[cfe-commits] r170387 - in /cfe/trunk: lib/CodeGen/CGExpr.cpp test/CodeGenCXX/catch-undef-behavior.cpp

[Richard Smith]

On Mon, Dec 17, 2012 at 4:37 PM, Jordan Rose <jordan_rose at apple.com> wrote:
>
> On Dec 17, 2012, at 16:22 , Richard Smith <richard-llvm at metafoo.co.uk> wrote:
>
>> Author: rsmith
>> Date: Mon Dec 17 18:22:45 2012
>> New Revision: 170387
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=170387&view=rev
>> Log:
>> Rein ubsan's vptr sanitizer back a bit. Per core issue 453, binding a reference
>> to an object outside its lifetime does not have undefined behavior.
>>
>> Modified:
>>    cfe/trunk/lib/CodeGen/CGExpr.cpp
>>    cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp
>>
>> Modified: cfe/trunk/lib/CodeGen/CGExpr.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExpr.cpp?rev=170387&r1=170386&r2=170387&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/CodeGen/CGExpr.cpp (original)
>> +++ cfe/trunk/lib/CodeGen/CGExpr.cpp Mon Dec 17 18:22:45 2012
>> @@ -538,8 +538,15 @@
>>
>>   // If possible, check that the vptr indicates that there is a subobject of
>>   // type Ty at offset zero within this object.
>> +  //
>> +  // C++11 [basic.life]p5,6:
>> +  //   [For storage which does not refer to an object within its lifetime]
>> +  //   The program has undefined behavior if:
>> +  //    -- the [pointer or glvalue] is used to access a non-static data member
>> +  //       or call a non-stastic member function
>
> Typo: stastic

Ta, r170403.

>>   CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
>> -  if (getLangOpts().SanitizeVptr && TCK != TCK_ConstructorCall &&
>> +  if (getLangOpts().SanitizeVptr &&
>> +      (TCK == TCK_MemberAccess || TCK == TCK_MemberCall) &&
>>       RD && RD->hasDefinition() && RD->isDynamicClass()) {
>>     // Compute a hash of the mangled name of the type.
>>     //
>>
>> Modified: cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp?rev=170387&r1=170386&r2=170387&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp (original)
>> +++ cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp Mon Dec 17 18:22:45 2012
>> @@ -1,7 +1,13 @@
>> // RUN: %clang_cc1 -fsanitize=signed-integer-overflow,integer-divide-by-zero,float-divide-by-zero,shift,unreachable,return,vla-bound,alignment,null,vptr,object-size,float-cast-overflow,bool,enum -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
>>
>> +struct S {
>> +  double d;
>> +  int a, b;
>> +  virtual int f();
>> +};
>> +
>> // CHECK: @_Z17reference_binding
>> -void reference_binding(int *p) {
>> +void reference_binding(int *p, S *q) {
>>   // C++ core issue 453: If an lvalue to which a reference is directly bound
>>   // designates neither an existing object or function of an appropriate type,
>>   // nor a region of storage of suitable size and alignment to contain an object
>> @@ -16,13 +22,11 @@
>>   // CHECK-NEXT: %[[MISALIGN:.*]] = and i64 %[[PTRINT]], 3
>>   // CHECK-NEXT: icmp eq i64 %[[MISALIGN]], 0
>>   int &r = *p;
>> -}
>>
>> -struct S {
>> -  double d;
>> -  int a, b;
>> -  virtual int f();
>> -};
>> +  // A reference is not required to refer to an object within its lifetime.
>> +  // CHECK-NOT: __ubsan_handle_dynamic_type_cache_miss
>> +  S &r2 = *q;
>> +}
>>
>> // CHECK: @_Z13member_access
>> void member_access(S *p) {
>>
>>
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>