On Fri, Dec 08, 2023 at 11:09:15PM -0500, Jason Merrill wrote:
> On 12/8/23 16:15, Marek Polacek wrote:
> > On Fri, Dec 08, 2023 at 12:09:18PM -0500, Jason Merrill wrote:
> > > On 12/5/23 15:31, Marek Polacek wrote:
> > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > > >
> > > > -- >8 --
> > > > This test shows that we cannot clear *walk_subtrees in
> > > > cp_fold_immediate_r when we're in_immediate_context, because that,
> > > > as the comment says, affects cp_fold_r as well. Here we had an
> > > > expression with
> > > >
> > > > min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount),
> > > > (long int) <<< Unknown tree: sizeof_expr
> > > > (int) <<< error >>> >>>)
> > > >
> > > > as its sub-expression, and we never evaluated that into
> > > >
> > > > min ((long int) bytecount, 4)
> > > >
> > > > so the SIZEOF_EXPR leaked into the middle end.
> > > >
> > > > (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> > > > one should be OK.)
> > > >
> > > > PR c++/112869
> > > >
> > > > gcc/cp/ChangeLog:
> > > >
> > > > * cp-gimplify.cc (cp_fold_immediate_r): Don't clear
> > > > *walk_subtrees
> > > > for unevaluated operands.
> > >
> > > I agree that we want this change for in_immediate_context (), but I don't
> > > see why we want it for TYPE_P or unevaluated_p (code) or
> > > cp_unevaluated_operand?
> >
> > No particular reason, just paranoia. How's this?
> >
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> >
> > -- >8 --
> > This test shows that we cannot clear *walk_subtrees in
> > cp_fold_immediate_r when we're in_immediate_context, because that,
> > as the comment says, affects cp_fold_r as well. Here we had an
> > expression with
> >
> > min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long
> > int) <<< Unknown tree: sizeof_expr
> > (int) <<< error >>> >>>)
> >
> > as its sub-expression, and we never evaluated that into
> >
> > min ((long int) bytecount, 4)
> >
> > so the SIZEOF_EXPR leaked into the middle end.
> >
> > (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
> > one should be OK.)
> >
> > PR c++/112869
> >
> > gcc/cp/ChangeLog:
> >
> > * cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
> > for in_immediate_context.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/template/sizeof18.C: New test.
> > ---
> > gcc/cp/cp-gimplify.cc | 6 +++++-
> > gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
> > 2 files changed, 13 insertions(+), 1 deletion(-)
> > create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
> >
> > diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> > index 5abb91bbdd3..6af7c787372 100644
> > --- a/gcc/cp/cp-gimplify.cc
> > +++ b/gcc/cp/cp-gimplify.cc
> > @@ -1179,11 +1179,15 @@ cp_fold_immediate_r (tree *stmt_p, int
> > *walk_subtrees, void *data_)
> > /* No need to look into types or unevaluated operands.
> > NB: This affects cp_fold_r as well. */
> > - if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
> > + if (TYPE_P (stmt) || unevaluated_p (code))
> > {
> > *walk_subtrees = 0;
> > return NULL_TREE;
> > }
> > + else if (in_immediate_context ())
> > + /* Don't clear *walk_subtrees here: we still need to walk the subtrees
> > + of SIZEOF_EXPR and similar. */
> > + return NULL_TREE;
> > tree decl = NULL_TREE;
> > bool call_p = false;
> > diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C
> > b/gcc/testsuite/g++.dg/template/sizeof18.C
> > new file mode 100644
> > index 00000000000..afba9946258
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/template/sizeof18.C
> > @@ -0,0 +1,8 @@
> > +// PR c++/112869
> > +// { dg-do compile }
> > +
> > +void min(long, long);
> > +template <class T> void Binaryread(int &, T, unsigned long);
> > +template <> void Binaryread(int &, float, unsigned long bytecount) {
> > + min(bytecount, sizeof(int));
> > +}
>
> Hmm, actually, why does the above make a difference for this testcase?
>
> ...
>
> It seems that in_immediate_context always returns true in cp_fold_function
> because current_binding_level->kind == sk_template_parms. That seems like a
> problem. Maybe for cp_fold_immediate_r we only want to check
> cp_unevaluated_operand or DECL_IMMEDIATE_CONTEXT (current_function_decl)?
Yeah, I suppose that could become an issue. How about this, then?
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
This test shows that we cannot clear *walk_subtrees in
cp_fold_immediate_r when we're in_immediate_context, because that,
as the comment says, affects cp_fold_r as well. Here we had an
expression with
min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int)
<<< Unknown tree: sizeof_expr
(int) <<< error >>> >>>)
as its sub-expression, and we never evaluated that into
min ((long int) bytecount, 4)
so the SIZEOF_EXPR leaked into the middle end.
(There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that
one should be OK.)
PR c++/112869
gcc/cp/ChangeLog:
* cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees
in an unevaluated operand or immediate function.
gcc/testsuite/ChangeLog:
* g++.dg/template/sizeof18.C: New test.
---
gcc/cp/cp-gimplify.cc | 8 +++++++-
gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++
2 files changed, 15 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C
diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index c307e1b62db..413ebafbd1a 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1179,11 +1179,17 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees,
void *data_)
/* No need to look into types or unevaluated operands.
NB: This affects cp_fold_r as well. */
- if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ())
+ if (TYPE_P (stmt) || unevaluated_p (code))
{
*walk_subtrees = 0;
return NULL_TREE;
}
+ else if (cp_unevaluated_operand
+ || (current_function_decl
+ && DECL_IMMEDIATE_FUNCTION_P (current_function_decl)))
+ /* Don't clear *walk_subtrees here: we still need to walk the subtrees
+ of SIZEOF_EXPR and similar. */
+ return NULL_TREE;
tree decl = NULL_TREE;
bool call_p = false;
diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C
b/gcc/testsuite/g++.dg/template/sizeof18.C
new file mode 100644
index 00000000000..afba9946258
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/sizeof18.C
@@ -0,0 +1,8 @@
+// PR c++/112869
+// { dg-do compile }
+
+void min(long, long);
+template <class T> void Binaryread(int &, T, unsigned long);
+template <> void Binaryread(int &, float, unsigned long bytecount) {
+ min(bytecount, sizeof(int));
+}
base-commit: cd7d0b4cf789264cd75ab7df5df232dc58061ed7
--
2.43.0
