[PATCH] ignore -mconstructor-aliases when adding field paddings for asan

[Kostya Serebryany]

Hi rsmith,

When we are adding field paddings for asan even an empty dtor has to remain in 
the code,
so we ignore -mconstructor-aliases if the paddings are going to be added.

http://reviews.llvm.org/D6038

Files:
  lib/CodeGen/CGCXX.cpp
  test/CodeGen/sanitize-address-field-padding.cpp

Index: lib/CodeGen/CGCXX.cpp
===================================================================
--- lib/CodeGen/CGCXX.cpp
+++ lib/CodeGen/CGCXX.cpp
@@ -46,6 +46,11 @@
 
   const CXXRecordDecl *Class = D->getParent();
 
+  // We are going to instrument this destructor, so give up even if it is
+  // currently empty.
+  if (Class->mayInsertExtraPadding())
+    return true;
+
   // If we need to manipulate a VTT parameter, give up.
   if (Class->getNumVBases()) {
     // Extra Credit:  passing extra parameters is perfectly safe
Index: test/CodeGen/sanitize-address-field-padding.cpp
===================================================================
--- test/CodeGen/sanitize-address-field-padding.cpp
+++ test/CodeGen/sanitize-address-field-padding.cpp
@@ -2,6 +2,7 @@
 // RUN: echo 'type:SomeNamespace::BlacklistedByName=field-padding' > %t.type.blacklist
 // RUN: echo 'src:*sanitize-address-field-padding.cpp=field-padding' > %t.file.blacklist
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsanitize=address -fsanitize-address-field-padding=1 -fsanitize-blacklist=%t.type.blacklist -Rsanitize-address -emit-llvm -o - %s 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsanitize=address -fsanitize-address-field-padding=1 -fsanitize-blacklist=%t.type.blacklist -Rsanitize-address -emit-llvm -o - %s -O1 -mconstructor-aliases 2>&1 | FileCheck %s --check-prefix=WITH_CTOR_ALIASES
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsanitize=address -fsanitize-address-field-padding=1 -fsanitize-blacklist=%t.file.blacklist -Rsanitize-address -emit-llvm -o - %s 2>&1 | FileCheck %s --check-prefix=FILE_BLACKLIST
 // RUN: %clang_cc1 -fsanitize=address -emit-llvm -o - %s 2>&1 | FileCheck %s --check-prefix=NO_PADDING
 // REQUIRES: shell
@@ -193,3 +194,22 @@
 // CHECK-NOT: __asan_poison_intra_object_redzone
 // CHECK: ret void
 //
+
+struct WithVirtualDtor { virtual ~WithVirtualDtor(); };
+struct InheritsFrom_WithVirtualDtor: WithVirtualDtor {
+  int a;
+  InheritsFrom_WithVirtualDtor() {}
+  ~InheritsFrom_WithVirtualDtor() {}
+};
+
+void Create_InheritsFrom_WithVirtualDtor() {
+  InheritsFrom_WithVirtualDtor x;
+}
+
+
+// Make sure the dtor of InheritsFrom_WithVirtualDtor remains in the code,
+// i.e. we ignore -mconstructor-aliases when field paddings are added.
+// WITH_CTOR_ALIASES-LABEL: define void @_Z35Create_InheritsFrom_WithVirtualDtor
+// WITH_CTOR_ALIASES-NOT: call void @_ZN15WithVirtualDtorD2Ev
+// WITH_CTOR_ALIASES: call void @_ZN28InheritsFrom_WithVirtualDtorD2Ev
+// WITH_CTOR_ALIASES: ret void

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