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author | Noah Goldstein <goldstein.w.n@gmail.com> | 2021-05-04 19:02:40 -0400 |
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committer | Noah Goldstein <goldstein.w.n@gmail.com> | 2021-05-08 16:26:30 -0400 |
commit | 104c7b1967c3e78435c6f7eab5e225a7eddf9c6e (patch) | |
tree | 0b79a2d6c085b43bcf667f74f4bc974cbf970bd6 /sysdeps/x86_64/multiarch/memchr-evex.S | |
parent | 6ea916adfa0ab9af6e7dc6adcf6f977dfe017835 (diff) | |
download | glibc-104c7b1967c3e78435c6f7eab5e225a7eddf9c6e.tar.gz glibc-104c7b1967c3e78435c6f7eab5e225a7eddf9c6e.tar.xz glibc-104c7b1967c3e78435c6f7eab5e225a7eddf9c6e.zip |
x86: Add EVEX optimized memchr family not safe for RTM
No bug. This commit adds a new implementation for EVEX memchr that is not safe for RTM because it uses vzeroupper. The benefit is that by using ymm0-ymm15 it can use vpcmpeq and vpternlogd in the 4x loop which is faster than the RTM safe version which cannot use vpcmpeq because there is no EVEX encoding for the instruction. All parts of the implementation aside from the 4x loop are the same for the two versions and the optimization is only relevant for large sizes. Tigerlake: size , algn , Pos , Cur T , New T , Win , Dif 512 , 6 , 192 , 9.2 , 9.04 , no-RTM , 0.16 512 , 7 , 224 , 9.19 , 8.98 , no-RTM , 0.21 2048 , 0 , 256 , 10.74 , 10.54 , no-RTM , 0.2 2048 , 0 , 512 , 14.81 , 14.87 , RTM , 0.06 2048 , 0 , 1024 , 22.97 , 22.57 , no-RTM , 0.4 2048 , 0 , 2048 , 37.49 , 34.51 , no-RTM , 2.98 <-- Icelake: size , algn , Pos , Cur T , New T , Win , Dif 512 , 6 , 192 , 7.6 , 7.3 , no-RTM , 0.3 512 , 7 , 224 , 7.63 , 7.27 , no-RTM , 0.36 2048 , 0 , 256 , 8.48 , 8.38 , no-RTM , 0.1 2048 , 0 , 512 , 11.57 , 11.42 , no-RTM , 0.15 2048 , 0 , 1024 , 17.92 , 17.38 , no-RTM , 0.54 2048 , 0 , 2048 , 30.37 , 27.34 , no-RTM , 3.03 <-- test-memchr, test-wmemchr, and test-rawmemchr are all passing. Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diffstat (limited to 'sysdeps/x86_64/multiarch/memchr-evex.S')
-rw-r--r-- | sysdeps/x86_64/multiarch/memchr-evex.S | 161 |
1 files changed, 125 insertions, 36 deletions
diff --git a/sysdeps/x86_64/multiarch/memchr-evex.S b/sysdeps/x86_64/multiarch/memchr-evex.S index f3fdad4fda..4d0ed6d136 100644 --- a/sysdeps/x86_64/multiarch/memchr-evex.S +++ b/sysdeps/x86_64/multiarch/memchr-evex.S @@ -38,10 +38,32 @@ # define CHAR_SIZE 1 # endif + /* In the 4x loop the RTM and non-RTM versions have data pointer + off by VEC_SIZE * 4 with RTM version being VEC_SIZE * 4 greater. + This is represented by BASE_OFFSET. As well because the RTM + version uses vpcmp which stores a bit per element compared where + the non-RTM version uses vpcmpeq which stores a bit per byte + compared RET_SCALE of CHAR_SIZE is only relevant for the RTM + version. */ +# ifdef USE_IN_RTM +# define VZEROUPPER +# define BASE_OFFSET (VEC_SIZE * 4) +# define RET_SCALE CHAR_SIZE +# else +# define VZEROUPPER vzeroupper +# define BASE_OFFSET 0 +# define RET_SCALE 1 +# endif + + /* In the return from 4x loop memchr and rawmemchr versions have + data pointers off by VEC_SIZE * 4 with memchr version being + VEC_SIZE * 4 greater. */ # ifdef USE_AS_RAWMEMCHR +# define RET_OFFSET (BASE_OFFSET - (VEC_SIZE * 4)) # define RAW_PTR_REG rcx # define ALGN_PTR_REG rdi # else +# define RET_OFFSET BASE_OFFSET # define RAW_PTR_REG rdi # define ALGN_PTR_REG rcx # endif @@ -57,11 +79,15 @@ # define YMM5 ymm21 # define YMM6 ymm22 +# ifndef SECTION +# define SECTION(p) p##.evex +# endif + # define VEC_SIZE 32 # define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE) # define PAGE_SIZE 4096 - .section .text.evex,"ax",@progbits + .section SECTION(.text),"ax",@progbits ENTRY (MEMCHR) # ifndef USE_AS_RAWMEMCHR /* Check for zero length. */ @@ -237,14 +263,15 @@ L(cross_page_continue): /* Check if at last CHAR_PER_VEC * 4 length. */ subq $(CHAR_PER_VEC * 4), %rdx jbe L(last_4x_vec_or_less_cmpeq) - addq $VEC_SIZE, %rdi + /* +VEC_SIZE if USE_IN_RTM otherwise +VEC_SIZE * 5. */ + addq $(VEC_SIZE + (VEC_SIZE * 4 - BASE_OFFSET)), %rdi /* Align data to VEC_SIZE * 4 for the loop and readjust length. */ # ifdef USE_AS_WMEMCHR movl %edi, %ecx andq $-(4 * VEC_SIZE), %rdi - andl $(VEC_SIZE * 4 - 1), %ecx + subl %edi, %ecx /* NB: Divide bytes by 4 to get the wchar_t count. */ sarl $2, %ecx addq %rcx, %rdx @@ -254,15 +281,28 @@ L(cross_page_continue): subq %rdi, %rdx # endif # else - addq $VEC_SIZE, %rdi + addq $(VEC_SIZE + (VEC_SIZE * 4 - BASE_OFFSET)), %rdi andq $-(4 * VEC_SIZE), %rdi # endif - +# ifdef USE_IN_RTM vpxorq %XMMZERO, %XMMZERO, %XMMZERO +# else + /* copy ymmmatch to ymm0 so we can use vpcmpeq which is not + encodable with EVEX registers (ymm16-ymm31). */ + vmovdqa64 %YMMMATCH, %ymm0 +# endif /* Compare 4 * VEC at a time forward. */ .p2align 4 L(loop_4x_vec): + /* Two versions of the loop. One that does not require + vzeroupper by not using ymm0-ymm15 and another does that require + vzeroupper because it uses ymm0-ymm15. The reason why ymm0-ymm15 + is used at all is because there is no EVEX encoding vpcmpeq and + with vpcmpeq this loop can be performed more efficiently. The + non-vzeroupper version is safe for RTM while the vzeroupper + version should be prefered if RTM are not supported. */ +# ifdef USE_IN_RTM /* It would be possible to save some instructions using 4x VPCMP but bottleneck on port 5 makes it not woth it. */ VPCMP $4, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k1 @@ -273,12 +313,55 @@ L(loop_4x_vec): /* Reduce VEC2 / VEC3 with min and VEC1 with zero mask. */ VPMINU %YMM2, %YMM3, %YMM3{%k1}{z} VPCMP $0, %YMM3, %YMMZERO, %k2 +# else + /* Since vptern can only take 3x vectors fastest to do 1 vec + seperately with EVEX vpcmp. */ +# ifdef USE_AS_WMEMCHR + /* vptern can only accept masks for epi32/epi64 so can only save + instruction using not equals mask on vptern with wmemchr. */ + VPCMP $4, (%rdi), %YMMMATCH, %k1 +# else + VPCMP $0, (%rdi), %YMMMATCH, %k1 +# endif + /* Compare 3x with vpcmpeq and or them all together with vptern. + */ + VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm2 + VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm0, %ymm3 + VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm0, %ymm4 +# ifdef USE_AS_WMEMCHR + /* This takes the not of or between ymm2, ymm3, ymm4 as well as + combines result from VEC0 with zero mask. */ + vpternlogd $1, %ymm2, %ymm3, %ymm4{%k1}{z} + vpmovmskb %ymm4, %ecx +# else + /* 254 is mask for oring ymm2, ymm3, ymm4 into ymm4. */ + vpternlogd $254, %ymm2, %ymm3, %ymm4 + vpmovmskb %ymm4, %ecx + kmovd %k1, %eax +# endif +# endif + # ifdef USE_AS_RAWMEMCHR subq $-(VEC_SIZE * 4), %rdi +# endif +# ifdef USE_IN_RTM kortestd %k2, %k3 +# else +# ifdef USE_AS_WMEMCHR + /* ecx contains not of matches. All 1s means no matches. incl will + overflow and set zeroflag if that is the case. */ + incl %ecx +# else + /* If either VEC1 (eax) or VEC2-VEC4 (ecx) are not zero. Adding + to ecx is not an issue because if eax is non-zero it will be + used for returning the match. If it is zero the add does + nothing. */ + addq %rax, %rcx +# endif +# endif +# ifdef USE_AS_RAWMEMCHR jz L(loop_4x_vec) # else - kortestd %k2, %k3 jnz L(loop_4x_vec_end) subq $-(VEC_SIZE * 4), %rdi @@ -288,10 +371,11 @@ L(loop_4x_vec): /* Fall through into less than 4 remaining vectors of length case. */ - VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0 + VPCMP $0, BASE_OFFSET(%rdi), %YMMMATCH, %k0 + addq $(BASE_OFFSET - VEC_SIZE), %rdi kmovd %k0, %eax - addq $(VEC_SIZE * 3), %rdi - .p2align 4 + VZEROUPPER + L(last_4x_vec_or_less): /* Check if first VEC contained match. */ testl %eax, %eax @@ -338,73 +422,78 @@ L(loop_4x_vec_end): /* rawmemchr will fall through into this if match was found in loop. */ +# if defined USE_IN_RTM || defined USE_AS_WMEMCHR /* k1 has not of matches with VEC1. */ kmovd %k1, %eax -# ifdef USE_AS_WMEMCHR +# ifdef USE_AS_WMEMCHR subl $((1 << CHAR_PER_VEC) - 1), %eax -# else +# else incl %eax +# endif +# else + /* eax already has matches for VEC1. */ + testl %eax, %eax # endif jnz L(last_vec_x1_return) +# ifdef USE_IN_RTM VPCMP $0, %YMM2, %YMMZERO, %k0 kmovd %k0, %eax +# else + vpmovmskb %ymm2, %eax +# endif testl %eax, %eax jnz L(last_vec_x2_return) +# ifdef USE_IN_RTM kmovd %k2, %eax testl %eax, %eax jnz L(last_vec_x3_return) kmovd %k3, %eax tzcntl %eax, %eax -# ifdef USE_AS_RAWMEMCHR - leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax + leaq (VEC_SIZE * 3 + RET_OFFSET)(%rdi, %rax, CHAR_SIZE), %rax # else - leaq (VEC_SIZE * 7)(%rdi, %rax, CHAR_SIZE), %rax + vpmovmskb %ymm3, %eax + /* Combine matches in VEC3 (eax) with matches in VEC4 (ecx). */ + salq $VEC_SIZE, %rcx + orq %rcx, %rax + tzcntq %rax, %rax + leaq (VEC_SIZE * 2 + RET_OFFSET)(%rdi, %rax), %rax + VZEROUPPER # endif ret .p2align 4 L(last_vec_x1_return): tzcntl %eax, %eax -# ifdef USE_AS_RAWMEMCHR -# ifdef USE_AS_WMEMCHR +# if defined USE_AS_WMEMCHR || RET_OFFSET != 0 /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */ - leaq (%rdi, %rax, CHAR_SIZE), %rax -# else - addq %rdi, %rax -# endif + leaq RET_OFFSET(%rdi, %rax, CHAR_SIZE), %rax # else - /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */ - leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax + addq %rdi, %rax # endif + VZEROUPPER ret .p2align 4 L(last_vec_x2_return): tzcntl %eax, %eax -# ifdef USE_AS_RAWMEMCHR - /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */ - leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax -# else - /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */ - leaq (VEC_SIZE * 5)(%rdi, %rax, CHAR_SIZE), %rax -# endif + /* NB: Multiply bytes by RET_SCALE to get the wchar_t count + if relevant (RET_SCALE = CHAR_SIZE if USE_AS_WMEMCHAR and + USE_IN_RTM are both defined. Otherwise RET_SCALE = 1. */ + leaq (VEC_SIZE + RET_OFFSET)(%rdi, %rax, RET_SCALE), %rax + VZEROUPPER ret +# ifdef USE_IN_RTM .p2align 4 L(last_vec_x3_return): tzcntl %eax, %eax -# ifdef USE_AS_RAWMEMCHR - /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */ - leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax -# else /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */ - leaq (VEC_SIZE * 6)(%rdi, %rax, CHAR_SIZE), %rax -# endif + leaq (VEC_SIZE * 2 + RET_OFFSET)(%rdi, %rax, CHAR_SIZE), %rax ret - +# endif # ifndef USE_AS_RAWMEMCHR L(last_4x_vec_or_less_cmpeq): |