On Mon, 23 Jan 2023, Jakub Jelinek wrote:
> On Mon, Jan 23, 2023 at 12:37:59PM +0000, Richard Biener wrote:
> > Guess it should work. Do we (accidentially?) do anything special
> > to static var initializers in nested functions?
>
> I don't think we touch those, we walk the bodies of functions, I don't
> think we traverse static var DECL_INITIALs.
>
> > Can you think of
> > any other C/C++ construct that would have DECL_VALUE_EXPR in them?
>
> A lot of them, coroutines, FE NRV, anon union vars, lambdas,
> in modules, OpenMP privatized members, structured bindings,
> __FUNCTION__ etc., later VLAs, tree-nested, OpenMP lowering.
>
> But anon union vars and structured bindings are the only ones
> known for which this is actually needed in static initializers.
> I'm afraid no idea about modules case, for OpenMP one needs executable
> code, tried the __FUNCTION__ case and while there is DECL_VALUE_EXPR
> used, the initializer is already replaced by STRING_CST in the FE somewhere,
> VLAs aren't allowed.
>
> BTW, the patch successfully passed bootstrap/regtested on x86_64-linux and
> i686-linux.
So let's try and revert quickly if any odd fallout appears?
Richard.
>
> > > 2023-01-23 Jakub Jelinek <ja...@redhat.com>
> > >
> > > PR c++/108474
> > > * cgraphbuild.cc: Include gimplify.h.
> > > (record_reference): Replace VAR_DECLs with DECL_HAS_VALUE_EXPR_P with
> > > their corresponding DECL_VALUE_EXPR expressions after unsharing.
> > >
> > > * cp-gimplify.cc (cp_fold_r): Revert 2023-01-19 changes.
> > >
> > > * g++.dg/cpp1z/decomp57.C: New test.
> > > * g++.dg/cpp1z/decomp58.C: New test.
> > >
> > > --- gcc/cgraphbuild.cc.jj 2023-01-02 09:32:34.889104620 +0100
> > > +++ gcc/cgraphbuild.cc 2023-01-23 12:10:35.042067571 +0100
> > > @@ -31,6 +31,7 @@ along with GCC; see the file COPYING3.
> > > #include "gimple-walk.h"
> > > #include "ipa-utils.h"
> > > #include "except.h"
> > > +#include "gimplify.h"
> > >
> > > /* Context of record_reference. */
> > > struct record_reference_ctx
> > > @@ -79,6 +80,17 @@ record_reference (tree *tp, int *walk_su
> > >
> > > if (VAR_P (decl))
> > > {
> > > + /* Replace vars with their DECL_VALUE_EXPR if any.
> > > + This is normally done during gimplification, but
> > > + static var initializers are never gimplified. */
> > > + if (DECL_HAS_VALUE_EXPR_P (decl))
> > > + {
> > > + tree *p;
> > > + for (p = tp; *p != decl; p = &TREE_OPERAND (*p, 0))
> > > + ;
> > > + *p = unshare_expr (DECL_VALUE_EXPR (decl));
> > > + return record_reference (tp, walk_subtrees, data);
> > > + }
> > > varpool_node *vnode = varpool_node::get_create (decl);
> > > ctx->varpool_node->create_reference (vnode, IPA_REF_ADDR);
> > > }
> > > --- gcc/cp/cp-gimplify.cc.jj 2023-01-23 11:47:49.889875804 +0100
> > > +++ gcc/cp/cp-gimplify.cc 2023-01-23 11:49:01.227841759 +0100
> > > @@ -1010,16 +1010,6 @@ cp_fold_r (tree *stmt_p, int *walk_subtr
> > > }
> > > break;
> > >
> > > - case VAR_DECL:
> > > - /* In initializers replace anon union artificial VAR_DECLs
> > > - with their DECL_VALUE_EXPRs, as nothing will do it later. */
> > > - if (DECL_ANON_UNION_VAR_P (stmt) && !data->genericize)
> > > - {
> > > - *stmt_p = stmt = unshare_expr (DECL_VALUE_EXPR (stmt));
> > > - break;
> > > - }
> > > - break;
> > > -
> > > default:
> > > break;
> > > }
> > > --- gcc/testsuite/g++.dg/cpp1z/decomp57.C.jj 2023-01-23
> > > 11:48:36.367202107 +0100
> > > +++ gcc/testsuite/g++.dg/cpp1z/decomp57.C 2023-01-23 11:48:36.367202107
> > > +0100
> > > @@ -0,0 +1,27 @@
> > > +// PR c++/108474
> > > +// { dg-do link { target c++17 } }
> > > +
> > > +struct T { int i, j; };
> > > +T h;
> > > +auto [i, j] = h;
> > > +int &r = i;
> > > +int s = i;
> > > +int *t = &i;
> > > +
> > > +void
> > > +foo (int **p, int *q)
> > > +{
> > > + static int &u = i;
> > > + static int v = i;
> > > + static int *w = &i;
> > > + int &x = i;
> > > + int y = i;
> > > + int *z = &i;
> > > + *p = &i;
> > > + *q = i;
> > > +}
> > > +
> > > +int
> > > +main ()
> > > +{
> > > +}
> > > --- gcc/testsuite/g++.dg/cpp1z/decomp58.C.jj 2023-01-23
> > > 11:48:36.367202107 +0100
> > > +++ gcc/testsuite/g++.dg/cpp1z/decomp58.C 2023-01-23 11:48:36.367202107
> > > +0100
> > > @@ -0,0 +1,39 @@
> > > +// PR c++/108474
> > > +// { dg-do link { target c++17 } }
> > > +
> > > +namespace std {
> > > + template <typename T> struct tuple_size;
> > > + template <int, typename> struct tuple_element;
> > > +}
> > > +
> > > +struct A {
> > > + int i;
> > > + template <int I> int& get() { return i; }
> > > +};
> > > +
> > > +template <> struct std::tuple_size <A> { static const int value = 2; };
> > > +template <int I> struct std::tuple_element <I, A> { using type = int; };
> > > +
> > > +struct A a;
> > > +auto [i, j] = a;
> > > +int &r = i;
> > > +int s = i;
> > > +int *t = &i;
> > > +
> > > +void
> > > +foo (int **p, int *q)
> > > +{
> > > + static int &u = i;
> > > + static int v = i;
> > > + static int *w = &i;
> > > + int &x = i;
> > > + int y = i;
> > > + int *z = &i;
> > > + *p = &i;
> > > + *q = i;
> > > +}
> > > +
> > > +int
> > > +main ()
> > > +{
> > > +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)
