Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
Thanks for the comment. I just committed the following: >From fc681f5412c421ff9609aea448310106d2570fd5 Mon Sep 17 00:00:00 2001 From: Qing Zhao Date: Tue, 17 Jan 2023 15:52:15 + Subject: [PATCH] gcc13/changes: update id 'flexible array' to 'flexible-arrays' since ids must not contain white space --- htdocs/gcc-13/changes.html | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html index 08e36fb3..ca9cd2da 100644 --- a/htdocs/gcc-13/changes.html +++ b/htdocs/gcc-13/changes.html @@ -438,7 +438,7 @@ a work-in-progress. Other significant improvements -Treating trailing arrays as flexible array members +Treating trailing arrays as flexible array members GCC can now control when to treat the trailing array of a structure as a -- 2.31.1 > On Jan 13, 2023, at 3:59 PM, Gerald Pfeifer wrote: > > On Tue, 20 Dec 2022, Qing Zhao via Gcc-patches wrote: >> +Treating trailing arrays as flexible array >> members > > Please note that ids must not contain white space. > > Would you mind following up making this "flexiblearray" or similiar? > > Thank you, > Gerald
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
On Tue, 20 Dec 2022, Qing Zhao via Gcc-patches wrote: > +Treating trailing arrays as flexible array > members Please note that ids must not contain white space. Would you mind following up making this "flexiblearray" or similiar? Thank you, Gerald
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
> On Jan 10, 2023, at 3:06 AM, Richard Biener wrote: > > On Mon, 9 Jan 2023, Qing Zhao wrote: > >> >> >>> On Jan 9, 2023, at 2:11 AM, Richard Biener wrote: >>> >>> On Thu, 22 Dec 2022, Qing Zhao wrote: >>> >>>> >>>> >>>>> On Dec 22, 2022, at 2:09 AM, Richard Biener wrote: >>>>> >>>>> On Wed, 21 Dec 2022, Qing Zhao wrote: >>>>> >>>>>> Hi, Richard, >>>>>> >>>>>> Thanks a lot for your comments. >>>>>> >>>>>>> On Dec 21, 2022, at 2:12 AM, Richard Biener wrote: >>>>>>> >>>>>>> On Tue, 20 Dec 2022, Qing Zhao wrote: >>>>>>> >>>>>>>> Hi, >>>>>>>> >>>>>>>> This is the patch for mentioning -fstrict-flex-arrays and >>>>>>>> -Warray-bounds=2 changes in gcc-13/changes.html. >>>>>>>> >>>>>>>> Let me know if you have any comment or suggestions. >>>>>>> >>>>>>> Some copy editing below >>>>>>> >>>>>>>> Thanks. >>>>>>>> >>>>>>>> Qing. >>>>>>>> >>>>>>>> === >>>>>>>> From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001 >>>>>>>> From: Qing Zhao >>>>>>>> Date: Tue, 20 Dec 2022 16:13:04 + >>>>>>>> Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its >>>>>>>> impact. >>>>>>>> >>>>>>>> --- >>>>>>>> htdocs/gcc-13/changes.html | 15 +++ >>>>>>>> 1 file changed, 15 insertions(+) >>>>>>>> >>>>>>>> diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html >>>>>>>> index 689178f9..47b3d40f 100644 >>>>>>>> --- a/htdocs/gcc-13/changes.html >>>>>>>> +++ b/htdocs/gcc-13/changes.html >>>>>>>> @@ -39,6 +39,10 @@ a work-in-progress. >>>>>>>> Legacy debug info compression option -gz=zlib-gnu >>>>>>>> was removed >>>>>>>>and the option is ignored right now. >>>>>>>> New debug info compression option value -gz=zstd has >>>>>>>> been added. >>>>>>>> +-Warray-bounds=2 will no longer issue warnings >>>>>>>> for out of bounds >>>>>>>> + accesses to trailing struct members of one-element array type >>>>>>>> anymore. Please >>>>>>>> + add -fstrict-flex-arrays=level to control how the >>>>>>>> compiler treat >>>>>>>> + trailing arrays of structures as flexible array members. >>>>>>> >>>>>>> "Instead it diagnoses accesses to trailing arrays according to >>>>>>> -fstrict-flex-arrays." >>>>>> >>>>>> Okay. >>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> @@ -409,6 +413,17 @@ a work-in-progress. >>>>>>>> Other significant improvements >>>>>>>> >>>>>>>> >>>>>>>> +Treating trailing arrays as flexible array >>>>>>>> members >>>>>>>> + >>>>>>>> + >>>>>>>> + GCC can now control when to treat the trailing array of a >>>>>>>> structure as a >>>>>>>> + flexible array member for the purpose of accessing the elements >>>>>>>> of such >>>>>>>> + an array. By default, all trailing arrays of structures are >>>>>>>> treated as >>>>>>> >>>>>>> all trailing arrays in aggregates are treated >>>>>> Okay. >>>>>>> >>>>>>>> + flexible array members. Use the new command-line option >>>>>>>> + -fstrict-flex-array=level to control how GCC treats >>>>>>>> the trailing
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
On Mon, 9 Jan 2023, Qing Zhao wrote: > > > > On Jan 9, 2023, at 2:11 AM, Richard Biener wrote: > > > > On Thu, 22 Dec 2022, Qing Zhao wrote: > > > >> > >> > >>> On Dec 22, 2022, at 2:09 AM, Richard Biener wrote: > >>> > >>> On Wed, 21 Dec 2022, Qing Zhao wrote: > >>> > >>>> Hi, Richard, > >>>> > >>>> Thanks a lot for your comments. > >>>> > >>>>> On Dec 21, 2022, at 2:12 AM, Richard Biener wrote: > >>>>> > >>>>> On Tue, 20 Dec 2022, Qing Zhao wrote: > >>>>> > >>>>>> Hi, > >>>>>> > >>>>>> This is the patch for mentioning -fstrict-flex-arrays and > >>>>>> -Warray-bounds=2 changes in gcc-13/changes.html. > >>>>>> > >>>>>> Let me know if you have any comment or suggestions. > >>>>> > >>>>> Some copy editing below > >>>>> > >>>>>> Thanks. > >>>>>> > >>>>>> Qing. > >>>>>> > >>>>>> === > >>>>>> From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001 > >>>>>> From: Qing Zhao > >>>>>> Date: Tue, 20 Dec 2022 16:13:04 + > >>>>>> Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its > >>>>>> impact. > >>>>>> > >>>>>> --- > >>>>>> htdocs/gcc-13/changes.html | 15 +++ > >>>>>> 1 file changed, 15 insertions(+) > >>>>>> > >>>>>> diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html > >>>>>> index 689178f9..47b3d40f 100644 > >>>>>> --- a/htdocs/gcc-13/changes.html > >>>>>> +++ b/htdocs/gcc-13/changes.html > >>>>>> @@ -39,6 +39,10 @@ a work-in-progress. > >>>>>> Legacy debug info compression option -gz=zlib-gnu > >>>>>> was removed > >>>>>> and the option is ignored right now. > >>>>>> New debug info compression option value -gz=zstd > >>>>>> has been added. > >>>>>> +-Warray-bounds=2 will no longer issue warnings > >>>>>> for out of bounds > >>>>>> + accesses to trailing struct members of one-element array type > >>>>>> anymore. Please > >>>>>> + add -fstrict-flex-arrays=level to control how the > >>>>>> compiler treat > >>>>>> + trailing arrays of structures as flexible array members. > >>>>> > >>>>> "Instead it diagnoses accesses to trailing arrays according to > >>>>> -fstrict-flex-arrays." > >>>> > >>>> Okay. > >>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> @@ -409,6 +413,17 @@ a work-in-progress. > >>>>>> Other significant improvements > >>>>>> > >>>>>> > >>>>>> +Treating trailing arrays as flexible array > >>>>>> members > >>>>>> + > >>>>>> + > >>>>>> + GCC can now control when to treat the trailing array of a > >>>>>> structure as a > >>>>>> + flexible array member for the purpose of accessing the elements > >>>>>> of such > >>>>>> + an array. By default, all trailing arrays of structures are > >>>>>> treated as > >>>>> > >>>>> all trailing arrays in aggregates are treated > >>>> Okay. > >>>>> > >>>>>> + flexible array members. Use the new command-line option > >>>>>> + -fstrict-flex-array=level to control how GCC treats > >>>>>> the trailing > >>>>>> + array of a structure as a flexible array member at different > >>>>>> levels. > >>>>> > >>>>> -fstrict-flex-arrays to control which trailing array > >>>>> members are streated as flexible arrays. > >>>> > >>&g
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
> On Jan 9, 2023, at 2:11 AM, Richard Biener wrote: > > On Thu, 22 Dec 2022, Qing Zhao wrote: > >> >> >>> On Dec 22, 2022, at 2:09 AM, Richard Biener wrote: >>> >>> On Wed, 21 Dec 2022, Qing Zhao wrote: >>> >>>> Hi, Richard, >>>> >>>> Thanks a lot for your comments. >>>> >>>>> On Dec 21, 2022, at 2:12 AM, Richard Biener wrote: >>>>> >>>>> On Tue, 20 Dec 2022, Qing Zhao wrote: >>>>> >>>>>> Hi, >>>>>> >>>>>> This is the patch for mentioning -fstrict-flex-arrays and >>>>>> -Warray-bounds=2 changes in gcc-13/changes.html. >>>>>> >>>>>> Let me know if you have any comment or suggestions. >>>>> >>>>> Some copy editing below >>>>> >>>>>> Thanks. >>>>>> >>>>>> Qing. >>>>>> >>>>>> === >>>>>> From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001 >>>>>> From: Qing Zhao >>>>>> Date: Tue, 20 Dec 2022 16:13:04 + >>>>>> Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its >>>>>> impact. >>>>>> >>>>>> --- >>>>>> htdocs/gcc-13/changes.html | 15 +++ >>>>>> 1 file changed, 15 insertions(+) >>>>>> >>>>>> diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html >>>>>> index 689178f9..47b3d40f 100644 >>>>>> --- a/htdocs/gcc-13/changes.html >>>>>> +++ b/htdocs/gcc-13/changes.html >>>>>> @@ -39,6 +39,10 @@ a work-in-progress. >>>>>> Legacy debug info compression option -gz=zlib-gnu was >>>>>> removed >>>>>> and the option is ignored right now. >>>>>> New debug info compression option value -gz=zstd has >>>>>> been added. >>>>>> +-Warray-bounds=2 will no longer issue warnings for >>>>>> out of bounds >>>>>> + accesses to trailing struct members of one-element array type >>>>>> anymore. Please >>>>>> + add -fstrict-flex-arrays=level to control how the >>>>>> compiler treat >>>>>> + trailing arrays of structures as flexible array members. >>>>> >>>>> "Instead it diagnoses accesses to trailing arrays according to >>>>> -fstrict-flex-arrays." >>>> >>>> Okay. >>>>> >>>>>> >>>>>> >>>>>> >>>>>> @@ -409,6 +413,17 @@ a work-in-progress. >>>>>> Other significant improvements >>>>>> >>>>>> >>>>>> +Treating trailing arrays as flexible array >>>>>> members >>>>>> + >>>>>> + >>>>>> + GCC can now control when to treat the trailing array of a >>>>>> structure as a >>>>>> + flexible array member for the purpose of accessing the elements of >>>>>> such >>>>>> + an array. By default, all trailing arrays of structures are >>>>>> treated as >>>>> >>>>> all trailing arrays in aggregates are treated >>>> Okay. >>>>> >>>>>> + flexible array members. Use the new command-line option >>>>>> + -fstrict-flex-array=level to control how GCC treats >>>>>> the trailing >>>>>> + array of a structure as a flexible array member at different >>>>>> levels. >>>>> >>>>> -fstrict-flex-arrays to control which trailing array >>>>> members are streated as flexible arrays. >>>> >>>> Okay. >>>> >>>>> >>>>> I've also just now noticed that there's now a flag_strict_flex_arrays >>>>> check in the middle-end (in array bound diagnostics) but this option >>>>> isn't streamed or handled with LTO. I think you want to replace that >>>>> with the appropriate DECL_NOT_FLEXARRAY check. >>>> >>>> We need to know the level value of the strict_flex_arrays on the struct >>>
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
On Thu, 22 Dec 2022, Qing Zhao wrote:
>
>
> > On Dec 22, 2022, at 2:09 AM, Richard Biener wrote:
> >
> > On Wed, 21 Dec 2022, Qing Zhao wrote:
> >
> >> Hi, Richard,
> >>
> >> Thanks a lot for your comments.
> >>
> >>> On Dec 21, 2022, at 2:12 AM, Richard Biener wrote:
> >>>
> >>> On Tue, 20 Dec 2022, Qing Zhao wrote:
> >>>
> >>>> Hi,
> >>>>
> >>>> This is the patch for mentioning -fstrict-flex-arrays and
> >>>> -Warray-bounds=2 changes in gcc-13/changes.html.
> >>>>
> >>>> Let me know if you have any comment or suggestions.
> >>>
> >>> Some copy editing below
> >>>
> >>>> Thanks.
> >>>>
> >>>> Qing.
> >>>>
> >>>> =======
> >>>> From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001
> >>>> From: Qing Zhao
> >>>> Date: Tue, 20 Dec 2022 16:13:04 +
> >>>> Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its
> >>>> impact.
> >>>>
> >>>> ---
> >>>> htdocs/gcc-13/changes.html | 15 +++
> >>>> 1 file changed, 15 insertions(+)
> >>>>
> >>>> diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html
> >>>> index 689178f9..47b3d40f 100644
> >>>> --- a/htdocs/gcc-13/changes.html
> >>>> +++ b/htdocs/gcc-13/changes.html
> >>>> @@ -39,6 +39,10 @@ a work-in-progress.
> >>>>Legacy debug info compression option -gz=zlib-gnu
> >>>> was removed
> >>>> and the option is ignored right now.
> >>>>New debug info compression option value -gz=zstd has
> >>>> been added.
> >>>> +-Warray-bounds=2 will no longer issue warnings for
> >>>> out of bounds
> >>>> + accesses to trailing struct members of one-element array type
> >>>> anymore. Please
> >>>> + add -fstrict-flex-arrays=level to control how the
> >>>> compiler treat
> >>>> + trailing arrays of structures as flexible array members.
> >>>
> >>> "Instead it diagnoses accesses to trailing arrays according to
> >>> -fstrict-flex-arrays."
> >>
> >> Okay.
> >>>
> >>>>
> >>>>
> >>>>
> >>>> @@ -409,6 +413,17 @@ a work-in-progress.
> >>>> Other significant improvements
> >>>>
> >>>>
> >>>> +Treating trailing arrays as flexible array
> >>>> members
> >>>> +
> >>>> +
> >>>> + GCC can now control when to treat the trailing array of a
> >>>> structure as a
> >>>> + flexible array member for the purpose of accessing the elements of
> >>>> such
> >>>> + an array. By default, all trailing arrays of structures are
> >>>> treated as
> >>>
> >>> all trailing arrays in aggregates are treated
> >> Okay.
> >>>
> >>>> + flexible array members. Use the new command-line option
> >>>> + -fstrict-flex-array=level to control how GCC treats
> >>>> the trailing
> >>>> + array of a structure as a flexible array member at different
> >>>> levels.
> >>>
> >>> -fstrict-flex-arrays to control which trailing array
> >>> members are streated as flexible arrays.
> >>
> >> Okay.
> >>
> >>>
> >>> I've also just now noticed that there's now a flag_strict_flex_arrays
> >>> check in the middle-end (in array bound diagnostics) but this option
> >>> isn't streamed or handled with LTO. I think you want to replace that
> >>> with the appropriate DECL_NOT_FLEXARRAY check.
> >>
> >> We need to know the level value of the strict_flex_arrays on the struct
> >> field to issue proper warnings at different levels. DECL_NOT_FLEXARRAY
> >> does not include such info. So, what should I do? Streaming the
> >> flag_strict_flex_arrays with LTO?
> >
> > But you do
> >
> > if (compref)
> >{
> > /* Try to determine special array member type for this
> > COMPONENT_REF. */
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
> On Dec 22, 2022, at 2:09 AM, Richard Biener wrote:
>
> On Wed, 21 Dec 2022, Qing Zhao wrote:
>
>> Hi, Richard,
>>
>> Thanks a lot for your comments.
>>
>>> On Dec 21, 2022, at 2:12 AM, Richard Biener wrote:
>>>
>>> On Tue, 20 Dec 2022, Qing Zhao wrote:
>>>
>>>> Hi,
>>>>
>>>> This is the patch for mentioning -fstrict-flex-arrays and -Warray-bounds=2
>>>> changes in gcc-13/changes.html.
>>>>
>>>> Let me know if you have any comment or suggestions.
>>>
>>> Some copy editing below
>>>
>>>> Thanks.
>>>>
>>>> Qing.
>>>>
>>>> ===============
>>>> From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001
>>>> From: Qing Zhao
>>>> Date: Tue, 20 Dec 2022 16:13:04 +
>>>> Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its
>>>> impact.
>>>>
>>>> ---
>>>> htdocs/gcc-13/changes.html | 15 +++
>>>> 1 file changed, 15 insertions(+)
>>>>
>>>> diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html
>>>> index 689178f9..47b3d40f 100644
>>>> --- a/htdocs/gcc-13/changes.html
>>>> +++ b/htdocs/gcc-13/changes.html
>>>> @@ -39,6 +39,10 @@ a work-in-progress.
>>>>Legacy debug info compression option -gz=zlib-gnu was
>>>> removed
>>>> and the option is ignored right now.
>>>>New debug info compression option value -gz=zstd has
>>>> been added.
>>>> +-Warray-bounds=2 will no longer issue warnings for
>>>> out of bounds
>>>> + accesses to trailing struct members of one-element array type
>>>> anymore. Please
>>>> + add -fstrict-flex-arrays=level to control how the
>>>> compiler treat
>>>> + trailing arrays of structures as flexible array members.
>>>
>>> "Instead it diagnoses accesses to trailing arrays according to
>>> -fstrict-flex-arrays."
>>
>> Okay.
>>>
>>>>
>>>>
>>>>
>>>> @@ -409,6 +413,17 @@ a work-in-progress.
>>>> Other significant improvements
>>>>
>>>>
>>>> +Treating trailing arrays as flexible array
>>>> members
>>>> +
>>>> +
>>>> + GCC can now control when to treat the trailing array of a structure
>>>> as a
>>>> + flexible array member for the purpose of accessing the elements of
>>>> such
>>>> + an array. By default, all trailing arrays of structures are treated
>>>> as
>>>
>>> all trailing arrays in aggregates are treated
>> Okay.
>>>
>>>> + flexible array members. Use the new command-line option
>>>> + -fstrict-flex-array=level to control how GCC treats the
>>>> trailing
>>>> + array of a structure as a flexible array member at different levels.
>>>
>>> -fstrict-flex-arrays to control which trailing array
>>> members are streated as flexible arrays.
>>
>> Okay.
>>
>>>
>>> I've also just now noticed that there's now a flag_strict_flex_arrays
>>> check in the middle-end (in array bound diagnostics) but this option
>>> isn't streamed or handled with LTO. I think you want to replace that
>>> with the appropriate DECL_NOT_FLEXARRAY check.
>>
>> We need to know the level value of the strict_flex_arrays on the struct
>> field to issue proper warnings at different levels. DECL_NOT_FLEXARRAY
>> does not include such info. So, what should I do? Streaming the
>> flag_strict_flex_arrays with LTO?
>
> But you do
>
> if (compref)
>{
> /* Try to determine special array member type for this
> COMPONENT_REF. */
> sam = component_ref_sam_type (arg);
> /* Get the level of strict_flex_array for this array field. */
> tree afield_decl = TREE_OPERAND (arg, 1);
> strict_flex_array_level = strict_flex_array_level_of (afield_decl);
>
> I see that function doesn't look at DECL_NOT_FLEXARRAY but just
> checks attributes (those are streamed in LTO).
Yes, checked both flag_strict_flex_arrays and attributes.
There are two places in middle end calling “strict_flex_array_level_of”
function,
one inside “array_bounds_checker::check_array_ref”, another one inside
“component
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
On Wed, 21 Dec 2022, Qing Zhao wrote:
> Hi, Richard,
>
> Thanks a lot for your comments.
>
> > On Dec 21, 2022, at 2:12 AM, Richard Biener wrote:
> >
> > On Tue, 20 Dec 2022, Qing Zhao wrote:
> >
> >> Hi,
> >>
> >> This is the patch for mentioning -fstrict-flex-arrays and -Warray-bounds=2
> >> changes in gcc-13/changes.html.
> >>
> >> Let me know if you have any comment or suggestions.
> >
> > Some copy editing below
> >
> >> Thanks.
> >>
> >> Qing.
> >>
> >> ===
> >> From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001
> >> From: Qing Zhao
> >> Date: Tue, 20 Dec 2022 16:13:04 +
> >> Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its
> >> impact.
> >>
> >> ---
> >> htdocs/gcc-13/changes.html | 15 +++
> >> 1 file changed, 15 insertions(+)
> >>
> >> diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html
> >> index 689178f9..47b3d40f 100644
> >> --- a/htdocs/gcc-13/changes.html
> >> +++ b/htdocs/gcc-13/changes.html
> >> @@ -39,6 +39,10 @@ a work-in-progress.
> >> Legacy debug info compression option -gz=zlib-gnu was
> >> removed
> >> and the option is ignored right now.
> >> New debug info compression option value -gz=zstd has
> >> been added.
> >> +-Warray-bounds=2 will no longer issue warnings for
> >> out of bounds
> >> + accesses to trailing struct members of one-element array type
> >> anymore. Please
> >> + add -fstrict-flex-arrays=level to control how the
> >> compiler treat
> >> + trailing arrays of structures as flexible array members.
> >
> > "Instead it diagnoses accesses to trailing arrays according to
> > -fstrict-flex-arrays."
>
> Okay.
> >
> >>
> >>
> >>
> >> @@ -409,6 +413,17 @@ a work-in-progress.
> >> Other significant improvements
> >>
> >>
> >> +Treating trailing arrays as flexible array
> >> members
> >> +
> >> +
> >> + GCC can now control when to treat the trailing array of a structure
> >> as a
> >> + flexible array member for the purpose of accessing the elements of
> >> such
> >> + an array. By default, all trailing arrays of structures are treated
> >> as
> >
> > all trailing arrays in aggregates are treated
> Okay.
> >
> >> + flexible array members. Use the new command-line option
> >> + -fstrict-flex-array=level to control how GCC treats the
> >> trailing
> >> + array of a structure as a flexible array member at different levels.
> >
> > -fstrict-flex-arrays to control which trailing array
> > members are streated as flexible arrays.
>
> Okay.
>
> >
> > I've also just now noticed that there's now a flag_strict_flex_arrays
> > check in the middle-end (in array bound diagnostics) but this option
> > isn't streamed or handled with LTO. I think you want to replace that
> > with the appropriate DECL_NOT_FLEXARRAY check.
>
> We need to know the level value of the strict_flex_arrays on the struct
> field to issue proper warnings at different levels. DECL_NOT_FLEXARRAY
> does not include such info. So, what should I do? Streaming the
> flag_strict_flex_arrays with LTO?
But you do
if (compref)
{
/* Try to determine special array member type for this
COMPONENT_REF. */
sam = component_ref_sam_type (arg);
/* Get the level of strict_flex_array for this array field. */
tree afield_decl = TREE_OPERAND (arg, 1);
strict_flex_array_level = strict_flex_array_level_of (afield_decl);
I see that function doesn't look at DECL_NOT_FLEXARRAY but just
checks attributes (those are streamed in LTO).
OK, so I suppose the diagnostic itself would become just less precise
as in "trailing array %qT should not be used as a flexible array member"
without the "for level N and above" part of the diagnostic?
> > We might also want
> > to see how inlining accesses from TUs with different -fstrict-flex-arrays
> > setting behaves when accessing the same structure (and whether we might
> > want to issue an ODR style diagnostic there).
This mixing also means streaming -fstrict-flex-arrays won't be of much
help in general.
> Yes, good point, I will check on this part.
>
> BTW, a stupid question: what does ODR mean?
It's the One-Definition-Rule (of C++). Basically we'd diagnose
same struct declarations with different -fstrict-flex-arrays setting.
I see we miss comparing DECL_NOT_FLEXARRAY for tree merging, I'm
testing a patch to fix that now.
Richard.
> thanks.
>
> Qing
> >
> > Thanks,
> > Richard.
>
>
--
Richard Biener
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
Hi, Richard, Thanks a lot for your comments. > On Dec 21, 2022, at 2:12 AM, Richard Biener wrote: > > On Tue, 20 Dec 2022, Qing Zhao wrote: > >> Hi, >> >> This is the patch for mentioning -fstrict-flex-arrays and -Warray-bounds=2 >> changes in gcc-13/changes.html. >> >> Let me know if you have any comment or suggestions. > > Some copy editing below > >> Thanks. >> >> Qing. >> >> === >> From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001 >> From: Qing Zhao >> Date: Tue, 20 Dec 2022 16:13:04 +0000 >> Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its impact. >> >> --- >> htdocs/gcc-13/changes.html | 15 +++ >> 1 file changed, 15 insertions(+) >> >> diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html >> index 689178f9..47b3d40f 100644 >> --- a/htdocs/gcc-13/changes.html >> +++ b/htdocs/gcc-13/changes.html >> @@ -39,6 +39,10 @@ a work-in-progress. >> Legacy debug info compression option -gz=zlib-gnu was >> removed >> and the option is ignored right now. >> New debug info compression option value -gz=zstd has >> been added. >> +-Warray-bounds=2 will no longer issue warnings for out >> of bounds >> + accesses to trailing struct members of one-element array type >> anymore. Please >> + add -fstrict-flex-arrays=level to control how the >> compiler treat >> + trailing arrays of structures as flexible array members. > > "Instead it diagnoses accesses to trailing arrays according to > -fstrict-flex-arrays." Okay. > >> >> >> >> @@ -409,6 +413,17 @@ a work-in-progress. >> Other significant improvements >> >> >> +Treating trailing arrays as flexible array >> members >> + >> + >> + GCC can now control when to treat the trailing array of a structure as >> a >> + flexible array member for the purpose of accessing the elements of such >> + an array. By default, all trailing arrays of structures are treated as > > all trailing arrays in aggregates are treated Okay. > >> + flexible array members. Use the new command-line option >> + -fstrict-flex-array=level to control how GCC treats the >> trailing >> + array of a structure as a flexible array member at different levels. > > -fstrict-flex-arrays to control which trailing array > members are streated as flexible arrays. Okay. > > I've also just now noticed that there's now a flag_strict_flex_arrays > check in the middle-end (in array bound diagnostics) but this option > isn't streamed or handled with LTO. I think you want to replace that > with the appropriate DECL_NOT_FLEXARRAY check. We need to know the level value of the strict_flex_arrays on the struct field to issue proper warnings at different levels. DECL_NOT_FLEXARRAY does not include such info. So, what should I do? Streaming the flag_strict_flex_arrays with LTO? > We might also want > to see how inlining accesses from TUs with different -fstrict-flex-arrays > setting behaves when accessing the same structure (and whether we might > want to issue an ODR style diagnostic there). Yes, good point, I will check on this part. BTW, a stupid question: what does ODR mean? thanks. Qing > > Thanks, > Richard.
Re: gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
On Tue, 20 Dec 2022, Qing Zhao wrote: > Hi, > > This is the patch for mentioning -fstrict-flex-arrays and -Warray-bounds=2 > changes in gcc-13/changes.html. > > Let me know if you have any comment or suggestions. Some copy editing below > Thanks. > > Qing. > > === > From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001 > From: Qing Zhao > Date: Tue, 20 Dec 2022 16:13:04 + > Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its impact. > > --- > htdocs/gcc-13/changes.html | 15 +++ > 1 file changed, 15 insertions(+) > > diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html > index 689178f9..47b3d40f 100644 > --- a/htdocs/gcc-13/changes.html > +++ b/htdocs/gcc-13/changes.html > @@ -39,6 +39,10 @@ a work-in-progress. > Legacy debug info compression option -gz=zlib-gnu was > removed >and the option is ignored right now. > New debug info compression option value -gz=zstd has > been added. > +-Warray-bounds=2 will no longer issue warnings for out > of bounds > + accesses to trailing struct members of one-element array type anymore. > Please > + add -fstrict-flex-arrays=level to control how the > compiler treat > + trailing arrays of structures as flexible array members. "Instead it diagnoses accesses to trailing arrays according to -fstrict-flex-arrays." > > > > @@ -409,6 +413,17 @@ a work-in-progress. > Other significant improvements > > > +Treating trailing arrays as flexible array > members > + > + > + GCC can now control when to treat the trailing array of a structure as > a > + flexible array member for the purpose of accessing the elements of such > + an array. By default, all trailing arrays of structures are treated as all trailing arrays in aggregates are treated > + flexible array members. Use the new command-line option > + -fstrict-flex-array=level to control how GCC treats the > trailing > + array of a structure as a flexible array member at different levels. -fstrict-flex-arrays to control which trailing array members are streated as flexible arrays. I've also just now noticed that there's now a flag_strict_flex_arrays check in the middle-end (in array bound diagnostics) but this option isn't streamed or handled with LTO. I think you want to replace that with the appropriate DECL_NOT_FLEXARRAY check. We might also want to see how inlining accesses from TUs with different -fstrict-flex-arrays setting behaves when accessing the same structure (and whether we might want to issue an ODR style diagnostic there). Thanks, Richard.
gcc-13/changes.html: Mention -fstrict-flex-arrays and its impact
Hi, This is the patch for mentioning -fstrict-flex-arrays and -Warray-bounds=2 changes in gcc-13/changes.html. Let me know if you have any comment or suggestions. Thanks. Qing. === >From c022076169b4f1990b91f7daf4cc52c6c5535228 Mon Sep 17 00:00:00 2001 From: Qing Zhao Date: Tue, 20 Dec 2022 16:13:04 + Subject: [PATCH] gcc-13/changes: Mention -fstrict-flex-arrays and its impact. --- htdocs/gcc-13/changes.html | 15 +++ 1 file changed, 15 insertions(+) diff --git a/htdocs/gcc-13/changes.html b/htdocs/gcc-13/changes.html index 689178f9..47b3d40f 100644 --- a/htdocs/gcc-13/changes.html +++ b/htdocs/gcc-13/changes.html @@ -39,6 +39,10 @@ a work-in-progress. Legacy debug info compression option -gz=zlib-gnu was removed and the option is ignored right now. New debug info compression option value -gz=zstd has been added. +-Warray-bounds=2 will no longer issue warnings for out of bounds + accesses to trailing struct members of one-element array type anymore. Please + add -fstrict-flex-arrays=level to control how the compiler treat + trailing arrays of structures as flexible array members. @@ -409,6 +413,17 @@ a work-in-progress. Other significant improvements +Treating trailing arrays as flexible array members + + + GCC can now control when to treat the trailing array of a structure as a + flexible array member for the purpose of accessing the elements of such + an array. By default, all trailing arrays of structures are treated as + flexible array members. Use the new command-line option + -fstrict-flex-array=level to control how GCC treats the trailing + array of a structure as a flexible array member at different levels. + + -- 2.31.1
