c++, v2: Drop TREE_READONLY on vars (possibly) initialized by tls wrapper [PR109164]
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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 <jakub@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.
Jakub
Comments
On Sat, Mar 18, 2023 at 04:09:55PM +0100, Jakub Jelinek via Gcc-patches wrote:
> 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:
And successfully bootstrapped/regtested on x86_64-linux and i686-linux over
the weekend.
> 2023-03-18 Jakub Jelinek <jakub@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.
Jakub
On 3/18/23 11:09, Jakub Jelinek wrote:
> 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 <jakub@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)
Hmm, I wonder why we don't check the above line in var_needs_tls_wrapper?
But the patch is OK.
> + && (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
>
On Mon, Mar 20, 2023 at 03:15:32PM -0400, Jason Merrill wrote:
> > + else if (VAR_P (decl)
> > + && CP_DECL_THREAD_LOCAL_P (decl)
> > + && (!DECL_EXTERNAL (decl) || flag_extern_tls_init)
>
> Hmm, I wonder why we don't check the above line in var_needs_tls_wrapper?
It is tested in get_tls_init_fn (one of the 2 previous callers of
var_needs_tls_wrapper). No idea why it isn't in get_tls_wrapper_fn (the
other caller of it).
Jakub
On 3/20/23 15:26, Jakub Jelinek wrote:
> On Mon, Mar 20, 2023 at 03:15:32PM -0400, Jason Merrill wrote:
>>> + else if (VAR_P (decl)
>>> + && CP_DECL_THREAD_LOCAL_P (decl)
>>> + && (!DECL_EXTERNAL (decl) || flag_extern_tls_init)
>>
>> Hmm, I wonder why we don't check the above line in var_needs_tls_wrapper?
>
> It is tested in get_tls_init_fn (one of the 2 previous callers of
> var_needs_tls_wrapper). No idea why it isn't in get_tls_wrapper_fn (the
> other caller of it).
I suppose because we might see a definition of the variable later on,
and we don't want to have previously decided to omit the wrapper because
we hadn't seen it yet.
Jason
@@ -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);
@@ -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)
@@ -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);
@@ -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;
+ }
+}
@@ -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 ();
+}
@@ -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;
+ }
+}
@@ -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 ();
+}