Re: [PATCH] Fix wrong assumption in contains_type_p (PR ipa/71207).

[Jan Hubicka <hubicka at ucw dot cz>]

> 
> gcc/testsuite/ChangeLog:
> 
> 2017-01-12  Martin Liska  <mliska@suse.cz>
> 
> 	PR ipa/71207
> 	* g++.dg/ipa/pr71207.C: New test.
> 
> gcc/ChangeLog:
> 
> 2017-01-12  Martin Liska  <mliska@suse.cz>
> 
> 	PR ipa/71207
> 	* ipa-polymorphic-call.c (contains_type_p): Fix wrong
> 	assumption, add comment and renamed otr_type to inner_type.
> ---
>  gcc/ipa-polymorphic-call.c         | 22 ++++++++++----------
>  gcc/testsuite/g++.dg/ipa/pr71207.C | 42 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 53 insertions(+), 11 deletions(-)
>  create mode 100644 gcc/testsuite/g++.dg/ipa/pr71207.C
> 
> diff --git a/gcc/ipa-polymorphic-call.c b/gcc/ipa-polymorphic-call.c
> index da64ce4c6e0..c13fc858c86 100644
> --- a/gcc/ipa-polymorphic-call.c
> +++ b/gcc/ipa-polymorphic-call.c
> @@ -446,15 +446,15 @@ no_useful_type_info:
>      }
>  }
>  
> -/* Return true if OUTER_TYPE contains OTR_TYPE at OFFSET.
> -   CONSIDER_PLACEMENT_NEW makes function to accept cases where OTR_TYPE can
> +/* Return true if OUTER_TYPE contains INNER_TYPE at OFFSET.
> +   CONSIDER_PLACEMENT_NEW makes function to accept cases where INNER_TYPE can
>     be built within OUTER_TYPE by means of placement new.  CONSIDER_BASES makes
> -   function to accept cases where OTR_TYPE appears as base of OUTER_TYPE or as
> +   function to accept cases where INNER_TYPE appears as base of OUTER_TYPE or as
>     base of one of fields of OUTER_TYPE.  */
>  
>  static bool
>  contains_type_p (tree outer_type, HOST_WIDE_INT offset,
> -		 tree otr_type,
> +		 tree inner_type,

I would actually keep otr_type (or change it consistently in all cases).
otr comes from OBJ_TYPE_REF and is used thorough the code (not my invention,
comming from original binfo walking routine).

OK with that change.  I bleive I added the size check only to cut the recurision
early which is not a big deal.
>  		 bool consider_placement_new,
>  		 bool consider_bases)
>  {
> @@ -463,18 +463,18 @@ contains_type_p (tree outer_type, HOST_WIDE_INT offset,
>    /* Check that type is within range.  */
>    if (offset < 0)
>      return false;
> -  if (TYPE_SIZE (outer_type) && TYPE_SIZE (otr_type)
> -      && TREE_CODE (TYPE_SIZE (outer_type)) == INTEGER_CST
> -      && TREE_CODE (TYPE_SIZE (otr_type)) == INTEGER_CST
> -      && wi::ltu_p (wi::to_offset (TYPE_SIZE (outer_type)),
> -		    (wi::to_offset (TYPE_SIZE (otr_type)) + offset)))
> -    return false;
> +
> +  /* PR ipa/71207
> +     As OUTER_TYPE can be a type which has a diamond virtual inheritance,
> +     it's not necessary that INNER_TYPE will fit within OUTER_TYPE with
> +     a given offset.  It can happen that INNER_TYPE also contains a base object,
> +     however it would point to the same instance in the OUTER_TYPE.  */
>  
>    context.offset = offset;
>    context.outer_type = TYPE_MAIN_VARIANT (outer_type);
>    context.maybe_derived_type = false;
>    context.dynamic = false;
> -  return context.restrict_to_inner_class (otr_type, consider_placement_new,
> +  return context.restrict_to_inner_class (inner_type, consider_placement_new,
>  					  consider_bases);
>  }
>  
> diff --git a/gcc/testsuite/g++.dg/ipa/pr71207.C b/gcc/testsuite/g++.dg/ipa/pr71207.C
> new file mode 100644
> index 00000000000..19a03998460
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ipa/pr71207.C
> @@ -0,0 +1,42 @@
> +/* PR ipa/71207 */
> +/* { dg-do run } */
> +
> +class Class1
> +{
> +public:
> +  Class1() {};
> +  virtual ~Class1() {};
> +
> +protected:
> +  unsigned Field1;
> +};
> +
> +class Class2 : public virtual Class1
> +{
> +};
> +
> +class Class3 : public virtual Class1
> +{
> +public:
> +  virtual void Method1() = 0;
> +
> +  void Method2()
> +  {
> +    Method1();
> +  }
> +};
> +
> +class Class4 : public Class2, public virtual Class3
> +{
> +public:
> +  Class4() {};
> +  virtual void Method1() {};
> +};
> +
> +int main()
> +{
> +  Class4 var1;
> +  var1.Method2();
> +
> +  return 0;
> +}
> -- 
> 2.11.0
>