Fix wrong assumption in contains_type_p (PR ipa/71207).

Hello.

As mentioned in the PR, having a diamond virtual inheritance can cause a wrong
assumption done in contains_type_p. I also decided to rename one argument of the
function as otr_type and outer_type names are very confusing. Apart from what was
written in bugzilla I also verified that after the hunk removal, there's no situation
on Firefox where the function would return true, which used to return false.

Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.

Ready to be installed?
Martin

> 
> 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
>

On 01/17/2017 11:43 AM, Jan Hubicka wrote:
>>
>> 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.

Ok, applied without the renaming as r244530. I guess you added that to cut the recursion.

Would it be fine to install the patch to active branches after proper testing?
Thanks,
Martin

>>  		 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
>>
>

> 
> Ok, applied without the renaming as r244530. I guess you added that to cut the recursion.
> 
> Would it be fine to install the patch to active branches after proper testing?
OK
Honza
> Thanks,
> Martin
> 
> >>  		 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
> >>
> >