Fix for clang memcpyizer bugs 23911 and 23924 (patch by Denis Zobnin)

The fix is to remove duplicate copy-initialization of the only memcpy-able struct member and to correct the address of aggregately initialized members in destructors' calls during stack unwinding (in order to obtain address of struct member by using GEP instead of 'bitcast').
Differential Revision: http://reviews.llvm.org/D10990

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@242127 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/CGClass.cpp b/lib/CodeGen/CGClass.cpp
index b977824888d9be2cb761ed1c2e58adae0fe81637..c49f182c21d8593dbc8a5e613e0cbafa22bee086 100644 (file)
--- a/lib/CodeGen/CGClass.cpp
+++ b/lib/CodeGen/CGClass.cpp
@@ -554,6 +554,20 @@ static bool isMemcpyEquivalentSpecialMember(const CXXMethodDecl *D) {
   return false;
 }
 
+static void EmitLValueForAnyFieldInitialization(CodeGenFunction &CGF,
+                                                CXXCtorInitializer *MemberInit,
+                                                LValue &LHS) {
+  FieldDecl *Field = MemberInit->getAnyMember();
+  if (MemberInit->isIndirectMemberInitializer()) {
+    // If we are initializing an anonymous union field, drill down to the field.
+    IndirectFieldDecl *IndirectField = MemberInit->getIndirectMember();
+    for (const auto *I : IndirectField->chain())
+      LHS = CGF.EmitLValueForFieldInitialization(LHS, cast<FieldDecl>(I));
+  } else {
+    LHS = CGF.EmitLValueForFieldInitialization(LHS, Field);
+  }
+}
+
 static void EmitMemberInitializer(CodeGenFunction &CGF,
                                   const CXXRecordDecl *ClassDecl,
                                   CXXCtorInitializer *MemberInit,
@@ -572,16 +586,7 @@ static void EmitMemberInitializer(CodeGenFunction &CGF,
   QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl);
   LValue LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
 
-  if (MemberInit->isIndirectMemberInitializer()) {
-    // If we are initializing an anonymous union field, drill down to
-    // the field.
-    IndirectFieldDecl *IndirectField = MemberInit->getIndirectMember();
-    for (const auto *I : IndirectField->chain())
-      LHS = CGF.EmitLValueForFieldInitialization(LHS, cast<FieldDecl>(I));
-    FieldType = MemberInit->getIndirectMember()->getAnonField()->getType();
-  } else {
-    LHS = CGF.EmitLValueForFieldInitialization(LHS, Field);
-  }
+  EmitLValueForAnyFieldInitialization(CGF, MemberInit, LHS);
 
   // Special case: if we are in a copy or move constructor, and we are copying
   // an array of PODs or classes with trivial copy constructors, ignore the
@@ -1072,6 +1077,7 @@ namespace {
           CopyingValueRepresentation CVR(CGF);
           EmitMemberInitializer(CGF, ConstructorDecl->getParent(),
                                 AggregatedInits[0], ConstructorDecl, Args);
+          AggregatedInits.clear();
         }
         reset();
         return;
@@ -1088,10 +1094,14 @@ namespace {
       LValue LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
 
       for (unsigned i = 0; i < AggregatedInits.size(); ++i) {
-        QualType FieldType = AggregatedInits[i]->getMember()->getType();
+        CXXCtorInitializer *MemberInit = AggregatedInits[i];
+        QualType FieldType = MemberInit->getAnyMember()->getType();
         QualType::DestructionKind dtorKind = FieldType.isDestructedType();
-        if (CGF.needsEHCleanup(dtorKind))
-          CGF.pushEHDestroy(dtorKind, LHS.getAddress(), FieldType);
+        if (!CGF.needsEHCleanup(dtorKind))
+          continue;
+        LValue FieldLHS = LHS;
+        EmitLValueForAnyFieldInitialization(CGF, MemberInit, FieldLHS);
+        CGF.pushEHDestroy(dtorKind, FieldLHS.getAddress(), FieldType);
       }
     }
 

diff --git a/test/CodeGenCXX/eh-aggregated-inits-unwind.cpp b/test/CodeGenCXX/eh-aggregated-inits-unwind.cpp
new file mode 100644 (file)
index 0000000..9772564
--- /dev/null
+++ b/test/CodeGenCXX/eh-aggregated-inits-unwind.cpp
@@ -0,0 +1,47 @@
+// Check that destructors of memcpy-able struct members are called properly
+// during stack unwinding after an exception.
+//
+// Check that destructor's argument (address of member to be destroyed) is
+// obtained by taking offset from struct, not by bitcasting pointers.
+//
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fexceptions -fcxx-exceptions -O0 -fno-elide-constructors -emit-llvm %s -o - | FileCheck %s
+
+struct ImplicitCopy {
+  int id;
+  ImplicitCopy() { id = 10; }
+  ~ImplicitCopy() { id = 20; }
+};
+
+struct ThrowCopy {
+  int id;
+  ThrowCopy() { id = 15; }
+  ThrowCopy(const ThrowCopy &x) {
+    id = 25;
+    throw 1;
+  }
+  ~ThrowCopy() { id = 35; }
+};
+
+struct Container {
+  int id;
+  ImplicitCopy o1;
+  ThrowCopy o2;
+
+  Container() { id = 1000; }
+  ~Container() { id = 2000; }
+};
+
+int main() {
+  try {
+    Container c1;
+    // CHECK-LABEL: main
+    // CHECK: %{{.+}} = getelementptr inbounds %struct.Container, %struct.Container* %{{.+}}, i32 0, i32 1
+    // CHECK-NOT: %{{.+}} = bitcast %struct.Container* %{{.+}} to %struct.ImplicitCopy*
+    Container c2(c1);
+
+    return 2;
+  } catch (...) {
+    return 1;
+  }
+  return 0;
+}

diff --git a/test/CodeGenCXX/eh-aggregated-inits.cpp b/test/CodeGenCXX/eh-aggregated-inits.cpp
new file mode 100644 (file)
index 0000000..cb34b65
--- /dev/null
+++ b/test/CodeGenCXX/eh-aggregated-inits.cpp
@@ -0,0 +1,46 @@
+// Check that initialization of the only one memcpy-able struct member will not
+// be performed twice after successful non-trivial initializtion of the second
+// member.
+//
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fexceptions -fcxx-exceptions -O0 -fno-elide-constructors -emit-llvm %s -o - | FileCheck %s
+
+int globId = 0;
+
+struct ImplicitCopy {
+  int id;
+
+  ImplicitCopy() { id = 10; }
+  ~ImplicitCopy() { id = 20; }
+};
+
+struct ExplicitCopy {
+  int id;
+
+  ExplicitCopy() { id = 15; }
+  ExplicitCopy(const ExplicitCopy &x) { id = 25; }
+  ~ExplicitCopy() { id = 35; }
+};
+
+struct Container {
+  ImplicitCopy o1; // memcpy-able member.
+  ExplicitCopy o2; // non-trivial initialization.
+
+  Container() { globId = 1000; }
+  ~Container() { globId = 2000; }
+};
+
+int main() {
+  try {
+    Container c1;
+    // CHECK-DAG: call void @llvm.memcpy
+    // CHECK-DAG: declare void @llvm.memcpy
+    // CHECK-NOT: @llvm.memcpy
+    Container c2(c1);
+
+    return 2;
+  }
+  catch (...) {
+    return 1;
+  }
+  return 0;
+}