* [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization @ 2023-12-20 6:10 Xiao Zeng 2023-12-20 6:25 ` Xiao Zeng 2023-12-20 22:48 ` Jeff Johnston 0 siblings, 2 replies; 6+ messages in thread From: Xiao Zeng @ 2023-12-20 6:10 UTC (permalink / raw) To: newlib; +Cc: jjohnstn, palmer, jeffreyalaw, torbjorn.svensson, Xiao Zeng Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com> --- newlib/libc/string/strpbrk.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/newlib/libc/string/strpbrk.c b/newlib/libc/string/strpbrk.c index 774db1e6d..95e89c20c 100644 --- a/newlib/libc/string/strpbrk.c +++ b/newlib/libc/string/strpbrk.c @@ -37,15 +37,14 @@ strpbrk (const char *s1, for (c = s2; *c; c++) { if (*s1 == *c) - break; + goto end; } - if (*c) - break; s1++; } if (*c == '\0') s1 = NULL; +end: return (char *) s1; } -- 2.17.1 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization 2023-12-20 6:10 [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization Xiao Zeng @ 2023-12-20 6:25 ` Xiao Zeng 2023-12-20 22:48 ` Jeff Johnston 1 sibling, 0 replies; 6+ messages in thread From: Xiao Zeng @ 2023-12-20 6:25 UTC (permalink / raw) To: Xiao Zeng, newlib; +Cc: Jeff Johnston, palmer, jeffreyalaw, Torbjorn SVENSSON As mentioned in [PATCH] newlib: libc: Improved the readability of strcspn with minor optimization: <https://sourceware.org/pipermail/newlib/2023/020766.html> This patch did the same thing and passed the testcases. Similarly, provide a comparison of risc-v assembly: no-patch: --------------------------------------------------------- libc_a-strpbrk.o: file format elf64-littleriscv Disassembly of section .text: 0000000000000000 <strpbrk>: 0: 00054683 lbu a3,0(a0) 0000000000000004 <.LVL1>: 4: 06068463 beqz a3,6c <.L8> 8: 0005c603 lbu a2,0(a1) 000000000000000c <.LVL2>: c: 02060e63 beqz a2,48 <.L14> 0000000000000010 <.L6>: 10: 00058713 mv a4,a1 14: 00060793 mv a5,a2 0000000000000018 <.L5>: 18: 00f68e63 beq a3,a5,34 <.L4> 1c: 00174783 lbu a5,1(a4) 20: 00170713 addi a4,a4,1 0000000000000024 <.LVL4>: 24: fe079ae3 bnez a5,18 <.L5> 28: 00154683 lbu a3,1(a0) 2c: 00150513 addi a0,a0,1 0000000000000030 <.LVL5>: 30: fe0690e3 bnez a3,10 <.L6> 0000000000000034 <.L4>: 34: 00074783 lbu a5,0(a4) 38: 00f037b3 snez a5,a5 3c: 40f007b3 neg a5,a5 40: 00f57533 and a0,a0,a5 44: 00008067 ret 0000000000000048 <.L14>: 48: 00154683 lbu a3,1(a0) 4c: 00150513 addi a0,a0,1 0000000000000050 <.LVL8>: 50: fe069ce3 bnez a3,48 <.L14> 54: 00058713 mv a4,a1 58: 00074783 lbu a5,0(a4) 5c: 00f037b3 snez a5,a5 60: 40f007b3 neg a5,a5 64: 00f57533 and a0,a0,a5 0000000000000068 <.LVL9>: 68: 00008067 ret 000000000000006c <.L8>: 6c: 00000513 li a0,0 0000000000000070 <.LVL11>: 70: 00008067 ret --------------------------------------------------------- patch --------------------------------------------------------- libc_a-strpbrk.o: file format elf64-littleriscv Disassembly of section .text: 0000000000000000 <strpbrk>: 0: 00054683 lbu a3,0(a0) 0000000000000004 <.LVL1>: 4: 04068063 beqz a3,44 <.L10> 8: 0005c603 lbu a2,0(a1) c: 04060063 beqz a2,4c <.L14> 0000000000000010 <.L5>: 10: 00058793 mv a5,a1 14: 00060713 mv a4,a2 18: 00c0006f j 24 <.L4> 000000000000001c <.L17>: 1c: 0007c703 lbu a4,0(a5) 20: 00070863 beqz a4,30 <.L16> 0000000000000024 <.L4>: 24: 00178793 addi a5,a5,1 0000000000000028 <.LVL5>: 28: fee69ae3 bne a3,a4,1c <.L17> 000000000000002c <.L1>: 2c: 00008067 ret 0000000000000030 <.L16>: 30: 00154683 lbu a3,1(a0) 34: 00150513 addi a0,a0,1 0000000000000038 <.LVL8>: 38: fc069ce3 bnez a3,10 <.L5> 000000000000003c <.L6>: 3c: 0007c783 lbu a5,0(a5) 0000000000000040 <.LVL9>: 40: fe0796e3 bnez a5,2c <.L1> 0000000000000044 <.L10>: 44: 00000513 li a0,0 0000000000000048 <.LVL11>: 48: 00008067 ret 000000000000004c <.L14>: 4c: 00154683 lbu a3,1(a0) 50: 00150513 addi a0,a0,1 54: fe069ce3 bnez a3,4c <.L14> 58: 00058793 mv a5,a1 5c: fe1ff06f j 3c <.L6> --------------------------------------------------------- After careful comparison, it was found that there are fewer assembly instructions after the patch. 2023-12-20 14:10 Xiao Zeng <zengxiao@eswincomputing.com> wrote: > >Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com> >--- > newlib/libc/string/strpbrk.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > >diff --git a/newlib/libc/string/strpbrk.c b/newlib/libc/string/strpbrk.c >index 774db1e6d..95e89c20c 100644 >--- a/newlib/libc/string/strpbrk.c >+++ b/newlib/libc/string/strpbrk.c >@@ -37,15 +37,14 @@ strpbrk (const char *s1, > for (c = s2; *c; c++) > { > if (*s1 == *c) >- break; >+ goto end; > } >- if (*c) >- break; > s1++; > } > > if (*c == '\0') > s1 = NULL; > >+end: > return (char *) s1; > } >-- >2.17.1 Thanks Xiao Zeng ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization 2023-12-20 6:10 [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization Xiao Zeng 2023-12-20 6:25 ` Xiao Zeng @ 2023-12-20 22:48 ` Jeff Johnston 2023-12-21 1:16 ` Xiao Zeng 1 sibling, 1 reply; 6+ messages in thread From: Jeff Johnston @ 2023-12-20 22:48 UTC (permalink / raw) To: Xiao Zeng; +Cc: newlib, palmer, jeffreyalaw, torbjorn.svensson [-- Attachment #1: Type: text/plain, Size: 1482 bytes --] Unless I am missing something, I think the code could be made even simpler to return the pointer when found and return NULL otherwise. index 774db1e..d984745 100644 --- a/newlib/libc/string/strpbrk.c +++ b/newlib/libc/string/strpbrk.c @@ -29,23 +29,16 @@ strpbrk (const char *s1, const char *s2) { const char *c = s2; - if (!*s1) - return (char *) NULL; while (*s1) { for (c = s2; *c; c++) { if (*s1 == *c) - break; + return (char *) s1; } - if (*c) - break; s1++; } - if (*c == '\0') - s1 = NULL; - - return (char *) s1; + return (char *) NULL; } On Wed, Dec 20, 2023 at 1:12 AM Xiao Zeng <zengxiao@eswincomputing.com> wrote: > Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com> > --- > newlib/libc/string/strpbrk.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/newlib/libc/string/strpbrk.c b/newlib/libc/string/strpbrk.c > index 774db1e6d..95e89c20c 100644 > --- a/newlib/libc/string/strpbrk.c > +++ b/newlib/libc/string/strpbrk.c > @@ -37,15 +37,14 @@ strpbrk (const char *s1, > for (c = s2; *c; c++) > { > if (*s1 == *c) > - break; > + goto end; > } > - if (*c) > - break; > s1++; > } > > if (*c == '\0') > s1 = NULL; > > +end: > return (char *) s1; > } > -- > 2.17.1 > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Re: [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization 2023-12-20 22:48 ` Jeff Johnston @ 2023-12-21 1:16 ` Xiao Zeng 2023-12-21 19:05 ` Jeff Johnston 0 siblings, 1 reply; 6+ messages in thread From: Xiao Zeng @ 2023-12-21 1:16 UTC (permalink / raw) To: Jeff Johnston; +Cc: newlib, palmer, jeffreyalaw, Torbjorn SVENSSON 2023-12-21 06:48 Jeff Johnston <jjohnstn@redhat.com> wrote: > >Unless I am missing something, I think the code could be made even simpler >to return the pointer when found and return NULL otherwise. Yes, you have found a more efficient method. After my testing, fewer assembly instructions were generated. This is really exciting. Xiao's patch: --------------------------------------------------------- libc_a-strpbrk.o: file format elf64-littleriscv Disassembly of section .text: 0000000000000000 <strpbrk>: 0: 00054683 lbu a3,0(a0) 0000000000000004 <.LVL1>: 4: 04068063 beqz a3,44 <.L10> 8: 0005c603 lbu a2,0(a1) c: 04060063 beqz a2,4c <.L14> 0000000000000010 <.L5>: 10: 00058793 mv a5,a1 14: 00060713 mv a4,a2 18: 00c0006f j 24 <.L4> 000000000000001c <.L17>: 1c: 0007c703 lbu a4,0(a5) 20: 00070863 beqz a4,30 <.L16> 0000000000000024 <.L4>: 24: 00178793 addi a5,a5,1 0000000000000028 <.LVL5>: 28: fee69ae3 bne a3,a4,1c <.L17> 000000000000002c <.L1>: 2c: 00008067 ret 0000000000000030 <.L16>: 30: 00154683 lbu a3,1(a0) 34: 00150513 addi a0,a0,1 0000000000000038 <.LVL8>: 38: fc069ce3 bnez a3,10 <.L5> 000000000000003c <.L6>: 3c: 0007c783 lbu a5,0(a5) 0000000000000040 <.LVL9>: 40: fe0796e3 bnez a5,2c <.L1> 0000000000000044 <.L10>: 44: 00000513 li a0,0 0000000000000048 <.LVL11>: 48: 00008067 ret 000000000000004c <.L14>: 4c: 00154683 lbu a3,1(a0) 50: 00150513 addi a0,a0,1 54: fe069ce3 bnez a3,4c <.L14> 58: 00058793 mv a5,a1 5c: fe1ff06f j 3c <.L6> --------------------------------------------------------- Jeff's patch --------------------------------------------------------- libc_a-strpbrk.o: file format elf64-littleriscv Disassembly of section .text: 0000000000000000 <strpbrk>: 0: 00054683 lbu a3,0(a0) 4: 02068c63 beqz a3,3c <.L8> 8: 0005c603 lbu a2,0(a1) c: 02060c63 beqz a2,44 <.L12> 0000000000000010 <.L5>: 10: 00058793 mv a5,a1 14: 00060713 mv a4,a2 18: 00c0006f j 24 <.L4> 000000000000001c <.L15>: 1c: 0007c703 lbu a4,0(a5) 20: 00070863 beqz a4,30 <.L14> 0000000000000024 <.L4>: 24: 00178793 addi a5,a5,1 0000000000000028 <.LVL4>: 28: fed71ae3 bne a4,a3,1c <.L15> 2c: 00008067 ret 0000000000000030 <.L14>: 30: 00154683 lbu a3,1(a0) 34: 00150513 addi a0,a0,1 0000000000000038 <.LVL6>: 38: fc069ce3 bnez a3,10 <.L5> 000000000000003c <.L8>: 3c: 00000513 li a0,0 0000000000000040 <.LVL7>: 40: 00008067 ret 0000000000000044 <.L12>: 44: 00154683 lbu a3,1(a0) 48: 00150513 addi a0,a0,1 4c: fe069ce3 bnez a3,44 <.L12> 50: fedff06f j 3c <.L8> --------------------------------------------------------- After careful comparison, it was found that there are fewer assembly instructions after the Jeff's patch. > >index 774db1e..d984745 100644 >--- a/newlib/libc/string/strpbrk.c >+++ b/newlib/libc/string/strpbrk.c >@@ -29,23 +29,16 @@ strpbrk (const char *s1, > const char *s2) > { > const char *c = s2; >- if (!*s1) >- return (char *) NULL; > > while (*s1) > { > for (c = s2; *c; c++) > { > if (*s1 == *c) >- break; >+ return (char *) s1; > } >- if (*c) >- break; > s1++; > } > >- if (*c == '\0') >- s1 = NULL; >- >- return (char *) s1; >+ return (char *) NULL; > } > >On Wed, Dec 20, 2023 at 1:12 AM Xiao Zeng <zengxiao@eswincomputing.com> >wrote: > >> Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com> >> --- >> newlib/libc/string/strpbrk.c | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/newlib/libc/string/strpbrk.c b/newlib/libc/string/strpbrk.c >> index 774db1e6d..95e89c20c 100644 >> --- a/newlib/libc/string/strpbrk.c >> +++ b/newlib/libc/string/strpbrk.c >> @@ -37,15 +37,14 @@ strpbrk (const char *s1, >> for (c = s2; *c; c++) >> { >> if (*s1 == *c) >> - break; >> + goto end; >> } >> - if (*c) >> - break; >> s1++; >> } >> >> if (*c == '\0') >> s1 = NULL; >> >> +end: >> return (char *) s1; >> } >> -- >> 2.17.1 >> >> Thanks Xiao Zeng ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Re: [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization 2023-12-21 1:16 ` Xiao Zeng @ 2023-12-21 19:05 ` Jeff Johnston 2023-12-22 1:21 ` Xiao Zeng 0 siblings, 1 reply; 6+ messages in thread From: Jeff Johnston @ 2023-12-21 19:05 UTC (permalink / raw) To: Xiao Zeng; +Cc: newlib, palmer, jeffreyalaw, Torbjorn SVENSSON [-- Attachment #1: Type: text/plain, Size: 5704 bytes --] Patch merged. Thanks. -- Jeff J. On Wed, Dec 20, 2023 at 8:16 PM Xiao Zeng <zengxiao@eswincomputing.com> wrote: > 2023-12-21 06:48 Jeff Johnston <jjohnstn@redhat.com> wrote: > > > > >Unless I am missing something, I think the code could be made even simpler > >to return the pointer when found and return NULL otherwise. > Yes, you have found a more efficient method. > After my testing, fewer assembly instructions were generated. This is > really exciting. > > Xiao's patch: > --------------------------------------------------------- > libc_a-strpbrk.o: file format elf64-littleriscv > > > Disassembly of section .text: > > 0000000000000000 <strpbrk>: > 0: 00054683 lbu a3,0(a0) > > 0000000000000004 <.LVL1>: > 4: 04068063 beqz a3,44 <.L10> > 8: 0005c603 lbu a2,0(a1) > c: 04060063 beqz a2,4c <.L14> > > 0000000000000010 <.L5>: > 10: 00058793 mv a5,a1 > 14: 00060713 mv a4,a2 > 18: 00c0006f j 24 <.L4> > > 000000000000001c <.L17>: > 1c: 0007c703 lbu a4,0(a5) > 20: 00070863 beqz a4,30 <.L16> > > 0000000000000024 <.L4>: > 24: 00178793 addi a5,a5,1 > > 0000000000000028 <.LVL5>: > 28: fee69ae3 bne a3,a4,1c <.L17> > > 000000000000002c <.L1>: > 2c: 00008067 ret > > 0000000000000030 <.L16>: > 30: 00154683 lbu a3,1(a0) > 34: 00150513 addi a0,a0,1 > > 0000000000000038 <.LVL8>: > 38: fc069ce3 bnez a3,10 <.L5> > > 000000000000003c <.L6>: > 3c: 0007c783 lbu a5,0(a5) > > 0000000000000040 <.LVL9>: > 40: fe0796e3 bnez a5,2c <.L1> > > 0000000000000044 <.L10>: > 44: 00000513 li a0,0 > > 0000000000000048 <.LVL11>: > 48: 00008067 ret > > 000000000000004c <.L14>: > 4c: 00154683 lbu a3,1(a0) > 50: 00150513 addi a0,a0,1 > 54: fe069ce3 bnez a3,4c <.L14> > 58: 00058793 mv a5,a1 > 5c: fe1ff06f j 3c <.L6> > --------------------------------------------------------- > > Jeff's patch > --------------------------------------------------------- > libc_a-strpbrk.o: file format elf64-littleriscv > > > Disassembly of section .text: > > 0000000000000000 <strpbrk>: > 0: 00054683 lbu a3,0(a0) > 4: 02068c63 beqz a3,3c <.L8> > 8: 0005c603 lbu a2,0(a1) > c: 02060c63 beqz a2,44 <.L12> > > 0000000000000010 <.L5>: > 10: 00058793 mv a5,a1 > 14: 00060713 mv a4,a2 > 18: 00c0006f j 24 <.L4> > > 000000000000001c <.L15>: > 1c: 0007c703 lbu a4,0(a5) > 20: 00070863 beqz a4,30 <.L14> > > 0000000000000024 <.L4>: > 24: 00178793 addi a5,a5,1 > > 0000000000000028 <.LVL4>: > 28: fed71ae3 bne a4,a3,1c <.L15> > 2c: 00008067 ret > > 0000000000000030 <.L14>: > 30: 00154683 lbu a3,1(a0) > 34: 00150513 addi a0,a0,1 > > 0000000000000038 <.LVL6>: > 38: fc069ce3 bnez a3,10 <.L5> > > 000000000000003c <.L8>: > 3c: 00000513 li a0,0 > > 0000000000000040 <.LVL7>: > 40: 00008067 ret > > 0000000000000044 <.L12>: > 44: 00154683 lbu a3,1(a0) > 48: 00150513 addi a0,a0,1 > 4c: fe069ce3 bnez a3,44 <.L12> > 50: fedff06f j 3c <.L8> > --------------------------------------------------------- > After careful comparison, it was found that there are fewer assembly > instructions after the Jeff's patch. > > > > >index 774db1e..d984745 100644 > >--- a/newlib/libc/string/strpbrk.c > >+++ b/newlib/libc/string/strpbrk.c > >@@ -29,23 +29,16 @@ strpbrk (const char *s1, > > const char *s2) > > { > > const char *c = s2; > >- if (!*s1) > >- return (char *) NULL; > > > > while (*s1) > > { > > for (c = s2; *c; c++) > > { > > if (*s1 == *c) > >- break; > >+ return (char *) s1; > > } > >- if (*c) > >- break; > > s1++; > > } > > > >- if (*c == '\0') > >- s1 = NULL; > >- > >- return (char *) s1; > >+ return (char *) NULL; > > } > > > >On Wed, Dec 20, 2023 at 1:12 AM Xiao Zeng <zengxiao@eswincomputing.com> > >wrote: > > > >> Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com> > >> --- > >> newlib/libc/string/strpbrk.c | 5 ++--- > >> 1 file changed, 2 insertions(+), 3 deletions(-) > >> > >> diff --git a/newlib/libc/string/strpbrk.c b/newlib/libc/string/strpbrk.c > >> index 774db1e6d..95e89c20c 100644 > >> --- a/newlib/libc/string/strpbrk.c > >> +++ b/newlib/libc/string/strpbrk.c > >> @@ -37,15 +37,14 @@ strpbrk (const char *s1, > >> for (c = s2; *c; c++) > >> { > >> if (*s1 == *c) > >> - break; > >> + goto end; > >> } > >> - if (*c) > >> - break; > >> s1++; > >> } > >> > >> if (*c == '\0') > >> s1 = NULL; > >> > >> +end: > >> return (char *) s1; > >> } > >> -- > >> 2.17.1 > >> > >> > > Thanks > Xiao Zeng > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Re: [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization 2023-12-21 19:05 ` Jeff Johnston @ 2023-12-22 1:21 ` Xiao Zeng 0 siblings, 0 replies; 6+ messages in thread From: Xiao Zeng @ 2023-12-22 1:21 UTC (permalink / raw) To: Jeff Johnston; +Cc: newlib, palmer, jeffreyalaw, Torbjorn SVENSSON 2023-12-22 03:05 Jeff Johnston <jjohnstn@redhat.com> wrote: > >Patch merged. Thanks. Thank you, Jeff. Perhaps the two emails are too similar, I would like to remind you that there is a similar optimization on <https://sourceware.org/pipermail/newlib/2023/020771.html>. > >-- Jeff J. > >On Wed, Dec 20, 2023 at 8:16 PM Xiao Zeng <zengxiao@eswincomputing.com> >wrote: > >> 2023-12-21 06:48 Jeff Johnston <jjohnstn@redhat.com> wrote: >> > >> >> >Unless I am missing something, I think the code could be made even simpler >> >to return the pointer when found and return NULL otherwise. >> Yes, you have found a more efficient method. >> After my testing, fewer assembly instructions were generated. This is >> really exciting. >> >> Xiao's patch: >> --------------------------------------------------------- >> libc_a-strpbrk.o: file format elf64-littleriscv >> >> >> Disassembly of section .text: >> >> 0000000000000000 <strpbrk>: >> 0: 00054683 lbu a3,0(a0) >> >> 0000000000000004 <.LVL1>: >> 4: 04068063 beqz a3,44 <.L10> >> 8: 0005c603 lbu a2,0(a1) >> c: 04060063 beqz a2,4c <.L14> >> >> 0000000000000010 <.L5>: >> 10: 00058793 mv a5,a1 >> 14: 00060713 mv a4,a2 >> 18: 00c0006f j 24 <.L4> >> >> 000000000000001c <.L17>: >> 1c: 0007c703 lbu a4,0(a5) >> 20: 00070863 beqz a4,30 <.L16> >> >> 0000000000000024 <.L4>: >> 24: 00178793 addi a5,a5,1 >> >> 0000000000000028 <.LVL5>: >> 28: fee69ae3 bne a3,a4,1c <.L17> >> >> 000000000000002c <.L1>: >> 2c: 00008067 ret >> >> 0000000000000030 <.L16>: >> 30: 00154683 lbu a3,1(a0) >> 34: 00150513 addi a0,a0,1 >> >> 0000000000000038 <.LVL8>: >> 38: fc069ce3 bnez a3,10 <.L5> >> >> 000000000000003c <.L6>: >> 3c: 0007c783 lbu a5,0(a5) >> >> 0000000000000040 <.LVL9>: >> 40: fe0796e3 bnez a5,2c <.L1> >> >> 0000000000000044 <.L10>: >> 44: 00000513 li a0,0 >> >> 0000000000000048 <.LVL11>: >> 48: 00008067 ret >> >> 000000000000004c <.L14>: >> 4c: 00154683 lbu a3,1(a0) >> 50: 00150513 addi a0,a0,1 >> 54: fe069ce3 bnez a3,4c <.L14> >> 58: 00058793 mv a5,a1 >> 5c: fe1ff06f j 3c <.L6> >> --------------------------------------------------------- >> >> Jeff's patch >> --------------------------------------------------------- >> libc_a-strpbrk.o: file format elf64-littleriscv >> >> >> Disassembly of section .text: >> >> 0000000000000000 <strpbrk>: >> 0: 00054683 lbu a3,0(a0) >> 4: 02068c63 beqz a3,3c <.L8> >> 8: 0005c603 lbu a2,0(a1) >> c: 02060c63 beqz a2,44 <.L12> >> >> 0000000000000010 <.L5>: >> 10: 00058793 mv a5,a1 >> 14: 00060713 mv a4,a2 >> 18: 00c0006f j 24 <.L4> >> >> 000000000000001c <.L15>: >> 1c: 0007c703 lbu a4,0(a5) >> 20: 00070863 beqz a4,30 <.L14> >> >> 0000000000000024 <.L4>: >> 24: 00178793 addi a5,a5,1 >> >> 0000000000000028 <.LVL4>: >> 28: fed71ae3 bne a4,a3,1c <.L15> >> 2c: 00008067 ret >> >> 0000000000000030 <.L14>: >> 30: 00154683 lbu a3,1(a0) >> 34: 00150513 addi a0,a0,1 >> >> 0000000000000038 <.LVL6>: >> 38: fc069ce3 bnez a3,10 <.L5> >> >> 000000000000003c <.L8>: >> 3c: 00000513 li a0,0 >> >> 0000000000000040 <.LVL7>: >> 40: 00008067 ret >> >> 0000000000000044 <.L12>: >> 44: 00154683 lbu a3,1(a0) >> 48: 00150513 addi a0,a0,1 >> 4c: fe069ce3 bnez a3,44 <.L12> >> 50: fedff06f j 3c <.L8> >> --------------------------------------------------------- >> After careful comparison, it was found that there are fewer assembly >> instructions after the Jeff's patch. >> >> > >> >index 774db1e..d984745 100644 >> >--- a/newlib/libc/string/strpbrk.c >> >+++ b/newlib/libc/string/strpbrk.c >> >@@ -29,23 +29,16 @@ strpbrk (const char *s1, >> > const char *s2) >> > { >> > const char *c = s2; >> >- if (!*s1) >> >- return (char *) NULL; >> > >> > while (*s1) >> > { >> > for (c = s2; *c; c++) >> > { >> > if (*s1 == *c) >> >- break; >> >+ return (char *) s1; >> > } >> >- if (*c) >> >- break; >> > s1++; >> > } >> > >> >- if (*c == '\0') >> >- s1 = NULL; >> >- >> >- return (char *) s1; >> >+ return (char *) NULL; >> > } >> > >> >On Wed, Dec 20, 2023 at 1:12 AM Xiao Zeng <zengxiao@eswincomputing.com> >> >wrote: >> > >> >> Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com> >> >> --- >> >> newlib/libc/string/strpbrk.c | 5 ++--- >> >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> >> >> diff --git a/newlib/libc/string/strpbrk.c b/newlib/libc/string/strpbrk.c >> >> index 774db1e6d..95e89c20c 100644 >> >> --- a/newlib/libc/string/strpbrk.c >> >> +++ b/newlib/libc/string/strpbrk.c >> >> @@ -37,15 +37,14 @@ strpbrk (const char *s1, >> >> for (c = s2; *c; c++) >> >> { >> >> if (*s1 == *c) >> >> - break; >> >> + goto end; >> >> } >> >> - if (*c) >> >> - break; >> >> s1++; >> >> } >> >> >> >> if (*c == '\0') >> >> s1 = NULL; >> >> >> >> +end: >> >> return (char *) s1; >> >> } >> >> -- >> >> 2.17.1 >> >> >> >> >> >> Thanks >> Xiao Zeng >> >> Thanks Xiao Zeng ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-12-22 1:22 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-12-20 6:10 [PATCH] newlib: libc: Improved the readability of strpbrk with minor optimization Xiao Zeng 2023-12-20 6:25 ` Xiao Zeng 2023-12-20 22:48 ` Jeff Johnston 2023-12-21 1:16 ` Xiao Zeng 2023-12-21 19:05 ` Jeff Johnston 2023-12-22 1:21 ` Xiao Zeng
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