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Tue, 27 Feb 2024 14:57:56 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.192.25]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E79BA492BC7; Tue, 27 Feb 2024 14:57:55 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.17.1/8.17.1) with ESMTPS id 41REvrxd072522 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 27 Feb 2024 15:57:53 +0100 Received: (from jakub@localhost) by tucnak.zalov.cz (8.17.1/8.17.1/Submit) id 41REvqmj072521; Tue, 27 Feb 2024 15:57:52 +0100 Date: Tue, 27 Feb 2024 15:57:52 +0100 From: Jakub Jelinek To: Richard Biener , Uros Bizjak , hjl.tools@gmail.com, gcc-patches@gcc.gnu.org Subject: [PATCH] i386: Guard noreturn no-callee-saved-registers optimization with -mnoreturn-no-callee-saved-registers [PR38534] Message-ID: References: MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-Spam-Status: No, score=-3.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Jakub Jelinek Errors-To: gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1792064554854686763 X-GMAIL-MSGID: 1792064554854686763 On Tue, Feb 27, 2024 at 01:09:09PM +0100, Jakub Jelinek wrote: > So, IMHO either revert the changes altogether, or guard on -mcmodel=kernel > (but talk to kernel people on linux-toolchains if that is what they actually > want). Here is a patch which guards this by non-default option, so kernel and other users can choose if they want this or not. On top of the PR114116 patch. Only lightly tested so far. 2024-02-27 Jakub Jelinek PR target/38534 * config/i386/i386.opt (mnoreturn-no-callee-saved-registers): New option. * config/i386/i386-options.cc (ix86_set_func_type): Don't use TYPE_NO_CALLEE_SAVED_REGISTERS_EXCEPT_BP unless ix86_noreturn_no_callee_saved_registers is enabled. * doc/invoke.texi (-mnoreturn-no-callee-saved-registers): Document. * gcc.target/i386/pr38534-1.c: Add -mnoreturn-no-callee-saved-registers to dg-options. * gcc.target/i386/pr38534-2.c: Likewise. * gcc.target/i386/pr38534-3.c: Likewise. * gcc.target/i386/pr38534-4.c: Likewise. * gcc.target/i386/pr38534-5.c: Likewise. * gcc.target/i386/pr38534-6.c: Likewise. * gcc.target/i386/pr114097-1.c: Likewise. * gcc.target/i386/stack-check-17.c: Likewise. Jakub --- gcc/config/i386/i386.opt.jj 2024-01-10 12:19:07.694681189 +0100 +++ gcc/config/i386/i386.opt 2024-02-27 14:18:34.439240869 +0100 @@ -659,6 +659,10 @@ mstore-max= Target RejectNegative Joined Var(ix86_store_max) Enum(prefer_vector_width) Init(PVW_NONE) Save Maximum number of bits that can be stored to memory efficiently. +mnoreturn-no-callee-saved-registers +Target Var(ix86_noreturn_no_callee_saved_registers) +Optimize noreturn functions by not saving callee-saved registers used in the function. + ;; ISA support m32 --- gcc/config/i386/i386-options.cc.jj 2024-02-27 14:20:59.972228314 +0100 +++ gcc/config/i386/i386-options.cc 2024-02-27 14:23:26.042208182 +0100 @@ -3384,7 +3384,8 @@ ix86_set_func_type (tree fndecl) { /* No need to save and restore callee-saved registers for a noreturn function with nothrow or compiled with -fno-exceptions unless when - compiling with -O0 or -Og. So that backtrace works for those at least + compiling with -O0 or -Og, except that it interferes with debugging + of callers. So that backtrace works for those at least in most cases, save the bp register if it is used, because it often is used in callers to compute CFA. @@ -3401,7 +3402,8 @@ ix86_set_func_type (tree fndecl) if (lookup_attribute ("no_callee_saved_registers", TYPE_ATTRIBUTES (TREE_TYPE (fndecl)))) no_callee_saved_registers = TYPE_NO_CALLEE_SAVED_REGISTERS; - else if (TREE_THIS_VOLATILE (fndecl) + else if (ix86_noreturn_no_callee_saved_registers + && TREE_THIS_VOLATILE (fndecl) && optimize && !optimize_debug && (TREE_NOTHROW (fndecl) || !flag_exceptions) --- gcc/doc/invoke.texi.jj 2024-02-23 11:34:34.278287553 +0100 +++ gcc/doc/invoke.texi 2024-02-27 14:29:18.071339182 +0100 @@ -1450,6 +1450,7 @@ See RS/6000 and PowerPC Options. -mvzeroupper -mprefer-avx128 -mprefer-vector-width=@var{opt} -mpartial-vector-fp-math -mmove-max=@var{bits} -mstore-max=@var{bits} +-mnoreturn-no-callee-saved-registers -mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx -mavx2 -mavx512f -mavx512pf -mavx512er -mavx512cd -mavx512vl -mavx512bw -mavx512dq -mavx512ifma -mavx512vbmi -msha -maes @@ -35376,6 +35377,15 @@ Prefer 256-bit vector width for instruct Prefer 512-bit vector width for instructions. @end table +@opindex mnoreturn-no-callee-saved-registers +@item -mnoreturn-no-callee-saved-registers +This option optimizes functions with @code{noreturn} attribute or +@code{_Noreturn} specifier by not saving in the function prologue callee-saved +registers which are used in the function (except for the @code{BP} +register). This option can interfere with debugging of the caller of the +@code{noreturn} function or any function further up in the call stack, so it +is not enabled by default. + @opindex mcx16 @item -mcx16 This option enables GCC to generate @code{CMPXCHG16B} instructions in 64-bit --- gcc/testsuite/gcc.target/i386/pr38534-1.c.jj 2024-02-27 14:21:00.385222600 +0100 +++ gcc/testsuite/gcc.target/i386/pr38534-1.c 2024-02-27 15:39:44.687716915 +0100 @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer" } */ +/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer -mnoreturn-no-callee-saved-registers" } */ #define ARRAY_SIZE 256 --- gcc/testsuite/gcc.target/i386/pr38534-2.c.jj 2024-02-27 14:21:00.385222600 +0100 +++ gcc/testsuite/gcc.target/i386/pr38534-2.c 2024-02-27 15:39:51.569621585 +0100 @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer" } */ +/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer -mnoreturn-no-callee-saved-registers" } */ extern void bar (void) __attribute__ ((no_callee_saved_registers)); extern void fn (void) __attribute__ ((noreturn)); --- gcc/testsuite/gcc.target/i386/pr38534-3.c.jj 2024-02-27 14:21:00.385222600 +0100 +++ gcc/testsuite/gcc.target/i386/pr38534-3.c 2024-02-27 15:39:57.420540547 +0100 @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer" } */ +/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer -mnoreturn-no-callee-saved-registers" } */ typedef void (*fn_t) (void) __attribute__ ((no_callee_saved_registers)); extern fn_t bar; --- gcc/testsuite/gcc.target/i386/pr38534-4.c.jj 2024-02-27 14:21:00.385222600 +0100 +++ gcc/testsuite/gcc.target/i386/pr38534-4.c 2024-02-27 15:40:08.185391436 +0100 @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer" } */ +/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer -mnoreturn-no-callee-saved-registers" } */ typedef void (*fn_t) (void) __attribute__ ((no_callee_saved_registers)); extern void fn (void) __attribute__ ((noreturn)); --- gcc/testsuite/gcc.target/i386/pr38534-5.c.jj 2024-01-30 08:45:06.904842201 +0100 +++ gcc/testsuite/gcc.target/i386/pr38534-5.c 2024-02-27 15:49:17.382784286 +0100 @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O0 -mtune-ctrl=^prologue_using_move,^epilogue_using_move" } */ +/* { dg-options "-O0 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mnoreturn-no-callee-saved-registers" } */ #define ARRAY_SIZE 256 --- gcc/testsuite/gcc.target/i386/pr38534-6.c.jj 2024-01-30 08:45:06.904842201 +0100 +++ gcc/testsuite/gcc.target/i386/pr38534-6.c 2024-02-27 15:49:32.123580145 +0100 @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move" } */ +/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -mnoreturn-no-callee-saved-registers" } */ #define ARRAY_SIZE 256 --- gcc/testsuite/gcc.target/i386/pr114097-1.c.jj 2024-02-27 14:21:00.386222586 +0100 +++ gcc/testsuite/gcc.target/i386/pr114097-1.c 2024-02-27 15:41:12.758496992 +0100 @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer" } */ +/* { dg-options "-O2 -mtune-ctrl=^prologue_using_move,^epilogue_using_move -fomit-frame-pointer -mnoreturn-no-callee-saved-registers" } */ #define ARRAY_SIZE 256 --- gcc/testsuite/gcc.target/i386/stack-check-17.c.jj 2024-02-27 14:21:00.386222586 +0100 +++ gcc/testsuite/gcc.target/i386/stack-check-17.c 2024-02-27 15:41:42.269088224 +0100 @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O2 -fstack-clash-protection -mtune=generic -fomit-frame-pointer" } */ +/* { dg-options "-O2 -fstack-clash-protection -mtune=generic -fomit-frame-pointer -mnoreturn-no-callee-saved-registers" } */ /* { dg-require-effective-target supports_stack_clash_protection } */ /* { dg-skip-if "" { *-*-* } { "-fstack-protector*" } { "" } } */