[CodeGen] Ubsan missed source location fix for constructor type mismatch checking

[lenykholodov]

Summary

When clang generates ubsan_handle_type_mismatch call for constructor call, it uses zero filled source location. This is not correct because in runtime ubsan_handle_type_mismatch receives empty location and can't warn with readable message. The patch fixes this case.

lib/CodeGen/CGClass.cpp

 void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
                                              CXXCtorType Type,
                                              bool ForVirtualBase,
                                              bool Delegating, llvm::Value *This,
                                              const CXXConstructExpr *E) {
   // C++11 [class.mfct.non-static]p2:
   //   If a non-static member function of a class X is called for an object that
   //   is not of type X, or of a type derived from X, the behavior is undefined.
-  // FIXME: Provide a source location here.
-  EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, SourceLocation(), This,
+  EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, E->getExprLoc(), This,
                 getContext().getRecordType(D->getParent()));
 
   if (D->isTrivial() && D->isDefaultConstructor()) {
     assert(E->getNumArgs() == 0 && "trivial default ctor with args");
     return;
   }
 
   // If this is a trivial constructor, just emit what's needed. If this is a

test/CodeGen/ubsan-constructor-type-mismatch.cpp

+// Verify ubsan type mismatch checking works with correct source location
+// RUN: %clang -target armv7l-unknown-linux-gnueabihf -S %s -o - -emit-llvm -g -fsanitize=alignment -O3 -W0 | FileCheck %s
+
+struct S {
+  S() {}
+  int k;
+
+  void* operator new (unsigned int, void* p) { return p; }
+};
+
+int f(char x)
+{
+  char c[] __attribute__((aligned(8))) = { 0, 0, 0, 0, 1, 2, 3, 4, 5 };
+
+  // Pointer value may be unspecified here, but behavior is not undefined.
+  int *p = (int*)&c[4 + x - '0'];
+  S *s1 = (S*)p;
+
+// CHECK: @1 = private unnamed_addr global { { [98 x i8]*, i32, i32 }, { i16, i16, [4 x i8] }*, i32, i8 } { { [98 x i8]*, i32, i32 } { [98 x i8]* @.src, i32 22, i32 20 }, { i16, i16, [4 x i8] }* @0, i32 4, i8 5 }
+// CHECK: call void @__ubsan_handle_type_mismatch(i8* bitcast ({ { [98 x i8]*, i32, i32 }, { i16, i16, [4 x i8] }*, i32, i8 }* @1 to i8*)
+
+  S *s2 = new (s1) S;
+
+  return s2->k && 0;
+}