[Lldb-commits] [lldb] 9dca3ac - [lldb][DataFormatter] Simplify libc++ std::map::iterator formatter (#97713)
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Mon Jul 8 07:56:10 PDT 2024
Author: Michael Buch
Date: 2024-07-08T15:56:05+01:00
New Revision: 9dca3ac2efb180398ef8e84bfa9f0ef283d0e6fd
URL: https://github.com/llvm/llvm-project/commit/9dca3ac2efb180398ef8e84bfa9f0ef283d0e6fd
DIFF: https://github.com/llvm/llvm-project/commit/9dca3ac2efb180398ef8e84bfa9f0ef283d0e6fd.diff
LOG: [lldb][DataFormatter] Simplify libc++ std::map::iterator formatter (#97713)
Depends on https://github.com/llvm/llvm-project/pull/97687
Similar to https://github.com/llvm/llvm-project/pull/97579, this patch
simplifies the way in which we retrieve the key/value pair of a
`std::map` (in this case of the `std::map::iterator`).
We do this for the same reason: not only was the old logic hard to
follow, and encoded the libc++ layout in non-obvious ways, it was also
fragile to alignment miscalculations
(https://github.com/llvm/llvm-project/pull/97443); this would break once
the new layout of std::map landed as part of
https://github.com/llvm/llvm-project/issues/93069.
Instead, this patch simply casts the `__iter_pointer` to the
`__node_pointer` and uses a straightforward
`GetChildMemberWithName("__value_")` to get to the key/value we care
about.
We can eventually re-use the core-part of the `std::map` and
`std::map::iterator` formatters. But it will be an easier to change to
review once both simplifications landed.
Added:
Modified:
lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/TestDataFormatterLibccIterator.py
Removed:
################################################################################
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp
index 9fcb9e22bfc38..0fe7fe69244ae 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp
@@ -17,6 +17,7 @@
#include "lldb/Utility/Endian.h"
#include "lldb/Utility/Status.h"
#include "lldb/Utility/Stream.h"
+#include "lldb/lldb-enumerations.h"
#include "lldb/lldb-forward.h"
using namespace lldb;
@@ -223,11 +224,10 @@ class LibCxxMapIteratorSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
size_t GetIndexOfChildWithName(ConstString name) override;
- ~LibCxxMapIteratorSyntheticFrontEnd() override;
+ ~LibCxxMapIteratorSyntheticFrontEnd() override = default;
private:
- ValueObject *m_pair_ptr;
- lldb::ValueObjectSP m_pair_sp;
+ ValueObjectSP m_pair_sp = nullptr;
};
} // namespace formatters
} // namespace lldb_private
@@ -464,7 +464,7 @@ lldb_private::formatters::LibcxxStdMapSyntheticFrontEndCreator(
lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
LibCxxMapIteratorSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
- : SyntheticChildrenFrontEnd(*valobj_sp), m_pair_ptr(), m_pair_sp() {
+ : SyntheticChildrenFrontEnd(*valobj_sp) {
if (valobj_sp)
Update();
}
@@ -472,117 +472,63 @@ lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
lldb::ChildCacheState
lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::Update() {
m_pair_sp.reset();
- m_pair_ptr = nullptr;
ValueObjectSP valobj_sp = m_backend.GetSP();
if (!valobj_sp)
return lldb::ChildCacheState::eRefetch;
TargetSP target_sp(valobj_sp->GetTargetSP());
-
if (!target_sp)
return lldb::ChildCacheState::eRefetch;
- // this must be a ValueObject* because it is a child of the ValueObject we
- // are producing children for it if were a ValueObjectSP, we would end up
- // with a loop (iterator -> synthetic -> child -> parent == iterator) and
- // that would in turn leak memory by never allowing the ValueObjects to die
- // and free their memory
- m_pair_ptr = valobj_sp
- ->GetValueForExpressionPath(
- ".__i_.__ptr_->__value_", nullptr, nullptr,
- ValueObject::GetValueForExpressionPathOptions()
- .DontCheckDotVsArrowSyntax()
- .SetSyntheticChildrenTraversal(
- ValueObject::GetValueForExpressionPathOptions::
- SyntheticChildrenTraversal::None),
- nullptr)
- .get();
-
- if (!m_pair_ptr) {
- m_pair_ptr = valobj_sp
- ->GetValueForExpressionPath(
- ".__i_.__ptr_", nullptr, nullptr,
- ValueObject::GetValueForExpressionPathOptions()
- .DontCheckDotVsArrowSyntax()
- .SetSyntheticChildrenTraversal(
- ValueObject::GetValueForExpressionPathOptions::
- SyntheticChildrenTraversal::None),
- nullptr)
- .get();
- if (m_pair_ptr) {
- auto __i_(valobj_sp->GetChildMemberWithName("__i_"));
- if (!__i_) {
- m_pair_ptr = nullptr;
- return lldb::ChildCacheState::eRefetch;
- }
- CompilerType pair_type(
- __i_->GetCompilerType().GetTypeTemplateArgument(0));
- std::string name;
- uint64_t bit_offset_ptr;
- uint32_t bitfield_bit_size_ptr;
- bool is_bitfield_ptr;
- pair_type = pair_type.GetFieldAtIndex(
- 0, name, &bit_offset_ptr, &bitfield_bit_size_ptr, &is_bitfield_ptr);
- if (!pair_type) {
- m_pair_ptr = nullptr;
- return lldb::ChildCacheState::eRefetch;
- }
+ // m_backend is a std::map::iterator
+ // ...which is a __map_iterator<__tree_iterator<..., __node_pointer, ...>>
+ //
+ // Then, __map_iterator::__i_ is a __tree_iterator
+ auto tree_iter_sp = valobj_sp->GetChildMemberWithName("__i_");
+ if (!tree_iter_sp)
+ return lldb::ChildCacheState::eRefetch;
- auto addr(m_pair_ptr->GetValueAsUnsigned(LLDB_INVALID_ADDRESS));
- m_pair_ptr = nullptr;
- if (addr && addr != LLDB_INVALID_ADDRESS) {
- auto ts = pair_type.GetTypeSystem();
- auto ast_ctx = ts.dyn_cast_or_null<TypeSystemClang>();
- if (!ast_ctx)
- return lldb::ChildCacheState::eRefetch;
-
- // Mimick layout of std::__tree_iterator::__ptr_ and read it in
- // from process memory.
- //
- // The following shows the contiguous block of memory:
- //
- // +-----------------------------+ class __tree_end_node
- // __ptr_ | pointer __left_; |
- // +-----------------------------+ class __tree_node_base
- // | pointer __right_; |
- // | __parent_pointer __parent_; |
- // | bool __is_black_; |
- // +-----------------------------+ class __tree_node
- // | __node_value_type __value_; | <<< our key/value pair
- // +-----------------------------+
- //
- CompilerType tree_node_type = ast_ctx->CreateStructForIdentifier(
- llvm::StringRef(),
- {{"ptr0",
- ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
- {"ptr1",
- ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
- {"ptr2",
- ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
- {"cw", ast_ctx->GetBasicType(lldb::eBasicTypeBool)},
- {"payload", pair_type}});
- std::optional<uint64_t> size = tree_node_type.GetByteSize(nullptr);
- if (!size)
- return lldb::ChildCacheState::eRefetch;
- WritableDataBufferSP buffer_sp(new DataBufferHeap(*size, 0));
- ProcessSP process_sp(target_sp->GetProcessSP());
- Status error;
- process_sp->ReadMemory(addr, buffer_sp->GetBytes(),
- buffer_sp->GetByteSize(), error);
- if (error.Fail())
- return lldb::ChildCacheState::eRefetch;
- DataExtractor extractor(buffer_sp, process_sp->GetByteOrder(),
- process_sp->GetAddressByteSize());
- auto pair_sp = CreateValueObjectFromData(
- "pair", extractor, valobj_sp->GetExecutionContextRef(),
- tree_node_type);
- if (pair_sp)
- m_pair_sp = pair_sp->GetChildAtIndex(4);
- }
- }
+ // Type is __tree_iterator::__node_pointer
+ // (We could alternatively also get this from the template argument)
+ auto node_pointer_type =
+ tree_iter_sp->GetCompilerType().GetDirectNestedTypeWithName(
+ "__node_pointer");
+ if (!node_pointer_type.IsValid())
+ return lldb::ChildCacheState::eRefetch;
+
+ // __ptr_ is a __tree_iterator::__iter_pointer
+ auto iter_pointer_sp = tree_iter_sp->GetChildMemberWithName("__ptr_");
+ if (!iter_pointer_sp)
+ return lldb::ChildCacheState::eRefetch;
+
+ // Cast the __iter_pointer to a __node_pointer (which stores our key/value
+ // pair)
+ auto node_pointer_sp = iter_pointer_sp->Cast(node_pointer_type);
+ if (!node_pointer_sp)
+ return lldb::ChildCacheState::eRefetch;
+
+ auto key_value_sp = node_pointer_sp->GetChildMemberWithName("__value_");
+ if (!key_value_sp)
+ return lldb::ChildCacheState::eRefetch;
+
+ // Create the synthetic child, which is a pair where the key and value can be
+ // retrieved by querying the synthetic frontend for
+ // GetIndexOfChildWithName("first") and GetIndexOfChildWithName("second")
+ // respectively.
+ //
+ // std::map stores the actual key/value pair in value_type::__cc_ (or
+ // previously __cc).
+ key_value_sp = key_value_sp->Clone(ConstString("pair"));
+ if (key_value_sp->GetNumChildrenIgnoringErrors() == 1) {
+ auto child0_sp = key_value_sp->GetChildAtIndex(0);
+ if (child0_sp &&
+ (child0_sp->GetName() == "__cc_" || child0_sp->GetName() == "__cc"))
+ key_value_sp = child0_sp->Clone(ConstString("pair"));
}
+ m_pair_sp = key_value_sp;
+
return lldb::ChildCacheState::eRefetch;
}
@@ -594,11 +540,10 @@ llvm::Expected<uint32_t> lldb_private::formatters::
lldb::ValueObjectSP
lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::GetChildAtIndex(
uint32_t idx) {
- if (m_pair_ptr)
- return m_pair_ptr->GetChildAtIndex(idx);
- if (m_pair_sp)
- return m_pair_sp->GetChildAtIndex(idx);
- return lldb::ValueObjectSP();
+ if (!m_pair_sp)
+ return nullptr;
+
+ return m_pair_sp->GetChildAtIndex(idx);
}
bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
@@ -608,17 +553,10 @@ bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
size_t lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
GetIndexOfChildWithName(ConstString name) {
- if (name == "first")
- return 0;
- if (name == "second")
- return 1;
- return UINT32_MAX;
-}
+ if (!m_pair_sp)
+ return UINT32_MAX;
-lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
- ~LibCxxMapIteratorSyntheticFrontEnd() {
- // this will be deleted when its parent dies (since it's a child object)
- // delete m_pair_ptr;
+ return m_pair_sp->GetIndexOfChildWithName(name);
}
SyntheticChildrenFrontEnd *
diff --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/TestDataFormatterLibccIterator.py b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/TestDataFormatterLibccIterator.py
index efd7128cd6ac7..dd7ac364fea04 100644
--- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/TestDataFormatterLibccIterator.py
+++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/TestDataFormatterLibccIterator.py
@@ -54,9 +54,19 @@ def cleanup():
self.expect("frame variable iimI", substrs=["first = 43981", "second = 61681"])
self.expect("expr iimI", substrs=["first = 43981", "second = 61681"])
+ self.expect("frame variable iimI.first", substrs=["first = 43981"])
+ self.expect("frame variable iimI.first", substrs=["second"], matching=False)
+ self.expect("frame variable iimI.second", substrs=["second = 61681"])
+ self.expect("frame variable iimI.second", substrs=["first"], matching=False)
+
self.expect("frame variable simI", substrs=['first = "world"', "second = 42"])
self.expect("expr simI", substrs=['first = "world"', "second = 42"])
+ self.expect("frame variable simI.first", substrs=['first = "world"'])
+ self.expect("frame variable simI.first", substrs=["second"], matching=False)
+ self.expect("frame variable simI.second", substrs=["second = 42"])
+ self.expect("frame variable simI.second", substrs=["first"], matching=False)
+
self.expect("frame variable svI", substrs=['item = "hello"'])
self.expect("expr svI", substrs=['item = "hello"'])
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