On Sat, Mar 18, 2023 at 01:54:58PM +0100, Jakub Jelinek via Gcc-patches wrote:
> The patch is mostly about DECL_EXTERNAL cases, the others are supposedly
> handled by the var_definition_p code there (or at least I assumed;
> testcases certainly test only DECL_EXTERNAL).
> I guess it could be done in cp_finish_decl, maybe better next to the
> /* A reference will be modified here, as it is initialized. */
> if (! DECL_EXTERNAL (decl)
> && TREE_READONLY (decl)
> && TYPE_REF_P (type))
> {
> was_readonly = 1;
> TREE_READONLY (decl) = 0;
> }
> spot, but we'd need to export the decl2.cc helpers for it,
> because not all DECL_THREAD_LOCAL_P vars need to be treated that way.
> if (VAR_P (decl)
> && CP_DECL_THREAD_LOCAL_P (decl)
> && var_needs_tls_wrapper (decl)
> && (!DECL_EXTERNAL (decl) || flag_extern_tls_init))
> TREE_READONLY (decl) = 0;
> where var_needs_tls_wrapper would need to be exported from decl2.cc.
> Though, var_needs_tls_wrapper -> var_defined_without_dynamic_init
> needs
> DECL_NONTRIVIALLY_INITIALIZED_P/DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P,
> so perhaps that is accurate only closer to the end of cp_finish_decl?
Here it is in patch form, tested so far on tls.exp:
2023-03-18 Jakub Jelinek <ja...@redhat.com>
PR c++/109164
* cp-tree.h (var_needs_tls_wrapper): Declare.
* decl2.cc (var_needs_tls_wrapper): No longer static.
* decl.cc (cp_finish_decl): Clear TREE_READONLY on TLS variables
for which a TLS wrapper will be needed.
* g++.dg/tls/thread_local13.C: New test.
* g++.dg/tls/thread_local13-aux.cc: New file.
* g++.dg/tls/thread_local14.C: New test.
* g++.dg/tls/thread_local14-aux.cc: New file.
--- gcc/cp/cp-tree.h.jj 2023-03-17 08:37:07.542937058 +0100
+++ gcc/cp/cp-tree.h 2023-03-18 16:02:46.771230806 +0100
@@ -6989,6 +6989,7 @@ extern void copy_linkage (tree, tree);
extern tree get_guard (tree);
extern tree get_guard_cond (tree, bool);
extern tree set_guard (tree);
+extern bool var_needs_tls_wrapper (tree);
extern tree maybe_get_tls_wrapper_call (tree);
extern void mark_needed (tree);
extern bool decl_needed_p (tree);
--- gcc/cp/decl2.cc.jj 2023-03-17 16:09:01.749244271 +0100
+++ gcc/cp/decl2.cc 2023-03-18 15:48:31.340642324 +0100
@@ -3623,7 +3623,7 @@ var_defined_without_dynamic_init (tree v
/* Returns true iff VAR is a variable that needs uses to be
wrapped for possible dynamic initialization. */
-static bool
+bool
var_needs_tls_wrapper (tree var)
{
return (!error_operand_p (var)
--- gcc/cp/decl.cc.jj 2023-03-18 15:47:32.198500421 +0100
+++ gcc/cp/decl.cc 2023-03-18 16:00:04.565584266 +0100
@@ -8706,6 +8706,18 @@ cp_finish_decl (tree decl, tree init, bo
if (!decl_maybe_constant_destruction (decl, type))
TREE_READONLY (decl) = 0;
}
+ else if (VAR_P (decl)
+ && CP_DECL_THREAD_LOCAL_P (decl)
+ && (!DECL_EXTERNAL (decl) || flag_extern_tls_init)
+ && (was_readonly || TREE_READONLY (decl))
+ && var_needs_tls_wrapper (decl))
+ {
+ /* TLS variables need dynamic initialization by the TLS wrapper
+ function, we don't want to hoist accesses to it before the
+ wrapper. */
+ was_readonly = 0;
+ TREE_READONLY (decl) = 0;
+ }
make_rtl_for_nonlocal_decl (decl, init, asmspec);
--- gcc/testsuite/g++.dg/tls/thread_local13.C.jj 2023-03-18
15:47:50.934228583 +0100
+++ gcc/testsuite/g++.dg/tls/thread_local13.C 2023-03-18 15:47:50.934228583
+0100
@@ -0,0 +1,21 @@
+// PR c++/109164
+// { dg-do run { target c++11 } }
+// { dg-options "-O2" }
+// { dg-add-options tls }
+// { dg-require-effective-target tls_runtime }
+// { dg-additional-sources "thread_local13-aux.cc" }
+
+struct S { virtual void foo (); int s; };
+extern thread_local S &t;
+bool bar ();
+
+bool
+baz ()
+{
+ while (1)
+ {
+ t.foo ();
+ if (!bar ())
+ return false;
+ }
+}
--- gcc/testsuite/g++.dg/tls/thread_local13-aux.cc.jj 2023-03-18
15:47:50.934228583 +0100
+++ gcc/testsuite/g++.dg/tls/thread_local13-aux.cc 2023-03-18
15:47:50.934228583 +0100
@@ -0,0 +1,35 @@
+// PR c++/109164
+
+struct S { virtual void foo (); int s; };
+extern bool baz ();
+
+void
+S::foo ()
+{
+ if (s != 42)
+ __builtin_abort ();
+}
+
+S s;
+
+S &
+qux ()
+{
+ s.s = 42;
+ return s;
+}
+
+thread_local S &t = qux ();
+
+bool
+bar ()
+{
+ return false;
+}
+
+int
+main ()
+{
+ if (baz ())
+ __builtin_abort ();
+}
--- gcc/testsuite/g++.dg/tls/thread_local14.C.jj 2023-03-18
15:47:50.934228583 +0100
+++ gcc/testsuite/g++.dg/tls/thread_local14.C 2023-03-18 15:47:50.934228583
+0100
@@ -0,0 +1,19 @@
+// PR c++/109164
+// { dg-do run { target c++11 } }
+// { dg-options "-O2" }
+// { dg-add-options tls }
+// { dg-require-effective-target tls_runtime }
+// { dg-additional-sources "thread_local14-aux.cc" }
+
+extern thread_local const int t;
+bool bar (int);
+
+bool
+baz ()
+{
+ while (1)
+ {
+ if (!bar (t))
+ return false;
+ }
+}
--- gcc/testsuite/g++.dg/tls/thread_local14-aux.cc.jj 2023-03-18
15:47:50.934228583 +0100
+++ gcc/testsuite/g++.dg/tls/thread_local14-aux.cc 2023-03-18
15:47:50.934228583 +0100
@@ -0,0 +1,26 @@
+// PR c++/109164
+
+extern bool baz ();
+
+int
+qux ()
+{
+ return 42;
+}
+
+extern thread_local const int t = qux ();
+
+bool
+bar (int x)
+{
+ if (x != 42)
+ __builtin_abort ();
+ return false;
+}
+
+int
+main ()
+{
+ if (baz ())
+ __builtin_abort ();
+}
Jakub
