[Lldb-commits] [PATCH] D101237: [lldb] Fix [[no_unique_address]] and libstdc++ 11's std::unique_ptr

[Jan Kratochvil via Phabricator via lldb-commits]

jankratochvil created this revision.
jankratochvil added reviewers: dblaikie, labath, clayborg.
jankratochvil added a project: LLDB.
Herald added a subscriber: JDevlieghere.
jankratochvil requested review of this revision.

libstc++ 11 started using `[[no_unique_address]]` which crashes LLDB:

  echo -e '#include <memory>\nstd::unique_ptr<int> p;'|clang -Wall -g -c -o a.o -x c++ -;lldb -b ./a.o -o 'p p'
  lldb: clang/lib/CodeGen/CGRecordLayoutBuilder.cpp:742: void (anonymous namespace)::CGRecordLowering::clipTailPadding(): Assertion `Prior->Kind == MemberInfo::Field && "Only storage fields have tail padding!"' failed.

As DWARF does not contain the `[[no_unique_address]]` attribute the patch adds it to every record member, could it be a problem?


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D101237

Files:
  lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
  lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
  lldb/test/Shell/Expr/no_unique_address.cpp
  lldb/test/Shell/SymbolFile/NativePDB/bitfields.cpp


Index: lldb/test/Shell/SymbolFile/NativePDB/bitfields.cpp
===================================================================
--- lldb/test/Shell/SymbolFile/NativePDB/bitfields.cpp
+++ lldb/test/Shell/SymbolFile/NativePDB/bitfields.cpp
@@ -44,18 +44,18 @@
 // CHECK: TranslationUnitDecl {{.*}}
 // CHECK: |-CXXRecordDecl {{.*}} struct Struct definition
 // CHECK: | |-FieldDecl {{.*}} A 'int'
-// CHECK: | | `-IntegerLiteral {{.*}} 'int' 5
+// CHECK: | | {{.}}-IntegerLiteral {{.*}} 'int' 5
 // CHECK: | |-FieldDecl {{.*}} B 'int'
-// CHECK: | | `-IntegerLiteral {{.*}} 'int' 7
+// CHECK: | | {{.}}-IntegerLiteral {{.*}} 'int' 7
 // CHECK: | |-FieldDecl {{.*}} C 'unsigned int'
-// CHECK: | | `-IntegerLiteral {{.*}} 'int' 3
+// CHECK: | | {{.}}-IntegerLiteral {{.*}} 'int' 3
 // CHECK: | |-FieldDecl {{.*}} D 'unsigned int'
-// CHECK: | | `-IntegerLiteral {{.*}} 'int' 15
+// CHECK: | | {{.}}-IntegerLiteral {{.*}} 'int' 15
 // CHECK: | |-FieldDecl {{.*}} E 'char'
-// CHECK: | | `-IntegerLiteral {{.*}} 'int' 1
+// CHECK: | | {{.}}-IntegerLiteral {{.*}} 'int' 1
 // CHECK: | |-FieldDecl {{.*}} F 'char'
-// CHECK: | | `-IntegerLiteral {{.*}} 'int' 2
+// CHECK: | | {{.}}-IntegerLiteral {{.*}} 'int' 2
 // CHECK: | |-FieldDecl {{.*}} G 'char'
-// CHECK: | | `-IntegerLiteral {{.*}} 'int' 3
+// CHECK: | | {{.}}-IntegerLiteral {{.*}} 'int' 3
 // CHECK: | `-FieldDecl {{.*}} H 'char'
-// CHECK: |   `-IntegerLiteral {{.*}} 'int' 3
+// CHECK: |   {{.}}-IntegerLiteral {{.*}} 'int' 3
Index: lldb/test/Shell/Expr/no_unique_address.cpp
===================================================================
--- /dev/null
+++ lldb/test/Shell/Expr/no_unique_address.cpp
@@ -0,0 +1,15 @@
+// Test LLDB does not assert on miscalculated field offsets.
+
+// RUN: %clang_host %s -g -c -o %t.o
+// RUN: %lldb %t.o -o "p c.c" -o exit | FileCheck %s
+
+// CHECK: (lldb) p c.c
+// CHECK-NEXT: (char) $0 = '\0'
+
+struct A {};
+struct B {
+  [[no_unique_address]] A a;
+};
+struct C : B {
+  char c;
+} c;
Index: lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
===================================================================
--- lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -7196,6 +7196,7 @@
     if (bit_width)
       field->setBitWidth(bit_width);
     SetMemberOwningModule(field, record_decl);
+    field->addAttr(NoUniqueAddressAttr::CreateImplicit(ast->getASTContext()));
 
     if (name.empty()) {
       // Determine whether this field corresponds to an anonymous struct or
Index: lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
@@ -99,9 +99,12 @@
   if (ptr_obj)
     m_ptr_obj = ptr_obj->Clone(ConstString("pointer")).get();
 
-  ValueObjectSP del_obj = tuple_frontend->GetChildAtIndex(1);
-  if (del_obj)
-    m_del_obj = del_obj->Clone(ConstString("deleter")).get();
+  // GCC 11 std::default_delete<...> has existing child with GetByteSize()==1.
+  if (tuple_sp->GetByteSize() > ptr_obj->GetByteSize()) {
+    ValueObjectSP del_obj = tuple_frontend->GetChildAtIndex(1);
+    if (del_obj)
+      m_del_obj = del_obj->Clone(ConstString("deleter")).get();
+  }
 
   if (m_ptr_obj) {
     Status error;


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