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Lu" , Libc-stable Mailing List Cc: Noah Goldstein , GNU C Library Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM, GIT_PATCH_0, HK_RANDOM_ENVFROM, HK_RANDOM_FROM, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, 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: libc-stable@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-stable mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 May 2022 19:32:59 -0000 On Thu, Mar 24, 2022 at 11:55 AM H.J. Lu via Libc-alpha wrote: > > On Wed, Mar 23, 2022 at 2:58 PM Noah Goldstein wrote: > > > > Small code cleanup for size: -81 bytes. > > > > Add comment justifying using a branch to do NULL/non-null return. > > > > All string/memory tests pass and no regressions in benchtests. > > > > geometric_mean(N=20) of all benchmarks New / Original: .985 > > --- > > Geomtric Mean N=20 runs; All functions page aligned > > length, alignment, pos, rand, seek_char/branch, max_char/perc-zero, New Time / Old Time > > 2048, 0, 32, 0, 23, 127, 0.878 > > 2048, 1, 32, 0, 23, 127, 0.88 > > 2048, 0, 64, 0, 23, 127, 0.997 > > 2048, 2, 64, 0, 23, 127, 1.001 > > 2048, 0, 128, 0, 23, 127, 0.973 > > 2048, 3, 128, 0, 23, 127, 0.971 > > 2048, 0, 256, 0, 23, 127, 0.976 > > 2048, 4, 256, 0, 23, 127, 0.973 > > 2048, 0, 512, 0, 23, 127, 1.001 > > 2048, 5, 512, 0, 23, 127, 1.004 > > 2048, 0, 1024, 0, 23, 127, 1.005 > > 2048, 6, 1024, 0, 23, 127, 1.007 > > 2048, 0, 2048, 0, 23, 127, 1.035 > > 2048, 7, 2048, 0, 23, 127, 1.03 > > 4096, 0, 32, 0, 23, 127, 0.889 > > 4096, 1, 32, 0, 23, 127, 0.891 > > 4096, 0, 64, 0, 23, 127, 1.012 > > 4096, 2, 64, 0, 23, 127, 1.017 > > 4096, 0, 128, 0, 23, 127, 0.975 > > 4096, 3, 128, 0, 23, 127, 0.974 > > 4096, 0, 256, 0, 23, 127, 0.974 > > 4096, 4, 256, 0, 23, 127, 0.972 > > 4096, 0, 512, 0, 23, 127, 1.002 > > 4096, 5, 512, 0, 23, 127, 1.016 > > 4096, 0, 1024, 0, 23, 127, 1.009 > > 4096, 6, 1024, 0, 23, 127, 1.008 > > 4096, 0, 2048, 0, 23, 127, 1.003 > > 4096, 7, 2048, 0, 23, 127, 1.004 > > 256, 1, 64, 0, 23, 127, 0.993 > > 256, 2, 64, 0, 23, 127, 0.999 > > 256, 3, 64, 0, 23, 127, 0.992 > > 256, 4, 64, 0, 23, 127, 0.99 > > 256, 5, 64, 0, 23, 127, 0.99 > > 256, 6, 64, 0, 23, 127, 0.994 > > 256, 7, 64, 0, 23, 127, 0.991 > > 512, 0, 256, 0, 23, 127, 0.971 > > 512, 16, 256, 0, 23, 127, 0.971 > > 512, 32, 256, 0, 23, 127, 1.005 > > 512, 48, 256, 0, 23, 127, 0.998 > > 512, 64, 256, 0, 23, 127, 1.001 > > 512, 80, 256, 0, 23, 127, 1.002 > > 512, 96, 256, 0, 23, 127, 1.005 > > 512, 112, 256, 0, 23, 127, 1.012 > > 1, 0, 0, 0, 23, 127, 1.024 > > 2, 0, 1, 0, 23, 127, 0.991 > > 3, 0, 2, 0, 23, 127, 0.997 > > 4, 0, 3, 0, 23, 127, 0.984 > > 5, 0, 4, 0, 23, 127, 0.993 > > 6, 0, 5, 0, 23, 127, 0.985 > > 7, 0, 6, 0, 23, 127, 0.979 > > 8, 0, 7, 0, 23, 127, 0.975 > > 9, 0, 8, 0, 23, 127, 0.965 > > 10, 0, 9, 0, 23, 127, 0.957 > > 11, 0, 10, 0, 23, 127, 0.979 > > 12, 0, 11, 0, 23, 127, 0.987 > > 13, 0, 12, 0, 23, 127, 1.023 > > 14, 0, 13, 0, 23, 127, 0.997 > > 15, 0, 14, 0, 23, 127, 0.983 > > 16, 0, 15, 0, 23, 127, 0.987 > > 17, 0, 16, 0, 23, 127, 0.993 > > 18, 0, 17, 0, 23, 127, 0.985 > > 19, 0, 18, 0, 23, 127, 0.999 > > 20, 0, 19, 0, 23, 127, 0.998 > > 21, 0, 20, 0, 23, 127, 0.983 > > 22, 0, 21, 0, 23, 127, 0.983 > > 23, 0, 22, 0, 23, 127, 1.002 > > 24, 0, 23, 0, 23, 127, 1.0 > > 25, 0, 24, 0, 23, 127, 1.002 > > 26, 0, 25, 0, 23, 127, 0.984 > > 27, 0, 26, 0, 23, 127, 0.994 > > 28, 0, 27, 0, 23, 127, 0.995 > > 29, 0, 28, 0, 23, 127, 1.017 > > 30, 0, 29, 0, 23, 127, 1.009 > > 31, 0, 30, 0, 23, 127, 1.001 > > 32, 0, 31, 0, 23, 127, 1.021 > > 2048, 0, 32, 0, 0, 127, 0.899 > > 2048, 1, 32, 0, 0, 127, 0.93 > > 2048, 0, 64, 0, 0, 127, 1.009 > > 2048, 2, 64, 0, 0, 127, 1.023 > > 2048, 0, 128, 0, 0, 127, 0.973 > > 2048, 3, 128, 0, 0, 127, 0.975 > > 2048, 0, 256, 0, 0, 127, 0.974 > > 2048, 4, 256, 0, 0, 127, 0.97 > > 2048, 0, 512, 0, 0, 127, 0.999 > > 2048, 5, 512, 0, 0, 127, 1.004 > > 2048, 0, 1024, 0, 0, 127, 1.008 > > 2048, 6, 1024, 0, 0, 127, 1.008 > > 2048, 0, 2048, 0, 0, 127, 0.996 > > 2048, 7, 2048, 0, 0, 127, 1.002 > > 4096, 0, 32, 0, 0, 127, 0.872 > > 4096, 1, 32, 0, 0, 127, 0.881 > > 4096, 0, 64, 0, 0, 127, 1.006 > > 4096, 2, 64, 0, 0, 127, 1.005 > > 4096, 0, 128, 0, 0, 127, 0.973 > > 4096, 3, 128, 0, 0, 127, 0.974 > > 4096, 0, 256, 0, 0, 127, 0.969 > > 4096, 4, 256, 0, 0, 127, 0.971 > > 4096, 0, 512, 0, 0, 127, 1.0 > > 4096, 5, 512, 0, 0, 127, 1.005 > > 4096, 0, 1024, 0, 0, 127, 1.007 > > 4096, 6, 1024, 0, 0, 127, 1.009 > > 4096, 0, 2048, 0, 0, 127, 1.005 > > 4096, 7, 2048, 0, 0, 127, 1.007 > > 256, 1, 64, 0, 0, 127, 0.994 > > 256, 2, 64, 0, 0, 127, 1.008 > > 256, 3, 64, 0, 0, 127, 1.019 > > 256, 4, 64, 0, 0, 127, 0.991 > > 256, 5, 64, 0, 0, 127, 0.992 > > 256, 6, 64, 0, 0, 127, 0.991 > > 256, 7, 64, 0, 0, 127, 0.988 > > 512, 0, 256, 0, 0, 127, 0.971 > > 512, 16, 256, 0, 0, 127, 0.967 > > 512, 32, 256, 0, 0, 127, 1.005 > > 512, 48, 256, 0, 0, 127, 1.001 > > 512, 64, 256, 0, 0, 127, 1.009 > > 512, 80, 256, 0, 0, 127, 1.008 > > 512, 96, 256, 0, 0, 127, 1.009 > > 512, 112, 256, 0, 0, 127, 1.016 > > 1, 0, 0, 0, 0, 127, 1.038 > > 2, 0, 1, 0, 0, 127, 1.009 > > 3, 0, 2, 0, 0, 127, 0.992 > > 4, 0, 3, 0, 0, 127, 1.004 > > 5, 0, 4, 0, 0, 127, 0.966 > > 6, 0, 5, 0, 0, 127, 0.968 > > 7, 0, 6, 0, 0, 127, 1.004 > > 8, 0, 7, 0, 0, 127, 0.99 > > 9, 0, 8, 0, 0, 127, 0.958 > > 10, 0, 9, 0, 0, 127, 0.96 > > 11, 0, 10, 0, 0, 127, 0.948 > > 12, 0, 11, 0, 0, 127, 0.984 > > 13, 0, 12, 0, 0, 127, 0.967 > > 14, 0, 13, 0, 0, 127, 0.993 > > 15, 0, 14, 0, 0, 127, 0.991 > > 16, 0, 15, 0, 0, 127, 1.0 > > 17, 0, 16, 0, 0, 127, 0.982 > > 18, 0, 17, 0, 0, 127, 0.977 > > 19, 0, 18, 0, 0, 127, 0.987 > > 20, 0, 19, 0, 0, 127, 0.978 > > 21, 0, 20, 0, 0, 127, 1.0 > > 22, 0, 21, 0, 0, 127, 0.99 > > 23, 0, 22, 0, 0, 127, 0.988 > > 24, 0, 23, 0, 0, 127, 0.997 > > 25, 0, 24, 0, 0, 127, 1.003 > > 26, 0, 25, 0, 0, 127, 1.004 > > 27, 0, 26, 0, 0, 127, 0.982 > > 28, 0, 27, 0, 0, 127, 0.972 > > 29, 0, 28, 0, 0, 127, 0.978 > > 30, 0, 29, 0, 0, 127, 0.992 > > 31, 0, 30, 0, 0, 127, 0.986 > > 32, 0, 31, 0, 0, 127, 1.0 > > > > 16, 0, 15, 1, 1, 0, 0.997 > > 16, 0, 15, 1, 0, 0, 1.001 > > 16, 0, 15, 1, 1, 0.1, 0.984 > > 16, 0, 15, 1, 0, 0.1, 0.999 > > 16, 0, 15, 1, 1, 0.25, 0.929 > > 16, 0, 15, 1, 0, 0.25, 1.001 > > 16, 0, 15, 1, 1, 0.33, 0.892 > > 16, 0, 15, 1, 0, 0.33, 0.996 > > 16, 0, 15, 1, 1, 0.5, 0.897 > > 16, 0, 15, 1, 0, 0.5, 1.009 > > 16, 0, 15, 1, 1, 0.66, 0.882 > > 16, 0, 15, 1, 0, 0.66, 0.967 > > 16, 0, 15, 1, 1, 0.75, 0.919 > > 16, 0, 15, 1, 0, 0.75, 1.027 > > 16, 0, 15, 1, 1, 0.9, 0.949 > > 16, 0, 15, 1, 0, 0.9, 1.021 > > 16, 0, 15, 1, 1, 1, 0.998 > > 16, 0, 15, 1, 0, 1, 0.999 > > > > sysdeps/x86_64/multiarch/strchr-evex.S | 146 ++++++++++++++----------- > > 1 file changed, 80 insertions(+), 66 deletions(-) > > > > diff --git a/sysdeps/x86_64/multiarch/strchr-evex.S b/sysdeps/x86_64/multiarch/strchr-evex.S > > index f62cd9d144..ec739fb8f9 100644 > > --- a/sysdeps/x86_64/multiarch/strchr-evex.S > > +++ b/sysdeps/x86_64/multiarch/strchr-evex.S > > @@ -30,6 +30,7 @@ > > # ifdef USE_AS_WCSCHR > > # define VPBROADCAST vpbroadcastd > > # define VPCMP vpcmpd > > +# define VPTESTN vptestnmd > > # define VPMINU vpminud > > # define CHAR_REG esi > > # define SHIFT_REG ecx > > @@ -37,6 +38,7 @@ > > # else > > # define VPBROADCAST vpbroadcastb > > # define VPCMP vpcmpb > > +# define VPTESTN vptestnmb > > # define VPMINU vpminub > > # define CHAR_REG sil > > # define SHIFT_REG edx > > @@ -61,13 +63,11 @@ > > # define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE) > > > > .section .text.evex,"ax",@progbits > > -ENTRY (STRCHR) > > +ENTRY_P2ALIGN (STRCHR, 5) > > /* Broadcast CHAR to YMM0. */ > > VPBROADCAST %esi, %YMM0 > > movl %edi, %eax > > andl $(PAGE_SIZE - 1), %eax > > - vpxorq %XMMZERO, %XMMZERO, %XMMZERO > > - > > /* Check if we cross page boundary with one vector load. > > Otherwise it is safe to use an unaligned load. */ > > cmpl $(PAGE_SIZE - VEC_SIZE), %eax > > @@ -81,49 +81,35 @@ ENTRY (STRCHR) > > vpxorq %YMM1, %YMM0, %YMM2 > > VPMINU %YMM2, %YMM1, %YMM2 > > /* Each bit in K0 represents a CHAR or a null byte in YMM1. */ > > - VPCMP $0, %YMMZERO, %YMM2, %k0 > > + VPTESTN %YMM2, %YMM2, %k0 > > kmovd %k0, %eax > > testl %eax, %eax > > jz L(aligned_more) > > tzcntl %eax, %eax > > +# ifndef USE_AS_STRCHRNUL > > + /* Found CHAR or the null byte. */ > > + cmp (%rdi, %rax, CHAR_SIZE), %CHAR_REG > > + /* NB: Use a branch instead of cmovcc here. The expectation is > > + that with strchr the user will branch based on input being > > + null. Since this branch will be 100% predictive of the user > > + branch a branch miss here should save what otherwise would > > + be branch miss in the user code. Otherwise using a branch 1) > > + saves code size and 2) is faster in highly predictable > > + environments. */ > > + jne L(zero) > > +# endif > > # ifdef USE_AS_WCSCHR > > /* NB: Multiply wchar_t count by 4 to get the number of bytes. > > */ > > leaq (%rdi, %rax, CHAR_SIZE), %rax > > # else > > addq %rdi, %rax > > -# endif > > -# ifndef USE_AS_STRCHRNUL > > - /* Found CHAR or the null byte. */ > > - cmp (%rax), %CHAR_REG > > - jne L(zero) > > # endif > > ret > > > > - /* .p2align 5 helps keep performance more consistent if ENTRY() > > - alignment % 32 was either 16 or 0. As well this makes the > > - alignment % 32 of the loop_4x_vec fixed which makes tuning it > > - easier. */ > > - .p2align 5 > > -L(first_vec_x3): > > - tzcntl %eax, %eax > > -# ifndef USE_AS_STRCHRNUL > > - /* Found CHAR or the null byte. */ > > - cmp (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %CHAR_REG > > - jne L(zero) > > -# endif > > - /* NB: Multiply sizeof char type (1 or 4) to get the number of > > - bytes. */ > > - leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax > > - ret > > > > -# ifndef USE_AS_STRCHRNUL > > -L(zero): > > - xorl %eax, %eax > > - ret > > -# endif > > > > - .p2align 4 > > + .p2align 4,, 10 > > L(first_vec_x4): > > # ifndef USE_AS_STRCHRNUL > > /* Check to see if first match was CHAR (k0) or null (k1). */ > > @@ -144,9 +130,18 @@ L(first_vec_x4): > > leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax > > ret > > > > +# ifndef USE_AS_STRCHRNUL > > +L(zero): > > + xorl %eax, %eax > > + ret > > +# endif > > + > > + > > .p2align 4 > > L(first_vec_x1): > > - tzcntl %eax, %eax > > + /* Use bsf here to save 1-byte keeping keeping the block in 1x > > + fetch block. eax guranteed non-zero. */ > > + bsfl %eax, %eax > > # ifndef USE_AS_STRCHRNUL > > /* Found CHAR or the null byte. */ > > cmp (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %CHAR_REG > > @@ -158,7 +153,7 @@ L(first_vec_x1): > > leaq (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %rax > > ret > > > > - .p2align 4 > > + .p2align 4,, 10 > > L(first_vec_x2): > > # ifndef USE_AS_STRCHRNUL > > /* Check to see if first match was CHAR (k0) or null (k1). */ > > @@ -179,6 +174,21 @@ L(first_vec_x2): > > leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax > > ret > > > > + .p2align 4,, 10 > > +L(first_vec_x3): > > + /* Use bsf here to save 1-byte keeping keeping the block in 1x > > + fetch block. eax guranteed non-zero. */ > > + bsfl %eax, %eax > > +# ifndef USE_AS_STRCHRNUL > > + /* Found CHAR or the null byte. */ > > + cmp (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %CHAR_REG > > + jne L(zero) > > +# endif > > + /* NB: Multiply sizeof char type (1 or 4) to get the number of > > + bytes. */ > > + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax > > + ret > > + > > .p2align 4 > > L(aligned_more): > > /* Align data to VEC_SIZE. */ > > @@ -195,7 +205,7 @@ L(cross_page_continue): > > vpxorq %YMM1, %YMM0, %YMM2 > > VPMINU %YMM2, %YMM1, %YMM2 > > /* Each bit in K0 represents a CHAR or a null byte in YMM1. */ > > - VPCMP $0, %YMMZERO, %YMM2, %k0 > > + VPTESTN %YMM2, %YMM2, %k0 > > kmovd %k0, %eax > > testl %eax, %eax > > jnz L(first_vec_x1) > > @@ -206,7 +216,7 @@ L(cross_page_continue): > > /* Each bit in K0 represents a CHAR in YMM1. */ > > VPCMP $0, %YMM1, %YMM0, %k0 > > /* Each bit in K1 represents a CHAR in YMM1. */ > > - VPCMP $0, %YMM1, %YMMZERO, %k1 > > + VPTESTN %YMM1, %YMM1, %k1 > > kortestd %k0, %k1 > > jnz L(first_vec_x2) > > > > @@ -215,7 +225,7 @@ L(cross_page_continue): > > vpxorq %YMM1, %YMM0, %YMM2 > > VPMINU %YMM2, %YMM1, %YMM2 > > /* Each bit in K0 represents a CHAR or a null byte in YMM1. */ > > - VPCMP $0, %YMMZERO, %YMM2, %k0 > > + VPTESTN %YMM2, %YMM2, %k0 > > kmovd %k0, %eax > > testl %eax, %eax > > jnz L(first_vec_x3) > > @@ -224,7 +234,7 @@ L(cross_page_continue): > > /* Each bit in K0 represents a CHAR in YMM1. */ > > VPCMP $0, %YMM1, %YMM0, %k0 > > /* Each bit in K1 represents a CHAR in YMM1. */ > > - VPCMP $0, %YMM1, %YMMZERO, %k1 > > + VPTESTN %YMM1, %YMM1, %k1 > > kortestd %k0, %k1 > > jnz L(first_vec_x4) > > > > @@ -265,33 +275,33 @@ L(loop_4x_vec): > > VPMINU %YMM3, %YMM4, %YMM4 > > VPMINU %YMM2, %YMM4, %YMM4{%k4}{z} > > > > - VPCMP $0, %YMMZERO, %YMM4, %k1 > > + VPTESTN %YMM4, %YMM4, %k1 > > kmovd %k1, %ecx > > subq $-(VEC_SIZE * 4), %rdi > > testl %ecx, %ecx > > jz L(loop_4x_vec) > > > > - VPCMP $0, %YMMZERO, %YMM1, %k0 > > + VPTESTN %YMM1, %YMM1, %k0 > > kmovd %k0, %eax > > testl %eax, %eax > > jnz L(last_vec_x1) > > > > - VPCMP $0, %YMMZERO, %YMM2, %k0 > > + VPTESTN %YMM2, %YMM2, %k0 > > kmovd %k0, %eax > > testl %eax, %eax > > jnz L(last_vec_x2) > > > > - VPCMP $0, %YMMZERO, %YMM3, %k0 > > + VPTESTN %YMM3, %YMM3, %k0 > > kmovd %k0, %eax > > /* Combine YMM3 matches (eax) with YMM4 matches (ecx). */ > > # ifdef USE_AS_WCSCHR > > sall $8, %ecx > > orl %ecx, %eax > > - tzcntl %eax, %eax > > + bsfl %eax, %eax > > # else > > salq $32, %rcx > > orq %rcx, %rax > > - tzcntq %rax, %rax > > + bsfq %rax, %rax > > # endif > > # ifndef USE_AS_STRCHRNUL > > /* Check if match was CHAR or null. */ > > @@ -303,28 +313,28 @@ L(loop_4x_vec): > > leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax > > ret > > > > -# ifndef USE_AS_STRCHRNUL > > -L(zero_end): > > - xorl %eax, %eax > > - ret > > + .p2align 4,, 8 > > +L(last_vec_x1): > > + bsfl %eax, %eax > > +# ifdef USE_AS_WCSCHR > > + /* NB: Multiply wchar_t count by 4 to get the number of bytes. > > + */ > > + leaq (%rdi, %rax, CHAR_SIZE), %rax > > +# else > > + addq %rdi, %rax > > # endif > > > > - .p2align 4 > > -L(last_vec_x1): > > - tzcntl %eax, %eax > > # ifndef USE_AS_STRCHRNUL > > /* Check if match was null. */ > > - cmp (%rdi, %rax, CHAR_SIZE), %CHAR_REG > > + cmp (%rax), %CHAR_REG > > jne L(zero_end) > > # endif > > - /* NB: Multiply sizeof char type (1 or 4) to get the number of > > - bytes. */ > > - leaq (%rdi, %rax, CHAR_SIZE), %rax > > + > > ret > > > > - .p2align 4 > > + .p2align 4,, 8 > > L(last_vec_x2): > > - tzcntl %eax, %eax > > + bsfl %eax, %eax > > # ifndef USE_AS_STRCHRNUL > > /* Check if match was null. */ > > cmp (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %CHAR_REG > > @@ -336,7 +346,7 @@ L(last_vec_x2): > > ret > > > > /* Cold case for crossing page with first load. */ > > - .p2align 4 > > + .p2align 4,, 8 > > L(cross_page_boundary): > > movq %rdi, %rdx > > /* Align rdi. */ > > @@ -346,9 +356,9 @@ L(cross_page_boundary): > > vpxorq %YMM1, %YMM0, %YMM2 > > VPMINU %YMM2, %YMM1, %YMM2 > > /* Each bit in K0 represents a CHAR or a null byte in YMM1. */ > > - VPCMP $0, %YMMZERO, %YMM2, %k0 > > + VPTESTN %YMM2, %YMM2, %k0 > > kmovd %k0, %eax > > - /* Remove the leading bits. */ > > + /* Remove the leading bits. */ > > # ifdef USE_AS_WCSCHR > > movl %edx, %SHIFT_REG > > /* NB: Divide shift count by 4 since each bit in K1 represent 4 > > @@ -360,20 +370,24 @@ L(cross_page_boundary): > > /* If eax is zero continue. */ > > testl %eax, %eax > > jz L(cross_page_continue) > > - tzcntl %eax, %eax > > -# ifndef USE_AS_STRCHRNUL > > - /* Check to see if match was CHAR or null. */ > > - cmp (%rdx, %rax, CHAR_SIZE), %CHAR_REG > > - jne L(zero_end) > > -# endif > > + bsfl %eax, %eax > > + > > # ifdef USE_AS_WCSCHR > > /* NB: Multiply wchar_t count by 4 to get the number of > > bytes. */ > > leaq (%rdx, %rax, CHAR_SIZE), %rax > > # else > > addq %rdx, %rax > > +# endif > > +# ifndef USE_AS_STRCHRNUL > > + /* Check to see if match was CHAR or null. */ > > + cmp (%rax), %CHAR_REG > > + je L(cross_page_ret) > > +L(zero_end): > > + xorl %eax, %eax > > +L(cross_page_ret): > > # endif > > ret > > > > END (STRCHR) > > -# endif > > +#endif > > -- > > 2.25.1 > > > > LGTM. > > Reviewed-by: H.J. Lu > > Thanks. > > -- > H.J. I would like to backport this patch to release branches. Any comments or objections? --Sunil