sp)
+    m_children[idx] = retval_sp;
+  return retval_sp;
+}
+
+lldb::ChildCacheState
+lldb_private::formatters::MsvcStlVectorBoolSyntheticFrontEnd::Update() {
+  m_children.clear();
+  ValueObjectSP valobj_sp = m_backend.GetSP();
+  if (!valobj_sp)
+    return lldb::ChildCacheState::eRefetch;
+  m_exe_ctx_ref = valobj_sp->GetExecutionContextRef();
+
+  ValueObjectSP size_sp = valobj_sp->GetChildMemberWithName("_Mysize");
+  if (!size_sp)
+    return lldb::ChildCacheState::eRefetch;
+  m_count = size_sp->GetValueAsUnsigned(0);
+  if (!m_count)
+    return lldb::ChildCacheState::eReuse;
+
+  ValueObjectSP begin_sp(valobj_sp->GetChildAtNamePath(
+      {"_Myvec", "_Mypair", "_Myval2", "_Myfirst"}));
+  if (!begin_sp) {
+    m_count = 0;
+    return lldb::ChildCacheState::eRefetch;
+  }
+
+  // FIXME: the STL exposes _EEN_VBITS as a constant - it should be used instead
+  CompilerType begin_ty = begin_sp->GetCompilerType().GetPointeeType();
+  if (!begin_ty.IsValid())
+    return lldb::ChildCacheState::eRefetch;
+  llvm::Expected<uint64_t> bit_size = begin_ty.GetBitSize(nullptr);
+  if (!bit_size)
+    return lldb::ChildCacheState::eRefetch;
+  m_element_bit_size = *bit_size;
+
+  m_base_data_address = begin_sp->GetValueAsUnsigned(0);
+  if (!m_base_data_address) {
+    m_count = 0;
+    return lldb::ChildCacheState::eRefetch;
+  }
+  return lldb::ChildCacheState::eRefetch;
+}
+
+llvm::Expected<size_t>
+lldb_private::formatters::MsvcStlVectorBoolSyntheticFrontEnd::
+    GetIndexOfChildWithName(ConstString name) {
+  if (!m_count || !m_base_data_address)
+    return llvm::createStringError("Type has no child named '%s'",
+                                   name.AsCString());
+  auto optional_idx = ExtractIndexFromString(name.AsCString());
+  if (!optional_idx) {
+    return llvm::createStringError("Type has no child named '%s'",
+                                   name.AsCString());
+  }
+  uint32_t idx = *optional_idx;
+  if (idx >= CalculateNumChildrenIgnoringErrors())
+    return llvm::createStringError("Type has no child named '%s'",
+                                   name.AsCString());
+  return idx;
+}
+
+lldb_private::SyntheticChildrenFrontEnd *
+lldb_private::formatters::MsvcStlVectorSyntheticFrontEndCreator(
+    lldb::ValueObjectSP valobj_sp) {
+  CompilerType type = valobj_sp->GetCompilerType();
+  if (!type.IsValid())
+    return nullptr;
+
+  std::vector<uint32_t> indexes;
+  // vector<T>
+  if (type.GetIndexOfChildMemberWithName("_Mypair", true, indexes) > 0)
+    return new MsvcStlVectorSyntheticFrontEnd(valobj_sp);
+  // vector<bool>
+  if (type.GetIndexOfChildMemberWithName("_Myvec", true, indexes) > 0)
----------------
Nerixyz wrote:

> Is it because PDB strips template info?

This. I don't know how this is done in DWARF exactly, but my thought was that PDB could use the demangling to add template parameters(?).

https://github.com/llvm/llvm-project/pull/147538