Hi!
The following testcase ICEs, because OpenMP lowering for shared clause
on l variable with REFERENCE_TYPE creates POINTER_TYPE to REFERENCE_TYPE.
The reason is that the automatic variable has non-trivial construction
(reference to a lambda) and -fmerge-all-constants is on and so TREE_READONLY
isn't set - omp-low will handle automatic TREE_READONLY vars in shared
specially and only copy to the construct and not back, while !TREE_READONLY
are assumed to be changeable.
The PR91529 change rationale was that the gimplification can change
some non-addressable automatic variables to TREE_STATIC with
-fmerge-all-constants and therefore TREE_READONLY on them is undesirable.
But, the gimplifier does that only for aggregate variables:
switch (TREE_CODE (type))
{
case RECORD_TYPE:
case UNION_TYPE:
case QUAL_UNION_TYPE:
case ARRAY_TYPE:
and not for anything else. So, I think clearing TREE_READONLY for
automatic integral or reference or pointer etc. vars for
-fmerge-all-constants only is unnecessary.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2022-11-24 Jakub Jelinek <ja...@redhat.com>
PR c++/107558
* decl.cc (cp_finish_decl): Don't clear TREE_READONLY on
automatic non-aggregate variables just because of
-fmerge-all-constants.
* g++.dg/gomp/pr107558.C: New test.
--- gcc/cp/decl.cc.jj 2022-11-19 09:21:14.662439877 +0100
+++ gcc/cp/decl.cc 2022-11-23 13:12:31.866553152 +0100
@@ -8679,8 +8679,10 @@ cp_finish_decl (tree decl, tree init, bo
if (var_definition_p
/* With -fmerge-all-constants, gimplify_init_constructor
- might add TREE_STATIC to the variable. */
- && (TREE_STATIC (decl) || flag_merge_constants >= 2))
+ might add TREE_STATIC to aggregate variables. */
+ && (TREE_STATIC (decl)
+ || (flag_merge_constants >= 2
+ && AGGREGATE_TYPE_P (type))))
{
/* If a TREE_READONLY variable needs initialization
at runtime, it is no longer readonly and we need to
--- gcc/testsuite/g++.dg/gomp/pr107558.C.jj 2022-11-23 13:13:27.260736525
+0100
+++ gcc/testsuite/g++.dg/gomp/pr107558.C 2022-11-23 13:15:22.271041005
+0100
@@ -0,0 +1,14 @@
+// PR c++/107558
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-fmerge-all-constants" }
+// { dg-additional-options "-flto" { target lto } }
+
+int a = 15;
+
+void
+foo ()
+{
+ auto &&l = [&]() { return a; };
+#pragma omp target parallel
+ l ();
+}
Jakub
