Fix verify_type ICE with -fshort-enum

Fix verify_type ICE with -fshort-enum

[Jan Hubicka]

Hi,
gcc.c-torture/execute/930408-1.c currently ICE on -fshort-enum target(s) because
TYPE_PACKED is not consistently set among type variants.

Bootstrapped/regtested ppc64le-linux, OK?
Honza

	PR middle-end/66325
	* c-decl.c (start_enum): Set TYPE_PACKED consistently among type variants.
Index: c-decl.c
===================================================================
--- c-decl.c	(revision 224250)
+++ c-decl.c	(working copy)
@@ -7946,7 +7946,8 @@
   the_enum->enum_overflow = 0;
 
   if (flag_short_enums)
-    TYPE_PACKED (enumtype) = 1;
+    for (tree v = TYPE_MAIN_VARIANT (enumtype); v ;v = TYPE_NEXT_VARIANT (v))
+      TYPE_PACKED (v) = 1;
 
   /* FIXME: This will issue a warning for a use of a type defined
      within sizeof in a statement expr.  This is not terribly serious

Re: Fix verify_type ICE with -fshort-enum

[Marek Polacek]

On Thu, Jun 11, 2015 at 11:47:43PM +0200, Jan Hubicka wrote:
> Hi,
> gcc.c-torture/execute/930408-1.c currently ICE on -fshort-enum target(s) because
> TYPE_PACKED is not consistently set among type variants.
 
I guess that's because of the forward declaration in the test.  But I have
no access to an ARM machine, so can't verify.

> Bootstrapped/regtested ppc64le-linux, OK?
> Honza
> 
> 	PR middle-end/66325
> 	* c-decl.c (start_enum): Set TYPE_PACKED consistently among type variants.
> Index: c-decl.c
> ===================================================================
> --- c-decl.c	(revision 224250)
> +++ c-decl.c	(working copy)
> @@ -7946,7 +7946,8 @@
>    the_enum->enum_overflow = 0;
>  
>    if (flag_short_enums)
> -    TYPE_PACKED (enumtype) = 1;
> +    for (tree v = TYPE_MAIN_VARIANT (enumtype); v ;v = TYPE_NEXT_VARIANT (v))

Please fix the formatting here: no space before ;.

Ok with that change.

	Marek

Re: Fix verify_type ICE with -fshort-enum

[Richard Biener]

On Fri, Jun 12, 2015 at 10:00 AM, Marek Polacek <polacek@redhat.com> wrote:
> On Thu, Jun 11, 2015 at 11:47:43PM +0200, Jan Hubicka wrote:
>> Hi,
>> gcc.c-torture/execute/930408-1.c currently ICE on -fshort-enum target(s) because
>> TYPE_PACKED is not consistently set among type variants.
>
> I guess that's because of the forward declaration in the test.  But I have
> no access to an ARM machine, so can't verify.
>
>> Bootstrapped/regtested ppc64le-linux, OK?
>> Honza
>>
>>       PR middle-end/66325
>>       * c-decl.c (start_enum): Set TYPE_PACKED consistently among type variants.
>> Index: c-decl.c
>> ===================================================================
>> --- c-decl.c  (revision 224250)
>> +++ c-decl.c  (working copy)
>> @@ -7946,7 +7946,8 @@
>>    the_enum->enum_overflow = 0;
>>
>>    if (flag_short_enums)
>> -    TYPE_PACKED (enumtype) = 1;
>> +    for (tree v = TYPE_MAIN_VARIANT (enumtype); v ;v = TYPE_NEXT_VARIANT (v))

Though I wonder why flag_short_enums was not true when building the
(main-)variant?
Looks like -fshort-enums is also 'Optimization', so the above is bogus for

enum foo {x = 1 };

void __attribute__((optimize(short-enums))) foo()
{
  const enum foo x = 1;
}

no?  The main variant is correctly _not_ packed but now you make it
packed as you reach foo ()?

Richard.

> Please fix the formatting here: no space before ;.
>
> Ok with that change.
>
>         Marek

Re: Fix verify_type ICE with -fshort-enum

[Jan Hubicka]

> >>       PR middle-end/66325
> >>       * c-decl.c (start_enum): Set TYPE_PACKED consistently among type variants.
> >> Index: c-decl.c
> >> ===================================================================
> >> --- c-decl.c  (revision 224250)
> >> +++ c-decl.c  (working copy)
> >> @@ -7946,7 +7946,8 @@
> >>    the_enum->enum_overflow = 0;
> >>
> >>    if (flag_short_enums)
> >> -    TYPE_PACKED (enumtype) = 1;
> >> +    for (tree v = TYPE_MAIN_VARIANT (enumtype); v ;v = TYPE_NEXT_VARIANT (v))
> 
> Though I wonder why flag_short_enums was not true when building the
> (main-)variant?

What I believe happens is that there is forward declaration of enum that leads
to biuld incomplete enum type that has no packed flag set.  Then we produce
a type variant and after that we complete the main variant, but do not update
the other variant.

Actually looking into where the variant is updated, it happens in finish_enum
that copies many flags, perhaps it would make more sense to copy TYPE_PACKED
there?

> Looks like -fshort-enums is also 'Optimization', so the above is bogus for
> 
> enum foo {x = 1 };
> 
> void __attribute__((optimize(short-enums))) foo()
> {
>   const enum foo x = 1;
> }
> 
> no?  The main variant is correctly _not_ packed but now you make it
> packed as you reach foo ()?

Perhaps it is defined as Optimization but it does not bind to uses of types:

enum foo {a,b,c};
 __attribute__((optimize("short-enums"))) 
main()
{
  const enum foo x;
  enum bar {a,b,c};
  printf ("%i %i\n",sizeof (x), sizeof(enum bar));
}

prints
4 1

it depends when the main variant is finished.  I wonder if there is any
practical value on support Optimization attribute for this kind of ABI breaking
options.  It may be easier to simply drop the Optimization flag completely from
-fshort-enums and friends.

-fshort-double ICEs at initialization time at least since 4.8.x
$ gcc t.c -fshort-double
<built-in>: internal compiler error: in layout_type, at stor-layout.c:2220
0xafe41b layout_type(tree_node*)
        ../../gcc/stor-layout.c:2219

so I suggest dropping that flag completely.

Honza
> 
> Richard.
> 
> > Please fix the formatting here: no space before ;.
> >
> > Ok with that change.
> >
> >         Marek

Re: Fix verify_type ICE with -fshort-enum

[Richard Biener]

On Wed, Jun 17, 2015 at 12:10 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> >>       PR middle-end/66325
>> >>       * c-decl.c (start_enum): Set TYPE_PACKED consistently among type variants.
>> >> Index: c-decl.c
>> >> ===================================================================
>> >> --- c-decl.c  (revision 224250)
>> >> +++ c-decl.c  (working copy)
>> >> @@ -7946,7 +7946,8 @@
>> >>    the_enum->enum_overflow = 0;
>> >>
>> >>    if (flag_short_enums)
>> >> -    TYPE_PACKED (enumtype) = 1;
>> >> +    for (tree v = TYPE_MAIN_VARIANT (enumtype); v ;v = TYPE_NEXT_VARIANT (v))
>>
>> Though I wonder why flag_short_enums was not true when building the
>> (main-)variant?
>
> What I believe happens is that there is forward declaration of enum that leads
> to biuld incomplete enum type that has no packed flag set.  Then we produce
> a type variant and after that we complete the main variant, but do not update
> the other variant.
>
> Actually looking into where the variant is updated, it happens in finish_enum
> that copies many flags, perhaps it would make more sense to copy TYPE_PACKED
> there?

Yes, it sounds like so.

>> Looks like -fshort-enums is also 'Optimization', so the above is bogus for
>>
>> enum foo {x = 1 };
>>
>> void __attribute__((optimize(short-enums))) foo()
>> {
>>   const enum foo x = 1;
>> }
>>
>> no?  The main variant is correctly _not_ packed but now you make it
>> packed as you reach foo ()?
>
> Perhaps it is defined as Optimization but it does not bind to uses of types:
>
> enum foo {a,b,c};
>  __attribute__((optimize("short-enums")))
> main()
> {
>   const enum foo x;
>   enum bar {a,b,c};
>   printf ("%i %i\n",sizeof (x), sizeof(enum bar));
> }
>
> prints
> 4 1
>
> it depends when the main variant is finished.  I wonder if there is any
> practical value on support Optimization attribute for this kind of ABI breaking
> options.  It may be easier to simply drop the Optimization flag completely from
> -fshort-enums and friends.
>
> -fshort-double ICEs at initialization time at least since 4.8.x
> $ gcc t.c -fshort-double
> <built-in>: internal compiler error: in layout_type, at stor-layout.c:2220
> 0xafe41b layout_type(tree_node*)
>         ../../gcc/stor-layout.c:2219
>
> so I suggest dropping that flag completely.

IIRC it "works" for -m32, but yes...

Yes also to _not_ make ABI changing flags 'Optimization'.

Richard.

> Honza
>>
>> Richard.
>>
>> > Please fix the formatting here: no space before ;.
>> >
>> > Ok with that change.
>> >
>> >         Marek