> On Mar 10, 2023, at 2:54 AM, Richard Biener <rguent...@suse.de> wrote:
>
> On Thu, 9 Mar 2023, Qing Zhao wrote:
>
>>
>>
>>> On Mar 9, 2023, at 7:20 AM, Richard Biener <rguent...@suse.de> wrote:
>>>
>>> On Fri, 24 Feb 2023, Qing Zhao wrote:
>>>
>>>> GCC extension accepts the case when a struct with a C99 flexible array
>>>> member
>>>> is embedded into another struct or union (possibly recursively).
>>>> __builtin_object_size should treat such struct as flexible size.
>>>>
>>>> gcc/c/ChangeLog:
>>>>
>>>> PR tree-optimization/101832
>>>> * c-decl.cc (finish_struct): Set TYPE_INCLUDE_FLEXARRAY for
>>>> struct/union type.
>>>
>>> I can't really comment on the correctness of this part but since
>>> only the C frontend will ever set this and you are using it from
>>> addr_object_size which is also used for other C family languages
>>> (at least), I wonder if you can really test
>>>
>>> + if (!TYPE_INCLUDE_FLEXARRAY (TREE_TYPE (v)))
>>>
>>> there.
>>
>> You mean for C++ and also other C family languages (other than C), the above
>> bit cannot be set?
>> Yes, that’s true. The bit is only set for C. So is the bit
>> DECL_NOT_FLEXARRAY, which is only set for C too.
>> So, I am wondering whether the bit DECL_NOT_FLEXARRAY should be also set in
>> middle end? Or we can set DECL_NOT_FLEXARRAY in C++ FE too? And then we can
>> set TYPE_INCLUDE_FLEXARRAY also in C++ FE?
>> What’s your suggestion?
>>
>> (I personally feel that DECL_NOT_FLEXARRAY and TYPE_INCLUDE_FLEXARRAY should
>> be set in the same places).
>
> I was wondering if the above test errors on the conservative side
> correctly - it will now, for all but C, cut off some thing where it
> didn't before?
As long as the default value of TYPE_INCLUDE_FLEXARRAY reflects the correct
conservative behavior, then the testing should be correct, right?
The default value of TYPE_INCLUDE_FLEXARRAY is 0, i.e, FALSE, means that the
TYPE does not include a flex array by default, this is the correct behavior.
Only when the TYPE does include a flexiarray, it will be set to TRUE. So, I
think it’s correct.
This is a different situation for DECL_NOT_FLEXARRAY, by default, the compiler
will treat ALL trailing arrays as FMA, so in order to keep the correct
conservative behavior, we should keep the default value for DECL_NOT_FLEXARRAY
as it’s a FMA, i.e, DECL_NOT_FLEXARRAY being FALSE, by default. Only when the
array is NOT a FMA, we set it to true.
So, the default value for TYPE_INCLUDE_FLEXARRAY is correct.
>
>>>
>>> Originally I was suggesting to set this flag in stor-layout.cc
>>> which eventually all languages funnel their types through and
>>> if there's language specific handling use a langhook (with the
>>> default implementation preserving the status quo).
>>
>> If we decide to set the bits in stor-layout.cc, where is the best place to
>> do it? I checked the star-layout.cc code, looks like “layout_type” might be
>> the place where we can set these bits for RECORD_TYPE, UNION_TYPE?
>
> Yes, it would be layout_type.
>
>>>
>>> Some more comments below ...
>>>
>>>> gcc/cp/ChangeLog:
>>>>
>>>> PR tree-optimization/101832
>>>> * module.cc (trees_out::core_bools): Stream out new bit
>>>> type_include_flexarray.
>>>> (trees_in::core_bools): Stream in new bit type_include_flexarray.
>>>>
>>>> gcc/ChangeLog:
>>>>
>>>> PR tree-optimization/101832
>>>> * print-tree.cc (print_node): Print new bit type_include_flexarray.
>>>> * tree-core.h (struct tree_type_common): New bit
>>>> type_include_flexarray.
>>>> * tree-object-size.cc (addr_object_size): Handle structure/union type
>>>> when it has flexible size.
>>>> * tree-streamer-in.cc (unpack_ts_type_common_value_fields): Stream
>>>> in new bit type_include_flexarray.
>>>> * tree-streamer-out.cc (pack_ts_type_common_value_fields): Stream
>>>> out new bit type_include_flexarray.
>>>> * tree.h (TYPE_INCLUDE_FLEXARRAY): New macro
>>>> TYPE_INCLUDE_FLEXARRAY.
>>>>
>>>> gcc/testsuite/ChangeLog:
>>>>
>>>> PR tree-optimization/101832
>>>> * gcc.dg/builtin-object-size-pr101832.c: New test.
>>>> ---
>>>> gcc/c/c-decl.cc | 12 ++
>>>> gcc/cp/module.cc | 2 +
>>>> gcc/print-tree.cc | 5 +
>>>> .../gcc.dg/builtin-object-size-pr101832.c | 134 ++++++++++++++++++
>>>> gcc/tree-core.h | 4 +-
>>>> gcc/tree-object-size.cc | 79 +++++++----
>>>> gcc/tree-streamer-in.cc | 1 +
>>>> gcc/tree-streamer-out.cc | 1 +
>>>> gcc/tree.h | 6 +
>>>> 9 files changed, 215 insertions(+), 29 deletions(-)
>>>> create mode 100644 gcc/testsuite/gcc.dg/builtin-object-size-pr101832.c
>>>>
>>>> diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
>>>> index 08078eadeb8..f589a2f5192 100644
>>>> --- a/gcc/c/c-decl.cc
>>>> +++ b/gcc/c/c-decl.cc
>>>> @@ -9284,6 +9284,18 @@ finish_struct (location_t loc, tree t, tree
>>>> fieldlist, tree attributes,
>>>> /* Set DECL_NOT_FLEXARRAY flag for FIELD_DECL x. */
>>>> DECL_NOT_FLEXARRAY (x) = !is_flexible_array_member_p (is_last_field,
>>>> x);
>>>>
>>>> + /* Set TYPE_INCLUDE_FLEXARRAY for the context of x, t
>>>> + * when x is an array. */
>>>> + if (TREE_CODE (TREE_TYPE (x)) == ARRAY_TYPE)
>>>> + TYPE_INCLUDE_FLEXARRAY (t) = flexible_array_member_type_p (TREE_TYPE
>>>> (x)) ;
>>>> + /* Recursively set TYPE_INCLUDE_FLEXARRAY for the context of x, t
>>>> + when x is the last field. */
>>>> + else if ((TREE_CODE (TREE_TYPE (x)) == RECORD_TYPE
>>>> + || TREE_CODE (TREE_TYPE (x)) == UNION_TYPE)
>>>> + && TYPE_INCLUDE_FLEXARRAY (TREE_TYPE (x))
>>>> + && is_last_field)
>>>> + TYPE_INCLUDE_FLEXARRAY (t) = true;
>>>> +
>>>> if (DECL_NAME (x)
>>>> || RECORD_OR_UNION_TYPE_P (TREE_TYPE (x)))
>>>> saw_named_field = true;
>>>> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
>>>> index ac2fe66b080..c750361b704 100644
>>>> --- a/gcc/cp/module.cc
>>>> +++ b/gcc/cp/module.cc
>>>> @@ -5371,6 +5371,7 @@ trees_out::core_bools (tree t)
>>>> WB (t->type_common.lang_flag_5);
>>>> WB (t->type_common.lang_flag_6);
>>>> WB (t->type_common.typeless_storage);
>>>> + WB (t->type_common.type_include_flexarray);
>>>> }
>>>>
>>>> if (CODE_CONTAINS_STRUCT (code, TS_DECL_COMMON))
>>>> @@ -5551,6 +5552,7 @@ trees_in::core_bools (tree t)
>>>> RB (t->type_common.lang_flag_5);
>>>> RB (t->type_common.lang_flag_6);
>>>> RB (t->type_common.typeless_storage);
>>>> + RB (t->type_common.type_include_flexarray);
>>>> }
>>>>
>>>> if (CODE_CONTAINS_STRUCT (code, TS_DECL_COMMON))
>>>> diff --git a/gcc/print-tree.cc b/gcc/print-tree.cc
>>>> index 1f3afcbbc86..efacdb7686f 100644
>>>> --- a/gcc/print-tree.cc
>>>> +++ b/gcc/print-tree.cc
>>>> @@ -631,6 +631,11 @@ print_node (FILE *file, const char *prefix, tree
>>>> node, int indent,
>>>> && TYPE_CXX_ODR_P (node))
>>>> fputs (" cxx-odr-p", file);
>>>>
>>>> + if ((code == RECORD_TYPE
>>>> + || code == UNION_TYPE)
>>>> + && TYPE_INCLUDE_FLEXARRAY (node))
>>>> + fputs (" include-flexarray", file);
>>>> +
>>>> /* The transparent-union flag is used for different things in
>>>> different nodes. */
>>>> if ((code == UNION_TYPE || code == RECORD_TYPE)
>>>> diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-pr101832.c
>>>> b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832.c
>>>> new file mode 100644
>>>> index 00000000000..60078e11634
>>>> --- /dev/null
>>>> +++ b/gcc/testsuite/gcc.dg/builtin-object-size-pr101832.c
>>>> @@ -0,0 +1,134 @@
>>>> +/* PR 101832:
>>>> + GCC extension accepts the case when a struct with a C99 flexible array
>>>> + member is embedded into another struct (possibly recursively).
>>>> + __builtin_object_size will treat such struct as flexible size.
>>>> + However, when a structure with non-C99 flexible array member, i.e,
>>>> trailing
>>>> + [0], [1], or [4], is embedded into anther struct, the stucture will not
>>>> + be treated as flexible size. */
>>>> +/* { dg-do run } */
>>>> +/* { dg-options "-O2" } */
>>>> +
>>>> +#include "builtin-object-size-common.h"
>>>> +
>>>> +#define expect(p, _v) do { \
>>>> + size_t v = _v; \
>>>> + if (p == v) \
>>>> + __builtin_printf ("ok: %s == %zd\n", #p, p); \
>>>> + else {\
>>>> + __builtin_printf ("WAT: %s == %zd (expected %zd)\n", #p, p, v); \
>>>> + FAIL (); \
>>>> + } \
>>>> +} while (0);
>>>> +
>>>> +
>>>> +struct A {
>>>> + int n;
>>>> + char data[];
>>>> +};
>>>> +
>>>> +struct B {
>>>> + int m;
>>>> + struct A a;
>>>> +};
>>>> +
>>>> +struct C {
>>>> + int q;
>>>> + struct B b;
>>>> +};
>>>> +
>>>> +struct A0 {
>>>> + int n;
>>>> + char data[0];
>>>> +};
>>>> +
>>>> +struct B0 {
>>>> + int m;
>>>> + struct A0 a;
>>>> +};
>>>> +
>>>> +struct C0 {
>>>> + int q;
>>>> + struct B0 b;
>>>> +};
>>>> +
>>>> +struct A1 {
>>>> + int n;
>>>> + char data[1];
>>>> +};
>>>> +
>>>> +struct B1 {
>>>> + int m;
>>>> + struct A1 a;
>>>> +};
>>>> +
>>>> +struct C1 {
>>>> + int q;
>>>> + struct B1 b;
>>>> +};
>>>> +
>>>> +struct An {
>>>> + int n;
>>>> + char data[8];
>>>> +};
>>>> +
>>>> +struct Bn {
>>>> + int m;
>>>> + struct An a;
>>>> +};
>>>> +
>>>> +struct Cn {
>>>> + int q;
>>>> + struct Bn b;
>>>> +};
>>>> +
>>>> +volatile void *magic1, *magic2;
>>>> +
>>>> +int main (int argc, char *argv[])
>>>> +{
>>>> + struct B *outer;
>>>> + struct C *outest;
>>>> +
>>>> + /* Make sure optimization can't find some other object size. */
>>>> + outer = (void *)magic1;
>>>> + outest = (void *)magic2;
>>>> +
>>>> + expect (__builtin_object_size (&outer->a, 1), -1);
>>>> + expect (__builtin_object_size (&outest->b, 1), -1);
>>>> + expect (__builtin_object_size (&outest->b.a, 1), -1);
>>>> +
>>>> + struct B0 *outer0;
>>>> + struct C0 *outest0;
>>>> +
>>>> + /* Make sure optimization can't find some other object size. */
>>>> + outer0 = (void *)magic1;
>>>> + outest0 = (void *)magic2;
>>>> +
>>>> + expect (__builtin_object_size (&outer0->a, 1), sizeof (outer0->a));
>>>> + expect (__builtin_object_size (&outest0->b, 1), sizeof (outest0->b));
>>>> + expect (__builtin_object_size (&outest0->b.a, 1), sizeof
>>>> (outest0->b.a));
>>>> +
>>>> + struct B1 *outer1;
>>>> + struct C1 *outest1;
>>>> +
>>>> + /* Make sure optimization can't find some other object size. */
>>>> + outer1 = (void *)magic1;
>>>> + outest1 = (void *)magic2;
>>>> +
>>>> + expect (__builtin_object_size (&outer1->a, 1), sizeof (outer1->a));
>>>> + expect (__builtin_object_size (&outest1->b, 1), sizeof (outest1->b));
>>>> + expect (__builtin_object_size (&outest1->b.a, 1), sizeof
>>>> (outest1->b.a));
>>>> +
>>>> + struct Bn *outern;
>>>> + struct Cn *outestn;
>>>> +
>>>> + /* Make sure optimization can't find some other object size. */
>>>> + outern = (void *)magic1;
>>>> + outestn = (void *)magic2;
>>>> +
>>>> + expect (__builtin_object_size (&outern->a, 1), sizeof (outern->a));
>>>> + expect (__builtin_object_size (&outestn->b, 1), sizeof (outestn->b));
>>>> + expect (__builtin_object_size (&outestn->b.a, 1), sizeof
>>>> (outestn->b.a));
>>>> +
>>>> + DONE ();
>>>> + return 0;
>>>> +}
>>>> diff --git a/gcc/tree-core.h b/gcc/tree-core.h
>>>> index acd8deea34e..705d5702b9c 100644
>>>> --- a/gcc/tree-core.h
>>>> +++ b/gcc/tree-core.h
>>>> @@ -1718,7 +1718,9 @@ struct GTY(()) tree_type_common {
>>>> unsigned empty_flag : 1;
>>>> unsigned indivisible_p : 1;
>>>> RECORD_OR_UNION_CHECK
>>>
>>> it looks like the bit could be eventually shared with
>>> no_named_args_stdarg_p (but its accessor doesn't use
>>> FUNC_OR_METHOD_CHECK)
>> You mean to let “type_include_flexarray” share the same bit with
>> “no_named_args_stdarg_p” in order to save 1-bit space in IR?
>> Then change the
>>
>> /* True if this is a stdarg function with no named arguments (C2x
>> (...) prototype, where arguments can be accessed with va_start and
>> va_arg), as opposed to an unprototyped function. */
>> #define TYPE_NO_NAMED_ARGS_STDARG_P(NODE) \
>> (TYPE_CHECK (NODE)->type_common.no_named_args_stdarg_p)
>>
>> /* True if this RECORD_TYPE or UNION_TYPE includes a flexible array member
>> at the last field recursively. */
>> #define TYPE_INCLUDE_FLEXARRAY(NODE) \
>> (TYPE_CHECK (NODE)->type_common.type_include_flexarray)
>>
>> To:
>>
>> union {
>> unsigned no_named_args_stdarg_p : 1;
>> /* TYPE_INCLUDE_FLEXARRAY flag for RECORD_TYPE and UNION_TYPE. */
>> unsigned int type_include_flexarray : 1;
>> } shared_bit;
>> unsigned spare : 15;
>>
>> /* True if this is a stdarg function with no named arguments (C2x
>> (...) prototype, where arguments can be accessed with va_start and
>> va_arg), as opposed to an unprototyped function. */
>> #define TYPE_NO_NAMED_ARGS_STDARG_P(NODE) \
>> (FUNC_OR_METHOD_CHECK (NODE)->type_common.shared_bit.no_named_args_stdarg_p)
>>
>> /* True if this RECORD_TYPE or UNION_TYPE includes a flexible array member
>> at the last field recursively. */
>> #define TYPE_INCLUDE_FLEXARRAY(NODE) \
>> (RECORD_OR_UNION_CHECK(NODE)->type_common.shared_bit.type_include_flexarray)
>
> No, we're just overloading bits by using the same name for different
> purposes. I don't think such a union would pack nicely. We overload
> by documenting the uses, in the above cases the uses are separated
> by the kind of the tree node, RECORD/UNION_TYPE vs. FUNCTION/METHOD_TYPE
> and the accessor macros should be updated to use the appropriate
> tree check macros covering that so we don't try to inspect the
> "wrong bit”.
Okay, I see. Then should I change the name of that bit to one that reflect two
usages?
>
>>>
>>>> alias_set_type alias_set;
>>>> tree pointer_to;
>>>> diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
>>>> index 9a936a91983..22b3c72ea6e 100644
>>>> --- a/gcc/tree-object-size.cc
>>>> +++ b/gcc/tree-object-size.cc
>>>> @@ -633,45 +633,68 @@ addr_object_size (struct object_size_info *osi,
>>>> const_tree ptr,
>>>> v = NULL_TREE;
>>>> break;
>>>> case COMPONENT_REF:
>>>> - if (TREE_CODE (TREE_TYPE (v)) != ARRAY_TYPE)
>>>> + /* When the ref is not to an array, a record or a union, it
>>>> + will not have flexible size, compute the object size
>>>> + directly. */
>>>> + if ((TREE_CODE (TREE_TYPE (v)) != ARRAY_TYPE)
>>>> + && (TREE_CODE (TREE_TYPE (v)) != RECORD_TYPE)
>>>> + && (TREE_CODE (TREE_TYPE (v)) != UNION_TYPE))
>>>> {
>>>> v = NULL_TREE;
>>>> break;
>>>> }
>>>> - is_flexible_array_mem_ref = array_ref_flexible_size_p (v);
>>>> - while (v != pt_var && TREE_CODE (v) == COMPONENT_REF)
>>>> - if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> - != UNION_TYPE
>>>> - && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> - != QUAL_UNION_TYPE)
>>>> - break;
>>>> - else
>>>> - v = TREE_OPERAND (v, 0);
>>>> - if (TREE_CODE (v) == COMPONENT_REF
>>>> - && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> - == RECORD_TYPE)
>>>> + if (TREE_CODE (TREE_TYPE (v)) == RECORD_TYPE
>>>> + || TREE_CODE (TREE_TYPE (v)) == UNION_TYPE)
>>>> + /* if the record or union does not include a flexible array
>>>> + recursively, compute the object size directly. */
>>>> {
>>>> - /* compute object size only if v is not a
>>>> - flexible array member. */
>>>> - if (!is_flexible_array_mem_ref)
>>>> + if (!TYPE_INCLUDE_FLEXARRAY (TREE_TYPE (v)))
>>>> {
>>>> v = NULL_TREE;
>>>> break;
>>>> }
>>>> - v = TREE_OPERAND (v, 0);
>>>> + else
>>>> + v = TREE_OPERAND (v, 0);
>>>> }
>>>> - while (v != pt_var && TREE_CODE (v) == COMPONENT_REF)
>>>> - if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> - != UNION_TYPE
>>>> - && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> - != QUAL_UNION_TYPE)
>>>> - break;
>>>> - else
>>>> - v = TREE_OPERAND (v, 0);
>>>> - if (v != pt_var)
>>>> - v = NULL_TREE;
>>>> else
>>>> - v = pt_var;
>>>> + {
>>>> + /* Now the ref is to an array type. */
>>>> + is_flexible_array_mem_ref
>>>> + = array_ref_flexible_size_p (v);
>>>> + while (v != pt_var && TREE_CODE (v) == COMPONENT_REF)
>>>> + if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> + != UNION_TYPE
>>>> + && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> + != QUAL_UNION_TYPE)
>>>> + break;
>>>> + else
>>>> + v = TREE_OPERAND (v, 0);
>>>> + if (TREE_CODE (v) == COMPONENT_REF
>>>> + && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> + == RECORD_TYPE)
>>>> + {
>>>> + /* compute object size only if v is not a
>>>> + flexible array member. */
>>>> + if (!is_flexible_array_mem_ref)
>>>> + {
>>>> + v = NULL_TREE;
>>>> + break;
>>>> + }
>>>> + v = TREE_OPERAND (v, 0);
>>>> + }
>>>> + while (v != pt_var && TREE_CODE (v) == COMPONENT_REF)
>>>> + if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> + != UNION_TYPE
>>>> + && TREE_CODE (TREE_TYPE (TREE_OPERAND (v, 0)))
>>>> + != QUAL_UNION_TYPE)
>>>> + break;
>>>> + else
>>>> + v = TREE_OPERAND (v, 0);
>>>> + if (v != pt_var)
>>>> + v = NULL_TREE;
>>>> + else
>>>> + v = pt_var;
>>>> + }
>>>> break;
>>>> default:
>>>> v = pt_var;
>>>> diff --git a/gcc/tree-streamer-in.cc b/gcc/tree-streamer-in.cc
>>>> index d4dc30f048f..c19ede0631d 100644
>>>> --- a/gcc/tree-streamer-in.cc
>>>> +++ b/gcc/tree-streamer-in.cc
>>>> @@ -390,6 +390,7 @@ unpack_ts_type_common_value_fields (struct bitpack_d
>>>> *bp, tree expr)
>>>> TYPE_TRANSPARENT_AGGR (expr) = (unsigned) bp_unpack_value (bp, 1);
>>>> TYPE_FINAL_P (expr) = (unsigned) bp_unpack_value (bp, 1);
>>>> TYPE_CXX_ODR_P (expr) = (unsigned) bp_unpack_value (bp, 1);
>>>> + TYPE_INCLUDE_FLEXARRAY (expr) = (unsigned) bp_unpack_value (bp, 1);
>>>> }
>>>> else if (TREE_CODE (expr) == ARRAY_TYPE)
>>>> TYPE_NONALIASED_COMPONENT (expr) = (unsigned) bp_unpack_value (bp, 1);
>>>> diff --git a/gcc/tree-streamer-out.cc b/gcc/tree-streamer-out.cc
>>>> index d107229da5c..73e4b4e547c 100644
>>>> --- a/gcc/tree-streamer-out.cc
>>>> +++ b/gcc/tree-streamer-out.cc
>>>> @@ -357,6 +357,7 @@ pack_ts_type_common_value_fields (struct bitpack_d
>>>> *bp, tree expr)
>>>> bp_pack_value (bp, flag_wpa && TYPE_CANONICAL (expr)
>>>> ? TYPE_CXX_ODR_P (TYPE_CANONICAL (expr))
>>>> : TYPE_CXX_ODR_P (expr), 1);
>>>> + bp_pack_value (bp, TYPE_INCLUDE_FLEXARRAY (expr), 1);
>>>> }
>>>> else if (TREE_CODE (expr) == ARRAY_TYPE)
>>>> bp_pack_value (bp, TYPE_NONALIASED_COMPONENT (expr), 1);
>>>> diff --git a/gcc/tree.h b/gcc/tree.h
>>>> index 92ac0e6a214..ab1cdc3dc85 100644
>>>> --- a/gcc/tree.h
>>>> +++ b/gcc/tree.h
>>>> @@ -778,6 +778,12 @@ extern void omp_clause_range_check_failed
>>>> (const_tree, const char *, int,
>>>> #define TYPE_NO_NAMED_ARGS_STDARG_P(NODE) \
>>>> (TYPE_CHECK (NODE)->type_common.no_named_args_stdarg_p)
>>>>
>>>> +/* True if this RECORD_TYPE or UNION_TYPE includes a flexible array member
>>>> + at the last field recursively. */
>>>> +#define TYPE_INCLUDE_FLEXARRAY(NODE) \
>>>> + (TYPE_CHECK (NODE)->type_common.type_include_flexarray)
>>>
>>> Please use RECORD_OR_UNION_CHECK.
>> Okay.
>>> The comment "at the last field"
>>> doesn't seem to match implementation? (at least not obviously)
>> The current implementation (in gcc/c/c-decl.cc) guarantees that it’s at the
>> last field. (And recursively).
>>> Given this is a generic header expanding on what a "flexible array member"
>>> is to the middle-end here would be good. Especially the guarantees
>>> made when the bit is _not_ set (we've evaded that with DECL_NOT_FLEXARRAY
>>> vs. DECL_FLEXARRAY).
>>
>> The bit TYPE_INCLUDE_FLEXARRAY default is FALSE, i.e, not including a flex
>> array by default.
>> It’s only set to TRUE when the struct/union includes a flex array at the
>> last field (and recursively). So, I think it should be correct.
>> Let me know if I missed anything here.
>
> See above - I was looking at the use (but I'm not familiar with that
> code), and wondered how the change affects uses from other frontends.
Please see my explanation above, I think the default behavior from other FE
should be kept correctly with this patch.
thanks.
Qing
>
> Richard.
