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

[Jordan Rose]

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

>   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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