On Mon, Jan 23, 2023 at 09:25:50AM +0100, Jakub Jelinek via Gcc-patches wrote:
> On Sun, Jan 22, 2023 at 07:19:07PM -0500, Jason Merrill wrote:
> > > I was just trying to be careful, because unfortunately this spot
> > > doesn't mean it really is only expanded in static var DECL_INITIAL,
> > > it can make it into dynamic initializers, and most of DECL_VALUE_EXPRs
> > > appear only in runtime code, otherwise we'd have much more of these
> > > issues.
> >
> > But it shouldn't be harmful anywhere, right?
> >
> > > But if you think it is ok, I'll test tonight a version just with
> > > if (!data->genericize && DECL_HAS_VALUE_EXPR_P (stmt)
> >
> > OK with that change.
> >
> > Though, actually, why not instead fix expand_expr_real_1 (and staticp) to
> > look through DECL_VALUE_EXPR?
>
> I'm afraid that is way too late. GIMPLE optimizations don't try to
> regimplify expressions they take from DECL_INITIAL of static vars, they
> just unshare them and use them. So, if this is to be done in the generic
> code, it would need to be done by cgraph around the time when it gimplifies
> function if there is any such point for variables.
I believe the right spot is record_reference, which is called through
walk_tree from record_references_in_initializer which is called from
varpool_node::analyze.
The new tests as well as g++.dg/init/pr53932.C pass with it, will do full
bootstrap/regtest soon.
What do you think about this?
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
