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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r11-10728] c++: Drop TREE_READONLY on vars (possibly) initialized by tls wrapper [PR109164] Date: Tue, 2 May 2023 20:16:08 +0000 (GMT) [thread overview] Message-ID: <20230502201608.61117394D83B@sourceware.org> (raw) https://gcc.gnu.org/g:6a4942ac236ce46499073daed7ebb8fa272aa7fa commit r11-10728-g6a4942ac236ce46499073daed7ebb8fa272aa7fa Author: Jakub Jelinek <jakub@redhat.com> Date: Mon Mar 20 20:29:47 2023 +0100 c++: Drop TREE_READONLY on vars (possibly) initialized by tls wrapper [PR109164] The following two testcases are miscompiled, because we keep TREE_READONLY on the vars even when they are (possibly) dynamically initialized by a TLS wrapper function. Normally cp_finish_decl drops TREE_READONLY from vars which need dynamic initialization, but for TLS we do this kind of initialization upon every access to those variables. Keeping them TREE_READONLY means e.g. PRE can hoist loads from those before loops which contain the TLS wrapper calls, so we can access the TLS variables before they are initialized. 2023-03-20 Jakub Jelinek <jakub@redhat.com> PR c++/109164 * cp-tree.h (var_needs_tls_wrapper): Declare. * decl2.c (var_needs_tls_wrapper): No longer static. * decl.c (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. (cherry picked from commit 0a846340b99675d57fc2f2923a0412134eed09d3) Diff: --- gcc/cp/cp-tree.h | 1 + gcc/cp/decl.c | 12 +++++++++ gcc/cp/decl2.c | 2 +- gcc/testsuite/g++.dg/tls/thread_local13-aux.cc | 35 ++++++++++++++++++++++++++ gcc/testsuite/g++.dg/tls/thread_local13.C | 21 ++++++++++++++++ gcc/testsuite/g++.dg/tls/thread_local14-aux.cc | 26 +++++++++++++++++++ gcc/testsuite/g++.dg/tls/thread_local14.C | 19 ++++++++++++++ 7 files changed, 115 insertions(+), 1 deletion(-) diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index fded2527e5e..620da867a6b 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -6789,6 +6789,7 @@ 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); diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 4c7c1374be3..2110e3142b4 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -8268,6 +8268,18 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p, 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); diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c index c00508103e9..3ea37e0831f 100644 --- a/gcc/cp/decl2.c +++ b/gcc/cp/decl2.c @@ -3449,7 +3449,7 @@ var_defined_without_dynamic_init (tree var) /* 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) diff --git a/gcc/testsuite/g++.dg/tls/thread_local13-aux.cc b/gcc/testsuite/g++.dg/tls/thread_local13-aux.cc new file mode 100644 index 00000000000..691f308cff1 --- /dev/null +++ b/gcc/testsuite/g++.dg/tls/thread_local13-aux.cc @@ -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 (); +} diff --git a/gcc/testsuite/g++.dg/tls/thread_local13.C b/gcc/testsuite/g++.dg/tls/thread_local13.C new file mode 100644 index 00000000000..b424b9f8acf --- /dev/null +++ b/gcc/testsuite/g++.dg/tls/thread_local13.C @@ -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; + } +} diff --git a/gcc/testsuite/g++.dg/tls/thread_local14-aux.cc b/gcc/testsuite/g++.dg/tls/thread_local14-aux.cc new file mode 100644 index 00000000000..e8f2a243fc1 --- /dev/null +++ b/gcc/testsuite/g++.dg/tls/thread_local14-aux.cc @@ -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 (); +} diff --git a/gcc/testsuite/g++.dg/tls/thread_local14.C b/gcc/testsuite/g++.dg/tls/thread_local14.C new file mode 100644 index 00000000000..a7402d0d631 --- /dev/null +++ b/gcc/testsuite/g++.dg/tls/thread_local14.C @@ -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; + } +}
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