Hi kcc, rsmith,
ASan init-order checking may print false positives for globals that
have no user-defined ctor, but have non-trivial dtor. Clang *should* emit
initializer for them to register dtor in __cxa_atexit, but the contents of the
global is not touched, and program may safely rely on zero-initialization.
http://llvm-reviews.chandlerc.com/D608
Files:
lib/CodeGen/CodeGenModule.cpp
test/CodeGen/sanitize-init-order.cpp
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -1812,22 +1812,31 @@
SetCommonAttributes(D, GV);
- // Emit the initializer function if necessary.
- if (NeedsGlobalCtor || NeedsGlobalDtor)
- EmitCXXGlobalVarDeclInitFunc(D, GV, NeedsGlobalCtor);
-
// If we are compiling with ASan, add metadata indicating dynamically
- // initialized globals.
+ // initialized globals. Do this before we emit initializer function.
if (SanOpts.Address && NeedsGlobalCtor) {
- llvm::Module &M = getModule();
+ // Check if this declaration is not a trivial default constructor.
+ bool IsTrivialDefaultCtor = false;
+ if (const CXXConstructExpr *E =
+ dyn_cast_or_null<CXXConstructExpr>(InitDecl->getInit())) {
+ const CXXConstructorDecl *CD = E->getConstructor();
+ IsTrivialDefaultCtor = (CD->isTrivial() && CD->isDefaultConstructor());
+ }
- llvm::NamedMDNode *DynamicInitializers =
-
M.getOrInsertNamedMetadata("llvm.asan.dynamically_initialized_globals");
- llvm::Value *GlobalToAdd[] = { GV };
- llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalToAdd);
- DynamicInitializers->addOperand(ThisGlobal);
+ if (!IsTrivialDefaultCtor) {
+ llvm::Module &M = getModule();
+ llvm::NamedMDNode *DynamicInitializers =
+
M.getOrInsertNamedMetadata("llvm.asan.dynamically_initialized_globals");
+ llvm::Value *GlobalToAdd[] = { GV };
+ llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalToAdd);
+ DynamicInitializers->addOperand(ThisGlobal);
+ }
}
+ // Emit the initializer function if necessary.
+ if (NeedsGlobalCtor || NeedsGlobalDtor)
+ EmitCXXGlobalVarDeclInitFunc(D, GV, NeedsGlobalCtor);
+
// Emit global variable debug information.
if (CGDebugInfo *DI = getModuleDebugInfo())
if (getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo)
Index: test/CodeGen/sanitize-init-order.cpp
===================================================================
--- /dev/null
+++ test/CodeGen/sanitize-init-order.cpp
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -fsanitize=address,init-order -emit-llvm -o - %s |
FileCheck %s
+
+struct PODStruct {
+ int x;
+};
+PODStruct s1;
+
+struct PODWithDtor {
+ ~PODWithDtor() { }
+ int x;
+};
+PODWithDtor s2;
+
+struct PODWithCtorAndDtor {
+ PODWithCtorAndDtor() { }
+ ~PODWithCtorAndDtor() { }
+ int x;
+};
+PODWithCtorAndDtor s3;
+
+// Check that ASan init-order checking ignores structs with trivial default
+// constructor.
+// CHECK: !llvm.asan.dynamically_initialized_globals = !{[[GLOB:![0-9]+]]}
+// CHECK: [[GLOB]] = metadata !{%struct.PODWithCtorAndDtor
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -1812,22 +1812,31 @@
SetCommonAttributes(D, GV);
- // Emit the initializer function if necessary.
- if (NeedsGlobalCtor || NeedsGlobalDtor)
- EmitCXXGlobalVarDeclInitFunc(D, GV, NeedsGlobalCtor);
-
// If we are compiling with ASan, add metadata indicating dynamically
- // initialized globals.
+ // initialized globals. Do this before we emit initializer function.
if (SanOpts.Address && NeedsGlobalCtor) {
- llvm::Module &M = getModule();
+ // Check if this declaration is not a trivial default constructor.
+ bool IsTrivialDefaultCtor = false;
+ if (const CXXConstructExpr *E =
+ dyn_cast_or_null<CXXConstructExpr>(InitDecl->getInit())) {
+ const CXXConstructorDecl *CD = E->getConstructor();
+ IsTrivialDefaultCtor = (CD->isTrivial() && CD->isDefaultConstructor());
+ }
- llvm::NamedMDNode *DynamicInitializers =
- M.getOrInsertNamedMetadata("llvm.asan.dynamically_initialized_globals");
- llvm::Value *GlobalToAdd[] = { GV };
- llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalToAdd);
- DynamicInitializers->addOperand(ThisGlobal);
+ if (!IsTrivialDefaultCtor) {
+ llvm::Module &M = getModule();
+ llvm::NamedMDNode *DynamicInitializers =
+ M.getOrInsertNamedMetadata("llvm.asan.dynamically_initialized_globals");
+ llvm::Value *GlobalToAdd[] = { GV };
+ llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalToAdd);
+ DynamicInitializers->addOperand(ThisGlobal);
+ }
}
+ // Emit the initializer function if necessary.
+ if (NeedsGlobalCtor || NeedsGlobalDtor)
+ EmitCXXGlobalVarDeclInitFunc(D, GV, NeedsGlobalCtor);
+
// Emit global variable debug information.
if (CGDebugInfo *DI = getModuleDebugInfo())
if (getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo)
Index: test/CodeGen/sanitize-init-order.cpp
===================================================================
--- /dev/null
+++ test/CodeGen/sanitize-init-order.cpp
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -fsanitize=address,init-order -emit-llvm -o - %s | FileCheck %s
+
+struct PODStruct {
+ int x;
+};
+PODStruct s1;
+
+struct PODWithDtor {
+ ~PODWithDtor() { }
+ int x;
+};
+PODWithDtor s2;
+
+struct PODWithCtorAndDtor {
+ PODWithCtorAndDtor() { }
+ ~PODWithCtorAndDtor() { }
+ int x;
+};
+PODWithCtorAndDtor s3;
+
+// Check that ASan init-order checking ignores structs with trivial default
+// constructor.
+// CHECK: !llvm.asan.dynamically_initialized_globals = !{[[GLOB:![0-9]+]]}
+// CHECK: [[GLOB]] = metadata !{%struct.PODWithCtorAndDtor
_______________________________________________
cfe-commits mailing list
[email protected]
http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
