From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yb1-xb2f.google.com (mail-yb1-xb2f.google.com [IPv6:2607:f8b0:4864:20::b2f]) by sourceware.org (Postfix) with ESMTPS id 2B53E3858407 for ; Wed, 15 Jun 2022 23:38:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 2B53E3858407 Received: by mail-yb1-xb2f.google.com with SMTP id h27so23197547ybj.4 for ; Wed, 15 Jun 2022 16:38:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=nQ8S2TnHYc95ZOO/1xf0u/AhGwiLz8k6K7XaAEtGeNs=; b=7B8vus/r7cN3LeUc3IwCxr6olxz8KDJ7R9o7zSHrrwWyO86quOemLXuKYGK5UpvngX 4CIJ7xmbhznQHzgrbqVlUjAebsBi7olBxBmPgFBxJfUBdtPDFyLmsWsMGNqWiyayRY9z CIJ8KcGUWr3uzqqYibCRoaWVVegeMb4jzpeTigDB7W2vhhePZutnZKtpkVGRHYgIJwK0 OyifSPNhexQtapI3t7tiKPhYn3gLaeBSRV6ckZkqGoRkmbiZEIgWBbGvl/JPbZzwbuMn hmL00MfGPlavYRHQzSz+EY70yyWPWZLBTaa4dZ08V9edftGZK3G55I0qrJnkrv7mgLVz e2Jw== X-Gm-Message-State: AJIora+04hmmQgkdmCy3NFQI4QZFWq3XqqOF6iGwwh2zpahnV9+sN3qs 9LmWRRHN//wbLxtuzZ9GJhVFkWIEtK3gaL7XFRiKmQ== X-Google-Smtp-Source: AGRyM1v6u2XFFRjNCMwsPsS5Pojn0cSzKyZWfOwAElxykLFT8syqYY5eZfi2rMVwcQ/1rBN0karjvlKib7m8ujTsvvA= X-Received: by 2002:a25:6784:0:b0:663:9b7b:5458 with SMTP id b126-20020a256784000000b006639b7b5458mr2478238ybc.605.1655336302221; Wed, 15 Jun 2022 16:38:22 -0700 (PDT) MIME-Version: 1.0 References: <466A0F0B-DB25-4866-AB4B-27992CEF9E2E@gmail.com> In-Reply-To: From: Fangrui Song Date: Wed, 15 Jun 2022 16:38:10 -0700 Message-ID: Subject: Re: [PATCH] Add -fextra-libc-function=memcmpeq for __memcmpeq To: "H.J. Lu" Cc: Richard Biener , Noah Goldstein , GCC Patches , "Joseph S. Myers" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-22.5 required=5.0 tests=BAYES_00, BODY_8BITS, DKIMWL_WL_MED, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE, USER_IN_DEF_DKIM_WL, USER_IN_DEF_SPF_WL 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: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Jun 2022 23:38:26 -0000 On Wed, Jun 15, 2022 at 2:44 PM H.J. Lu via Gcc-patches wrote: > > On Mon, Jun 13, 2022 at 9:01 AM Richard Biener > wrote: > > > > > > > > > Am 13.06.2022 um 16:36 schrieb H.J. Lu : > > > > > > =EF=BB=BFOn Mon, Jun 13, 2022 at 3:11 AM Richard Biener > > > wrote: > > >> > > >>> On Tue, Jun 7, 2022 at 9:02 PM H.J. Lu via Gcc-patches > > >>> wrote: > > >>> > > >>> Add -fextra-libc-function=3Dmemcmpeq to map > > >>> > > >>> extern int __memcmpeq (const void *, const void *, size_t); > > >>> > > >>> which was added to GLIBC 2.35, to __builtin_memcmp_eq. > > >> > > >> Humm. Can't we instead use the presence of a declaration > > >> of __memcmpeq with a GNU standard dialect as this instead of > > >> adding a weird -fextra-libc-function=3D option? Maybe that's even > > >> reasonable with a non-GNU dialect standard in effect since > > >> __ prefixed names are in the implementation namespace? > > > > > > But not all source codes include and GCC may generate > > > memcmp directly. How should we handle these cases? > > > > Not. Similar as to vectorized math functions. > > I think it=E2=80=99s not worth optimizing for this case. > > Another question. Should we consider any __memcmpeq prototype > or just the one in the system header file? An idea from https://reviews.llvm.org/D56593#3586673: -fbuiltin-__memcmpeq This requires making -fbuiltin-function available, see https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html ("There is no corresponding -fbuiltin-function option") I prefer an option over a magic behavior about whether a declaration exists= . > > Richard. > > > > > > > >> Richard. > > >> > > >>> gcc/ > > >>> > > >>> * builtins.cc: Include "opts.h". > > >>> (expand_builtin): Generate BUILT_IN_MEMCMP_EQ if __memcmpeq = is > > >>> available. > > >>> * builtins.def (BUILT_IN___MEMCMPEQ): New. > > >>> * common.opt: Add -fextra-libc-function=3D. > > >>> * opts.cc (extra_libc_functions): New. > > >>> (parse_extra_libc_function): New function. > > >>> (common_handle_option): Handle -fextra-libc-function=3D. > > >>> * opts.h (extra_libc_function_list): New. > > >>> (extra_libc_functions): Likewise. > > >>> * doc/invoke.texi: Document -fextra-libc-function=3Dmemcmpeq= . > > >>> > > >>> gcc/testsuite/ > > >>> > > >>> * c-c++-common/memcmpeq-1.c: New test. > > >>> * c-c++-common/memcmpeq-2.c: Likewise. > > >>> * c-c++-common/memcmpeq-3.c: Likewise. > > >>> * c-c++-common/memcmpeq-4.c: Likewise. > > >>> * c-c++-common/memcmpeq-5.c: Likewise. > > >>> * c-c++-common/memcmpeq-6.c: Likewise. > > >>> * c-c++-common/memcmpeq-7.c: Likewise. > > >>> --- > > >>> gcc/builtins.cc | 5 ++++- > > >>> gcc/builtins.def | 4 ++++ > > >>> gcc/common.opt | 4 ++++ > > >>> gcc/doc/invoke.texi | 6 ++++++ > > >>> gcc/opts.cc | 23 ++++++++++++++++++++++= + > > >>> gcc/opts.h | 7 +++++++ > > >>> gcc/testsuite/c-c++-common/memcmpeq-1.c | 11 +++++++++++ > > >>> gcc/testsuite/c-c++-common/memcmpeq-2.c | 11 +++++++++++ > > >>> gcc/testsuite/c-c++-common/memcmpeq-3.c | 11 +++++++++++ > > >>> gcc/testsuite/c-c++-common/memcmpeq-4.c | 11 +++++++++++ > > >>> gcc/testsuite/c-c++-common/memcmpeq-5.c | 11 +++++++++++ > > >>> gcc/testsuite/c-c++-common/memcmpeq-6.c | 11 +++++++++++ > > >>> gcc/testsuite/c-c++-common/memcmpeq-7.c | 11 +++++++++++ > > >>> 13 files changed, 125 insertions(+), 1 deletion(-) > > >>> create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-1.c > > >>> create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-2.c > > >>> create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-3.c > > >>> create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-4.c > > >>> create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-5.c > > >>> create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-6.c > > >>> create mode 100644 gcc/testsuite/c-c++-common/memcmpeq-7.c > > >>> > > >>> diff --git a/gcc/builtins.cc b/gcc/builtins.cc > > >>> index b9d89b409b8..22269318e8c 100644 > > >>> --- a/gcc/builtins.cc > > >>> +++ b/gcc/builtins.cc > > >>> @@ -81,6 +81,7 @@ along with GCC; see the file COPYING3. If not se= e > > >>> #include "demangle.h" > > >>> #include "gimple-range.h" > > >>> #include "pointer-query.h" > > >>> +#include "opts.h" > > >>> > > >>> struct target_builtins default_target_builtins; > > >>> #if SWITCHABLE_TARGET > > >>> @@ -7410,7 +7411,9 @@ expand_builtin (tree exp, rtx target, rtx sub= target, machine_mode mode, > > >>> return target; > > >>> if (fcode =3D=3D BUILT_IN_MEMCMP_EQ) > > >>> { > > >>> - tree newdecl =3D builtin_decl_explicit (BUILT_IN_MEMCMP); > > >>> + tree newdecl =3D builtin_decl_explicit > > >>> + (extra_libc_functions.has_memcmpeq > > >>> + ? BUILT_IN___MEMCMPEQ : BUILT_IN_MEMCMP); > > >>> TREE_OPERAND (exp, 1) =3D build_fold_addr_expr (newdecl); > > >>> } > > >>> break; > > >>> diff --git a/gcc/builtins.def b/gcc/builtins.def > > >>> index 005976f34e9..eb8d33b16e9 100644 > > >>> --- a/gcc/builtins.def > > >>> +++ b/gcc/builtins.def > > >>> @@ -965,6 +965,10 @@ DEF_BUILTIN_STUB (BUILT_IN_ALLOCA_WITH_ALIGN_A= ND_MAX, "__builtin_alloca_with_ali > > >>> equality with zero. */ > > >>> DEF_BUILTIN_STUB (BUILT_IN_MEMCMP_EQ, "__builtin_memcmp_eq") > > >>> > > >>> +/* Similar to BUILT_IN_MEMCMP_EQ, but is mapped to __memcmpeq only= with > > >>> + -fextra-libc-function=3Dmemcmpeq. */ > > >>> +DEF_EXT_LIB_BUILTIN (BUILT_IN___MEMCMPEQ, "__memcmpeq", BT_FN_INT_= CONST_PTR_CONST_PTR_SIZE, ATTR_PURE_NOTHROW_NONNULL_LEAF) > > >>> + > > >>> /* An internal version of strcmp/strncmp, used when the result is o= nly > > >>> tested for equality with zero. */ > > >>> DEF_BUILTIN_STUB (BUILT_IN_STRCMP_EQ, "__builtin_strcmp_eq") > > >>> diff --git a/gcc/common.opt b/gcc/common.opt > > >>> index 7ca0cceed82..7a7631682b0 100644 > > >>> --- a/gcc/common.opt > > >>> +++ b/gcc/common.opt > > >>> @@ -1587,6 +1587,10 @@ Enum(excess_precision) String(standard) Valu= e(EXCESS_PRECISION_STANDARD) > > >>> EnumValue > > >>> Enum(excess_precision) String(16) Value(EXCESS_PRECISION_FLOAT16) > > >>> > > >>> +fextra-libc-function=3D > > >>> +Common Driver Joined > > >>> +Specify the extra function in the C library. > > >>> + > > >>> ; Whether we permit the extended set of values for FLT_EVAL_METHOD > > >>> ; introduced in ISO/IEC TS 18661-3, or limit ourselves to those in = C99/C11. > > >>> fpermitted-flt-eval-methods=3D > > >>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > > >>> index 8cd5bdddc5d..fe1e3709953 100644 > > >>> --- a/gcc/doc/invoke.texi > > >>> +++ b/gcc/doc/invoke.texi > > >>> @@ -676,6 +676,7 @@ Objective-C and Objective-C++ Dialects}. > > >>> -ffixed-@var{reg} -fexceptions @gol > > >>> -fnon-call-exceptions -fdelete-dead-exceptions -funwind-tables @g= ol > > >>> -fasynchronous-unwind-tables @gol > > >>> +-fextra-libc-function=3Dmemcmpeq @gol > > >>> -fno-gnu-unique @gol > > >>> -finhibit-size-directive -fcommon -fno-ident @gol > > >>> -fpcc-struct-return -fpic -fPIC -fpie -fPIE -fno-plt @gol > > >>> @@ -17250,6 +17251,11 @@ Generate unwind table in DWARF format, if = supported by target machine. The > > >>> table is exact at each instruction boundary, so it can be used for = stack > > >>> unwinding from asynchronous events (such as debugger or garbage col= lector). > > >>> > > >>> +@item -fextra-libc-function=3Dmemcmpeq > > >>> +@opindex fextra-libc-function > > >>> +Generate @code{__memcmpeq}, which was added to GLIBC 2.35, for > > >>> +@code{__builtin_memcmp_eq}. > > >>> + > > >>> @item -fno-gnu-unique > > >>> @opindex fno-gnu-unique > > >>> @opindex fgnu-unique > > >>> diff --git a/gcc/opts.cc b/gcc/opts.cc > > >>> index bf06a55456a..e77f0922acc 100644 > > >>> --- a/gcc/opts.cc > > >>> +++ b/gcc/opts.cc > > >>> @@ -38,6 +38,9 @@ along with GCC; see the file COPYING3. If not se= e > > >>> /* In this file all option sets are explicit. */ > > >>> #undef OPTION_SET_P > > >>> > > >>> +/* The list of extra functions in the C library. */ > > >>> +extra_libc_function_list extra_libc_functions; > > >>> + > > >>> static void set_Wstrict_aliasing (struct gcc_options *opts, int ono= ff); > > >>> > > >>> /* Names of fundamental debug info formats indexed by enum > > >>> @@ -2269,6 +2272,22 @@ parse_no_sanitize_attribute (char *value) > > >>> return flags; > > >>> } > > >>> > > >>> +/* Parse -fextra-libc-function=3D suboptions from ARG. */ > > >>> + > > >>> +static void > > >>> +parse_extra_libc_function (const char *arg) > > >>> +{ > > >>> + /* Check to see if the string matches a sub-option name. */ > > >>> + if (strcmp (arg, "memcmpeq") =3D=3D 0) > > >>> + { > > >>> + extra_libc_functions.has_memcmpeq =3D 1; > > >>> + return; > > >>> + } > > >>> + > > >>> + error ("unrecognized argument to %<-fextra-libc-function=3D%>: %= qs", > > >>> + arg); > > >>> +} > > >>> + > > >>> /* Parse -fzero-call-used-regs suboptions from ARG, return the FLAG= S. */ > > >>> > > >>> unsigned int > > >>> @@ -2940,6 +2959,10 @@ common_handle_option (struct gcc_options *op= ts, > > >>> SET_OPTION_IF_UNSET (opts, opts_set, flag_profile_correction,= value); > > >>> break; > > >>> > > >>> + case OPT_fextra_libc_function_: > > >>> + parse_extra_libc_function (arg); > > >>> + break; > > >>> + > > >>> case OPT_fprofile_generate_: > > >>> opts->x_profile_data_prefix =3D xstrdup (arg); > > >>> value =3D true; > > >>> diff --git a/gcc/opts.h b/gcc/opts.h > > >>> index a43ce66cffe..e8d8835ba23 100644 > > >>> --- a/gcc/opts.h > > >>> +++ b/gcc/opts.h > > >>> @@ -345,6 +345,13 @@ struct cl_option_handlers > > >>> extern const char *opt_fstack_limit_symbol_arg; > > >>> extern int opt_fstack_limit_register_no; > > >>> > > >>> +/* The list of extra functions in the C library. */ > > >>> +struct extra_libc_function_list > > >>> +{ > > >>> + unsigned int has_memcmpeq : 1; > > >>> +}; > > >>> +extern extra_libc_function_list extra_libc_functions; > > >>> + > > >>> /* Input file names. */ > > >>> > > >>> extern const char **in_fnames; > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-1.c b/gcc/testsuit= e/c-c++-common/memcmpeq-1.c > > >>> new file mode 100644 > > >>> index 00000000000..487f6cd98db > > >>> --- /dev/null > > >>> +++ b/gcc/testsuite/c-c++-common/memcmpeq-1.c > > >>> @@ -0,0 +1,11 @@ > > >>> +/* { dg-do compile } */ > > >>> +/* { dg-options "-O2 -fextra-libc-function=3Dmemcmpeq" } */ > > >>> +/* { dg-final { scan-assembler "__memcmpeq" } } */ > > >>> + > > >>> +#include > > >>> + > > >>> +int > > >>> +foo (const char *s1, const char *s2, size_t len) > > >>> +{ > > >>> + return __builtin_memcmp (s1, s2, len) !=3D 0; > > >>> +} > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-2.c b/gcc/testsuit= e/c-c++-common/memcmpeq-2.c > > >>> new file mode 100644 > > >>> index 00000000000..1773dc2bee1 > > >>> --- /dev/null > > >>> +++ b/gcc/testsuite/c-c++-common/memcmpeq-2.c > > >>> @@ -0,0 +1,11 @@ > > >>> +/* { dg-do compile } */ > > >>> +/* { dg-options "-O2 -fextra-libc-function=3Dmemcmpeq" } */ > > >>> +/* { dg-final { scan-assembler "__memcmpeq" } } */ > > >>> + > > >>> +#include > > >>> + > > >>> +int > > >>> +foo (const char *s1, const char *s2, size_t len) > > >>> +{ > > >>> + return memcmp (s1, s2, len) =3D=3D 0; > > >>> +} > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-3.c b/gcc/testsuit= e/c-c++-common/memcmpeq-3.c > > >>> new file mode 100644 > > >>> index 00000000000..69c9537d572 > > >>> --- /dev/null > > >>> +++ b/gcc/testsuite/c-c++-common/memcmpeq-3.c > > >>> @@ -0,0 +1,11 @@ > > >>> +/* { dg-do compile } */ > > >>> +/* { dg-options "-O2 -fextra-libc-function=3Dmemcmpeq" } */ > > >>> +/* { dg-final { scan-assembler-not "__memcmpeq" } } */ > > >>> + > > >>> +#include > > >>> + > > >>> +int > > >>> +foo (const char *s1, const char *s2, size_t len) > > >>> +{ > > >>> + return memcmp (s1, s2, len); > > >>> +} > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-4.c b/gcc/testsuit= e/c-c++-common/memcmpeq-4.c > > >>> new file mode 100644 > > >>> index 00000000000..a448312ea96 > > >>> --- /dev/null > > >>> +++ b/gcc/testsuite/c-c++-common/memcmpeq-4.c > > >>> @@ -0,0 +1,11 @@ > > >>> +/* { dg-do compile } */ > > >>> +/* { dg-options "-O2" } */ > > >>> +/* { dg-final { scan-assembler-not "__memcmpeq" } } */ > > >>> + > > >>> +#include > > >>> + > > >>> +int > > >>> +foo (const char *s1, const char *s2, size_t len) > > >>> +{ > > >>> + return __builtin_memcmp (s1, s2, len) !=3D 0; > > >>> +} > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-5.c b/gcc/testsuit= e/c-c++-common/memcmpeq-5.c > > >>> new file mode 100644 > > >>> index 00000000000..4ef33a1c238 > > >>> --- /dev/null > > >>> +++ b/gcc/testsuite/c-c++-common/memcmpeq-5.c > > >>> @@ -0,0 +1,11 @@ > > >>> +/* { dg-do compile } */ > > >>> +/* { dg-options "-O2" } */ > > >>> +/* { dg-final { scan-assembler-not "__memcmpeq" } } */ > > >>> + > > >>> +#include > > >>> + > > >>> +int > > >>> +foo (const char *s1, const char *s2, size_t len) > > >>> +{ > > >>> + return memcmp (s1, s2, len) =3D=3D 0; > > >>> +} > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-6.c b/gcc/testsuit= e/c-c++-common/memcmpeq-6.c > > >>> new file mode 100644 > > >>> index 00000000000..52304df7079 > > >>> --- /dev/null > > >>> +++ b/gcc/testsuite/c-c++-common/memcmpeq-6.c > > >>> @@ -0,0 +1,11 @@ > > >>> +/* { dg-do compile } */ > > >>> +/* { dg-options "-O2 -fextra-libc-function=3Dmemcmpeq" } */ > > >>> +/* { dg-final { scan-assembler "__memcmpeq" } } */ > > >>> + > > >>> +#include > > >>> + > > >>> +int > > >>> +foo (const char *s1, const char *s2, size_t len) > > >>> +{ > > >>> + return __builtin_memcmp_eq (s1, s2, len) !=3D 0; > > >>> +} > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-7.c b/gcc/testsuit= e/c-c++-common/memcmpeq-7.c > > >>> new file mode 100644 > > >>> index 00000000000..d59765894e7 > > >>> --- /dev/null > > >>> +++ b/gcc/testsuite/c-c++-common/memcmpeq-7.c > > >>> @@ -0,0 +1,11 @@ > > >>> +/* { dg-do compile } */ > > >>> +/* { dg-options "-O2" } */ > > >>> +/* { dg-final { scan-assembler-not "__memcmpeq" } } */ > > >>> + > > >>> +#include > > >>> + > > >>> +int > > >>> +foo (const char *s1, const char *s2, size_t len) > > >>> +{ > > >>> + return __builtin_memcmp_eq (s1, s2, len) !=3D 0; > > >>> +} > > >>> -- > > >>> 2.36.1 > > >>> > > > > > > > > > > > > -- > > > H.J. > > > > -- > H.J. --=20 =E5=AE=8B=E6=96=B9=E7=9D=BF