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[130.44.159.43]) by smtp.gmail.com with ESMTPSA id c23-20020a379a17000000b007436d0e9408sm2819511qke.127.2023.03.20.12.15.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Mar 2023 12:15:34 -0700 (PDT) Message-ID: <70d76299-3cd0-6647-45c3-0aab6d21858a@redhat.com> Date: Mon, 20 Mar 2023 15:15:32 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH] c++, v2: Drop TREE_READONLY on vars (possibly) initialized by tls wrapper [PR109164] To: Jakub Jelinek Cc: gcc-patches@gcc.gnu.org References: From: Jason Merrill In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-6.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: 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 > > 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 >