[Lldb-commits] [lldb] [lldb] Avoid calling DataLayout constructor accepting Module pointer (NFC) (PR #102839)

[Sergei Barannikov via lldb-commits]

https://github.com/s-barannikov created https://github.com/llvm/llvm-project/pull/102839

The constructor initializes `*this` with a copy of `M->getDataLayout()`, which can just be spelled as `DataLayout DL = M->getDataLayout()`. In all places where the constructor is used, Module outlives DataLayout, so store a reference to it instead of cloning.

>From e3cdec63767738ca0e5fe640f9e01996ec1ecc22 Mon Sep 17 00:00:00 2001
From: Sergei Barannikov <barannikov88 at gmail.com>
Date: Mon, 12 Aug 2024 03:53:28 +0300
Subject: [PATCH] [lldb] Avoid calling DataLayout constructor accepting Module
 pointer (NFC)

The constructor initializes `*this` with a copy of `M->getDataLayout()`,
which can just be spelled as `DataLayout DL = M->getDataLayout()`.
In all places where the constructor is used, Module outlives DataLayout,
so store a reference to it instead of cloning.
---
 lldb/source/Expression/IRInterpreter.cpp                   | 6 +++---
 .../Plugins/ExpressionParser/Clang/IRDynamicChecks.cpp     | 7 +++----
 lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.cpp | 2 +-
 lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.h   | 4 ++--
 4 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/lldb/source/Expression/IRInterpreter.cpp b/lldb/source/Expression/IRInterpreter.cpp
index 5b670067b5c433..030b30f070ee35 100644
--- a/lldb/source/Expression/IRInterpreter.cpp
+++ b/lldb/source/Expression/IRInterpreter.cpp
@@ -96,7 +96,7 @@ class InterpreterStackFrame {
   typedef std::map<const Value *, lldb::addr_t> ValueMap;
 
   ValueMap m_values;
-  DataLayout &m_target_data;
+  const DataLayout &m_target_data;
   lldb_private::IRExecutionUnit &m_execution_unit;
   const BasicBlock *m_bb = nullptr;
   const BasicBlock *m_prev_bb = nullptr;
@@ -110,7 +110,7 @@ class InterpreterStackFrame {
   lldb::ByteOrder m_byte_order;
   size_t m_addr_byte_size;
 
-  InterpreterStackFrame(DataLayout &target_data,
+  InterpreterStackFrame(const DataLayout &target_data,
                         lldb_private::IRExecutionUnit &execution_unit,
                         lldb::addr_t stack_frame_bottom,
                         lldb::addr_t stack_frame_top)
@@ -703,7 +703,7 @@ bool IRInterpreter::Interpret(llvm::Module &module, llvm::Function &function,
               s.c_str());
   }
 
-  DataLayout data_layout(&module);
+  const DataLayout &data_layout = module.getDataLayout();
 
   InterpreterStackFrame frame(data_layout, execution_unit, stack_frame_bottom,
                               stack_frame_top);
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/IRDynamicChecks.cpp b/lldb/source/Plugins/ExpressionParser/Clang/IRDynamicChecks.cpp
index bc0f5993aad0d6..defd72bbd93106 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/IRDynamicChecks.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/IRDynamicChecks.cpp
@@ -280,10 +280,9 @@ class Instrumenter {
 
   IntegerType *GetIntptrTy() {
     if (!m_intptr_ty) {
-      llvm::DataLayout data_layout(&m_module);
-
-      m_intptr_ty = llvm::Type::getIntNTy(m_module.getContext(),
-                                          data_layout.getPointerSizeInBits());
+      m_intptr_ty = llvm::Type::getIntNTy(
+          m_module.getContext(),
+          m_module.getDataLayout().getPointerSizeInBits());
     }
 
     return m_intptr_ty;
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.cpp b/lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.cpp
index cc9bd14c6194e4..34461da46dfc7b 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.cpp
@@ -1606,7 +1606,7 @@ bool IRForTarget::runOnModule(Module &llvm_module) {
   lldb_private::Log *log(GetLog(LLDBLog::Expressions));
 
   m_module = &llvm_module;
-  m_target_data = std::make_unique<DataLayout>(m_module);
+  m_target_data = &m_module->getDataLayout();
   m_intptr_ty = llvm::Type::getIntNTy(m_module->getContext(),
                                       m_target_data->getPointerSizeInBits());
 
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.h b/lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.h
index a924187ba04c06..45027fcd6fa492 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.h
+++ b/lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.h
@@ -331,9 +331,9 @@ class IRForTarget {
   lldb_private::TypeFromParser m_result_type;
   /// The module being processed, or NULL if that has not been determined yet.
   llvm::Module *m_module = nullptr;
-  /// The target data for the module being processed, or NULL if there is no
+  /// The target data for the module being processed, or nullptr if there is no
   /// module.
-  std::unique_ptr<llvm::DataLayout> m_target_data;
+  const llvm::DataLayout *m_target_data = nullptr;
   /// The DeclMap containing the Decls
   lldb_private::ClangExpressionDeclMap *m_decl_map;
   /// The address of the function CFStringCreateWithBytes, cast to the