[Lldb-commits] [lldb] da827d0 - [lldb][DataFormatter] Simplify std::unordered_map::iterator formatter (#97754)
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lldb-commits at lists.llvm.org
Mon Jul 8 06:39:02 PDT 2024
Author: Michael Buch
Date: 2024-07-08T14:38:58+01:00
New Revision: da827d0896e5e66fe9130f8f4479537d3bbee1da
URL: https://github.com/llvm/llvm-project/commit/da827d0896e5e66fe9130f8f4479537d3bbee1da
DIFF: https://github.com/llvm/llvm-project/commit/da827d0896e5e66fe9130f8f4479537d3bbee1da.diff
LOG: [lldb][DataFormatter] Simplify std::unordered_map::iterator formatter (#97754)
Depends on https://github.com/llvm/llvm-project/pull/97752
This patch changes the way we retrieve the key/value pair in the
`std::unordered_map::iterator` formatter (similar to how we are changing
it for `std::map::iterator` in
https://github.com/llvm/llvm-project/pull/97713, the motivations being
the same).
The old logic was not very easy to follow, and encoded the libc++ layout
in non-obvious ways. But mainly it was also fragile to alignment
miscalculations (https://github.com/llvm/llvm-project/pull/97443); this
would break once the new layout of `std::unordered_map` landed as part
of https://github.com/llvm/llvm-project/issues/93069.
Instead, this patch simply casts the `__hash_iterator` to a
`__node_pointer` (which is what libc++ does too) and uses a
straightforward `GetChildMemberWithName("__value_")` to get to the
key/value we care about.
The `std::unordered_map` already does it this way, so we align the
iterator counterpart to do the same. We can eventually re-use the
core-part of the `std::unordered_map` and `std::unordered_map::iterator`
formatters. But it will be an easier to change to review once both
simplifications landed.
Added:
Modified:
lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/TestDataFormatterLibccIterator.py
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/main.cpp
Removed:
################################################################################
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp
index f5be2f5a5c317..93e7f4f4fd86c 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp
@@ -52,26 +52,6 @@ class LibcxxStdUnorderedMapSyntheticFrontEnd
std::vector<std::pair<ValueObject *, uint64_t>> m_elements_cache;
};
-/// Formats libcxx's std::unordered_map iterators
-///
-/// In raw form a std::unordered_map::iterator is represented as follows:
-///
-/// (lldb) var it --raw --ptr-depth 1
-/// (std::__1::__hash_map_iterator<
-/// std::__1::__hash_iterator<
-/// std::__1::__hash_node<
-/// std::__1::__hash_value_type<
-/// std::__1::basic_string<char, std::__1::char_traits<char>,
-/// std::__1::allocator<char> >, std::__1::basic_string<char,
-/// std::__1::char_traits<char>, std::__1::allocator<char> > >,
-/// void *> *> >)
-/// it = {
-/// __i_ = {
-/// __node_ = 0x0000600001700040 {
-/// __next_ = 0x0000600001704000
-/// }
-/// }
-/// }
class LibCxxUnorderedMapIteratorSyntheticFrontEnd
: public SyntheticChildrenFrontEnd {
public:
@@ -90,9 +70,6 @@ class LibCxxUnorderedMapIteratorSyntheticFrontEnd
size_t GetIndexOfChildWithName(ConstString name) override;
private:
- ValueObject *m_iter_ptr = nullptr; ///< Held, not owned. Child of iterator
- ///< ValueObject supplied at construction.
-
lldb::ValueObjectSP m_pair_sp; ///< ValueObject for the key/value pair
///< that the iterator currently points
///< to.
@@ -304,7 +281,6 @@ lldb_private::formatters::LibCxxUnorderedMapIteratorSyntheticFrontEnd::
lldb::ChildCacheState lldb_private::formatters::
LibCxxUnorderedMapIteratorSyntheticFrontEnd::Update() {
m_pair_sp.reset();
- m_iter_ptr = nullptr;
ValueObjectSP valobj_sp = m_backend.GetSP();
if (!valobj_sp)
@@ -315,98 +291,66 @@ lldb::ChildCacheState lldb_private::formatters::
if (!target_sp)
return lldb::ChildCacheState::eRefetch;
- if (!valobj_sp)
+ // Get the unordered_map::iterator
+ // m_backend is an 'unordered_map::iterator', aka a
+ // '__hash_map_iterator<__hash_table::iterator>'
+ //
+ // __hash_map_iterator::__i_ is a __hash_table::iterator (aka
+ // __hash_iterator<__node_pointer>)
+ auto hash_iter_sp = valobj_sp->GetChildMemberWithName("__i_");
+ if (!hash_iter_sp)
return lldb::ChildCacheState::eRefetch;
- auto exprPathOptions = ValueObject::GetValueForExpressionPathOptions()
- .DontCheckDotVsArrowSyntax()
- .SetSyntheticChildrenTraversal(
- ValueObject::GetValueForExpressionPathOptions::
- SyntheticChildrenTraversal::None);
-
- // 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_iter_ptr =
- valobj_sp
- ->GetValueForExpressionPath(".__i_.__node_", nullptr, nullptr,
- exprPathOptions, nullptr)
- .get();
-
- if (m_iter_ptr) {
- auto iter_child(valobj_sp->GetChildMemberWithName("__i_"));
- if (!iter_child) {
- m_iter_ptr = nullptr;
- return lldb::ChildCacheState::eRefetch;
- }
-
- CompilerType node_type(iter_child->GetCompilerType()
- .GetTypeTemplateArgument(0)
- .GetPointeeType());
-
- CompilerType pair_type(node_type.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_iter_ptr = nullptr;
- return lldb::ChildCacheState::eRefetch;
- }
+ // Type is '__hash_iterator<__node_pointer>'
+ auto hash_iter_type = hash_iter_sp->GetCompilerType();
+ if (!hash_iter_type.IsValid())
+ return lldb::ChildCacheState::eRefetch;
- uint64_t addr = m_iter_ptr->GetValueAsUnsigned(LLDB_INVALID_ADDRESS);
- m_iter_ptr = nullptr;
+ // Type is '__node_pointer'
+ auto node_pointer_type = hash_iter_type.GetTypeTemplateArgument(0);
+ if (!node_pointer_type.IsValid())
+ return lldb::ChildCacheState::eRefetch;
- if (addr == 0 || addr == LLDB_INVALID_ADDRESS)
- return lldb::ChildCacheState::eRefetch;
+ // Cast the __hash_iterator to a __node_pointer (which stores our key/value
+ // pair)
+ auto hash_node_sp = hash_iter_sp->Cast(node_pointer_type);
+ if (!hash_node_sp)
+ return lldb::ChildCacheState::eRefetch;
- auto ts = pair_type.GetTypeSystem();
- auto ast_ctx = ts.dyn_cast_or_null<TypeSystemClang>();
- if (!ast_ctx)
+ auto key_value_sp = hash_node_sp->GetChildMemberWithName("__value_");
+ if (!key_value_sp) {
+ // clang-format off
+ // Since D101206 (ba79fb2e1f), libc++ wraps the `__value_` in an
+ // anonymous union.
+ // Child 0: __hash_node_base base class
+ // Child 1: __hash_
+ // Child 2: anonymous union
+ // clang-format on
+ auto anon_union_sp = hash_node_sp->GetChildAtIndex(2);
+ if (!anon_union_sp)
return lldb::ChildCacheState::eRefetch;
- // Mimick layout of std::__hash_iterator::__node_ and read it in
- // from process memory.
- //
- // The following shows the contiguous block of memory:
- //
- // +-----------------------------+ class __hash_node_base
- // __node_ | __next_pointer __next_; |
- // +-----------------------------+ class __hash_node
- // | size_t __hash_; |
- // | __node_value_type __value_; | <<< our key/value pair
- // +-----------------------------+
- //
- CompilerType tree_node_type = ast_ctx->CreateStructForIdentifier(
- llvm::StringRef(),
- {{"__next_",
- ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
- {"__hash_", ast_ctx->GetBasicType(lldb::eBasicTypeUnsignedLongLong)},
- {"__value_", 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())
+ key_value_sp = anon_union_sp->GetChildMemberWithName("__value_");
+ if (!key_value_sp)
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(2);
}
+ // 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::unordered_map stores the actual key/value pair in
+ // __hash_value_type::__cc_ (or previously __cc).
+ auto potential_child_sp = key_value_sp->Clone(ConstString("pair"));
+ if (potential_child_sp)
+ if (potential_child_sp->GetNumChildrenIgnoringErrors() == 1)
+ if (auto child0_sp = potential_child_sp->GetChildAtIndex(0);
+ child0_sp->GetName() == "__cc_" || child0_sp->GetName() == "__cc")
+ potential_child_sp = child0_sp->Clone(ConstString("pair"));
+
+ m_pair_sp = potential_child_sp;
+
return lldb::ChildCacheState::eRefetch;
}
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 d9e316b9b8f4e..efd7128cd6ac7 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
@@ -59,3 +59,19 @@ def cleanup():
self.expect("frame variable svI", substrs=['item = "hello"'])
self.expect("expr svI", substrs=['item = "hello"'])
+
+ self.expect("frame variable iiumI", substrs=["first = 61453", "second = 51966"])
+ self.expect("expr iiumI", substrs=["first = 61453", "second = 51966"])
+
+ self.expect("frame variable siumI", substrs=['first = "hello"', "second = 137"])
+ self.expect("expr siumI", substrs=['first = "hello"', "second = 137"])
+
+ self.expect("frame variable iiumI.first", substrs=["first = 61453"])
+ self.expect("frame variable iiumI.first", substrs=["second"], matching=False)
+ self.expect("frame variable iiumI.second", substrs=["second = 51966"])
+ self.expect("frame variable iiumI.second", substrs=["first"], matching=False)
+
+ self.expect("frame variable siumI.first", substrs=['first = "hello"'])
+ self.expect("frame variable siumI.first", substrs=["second"], matching=False)
+ self.expect("frame variable siumI.second", substrs=["second = 137"])
+ self.expect("frame variable siumI.second", substrs=["first"], matching=False)
diff --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/main.cpp b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/main.cpp
index 9d1cbfd912868..e53c0f167c325 100644
--- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/main.cpp
+++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/iterator/main.cpp
@@ -1,38 +1,50 @@
-#include <string>
#include <map>
+#include <string>
#include <vector>
typedef std::map<int, int> intint_map;
typedef std::map<std::string, int> strint_map;
+typedef std::unordered_map<int, int> intint_umap;
+typedef std::unordered_map<std::string, int> strint_umap;
+
typedef std::vector<int> int_vector;
typedef std::vector<std::string> string_vector;
-typedef intint_map::iterator iimter;
-typedef strint_map::iterator simter;
+typedef intint_map::iterator ii_map_iter;
+typedef strint_map::iterator si_map_iter;
+typedef intint_umap::iterator ii_umap_iter;
+typedef strint_umap::iterator si_umap_iter;
typedef int_vector::iterator ivter;
typedef string_vector::iterator svter;
-int main()
-{
- intint_map iim;
- iim[0xABCD] = 0xF0F1;
+int main() {
+ intint_map iim;
+ iim[0xABCD] = 0xF0F1;
+
+ strint_map sim;
+ sim["world"] = 42;
+
+ intint_umap iium;
+ iium[0xF00D] = 0xCAFE;
- strint_map sim;
- sim["world"] = 42;
+ strint_umap sium;
+ sium["hello"] = 137;
- int_vector iv;
- iv.push_back(3);
+ int_vector iv;
+ iv.push_back(3);
- string_vector sv;
- sv.push_back("hello");
+ string_vector sv;
+ sv.push_back("hello");
- iimter iimI = iim.begin();
- simter simI = sim.begin();
+ ii_map_iter iimI = iim.begin();
+ si_map_iter simI = sim.begin();
+ ii_umap_iter iiumI = iium.begin();
+ si_umap_iter siumI = sium.begin();
- ivter ivI = iv.begin();
- svter svI = sv.begin();
+ ivter ivI = iv.begin();
+ svter svI = sv.begin();
- return 0; // Set break point at this line.
+ return 0; // Set break point at this line.
}
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