| Message ID | 20250406200323.52380-1-ericsalem@gmail.com |
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[73.176.204.61]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6ef0f164dc6sm49321726d6.120.2025.04.06.13.03.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Apr 2025 13:03:25 -0700 (PDT) From: Eric Salem <ericsalem@gmail.com> To: newlib@sourceware.org Subject: [PATCH] newlib: riscv: Remove unnecessary byte load/store for stpcpy()/strcpy() Date: Sun, 6 Apr 2025 15:03:23 -0500 Message-ID: <20250406200323.52380-1-ericsalem@gmail.com> X-Mailer: git-send-email 2.49.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-10.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, 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 X-BeenThere: newlib@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Newlib mailing list <newlib.sourceware.org> List-Unsubscribe: <https://sourceware.org/mailman/options/newlib>, <mailto:newlib-request@sourceware.org?subject=unsubscribe> List-Archive: <https://sourceware.org/pipermail/newlib/> List-Post: <mailto:newlib@sourceware.org> List-Help: <mailto:newlib-request@sourceware.org?subject=help> List-Subscribe: <https://sourceware.org/mailman/listinfo/newlib>, <mailto:newlib-request@sourceware.org?subject=subscribe> Errors-To: newlib-bounces~patchwork=sourceware.org@sourceware.org |
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newlib: riscv: Remove unnecessary byte load/store for stpcpy()/strcpy()
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Commit Message
Eric Salem
April 6, 2025, 8:03 p.m. UTC
For architectures where XLEN is 32 bits, when detecting a null byte, a word is read at a time. Once a null is found in the word, its precise location is then determined. Make clear to the compiler that if the first three bytes are not null, the last byte must be null, and does not need to be read from the source string, since its value is always zero. Reviewed-by: Christian Herber <christian.herber@oss.nxp.com> Signed-off-by: Eric Salem <ericsalem@gmail.com> --- newlib/libc/machine/riscv/rv_string.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
Comments
Kito, this patch seemed to slip through the cracks. Could you please review? Thanks -- Jeff J. On Sun, Apr 6, 2025 at 4:04 PM Eric Salem <ericsalem@gmail.com> wrote: > For architectures where XLEN is 32 bits, when detecting a null byte, a > word is read at a time. Once a null is found in the word, its precise > location is then determined. Make clear to the compiler that if the > first three bytes are not null, the last byte must be null, and does not > need to be read from the source string, since its value is always zero. > > Reviewed-by: Christian Herber <christian.herber@oss.nxp.com> > Signed-off-by: Eric Salem <ericsalem@gmail.com> > --- > newlib/libc/machine/riscv/rv_string.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/newlib/libc/machine/riscv/rv_string.h > b/newlib/libc/machine/riscv/rv_string.h > index 362f66a024bf..7754303064c9 100644 > --- a/newlib/libc/machine/riscv/rv_string.h > +++ b/newlib/libc/machine/riscv/rv_string.h > @@ -82,8 +82,8 @@ static __inline char *__libc_strcpy(char *dst, const > char *src, bool ret_start) > if (!(*dst++ = src[0])) return dst0; > if (!(*dst++ = src[1])) return dst0; > if (!(*dst++ = src[2])) return dst0; > - if (!(*dst++ = src[3])) return dst0; > #if __riscv_xlen == 64 > + if (!(*dst++ = src[3])) return dst0; > if (!(*dst++ = src[4])) return dst0; > if (!(*dst++ = src[5])) return dst0; > if (!(*dst++ = src[6])) return dst0; > @@ -94,13 +94,13 @@ static __inline char *__libc_strcpy(char *dst, const > char *src, bool ret_start) > if (!(*dst++ = src[0])) return dst - 1; > if (!(*dst++ = src[1])) return dst - 1; > if (!(*dst++ = src[2])) return dst - 1; > - if (!(*dst++ = src[3])) return dst - 1; > #if __riscv_xlen == 64 > + if (!(*dst++ = src[3])) return dst - 1; > if (!(*dst++ = src[4])) return dst - 1; > if (!(*dst++ = src[5])) return dst - 1; > if (!(*dst++ = src[6])) return dst - 1; > - dst0 = dst; > #endif > + dst0 = dst; > } > > *dst = 0; > -- > 2.49.0 > >
This patch LGTM, thanks :) On Tue, Apr 15, 2025 at 6:19 AM Jeff Johnston <jjohnstn@redhat.com> wrote: > > Kito, this patch seemed to slip through the cracks. Could you please review? > > Thanks > > -- Jeff J. > > On Sun, Apr 6, 2025 at 4:04 PM Eric Salem <ericsalem@gmail.com> wrote: >> >> For architectures where XLEN is 32 bits, when detecting a null byte, a >> word is read at a time. Once a null is found in the word, its precise >> location is then determined. Make clear to the compiler that if the >> first three bytes are not null, the last byte must be null, and does not >> need to be read from the source string, since its value is always zero. >> >> Reviewed-by: Christian Herber <christian.herber@oss.nxp.com> >> Signed-off-by: Eric Salem <ericsalem@gmail.com> >> --- >> newlib/libc/machine/riscv/rv_string.h | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/newlib/libc/machine/riscv/rv_string.h b/newlib/libc/machine/riscv/rv_string.h >> index 362f66a024bf..7754303064c9 100644 >> --- a/newlib/libc/machine/riscv/rv_string.h >> +++ b/newlib/libc/machine/riscv/rv_string.h >> @@ -82,8 +82,8 @@ static __inline char *__libc_strcpy(char *dst, const char *src, bool ret_start) >> if (!(*dst++ = src[0])) return dst0; >> if (!(*dst++ = src[1])) return dst0; >> if (!(*dst++ = src[2])) return dst0; >> - if (!(*dst++ = src[3])) return dst0; >> #if __riscv_xlen == 64 >> + if (!(*dst++ = src[3])) return dst0; >> if (!(*dst++ = src[4])) return dst0; >> if (!(*dst++ = src[5])) return dst0; >> if (!(*dst++ = src[6])) return dst0; >> @@ -94,13 +94,13 @@ static __inline char *__libc_strcpy(char *dst, const char *src, bool ret_start) >> if (!(*dst++ = src[0])) return dst - 1; >> if (!(*dst++ = src[1])) return dst - 1; >> if (!(*dst++ = src[2])) return dst - 1; >> - if (!(*dst++ = src[3])) return dst - 1; >> #if __riscv_xlen == 64 >> + if (!(*dst++ = src[3])) return dst - 1; >> if (!(*dst++ = src[4])) return dst - 1; >> if (!(*dst++ = src[5])) return dst - 1; >> if (!(*dst++ = src[6])) return dst - 1; >> - dst0 = dst; >> #endif >> + dst0 = dst; >> } >> >> *dst = 0; >> -- >> 2.49.0 >>
Thanks. Patch pushed. -- Jeff J. On Tue, Apr 15, 2025 at 9:02 AM Kito Cheng <kito.cheng@gmail.com> wrote: > This patch LGTM, thanks :) > > On Tue, Apr 15, 2025 at 6:19 AM Jeff Johnston <jjohnstn@redhat.com> wrote: > > > > Kito, this patch seemed to slip through the cracks. Could you please > review? > > > > Thanks > > > > -- Jeff J. > > > > On Sun, Apr 6, 2025 at 4:04 PM Eric Salem <ericsalem@gmail.com> wrote: > >> > >> For architectures where XLEN is 32 bits, when detecting a null byte, a > >> word is read at a time. Once a null is found in the word, its precise > >> location is then determined. Make clear to the compiler that if the > >> first three bytes are not null, the last byte must be null, and does not > >> need to be read from the source string, since its value is always zero. > >> > >> Reviewed-by: Christian Herber <christian.herber@oss.nxp.com> > >> Signed-off-by: Eric Salem <ericsalem@gmail.com> > >> --- > >> newlib/libc/machine/riscv/rv_string.h | 6 +++--- > >> 1 file changed, 3 insertions(+), 3 deletions(-) > >> > >> diff --git a/newlib/libc/machine/riscv/rv_string.h > b/newlib/libc/machine/riscv/rv_string.h > >> index 362f66a024bf..7754303064c9 100644 > >> --- a/newlib/libc/machine/riscv/rv_string.h > >> +++ b/newlib/libc/machine/riscv/rv_string.h > >> @@ -82,8 +82,8 @@ static __inline char *__libc_strcpy(char *dst, const > char *src, bool ret_start) > >> if (!(*dst++ = src[0])) return dst0; > >> if (!(*dst++ = src[1])) return dst0; > >> if (!(*dst++ = src[2])) return dst0; > >> - if (!(*dst++ = src[3])) return dst0; > >> #if __riscv_xlen == 64 > >> + if (!(*dst++ = src[3])) return dst0; > >> if (!(*dst++ = src[4])) return dst0; > >> if (!(*dst++ = src[5])) return dst0; > >> if (!(*dst++ = src[6])) return dst0; > >> @@ -94,13 +94,13 @@ static __inline char *__libc_strcpy(char *dst, > const char *src, bool ret_start) > >> if (!(*dst++ = src[0])) return dst - 1; > >> if (!(*dst++ = src[1])) return dst - 1; > >> if (!(*dst++ = src[2])) return dst - 1; > >> - if (!(*dst++ = src[3])) return dst - 1; > >> #if __riscv_xlen == 64 > >> + if (!(*dst++ = src[3])) return dst - 1; > >> if (!(*dst++ = src[4])) return dst - 1; > >> if (!(*dst++ = src[5])) return dst - 1; > >> if (!(*dst++ = src[6])) return dst - 1; > >> - dst0 = dst; > >> #endif > >> + dst0 = dst; > >> } > >> > >> *dst = 0; > >> -- > >> 2.49.0 > >> > >
diff --git a/newlib/libc/machine/riscv/rv_string.h b/newlib/libc/machine/riscv/rv_string.h index 362f66a024bf..7754303064c9 100644 --- a/newlib/libc/machine/riscv/rv_string.h +++ b/newlib/libc/machine/riscv/rv_string.h @@ -82,8 +82,8 @@ static __inline char *__libc_strcpy(char *dst, const char *src, bool ret_start) if (!(*dst++ = src[0])) return dst0; if (!(*dst++ = src[1])) return dst0; if (!(*dst++ = src[2])) return dst0; - if (!(*dst++ = src[3])) return dst0; #if __riscv_xlen == 64 + if (!(*dst++ = src[3])) return dst0; if (!(*dst++ = src[4])) return dst0; if (!(*dst++ = src[5])) return dst0; if (!(*dst++ = src[6])) return dst0; @@ -94,13 +94,13 @@ static __inline char *__libc_strcpy(char *dst, const char *src, bool ret_start) if (!(*dst++ = src[0])) return dst - 1; if (!(*dst++ = src[1])) return dst - 1; if (!(*dst++ = src[2])) return dst - 1; - if (!(*dst++ = src[3])) return dst - 1; #if __riscv_xlen == 64 + if (!(*dst++ = src[3])) return dst - 1; if (!(*dst++ = src[4])) return dst - 1; if (!(*dst++ = src[5])) return dst - 1; if (!(*dst++ = src[6])) return dst - 1; - dst0 = dst; #endif + dst0 = dst; } *dst = 0;