Am Dienstag, dem 23.05.2023 um 10:18 +0200 schrieb Richard Biener:
> On Tue, May 23, 2023 at 8:24 AM Martin Uecker <uec...@tugraz.at>
> wrote:
> >
> > Am Dienstag, dem 23.05.2023 um 08:13 +0200 schrieb Richard Biener:
> > > On Mon, May 22, 2023 at 7:24 PM Martin Uecker via Gcc-patches
> > > <gcc-patches@gcc.gnu.org> wrote:
> > > >
> > > >
> > > >
> > > > This version contains the middle-end changes for PR109450
> > > > and test cases as before. The main middle-end change is that
> > > > we use gimplify_type_sizes also for parameters and remove
> > > > the special code that also walked into pointers (which is
> > > > incorrect).
> > > >
> > > > In addition, in the C FE this patch now also adds DECL_EXPR
> > > > for vm-types which are pointed-to by parameters declared
> > > > as arrays. The new function created contains the exact
> > > > code previously used only for regular pointers, and is
> > > > now also called for parameters declared as arrays.
> > > >
> > > >
> > > > Martin
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Fix ICEs related to VM types in C 2/2 [PR109450]
> > > >
> > > > Size expressions were sometimes lost and not gimplified
> > > > correctly,
> > > > leading to ICEs and incorrect evaluation order. Fix this
> > > > by 1) not
> > > > recursing pointers when gimplifying parameters in the
> > > > middle-end
> > > > (the code is merged with gimplify_type_sizes), which is
> > > > incorrect
> > > > because it might access variables declared later for
> > > > incomplete
> > > > structs, and 2) adding a decl expr for variably-modified
> > > > arrays
> > > > that are pointed to by parameters declared as arrays.
> > > >
> > > > PR c/109450
> > > >
> > > > gcc/
> > > > * c/c-decl.cc (add_decl_expr): New function.
> > > > (grokdeclarator): Add decl expr for size expression
> > > > in
> > > > types pointed to by parameters declared as arrays.
> > > > * function.cc (gimplify_parm_type): Remove
> > > > function.
> > > > (gimplify_parameters): Call gimplify_parm_sizes.
> > > > * gimplify.cc (gimplify_type_sizes): Make function
> > > > static.
> > > > (gimplify_parm_sizes): New function.
> > > >
> > > > gcc/testsuite/
> > > > * gcc.dg/pr109450-1.c: New test.
> > > > * gcc.dg/pr109450-2.c: New test.
> > > > * gcc.dg/vla-26.c: New test.
> > > >
> > > > diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
> > > > index 494d3cf1747..c35347734b2 100644
> > > > --- a/gcc/c/c-decl.cc
> > > > +++ b/gcc/c/c-decl.cc
> > > > @@ -6490,6 +6490,55 @@ smallest_type_quals_location (const
> > > > location_t *locations,
> > > > return loc;
> > > > }
> > > >
> > > > +
> > > > +/* We attach an artificial TYPE_DECL to pointed-to type
> > > > + and arrange for it to be included in a DECL_EXPR. This
> > > > + forces the sizes evaluation at a safe point and ensures it
> > > > + is not deferred until e.g. within a deeper conditional
> > > > context.
> > > > +
> > > > + PARM contexts have no enclosing statement list that
> > > > + can hold the DECL_EXPR, so we need to use a BIND_EXPR
> > > > + instead, and add it to the list of expressions that
> > > > + need to be evaluated.
> > > > +
> > > > + TYPENAME contexts do have an enclosing statement list,
> > > > + but it would be incorrect to use it, as the size should
> > > > + only be evaluated if the containing expression is
> > > > + evaluated. We might also be in the middle of an
> > > > + expression with side effects on the pointed-to type size
> > > > + "arguments" prior to the pointer declaration point and
> > > > + the fake TYPE_DECL in the enclosing context would force
> > > > + the size evaluation prior to the side effects. We
> > > > therefore
> > > > + use BIND_EXPRs in TYPENAME contexts too. */
> > > > +static void
> > > > +add_decl_expr(location_t loc, enum decl_context decl_context,
> > > > tree type, tree *expr)
> > > > +{
> > > > + tree bind = NULL_TREE;
> > > > + if (decl_context == TYPENAME || decl_context == PARM ||
> > > > decl_context == FIELD)
> > > > + {
> > > > + bind = build3 (BIND_EXPR, void_type_node, NULL_TREE,
> > > > NULL_TREE, NULL_TREE);
> > > > + TREE_SIDE_EFFECTS (bind) = 1;
> > > > + BIND_EXPR_BODY (bind) = push_stmt_list ();
> > > > + push_scope ();
> > > > + }
> > > > +
> > > > + tree decl = build_decl (loc, TYPE_DECL, NULL_TREE, type);
> > > > + pushdecl (decl);
> > > > + DECL_ARTIFICIAL (decl) = 1;
> > > > + add_stmt (build_stmt (DECL_SOURCE_LOCATION (decl),
> > > > DECL_EXPR, decl));
> > > > + TYPE_NAME (type) = decl;
> > > > +
> > > > + if (bind)
> > > > + {
> > > > + pop_scope ();
> > > > + BIND_EXPR_BODY (bind) = pop_stmt_list (BIND_EXPR_BODY
> > > > (bind));
> > > > + if (*expr)
> > > > + *expr = build2 (COMPOUND_EXPR, void_type_node, *expr,
> > > > bind);
> > > > + else
> > > > + *expr = bind;
> > > > + }
> > > > +}
> > > > +
> > > > /* Given declspecs and a declarator,
> > > > determine the name and type of the object declared
> > > > and construct a ..._DECL node for it.
> > > > @@ -7474,58 +7523,9 @@ grokdeclarator (const struct
> > > > c_declarator *declarator,
> > > >
> > > > This is expected to happen automatically when
> > > > the pointed-to
> > > > type has a name/declaration of it's own, but
> > > > special attention
> > > > - is required if the type is anonymous.
> > > > -
> > > > - We attach an artificial TYPE_DECL to such
> > > > pointed-to type
> > > > - and arrange for it to be included in a
> > > > DECL_EXPR. This
> > > > - forces the sizes evaluation at a safe point and
> > > > ensures it
> > > > - is not deferred until e.g. within a deeper
> > > > conditional context.
> > > > -
> > > > - PARM contexts have no enclosing statement list
> > > > that
> > > > - can hold the DECL_EXPR, so we need to use a
> > > > BIND_EXPR
> > > > - instead, and add it to the list of expressions
> > > > that
> > > > - need to be evaluated.
> > > > -
> > > > - TYPENAME contexts do have an enclosing statement
> > > > list,
> > > > - but it would be incorrect to use it, as the size
> > > > should
> > > > - only be evaluated if the containing expression
> > > > is
> > > > - evaluated. We might also be in the middle of an
> > > > - expression with side effects on the pointed-to
> > > > type size
> > > > - "arguments" prior to the pointer declaration
> > > > point and
> > > > - the fake TYPE_DECL in the enclosing context
> > > > would force
> > > > - the size evaluation prior to the side effects.
> > > > We therefore
> > > > - use BIND_EXPRs in TYPENAME contexts too. */
> > > > - if (!TYPE_NAME (type)
> > > > - && c_type_variably_modified_p (type))
> > > > - {
> > > > - tree bind = NULL_TREE;
> > > > - if (decl_context == TYPENAME || decl_context ==
> > > > PARM
> > > > - || decl_context == FIELD)
> > > > - {
> > > > - bind = build3 (BIND_EXPR, void_type_node,
> > > > NULL_TREE,
> > > > - NULL_TREE, NULL_TREE);
> > > > - TREE_SIDE_EFFECTS (bind) = 1;
> > > > - BIND_EXPR_BODY (bind) = push_stmt_list ();
> > > > - push_scope ();
> > > > - }
> > > > - tree decl = build_decl (loc, TYPE_DECL,
> > > > NULL_TREE, type);
> > > > - pushdecl (decl);
> > > > - DECL_ARTIFICIAL (decl) = 1;
> > > > - add_stmt (build_stmt (DECL_SOURCE_LOCATION
> > > > (decl), DECL_EXPR, decl));
> > > > - TYPE_NAME (type) = decl;
> > > > -
> > > > - if (bind)
> > > > - {
> > > > - pop_scope ();
> > > > - BIND_EXPR_BODY (bind)
> > > > - = pop_stmt_list (BIND_EXPR_BODY (bind));
> > > > - if (*expr)
> > > > - *expr = build2 (COMPOUND_EXPR,
> > > > void_type_node, *expr,
> > > > - bind);
> > > > - else
> > > > - *expr = bind;
> > > > - }
> > > > - }
> > > > + is required if the type is anonymous. */
> > > > + if (!TYPE_NAME (type) && c_type_variably_modified_p
> > > > (type))
> > > > + add_decl_expr (loc, decl_context, type, expr);
> > > >
> > > > type = c_build_pointer_type (type);
> > > >
> > > > @@ -7787,6 +7787,11 @@ grokdeclarator (const struct
> > > > c_declarator *declarator,
> > > > if (type_quals)
> > > > type = c_build_qualified_type (type, type_quals,
> > > > orig_qual_type,
> > > >
> > > > orig_qual_indirect);
> > > > +
> > > > + /* The pointed-to type may need a decl expr (see
> > > > above). */
> > > > + if (!TYPE_NAME (type) && c_type_variably_modified_p
> > > > (type))
> > > > + add_decl_expr (loc, decl_context, type, expr);
> > > > +
> > > > type = c_build_pointer_type (type);
> > > > type_quals = array_ptr_quals;
> > > > if (type_quals)
> > > > diff --git a/gcc/function.cc b/gcc/function.cc
> > > > index f0ae641512d..5699b9d495d 100644
> > > > --- a/gcc/function.cc
> > > > +++ b/gcc/function.cc
> > > > @@ -3872,30 +3872,6 @@ assign_parms (tree fndecl)
> > > > }
> > > > }
> > > >
> > > > -/* A subroutine of gimplify_parameters, invoked via walk_tree.
> > > > - For all seen types, gimplify their sizes. */
> > > > -
> > > > -static tree
> > > > -gimplify_parm_type (tree *tp, int *walk_subtrees, void *data)
> > > > -{
> > > > - tree t = *tp;
> > > > -
> > > > - *walk_subtrees = 0;
> > > > - if (TYPE_P (t))
> > > > - {
> > > > - if (POINTER_TYPE_P (t))
> > > > - *walk_subtrees = 1;
> > > > - else if (TYPE_SIZE (t) && !TREE_CONSTANT (TYPE_SIZE (t))
> > > > - && !TYPE_SIZES_GIMPLIFIED (t))
> > > > - {
> > > > - gimplify_type_sizes (t, (gimple_seq *) data);
> > > > - *walk_subtrees = 1;
> > > > - }
> > > > - }
> > > > -
> > > > - return NULL;
> > > > -}
> > > > -
> > > > /* Gimplify the parameter list for current_function_decl.
> > > > This involves
> > > > evaluating SAVE_EXPRs of variable sized parameters and
> > > > generating code
> > > > to implement callee-copies reference parameters. Returns a
> > > > sequence of
> > > > @@ -3931,14 +3907,7 @@ gimplify_parameters (gimple_seq
> > > > *cleanup)
> > > > SAVE_EXPRs (amongst others) onto a pending sizes
> > > > list. This
> > > > turned out to be less than manageable in the gimple
> > > > world.
> > > > Now we have to hunt them down ourselves. */
> > > > - walk_tree_without_duplicates (&data.arg.type,
> > > > - gimplify_parm_type,
> > > > &stmts);
> > > > -
> > > > - if (TREE_CODE (DECL_SIZE_UNIT (parm)) != INTEGER_CST)
> > > > - {
> > > > - gimplify_one_sizepos (&DECL_SIZE (parm), &stmts);
> > > > - gimplify_one_sizepos (&DECL_SIZE_UNIT (parm),
> > > > &stmts);
> > > > - }
> > > > + gimplify_parm_sizes (parm, &stmts);
> > > >
> > > > if (data.arg.pass_by_reference)
> > > > {
> > > > diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
> > > > index d0d16a24820..fd990c328eb 100644
> > > > --- a/gcc/gimplify.cc
> > > > +++ b/gcc/gimplify.cc
> > > > @@ -242,6 +242,7 @@ static struct gimplify_omp_ctx
> > > > *gimplify_omp_ctxp;
> > > > static bool in_omp_construct;
> > > >
> > > > /* Forward declaration. */
> > > > +static void gimplify_type_sizes (tree type, gimple_seq
> > > > *list_p);
> > > > static enum gimplify_status gimplify_compound_expr (tree *,
> > > > gimple_seq *, bool);
> > > > static hash_map<tree, tree> *oacc_declare_returns;
> > > > static enum gimplify_status gimplify_expr (tree *, gimple_seq
> > > > *, gimple_seq *,
> > > > @@ -17425,7 +17426,7 @@ gimplify_expr (tree *expr_p, gimple_seq
> > > > *pre_p, gimple_seq *post_p,
> > > > /* Look through TYPE for variable-sized objects and gimplify
> > > > each such
> > > > size that we find. Add to LIST_P any statements
> > > > generated. */
> > > >
> > > > -void
> > > > +static void
> > > > gimplify_type_sizes (tree type, gimple_seq *list_p)
> > > > {
> > > > if (type == NULL || type == error_mark_node)
> > > > @@ -17533,6 +17534,21 @@ gimplify_type_sizes (tree type,
> > > > gimple_seq *list_p)
> > > > }
> > > > }
> > > >
> > > > +/* Gimplify sizes in parameter declarations. */
> > > > +
> > > > +void
> > > > +gimplify_parm_sizes (tree parm, gimple_seq *list_p)
> > >
> > > Can you instead inline this at the single caller in
> > > gimplify_parameters?
> > > It looks like both gimplify_type_sizes and gimplify_one_sizepos
> > > are
> > > already exported. So just add the missing gimplify_type_sizes ()
> > > call
> > > at the single call site.
> > >
> > > The middle-end changes are OK with that change.
> >
> > Thanks Richard!
> >
> > I did this in this way because this was the only outside use of
> > gimplify_type_sizes. Then one can unexport gimplify_type_size.
> > In fact, it is declared static (see above) and removed from the
> > header (see below) in the patch. I thought this is better logical
> > encapsulation. (BTW: gimplify_one_sizepos then has only
> > one remaining use in the Ada FE, so maybe we make a copy there
> > and also unexport it?).
> >
> > What do you think?
>
> I think any API streamlining should be done separately and as long
> as gimplify_one_sizepos is still exported it's odd to focus on
> gimplify_type_sizes, looking at the Ada FE use it doesn't look like
> that can be removed.
>
> Richard.
Ok, then I will make the change you described and commit it.
Thanks!
Martin
> > Martin
> >
> > > Thanks,
> > > Richard.
> > >
> > > > +{
> > > > + gimplify_type_sizes (TREE_TYPE (parm), list_p);
> > > > +
> > > > + if (TREE_CODE (DECL_SIZE_UNIT (parm)) != INTEGER_CST)
> > > > + {
> > > > + gimplify_one_sizepos (&DECL_SIZE (parm), list_p);
> > > > + gimplify_one_sizepos (&DECL_SIZE_UNIT (parm), list_p);
> > > > + }
> > > > +}
> > > > +
> > > > +
> > > > /* A subroutine of gimplify_type_sizes to make sure that
> > > > *EXPR_P,
> > > > a size or position, has had all of its SAVE_EXPRs
> > > > evaluated.
> > > > We add any required statements to *STMT_P. */
> > > > diff --git a/gcc/gimplify.h b/gcc/gimplify.h
> > > > index f4a3eea2606..17ea0580647 100644
> > > > --- a/gcc/gimplify.h
> > > > +++ b/gcc/gimplify.h
> > > > @@ -78,7 +78,7 @@ extern enum gimplify_status gimplify_expr
> > > > (tree *, gimple_seq *, gimple_seq *,
> > > >
> > > > int omp_construct_selector_matches (enum tree_code *, int, int
> > > > *);
> > > >
> > > > -extern void gimplify_type_sizes (tree, gimple_seq *);
> > > > +extern void gimplify_parm_sizes (tree, gimple_seq *);
> > > > extern void gimplify_one_sizepos (tree *, gimple_seq *);
> > > > extern gbind *gimplify_body (tree, bool);
> > > > extern enum gimplify_status gimplify_arg (tree *, gimple_seq
> > > > *, location_t,
> > > > diff --git a/gcc/testsuite/gcc.dg/pr109450-1.c
> > > > b/gcc/testsuite/gcc.dg/pr109450-1.c
> > > > new file mode 100644
> > > > index 00000000000..aec127f2afc
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/gcc.dg/pr109450-1.c
> > > > @@ -0,0 +1,21 @@
> > > > +/* PR c/109450
> > > > + * { dg-do run }
> > > > + * { dg-options "-std=gnu99" }
> > > > + * */
> > > > +
> > > > +int bar(int n, struct foo* x) /* { dg-warning "not be
> > > > visible" } */
> > > > +{
> > > > + int a = n;
> > > > + struct foo { char buf[n++]; }* p = x;
> > > > + return a;
> > > > +}
> > > > +
> > > > +int main()
> > > > +{
> > > > + if (1 != bar(1, 0))
> > > > + __builtin_abort();
> > > > +}
> > > > +
> > > > +
> > > > +
> > > > +
> > > > diff --git a/gcc/testsuite/gcc.dg/pr109450-2.c
> > > > b/gcc/testsuite/gcc.dg/pr109450-2.c
> > > > new file mode 100644
> > > > index 00000000000..06799f6df23
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/gcc.dg/pr109450-2.c
> > > > @@ -0,0 +1,18 @@
> > > > +/* PR c/109450
> > > > + * { dg-do run }
> > > > + * { dg-options "-std=gnu99" }
> > > > + * */
> > > > +
> > > > +int bar(int n, struct foo *x) /* { dg-warning "not be
> > > > visible" } */
> > > > +{
> > > > + int a = n;
> > > > + struct foo { char buf[a++]; }* p = x;
> > > > + return n == a;
> > > > +}
> > > > +
> > > > +int main()
> > > > +{
> > > > + if (bar(1, 0))
> > > > + __builtin_abort();
> > > > +}
> > > > +
> > > > diff --git a/gcc/testsuite/gcc.dg/vla-26.c
> > > > b/gcc/testsuite/gcc.dg/vla-26.c
> > > > new file mode 100644
> > > > index 00000000000..5d2fa3e280a
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/gcc.dg/vla-26.c
> > > > @@ -0,0 +1,15 @@
> > > > +/* { dg-do compile } */
> > > > +/* { dg-options "-std=c99 -O2" } */
> > > > +
> > > > +void ed(int n, float s[3][n])
> > > > +{
> > > > + for (int i = 0; i < n; i++)
> > > > + s[1][i];
> > > > +}
> > > > +
> > > > +void e(int n, float s[3][n])
> > > > +{
> > > > + ed(n, s);
> > > > +}
> > > > +
> > > > +
> > > >
> > > >
> >
> >
--
Univ.-Prof. Dr. rer. nat. Martin Uecker
Graz University of Technology
Institute of Biomedical Imaging
