On Thu, Jun 16, 2022 at 1:38 AM Fangrui Song <mask...@google.com> wrote: > > On Wed, Jun 15, 2022 at 2:44 PM H.J. Lu via Gcc-patches > <gcc-patches@gcc.gnu.org> wrote: > > > > On Mon, Jun 13, 2022 at 9:01 AM Richard Biener > > <richard.guent...@gmail.com> wrote: > > > > > > > > > > > > > Am 13.06.2022 um 16:36 schrieb H.J. Lu <hjl.to...@gmail.com>: > > > > > > > > On Mon, Jun 13, 2022 at 3:11 AM Richard Biener > > > > <richard.guent...@gmail.com> wrote: > > > >> > > > >>> On Tue, Jun 7, 2022 at 9:02 PM H.J. Lu via Gcc-patches > > > >>> <gcc-patches@gcc.gnu.org> wrote: > > > >>> > > > >>> Add -fextra-libc-function=memcmpeq 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= 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 <string.h> and GCC may generate > > > > memcmp directly. How should we handle these cases? > > > > > > Not. Similar as to vectorized math functions. > > > I think it’s not worth optimizing for this case. > > > > Another question. Should we consider any __memcmpeq prototype > > or just the one in the system header file?
Any. > 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. But we already have this behavior for multiple cases. It's also the only way that in practice __memcmpeq will be used - _nobody_ (but maybe special crafted SPEC peak runs) will add explicit -fbuiltin-__memcmpeq. Richard. > > > 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=. > > > >>> * opts.cc (extra_libc_functions): New. > > > >>> (parse_extra_libc_function): New function. > > > >>> (common_handle_option): Handle -fextra-libc-function=. > > > >>> * opts.h (extra_libc_function_list): New. > > > >>> (extra_libc_functions): Likewise. > > > >>> * doc/invoke.texi: Document -fextra-libc-function=memcmpeq. > > > >>> > > > >>> 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 see > > > >>> #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 > > > >>> subtarget, machine_mode mode, > > > >>> return target; > > > >>> if (fcode == BUILT_IN_MEMCMP_EQ) > > > >>> { > > > >>> - tree newdecl = builtin_decl_explicit (BUILT_IN_MEMCMP); > > > >>> + tree newdecl = builtin_decl_explicit > > > >>> + (extra_libc_functions.has_memcmpeq > > > >>> + ? BUILT_IN___MEMCMPEQ : BUILT_IN_MEMCMP); > > > >>> TREE_OPERAND (exp, 1) = 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_AND_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=memcmpeq. */ > > > >>> +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 only > > > >>> 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) > > > >>> Value(EXCESS_PRECISION_STANDARD) > > > >>> EnumValue > > > >>> Enum(excess_precision) String(16) Value(EXCESS_PRECISION_FLOAT16) > > > >>> > > > >>> +fextra-libc-function= > > > >>> +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= > > > >>> 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 @gol > > > >>> -fasynchronous-unwind-tables @gol > > > >>> +-fextra-libc-function=memcmpeq @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 > > > >>> collector). > > > >>> > > > >>> +@item -fextra-libc-function=memcmpeq > > > >>> +@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 see > > > >>> /* 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 > > > >>> onoff); > > > >>> > > > >>> /* 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= 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") == 0) > > > >>> + { > > > >>> + extra_libc_functions.has_memcmpeq = 1; > > > >>> + return; > > > >>> + } > > > >>> + > > > >>> + error ("unrecognized argument to %<-fextra-libc-function=%>: %qs", > > > >>> + arg); > > > >>> +} > > > >>> + > > > >>> /* Parse -fzero-call-used-regs suboptions from ARG, return the FLAGS. > > > >>> */ > > > >>> > > > >>> unsigned int > > > >>> @@ -2940,6 +2959,10 @@ common_handle_option (struct gcc_options *opts, > > > >>> 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 = xstrdup (arg); > > > >>> value = 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/testsuite/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=memcmpeq" } */ > > > >>> +/* { dg-final { scan-assembler "__memcmpeq" } } */ > > > >>> + > > > >>> +#include <stddef.h> > > > >>> + > > > >>> +int > > > >>> +foo (const char *s1, const char *s2, size_t len) > > > >>> +{ > > > >>> + return __builtin_memcmp (s1, s2, len) != 0; > > > >>> +} > > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-2.c > > > >>> b/gcc/testsuite/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=memcmpeq" } */ > > > >>> +/* { dg-final { scan-assembler "__memcmpeq" } } */ > > > >>> + > > > >>> +#include <string.h> > > > >>> + > > > >>> +int > > > >>> +foo (const char *s1, const char *s2, size_t len) > > > >>> +{ > > > >>> + return memcmp (s1, s2, len) == 0; > > > >>> +} > > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-3.c > > > >>> b/gcc/testsuite/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=memcmpeq" } */ > > > >>> +/* { dg-final { scan-assembler-not "__memcmpeq" } } */ > > > >>> + > > > >>> +#include <string.h> > > > >>> + > > > >>> +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/testsuite/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 <stddef.h> > > > >>> + > > > >>> +int > > > >>> +foo (const char *s1, const char *s2, size_t len) > > > >>> +{ > > > >>> + return __builtin_memcmp (s1, s2, len) != 0; > > > >>> +} > > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-5.c > > > >>> b/gcc/testsuite/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 <string.h> > > > >>> + > > > >>> +int > > > >>> +foo (const char *s1, const char *s2, size_t len) > > > >>> +{ > > > >>> + return memcmp (s1, s2, len) == 0; > > > >>> +} > > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-6.c > > > >>> b/gcc/testsuite/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=memcmpeq" } */ > > > >>> +/* { dg-final { scan-assembler "__memcmpeq" } } */ > > > >>> + > > > >>> +#include <stddef.h> > > > >>> + > > > >>> +int > > > >>> +foo (const char *s1, const char *s2, size_t len) > > > >>> +{ > > > >>> + return __builtin_memcmp_eq (s1, s2, len) != 0; > > > >>> +} > > > >>> diff --git a/gcc/testsuite/c-c++-common/memcmpeq-7.c > > > >>> b/gcc/testsuite/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 <stddef.h> > > > >>> + > > > >>> +int > > > >>> +foo (const char *s1, const char *s2, size_t len) > > > >>> +{ > > > >>> + return __builtin_memcmp_eq (s1, s2, len) != 0; > > > >>> +} > > > >>> -- > > > >>> 2.36.1 > > > >>> > > > > > > > > > > > > > > > > -- > > > > H.J. > > > > > > > > -- > > H.J. > > > > -- > 宋方睿
