diff options
| -rw-r--r-- | sysdeps/x86_64/multiarch/strcmp-avx2.S | 1590 |
1 files changed, 939 insertions, 651 deletions
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S index 9c73b5899d..28d6a0025a 100644 --- a/sysdeps/x86_64/multiarch/strcmp-avx2.S +++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S @@ -26,35 +26,57 @@ # define PAGE_SIZE 4096 -/* VEC_SIZE = Number of bytes in a ymm register */ + /* VEC_SIZE = Number of bytes in a ymm register. */ # define VEC_SIZE 32 -/* Shift for dividing by (VEC_SIZE * 4). */ -# define DIVIDE_BY_VEC_4_SHIFT 7 -# if (VEC_SIZE * 4) != (1 << DIVIDE_BY_VEC_4_SHIFT) -# error (VEC_SIZE * 4) != (1 << DIVIDE_BY_VEC_4_SHIFT) -# endif +# define VMOVU vmovdqu +# define VMOVA vmovdqa # ifdef USE_AS_WCSCMP -/* Compare packed dwords. */ + /* Compare packed dwords. */ # define VPCMPEQ vpcmpeqd -/* Compare packed dwords and store minimum. */ + /* Compare packed dwords and store minimum. */ # define VPMINU vpminud -/* 1 dword char == 4 bytes. */ + /* 1 dword char == 4 bytes. */ # define SIZE_OF_CHAR 4 # else -/* Compare packed bytes. */ + /* Compare packed bytes. */ # define VPCMPEQ vpcmpeqb -/* Compare packed bytes and store minimum. */ + /* Compare packed bytes and store minimum. */ # define VPMINU vpminub -/* 1 byte char == 1 byte. */ + /* 1 byte char == 1 byte. */ # define SIZE_OF_CHAR 1 # endif +# ifdef USE_AS_STRNCMP +# define LOOP_REG r9d +# define LOOP_REG64 r9 + +# define OFFSET_REG8 r9b +# define OFFSET_REG r9d +# define OFFSET_REG64 r9 +# else +# define LOOP_REG edx +# define LOOP_REG64 rdx + +# define OFFSET_REG8 dl +# define OFFSET_REG edx +# define OFFSET_REG64 rdx +# endif + # ifndef VZEROUPPER # define VZEROUPPER vzeroupper # endif +# if defined USE_AS_STRNCMP +# define VEC_OFFSET 0 +# else +# define VEC_OFFSET (-VEC_SIZE) +# endif + +# define xmmZERO xmm15 +# define ymmZERO ymm15 + # ifndef SECTION # define SECTION(p) p##.avx # endif @@ -79,783 +101,1049 @@ the maximum offset is reached before a difference is found, zero is returned. */ - .section SECTION(.text),"ax",@progbits -ENTRY (STRCMP) + .section SECTION(.text), "ax", @progbits +ENTRY(STRCMP) # ifdef USE_AS_STRNCMP - /* Check for simple cases (0 or 1) in offset. */ +# ifdef __ILP32__ + /* Clear the upper 32 bits. */ + movl %edx, %rdx +# endif cmp $1, %RDX_LP - je L(char0) - jb L(zero) + /* Signed comparison intentional. We use this branch to also + test cases where length >= 2^63. These very large sizes can be + handled with strcmp as there is no way for that length to + actually bound the buffer. */ + jle L(one_or_less) # ifdef USE_AS_WCSCMP -# ifndef __ILP32__ movq %rdx, %rcx - /* Check if length could overflow when multiplied by - sizeof(wchar_t). Checking top 8 bits will cover all potential - overflow cases as well as redirect cases where its impossible to - length to bound a valid memory region. In these cases just use - 'wcscmp'. */ + + /* Multiplying length by sizeof(wchar_t) can result in overflow. + Check if that is possible. All cases where overflow are possible + are cases where length is large enough that it can never be a + bound on valid memory so just use wcscmp. */ shrq $56, %rcx jnz __wcscmp_avx2 + + leaq (, %rdx, 4), %rdx # endif - /* Convert units: from wide to byte char. */ - shl $2, %RDX_LP -# endif - /* Register %r11 tracks the maximum offset. */ - mov %RDX_LP, %R11_LP # endif + vpxor %xmmZERO, %xmmZERO, %xmmZERO movl %edi, %eax - xorl %edx, %edx - /* Make %xmm7 (%ymm7) all zeros in this function. */ - vpxor %xmm7, %xmm7, %xmm7 orl %esi, %eax - andl $(PAGE_SIZE - 1), %eax - cmpl $(PAGE_SIZE - (VEC_SIZE * 4)), %eax - jg L(cross_page) - /* Start comparing 4 vectors. */ - vmovdqu (%rdi), %ymm1 - VPCMPEQ (%rsi), %ymm1, %ymm0 - VPMINU %ymm1, %ymm0, %ymm0 - VPCMPEQ %ymm7, %ymm0, %ymm0 - vpmovmskb %ymm0, %ecx - testl %ecx, %ecx - je L(next_3_vectors) - tzcntl %ecx, %edx + sall $20, %eax + /* Check if s1 or s2 may cross a page in next 4x VEC loads. */ + cmpl $((PAGE_SIZE -(VEC_SIZE * 4)) << 20), %eax + ja L(page_cross) + +L(no_page_cross): + /* Safe to compare 4x vectors. */ + VMOVU (%rdi), %ymm0 + /* 1s where s1 and s2 equal. */ + VPCMPEQ (%rsi), %ymm0, %ymm1 + /* 1s at null CHAR. */ + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + /* 1s where s1 and s2 equal AND not null CHAR. */ + vpandn %ymm1, %ymm2, %ymm1 + + /* All 1s -> keep going, any 0s -> return. */ + vpmovmskb %ymm1, %ecx # ifdef USE_AS_STRNCMP - /* Return 0 if the mismatched index (%rdx) is after the maximum - offset (%r11). */ - cmpq %r11, %rdx - jae L(zero) + cmpq $VEC_SIZE, %rdx + jbe L(vec_0_test_len) # endif + + /* All 1s represents all equals. incl will overflow to zero in + all equals case. Otherwise 1s will carry until position of first + mismatch. */ + incl %ecx + jz L(more_3x_vec) + + .p2align 4,, 4 +L(return_vec_0): + tzcntl %ecx, %ecx # ifdef USE_AS_WCSCMP + movl (%rdi, %rcx), %edx xorl %eax, %eax - movl (%rdi, %rdx), %ecx - cmpl (%rsi, %rdx), %ecx - je L(return) -L(wcscmp_return): + cmpl (%rsi, %rcx), %edx + je L(ret0) setl %al negl %eax orl $1, %eax -L(return): # else - movzbl (%rdi, %rdx), %eax - movzbl (%rsi, %rdx), %edx - subl %edx, %eax + movzbl (%rdi, %rcx), %eax + movzbl (%rsi, %rcx), %ecx + subl %ecx, %eax # endif +L(ret0): L(return_vzeroupper): ZERO_UPPER_VEC_REGISTERS_RETURN - .p2align 4 -L(return_vec_size): - tzcntl %ecx, %edx # ifdef USE_AS_STRNCMP - /* Return 0 if the mismatched index (%rdx + VEC_SIZE) is after - the maximum offset (%r11). */ - addq $VEC_SIZE, %rdx - cmpq %r11, %rdx - jae L(zero) -# ifdef USE_AS_WCSCMP + .p2align 4,, 8 +L(vec_0_test_len): + notl %ecx + bzhil %edx, %ecx, %eax + jnz L(return_vec_0) + /* Align if will cross fetch block. */ + .p2align 4,, 2 +L(ret_zero): xorl %eax, %eax - movl (%rdi, %rdx), %ecx - cmpl (%rsi, %rdx), %ecx - jne L(wcscmp_return) -# else - movzbl (%rdi, %rdx), %eax - movzbl (%rsi, %rdx), %edx - subl %edx, %eax -# endif -# else + VZEROUPPER_RETURN + + .p2align 4,, 5 +L(one_or_less): + jb L(ret_zero) # ifdef USE_AS_WCSCMP + /* 'nbe' covers the case where length is negative (large + unsigned). */ + jnbe __wcscmp_avx2 + movl (%rdi), %edx xorl %eax, %eax - movl VEC_SIZE(%rdi, %rdx), %ecx - cmpl VEC_SIZE(%rsi, %rdx), %ecx - jne L(wcscmp_return) + cmpl (%rsi), %edx + je L(ret1) + setl %al + negl %eax + orl $1, %eax # else - movzbl VEC_SIZE(%rdi, %rdx), %eax - movzbl VEC_SIZE(%rsi, %rdx), %edx - subl %edx, %eax + /* 'nbe' covers the case where length is negative (large + unsigned). */ + + jnbe __strcmp_avx2 + movzbl (%rdi), %eax + movzbl (%rsi), %ecx + subl %ecx, %eax # endif +L(ret1): + ret # endif - VZEROUPPER_RETURN - .p2align 4 -L(return_2_vec_size): - tzcntl %ecx, %edx + .p2align 4,, 10 +L(return_vec_1): + tzcntl %ecx, %ecx # ifdef USE_AS_STRNCMP - /* Return 0 if the mismatched index (%rdx + 2 * VEC_SIZE) is - after the maximum offset (%r11). */ - addq $(VEC_SIZE * 2), %rdx - cmpq %r11, %rdx - jae L(zero) -# ifdef USE_AS_WCSCMP + /* rdx must be > CHAR_PER_VEC so save to subtract w.o fear of + overflow. */ + addq $-VEC_SIZE, %rdx + cmpq %rcx, %rdx + jbe L(ret_zero) +# endif +# ifdef USE_AS_WCSCMP + movl VEC_SIZE(%rdi, %rcx), %edx xorl %eax, %eax - movl (%rdi, %rdx), %ecx - cmpl (%rsi, %rdx), %ecx - jne L(wcscmp_return) -# else - movzbl (%rdi, %rdx), %eax - movzbl (%rsi, %rdx), %edx - subl %edx, %eax -# endif + cmpl VEC_SIZE(%rsi, %rcx), %edx + je L(ret2) + setl %al + negl %eax + orl $1, %eax # else -# ifdef USE_AS_WCSCMP - xorl %eax, %eax - movl (VEC_SIZE * 2)(%rdi, %rdx), %ecx - cmpl (VEC_SIZE * 2)(%rsi, %rdx), %ecx - jne L(wcscmp_return) -# else - movzbl (VEC_SIZE * 2)(%rdi, %rdx), %eax - movzbl (VEC_SIZE * 2)(%rsi, %rdx), %edx - subl %edx, %eax -# endif + movzbl VEC_SIZE(%rdi, %rcx), %eax + movzbl VEC_SIZE(%rsi, %rcx), %ecx + subl %ecx, %eax # endif +L(ret2): VZEROUPPER_RETURN - .p2align 4 -L(return_3_vec_size): - tzcntl %ecx, %edx + .p2align 4,, 10 # ifdef USE_AS_STRNCMP - /* Return 0 if the mismatched index (%rdx + 3 * VEC_SIZE) is - after the maximum offset (%r11). */ - addq $(VEC_SIZE * 3), %rdx - cmpq %r11, %rdx - jae L(zero) -# ifdef USE_AS_WCSCMP +L(return_vec_3): + salq $32, %rcx +# endif + +L(return_vec_2): +# ifndef USE_AS_STRNCMP + tzcntl %ecx, %ecx +# else + tzcntq %rcx, %rcx + cmpq %rcx, %rdx + jbe L(ret_zero) +# endif + +# ifdef USE_AS_WCSCMP + movl (VEC_SIZE * 2)(%rdi, %rcx), %edx xorl %eax, %eax - movl (%rdi, %rdx), %ecx - cmpl (%rsi, %rdx), %ecx - jne L(wcscmp_return) -# else - movzbl (%rdi, %rdx), %eax - movzbl (%rsi, %rdx), %edx - subl %edx, %eax -# endif + cmpl (VEC_SIZE * 2)(%rsi, %rcx), %edx + je L(ret3) + setl %al + negl %eax + orl $1, %eax # else + movzbl (VEC_SIZE * 2)(%rdi, %rcx), %eax + movzbl (VEC_SIZE * 2)(%rsi, %rcx), %ecx + subl %ecx, %eax +# endif +L(ret3): + VZEROUPPER_RETURN + +# ifndef USE_AS_STRNCMP + .p2align 4,, 10 +L(return_vec_3): + tzcntl %ecx, %ecx # ifdef USE_AS_WCSCMP + movl (VEC_SIZE * 3)(%rdi, %rcx), %edx xorl %eax, %eax - movl (VEC_SIZE * 3)(%rdi, %rdx), %ecx - cmpl (VEC_SIZE * 3)(%rsi, %rdx), %ecx - jne L(wcscmp_return) + cmpl (VEC_SIZE * 3)(%rsi, %rcx), %edx + je L(ret4) + setl %al + negl %eax + orl $1, %eax # else - movzbl (VEC_SIZE * 3)(%rdi, %rdx), %eax - movzbl (VEC_SIZE * 3)(%rsi, %rdx), %edx - subl %edx, %eax + movzbl (VEC_SIZE * 3)(%rdi, %rcx), %eax + movzbl (VEC_SIZE * 3)(%rsi, %rcx), %ecx + subl %ecx, %eax # endif -# endif +L(ret4): VZEROUPPER_RETURN +# endif + + .p2align 4,, 10 +L(more_3x_vec): + /* Safe to compare 4x vectors. */ + VMOVU VEC_SIZE(%rdi), %ymm0 + VPCMPEQ VEC_SIZE(%rsi), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + incl %ecx + jnz L(return_vec_1) + +# ifdef USE_AS_STRNCMP + subq $(VEC_SIZE * 2), %rdx + jbe L(ret_zero) +# endif + + VMOVU (VEC_SIZE * 2)(%rdi), %ymm0 + VPCMPEQ (VEC_SIZE * 2)(%rsi), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + incl %ecx + jnz L(return_vec_2) + + VMOVU (VEC_SIZE * 3)(%rdi), %ymm0 + VPCMPEQ (VEC_SIZE * 3)(%rsi), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + incl %ecx + jnz L(return_vec_3) - .p2align 4 -L(next_3_vectors): - vmovdqu VEC_SIZE(%rdi), %ymm6 - VPCMPEQ VEC_SIZE(%rsi), %ymm6, %ymm3 - VPMINU %ymm6, %ymm3, %ymm3 - VPCMPEQ %ymm7, %ymm3, %ymm3 - vpmovmskb %ymm3, %ecx - testl %ecx, %ecx - jne L(return_vec_size) - vmovdqu (VEC_SIZE * 2)(%rdi), %ymm5 - vmovdqu (VEC_SIZE * 3)(%rdi), %ymm4 - vmovdqu (VEC_SIZE * 3)(%rsi), %ymm0 - VPCMPEQ (VEC_SIZE * 2)(%rsi), %ymm5, %ymm2 - VPMINU %ymm5, %ymm2, %ymm2 - VPCMPEQ %ymm4, %ymm0, %ymm0 - VPCMPEQ %ymm7, %ymm2, %ymm2 - vpmovmskb %ymm2, %ecx - testl %ecx, %ecx - jne L(return_2_vec_size) - VPMINU %ymm4, %ymm0, %ymm0 - VPCMPEQ %ymm7, %ymm0, %ymm0 - vpmovmskb %ymm0, %ecx - testl %ecx, %ecx - jne L(return_3_vec_size) -L(main_loop_header): - leaq (VEC_SIZE * 4)(%rdi), %rdx - movl $PAGE_SIZE, %ecx - /* Align load via RAX. */ - andq $-(VEC_SIZE * 4), %rdx - subq %rdi, %rdx - leaq (%rdi, %rdx), %rax # ifdef USE_AS_STRNCMP - /* Starting from this point, the maximum offset, or simply the - 'offset', DECREASES by the same amount when base pointers are - moved forward. Return 0 when: - 1) On match: offset <= the matched vector index. - 2) On mistmach, offset is before the mistmatched index. + cmpq $(VEC_SIZE * 2), %rdx + jbe L(ret_zero) +# endif + +# ifdef USE_AS_WCSCMP + /* any non-zero positive value that doesn't inference with 0x1. */ - subq %rdx, %r11 - jbe L(zero) -# endif - addq %rsi, %rdx - movq %rdx, %rsi - andl $(PAGE_SIZE - 1), %esi - /* Number of bytes before page crossing. */ - subq %rsi, %rcx - /* Number of VEC_SIZE * 4 blocks before page crossing. */ - shrq $DIVIDE_BY_VEC_4_SHIFT, %rcx - /* ESI: Number of VEC_SIZE * 4 blocks before page crossing. */ - movl %ecx, %esi - jmp L(loop_start) + movl $2, %r8d +# else + xorl %r8d, %r8d +# endif + + /* The prepare labels are various entry points from the page + cross logic. */ +L(prepare_loop): + +# ifdef USE_AS_STRNCMP + /* Store N + (VEC_SIZE * 4) and place check at the begining of + the loop. */ + leaq (VEC_SIZE * 2)(%rdi, %rdx), %rdx +# endif +L(prepare_loop_no_len): + + /* Align s1 and adjust s2 accordingly. */ + subq %rdi, %rsi + andq $-(VEC_SIZE * 4), %rdi + addq %rdi, %rsi + +# ifdef USE_AS_STRNCMP + subq %rdi, %rdx +# endif + +L(prepare_loop_aligned): + /* eax stores distance from rsi to next page cross. These cases + need to be handled specially as the 4x loop could potentially + read memory past the length of s1 or s2 and across a page + boundary. */ + movl $-(VEC_SIZE * 4), %eax + subl %esi, %eax + andl $(PAGE_SIZE - 1), %eax + + /* Loop 4x comparisons at a time. */ .p2align 4 L(loop): + + /* End condition for strncmp. */ # ifdef USE_AS_STRNCMP - /* Base pointers are moved forward by 4 * VEC_SIZE. Decrease - the maximum offset (%r11) by the same amount. */ - subq $(VEC_SIZE * 4), %r11 - jbe L(zero) -# endif - addq $(VEC_SIZE * 4), %rax - addq $(VEC_SIZE * 4), %rdx -L(loop_start): - testl %esi, %esi - leal -1(%esi), %esi - je L(loop_cross_page) -L(back_to_loop): - /* Main loop, comparing 4 vectors are a time. */ - vmovdqa (%rax), %ymm0 - vmovdqa VEC_SIZE(%rax), %ymm3 - VPCMPEQ (%rdx), %ymm0, %ymm4 - VPCMPEQ VEC_SIZE(%rdx), %ymm3, %ymm1 - VPMINU %ymm0, %ymm4, %ymm4 - VPMINU %ymm3, %ymm1, %ymm1 - vmovdqa (VEC_SIZE * 2)(%rax), %ymm2 - VPMINU %ymm1, %ymm4, %ymm0 - vmovdqa (VEC_SIZE * 3)(%rax), %ymm3 - VPCMPEQ (VEC_SIZE * 2)(%rdx), %ymm2, %ymm5 - VPCMPEQ (VEC_SIZE * 3)(%rdx), %ymm3, %ymm6 - VPMINU %ymm2, %ymm5, %ymm5 - VPMINU %ymm3, %ymm6, %ymm6 - VPMINU %ymm5, %ymm0, %ymm0 - VPMINU %ymm6, %ymm0, %ymm0 - VPCMPEQ %ymm7, %ymm0, %ymm0 - - /* Test each mask (32 bits) individually because for VEC_SIZE - == 32 is not possible to OR the four masks and keep all bits - in a 64-bit integer register, differing from SSE2 strcmp - where ORing is possible. */ - vpmovmskb %ymm0, %ecx + subq $(VEC_SIZE * 4), %rdx + jbe L(ret_zero) +# endif + + subq $-(VEC_SIZE * 4), %rdi + subq $-(VEC_SIZE * 4), %rsi + + /* Check if rsi loads will cross a page boundary. */ + addl $-(VEC_SIZE * 4), %eax + jnb L(page_cross_during_loop) + + /* Loop entry after handling page cross during loop. */ +L(loop_skip_page_cross_check): + VMOVA (VEC_SIZE * 0)(%rdi), %ymm0 + VMOVA (VEC_SIZE * 1)(%rdi), %ymm2 + VMOVA (VEC_SIZE * 2)(%rdi), %ymm4 + VMOVA (VEC_SIZE * 3)(%rdi), %ymm6 + + /* ymm1 all 1s where s1 and s2 equal. All 0s otherwise. */ + VPCMPEQ (VEC_SIZE * 0)(%rsi), %ymm0, %ymm1 + + VPCMPEQ (VEC_SIZE * 1)(%rsi), %ymm2, %ymm3 + VPCMPEQ (VEC_SIZE * 2)(%rsi), %ymm4, %ymm5 + VPCMPEQ (VEC_SIZE * 3)(%rsi), %ymm6, %ymm7 + + + /* If any mismatches or null CHAR then 0 CHAR, otherwise non- + zero. */ + vpand %ymm0, %ymm1, %ymm1 + + + vpand %ymm2, %ymm3, %ymm3 + vpand %ymm4, %ymm5, %ymm5 + vpand %ymm6, %ymm7, %ymm7 + + VPMINU %ymm1, %ymm3, %ymm3 + VPMINU %ymm5, %ymm7, %ymm7 + + /* Reduce all 0 CHARs for the 4x VEC into ymm7. */ + VPMINU %ymm3, %ymm7, %ymm7 + + /* If any 0 CHAR then done. */ + VPCMPEQ %ymm7, %ymmZERO, %ymm7 + vpmovmskb %ymm7, %LOOP_REG + testl %LOOP_REG, %LOOP_REG + jz L(loop) + + /* Find which VEC has the mismatch of end of string. */ + VPCMPEQ %ymm1, %ymmZERO, %ymm1 + vpmovmskb %ymm1, %ecx testl %ecx, %ecx - je L(loop) - VPCMPEQ %ymm7, %ymm4, %ymm0 - vpmovmskb %ymm0, %edi - testl %edi, %edi - je L(test_vec) - tzcntl %edi, %ecx + jnz L(return_vec_0_end) + + + VPCMPEQ %ymm3, %ymmZERO, %ymm3 + vpmovmskb %ymm3, %ecx + testl %ecx, %ecx + jnz L(return_vec_1_end) + +L(return_vec_2_3_end): # ifdef USE_AS_STRNCMP - cmpq %rcx, %r11 - jbe L(zero) -# ifdef USE_AS_WCSCMP - movq %rax, %rsi + subq $(VEC_SIZE * 2), %rdx + jbe L(ret_zero_end) +# endif + + VPCMPEQ %ymm5, %ymmZERO, %ymm5 + vpmovmskb %ymm5, %ecx + testl %ecx, %ecx + jnz L(return_vec_2_end) + + /* LOOP_REG contains matches for null/mismatch from the loop. If + VEC 0,1,and 2 all have no null and no mismatches then mismatch + must entirely be from VEC 3 which is fully represented by + LOOP_REG. */ + tzcntl %LOOP_REG, %LOOP_REG + +# ifdef USE_AS_STRNCMP + subl $-(VEC_SIZE), %LOOP_REG + cmpq %LOOP_REG64, %rdx + jbe L(ret_zero_end) +# endif + +# ifdef USE_AS_WCSCMP + movl (VEC_SIZE * 2 - VEC_OFFSET)(%rdi, %LOOP_REG64), %ecx xorl %eax, %eax - movl (%rsi, %rcx), %edi - cmpl (%rdx, %rcx), %edi - jne L(wcscmp_return) -# else - movzbl (%rax, %rcx), %eax - movzbl (%rdx, %rcx), %edx - subl %edx, %eax -# endif + cmpl (VEC_SIZE * 2 - VEC_OFFSET)(%rsi, %LOOP_REG64), %ecx + je L(ret5) + setl %al + negl %eax + xorl %r8d, %eax # else -# ifdef USE_AS_WCSCMP - movq %rax, %rsi - xorl %eax, %eax - movl (%rsi, %rcx), %edi - cmpl (%rdx, %rcx), %edi - jne L(wcscmp_return) -# else - movzbl (%rax, %rcx), %eax - movzbl (%rdx, %rcx), %edx - subl %edx, %eax -# endif + movzbl (VEC_SIZE * 2 - VEC_OFFSET)(%rdi, %LOOP_REG64), %eax + movzbl (VEC_SIZE * 2 - VEC_OFFSET)(%rsi, %LOOP_REG64), %ecx + subl %ecx, %eax + xorl %r8d, %eax + subl %r8d, %eax # endif +L(ret5): VZEROUPPER_RETURN - .p2align 4 -L(test_vec): # ifdef USE_AS_STRNCMP - /* The first vector matched. Return 0 if the maximum offset - (%r11) <= VEC_SIZE. */ - cmpq $VEC_SIZE, %r11 - jbe L(zero) + .p2align 4,, 2 +L(ret_zero_end): + xorl %eax, %eax + VZEROUPPER_RETURN # endif - VPCMPEQ %ymm7, %ymm1, %ymm1 - vpmovmskb %ymm1, %ecx - testl %ecx, %ecx - je L(test_2_vec) - tzcntl %ecx, %edi + + + /* The L(return_vec_N_end) differ from L(return_vec_N) in that + they use the value of `r8` to negate the return value. This is + because the page cross logic can swap `rdi` and `rsi`. */ + .p2align 4,, 10 # ifdef USE_AS_STRNCMP - addq $VEC_SIZE, %rdi - cmpq %rdi, %r11 - jbe L(zero) -# ifdef USE_AS_WCSCMP - movq %rax, %rsi +L(return_vec_1_end): + salq $32, %rcx +# endif +L(return_vec_0_end): +# ifndef USE_AS_STRNCMP + tzcntl %ecx, %ecx +# else + tzcntq %rcx, %rcx + cmpq %rcx, %rdx + jbe L(ret_zero_end) +# endif + +# ifdef USE_AS_WCSCMP + movl (%rdi, %rcx), %edx xorl %eax, %eax - movl (%rsi, %rdi), %ecx - cmpl (%rdx, %rdi), %ecx - jne L(wcscmp_return) -# else - movzbl (%rax, %rdi), %eax - movzbl (%rdx, %rdi), %edx - subl %edx, %eax -# endif + cmpl (%rsi, %rcx), %edx + je L(ret6) + setl %al + negl %eax + xorl %r8d, %eax # else + movzbl (%rdi, %rcx), %eax + movzbl (%rsi, %rcx), %ecx + subl %ecx, %eax + xorl %r8d, %eax + subl %r8d, %eax +# endif +L(ret6): + VZEROUPPER_RETURN + +# ifndef USE_AS_STRNCMP + .p2align 4,, 10 +L(return_vec_1_end): + tzcntl %ecx, %ecx # ifdef USE_AS_WCSCMP - movq %rax, %rsi + movl VEC_SIZE(%rdi, %rcx), %edx xorl %eax, %eax - movl VEC_SIZE(%rsi, %rdi), %ecx - cmpl VEC_SIZE(%rdx, %rdi), %ecx - jne L(wcscmp_return) + cmpl VEC_SIZE(%rsi, %rcx), %edx + je L(ret7) + setl %al + negl %eax + xorl %r8d, %eax # else - movzbl VEC_SIZE(%rax, %rdi), %eax - movzbl VEC_SIZE(%rdx, %rdi), %edx - subl %edx, %eax + movzbl VEC_SIZE(%rdi, %rcx), %eax + movzbl VEC_SIZE(%rsi, %rcx), %ecx + subl %ecx, %eax + xorl %r8d, %eax + subl %r8d, %eax # endif -# endif +L(ret7): VZEROUPPER_RETURN +# endif - .p2align 4 -L(test_2_vec): + .p2align 4,, 10 +L(return_vec_2_end): + tzcntl %ecx, %ecx # ifdef USE_AS_STRNCMP - /* The first 2 vectors matched. Return 0 if the maximum offset - (%r11) <= 2 * VEC_SIZE. */ - cmpq $(VEC_SIZE * 2), %r11 - jbe L(zero) + cmpq %rcx, %rdx + jbe L(ret_zero_page_cross) # endif - VPCMPEQ %ymm7, %ymm5, %ymm5 - vpmovmskb %ymm5, %ecx - testl %ecx, %ecx - je L(test_3_vec) - tzcntl %ecx, %edi -# ifdef USE_AS_STRNCMP - addq $(VEC_SIZE * 2), %rdi - cmpq %rdi, %r11 - jbe L(zero) -# ifdef USE_AS_WCSCMP - movq %rax, %rsi +# ifdef USE_AS_WCSCMP + movl (VEC_SIZE * 2)(%rdi, %rcx), %edx xorl %eax, %eax - movl (%rsi, %rdi), %ecx - cmpl (%rdx, %rdi), %ecx - jne L(wcscmp_return) -# else - movzbl (%rax, %rdi), %eax - movzbl (%rdx, %rdi), %edx - subl %edx, %eax -# endif + cmpl (VEC_SIZE * 2)(%rsi, %rcx), %edx + je L(ret11) + setl %al + negl %eax + xorl %r8d, %eax # else -# ifdef USE_AS_WCSCMP - movq %rax, %rsi - xorl %eax, %eax - movl (VEC_SIZE * 2)(%rsi, %rdi), %ecx - cmpl (VEC_SIZE * 2)(%rdx, %rdi), %ecx - jne L(wcscmp_return) -# else - movzbl (VEC_SIZE * 2)(%rax, %rdi), %eax - movzbl (VEC_SIZE * 2)(%rdx, %rdi), %edx - subl %edx, %eax -# endif + movzbl (VEC_SIZE * 2)(%rdi, %rcx), %eax + movzbl (VEC_SIZE * 2)(%rsi, %rcx), %ecx + subl %ecx, %eax + xorl %r8d, %eax + subl %r8d, %eax # endif +L(ret11): VZEROUPPER_RETURN - .p2align 4 -L(test_3_vec): + + /* Page cross in rsi in next 4x VEC. */ + + /* TODO: Improve logic here. */ + .p2align 4,, 10 +L(page_cross_during_loop): + /* eax contains [distance_from_page - (VEC_SIZE * 4)]. */ + + /* Optimistically rsi and rdi and both aligned inwhich case we + don't need any logic here. */ + cmpl $-(VEC_SIZE * 4), %eax + /* Don't adjust eax before jumping back to loop and we will + never hit page cross case again. */ + je L(loop_skip_page_cross_check) + + /* Check if we can safely load a VEC. */ + cmpl $-(VEC_SIZE * 3), %eax + jle L(less_1x_vec_till_page_cross) + + VMOVA (%rdi), %ymm0 + VPCMPEQ (%rsi), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + incl %ecx + jnz L(return_vec_0_end) + + /* if distance >= 2x VEC then eax > -(VEC_SIZE * 2). */ + cmpl $-(VEC_SIZE * 2), %eax + jg L(more_2x_vec_till_page_cross) + + .p2align 4,, 4 +L(less_1x_vec_till_page_cross): + subl $-(VEC_SIZE * 4), %eax + /* Guranteed safe to read from rdi - VEC_SIZE here. The only + concerning case is first iteration if incoming s1 was near start + of a page and s2 near end. If s1 was near the start of the page + we already aligned up to nearest VEC_SIZE * 4 so gurnateed safe + to read back -VEC_SIZE. If rdi is truly at the start of a page + here, it means the previous page (rdi - VEC_SIZE) has already + been loaded earlier so must be valid. */ + VMOVU -VEC_SIZE(%rdi, %rax), %ymm0 + VPCMPEQ -VEC_SIZE(%rsi, %rax), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + + /* Mask of potentially valid bits. The lower bits can be out of + range comparisons (but safe regarding page crosses). */ + movl $-1, %r10d + shlxl %esi, %r10d, %r10d + notl %ecx + # ifdef USE_AS_STRNCMP - /* The first 3 vectors matched. Return 0 if the maximum offset - (%r11) <= 3 * VEC_SIZE. */ - cmpq $(VEC_SIZE * 3), %r11 - jbe L(zero) -# endif - VPCMPEQ %ymm7, %ymm6, %ymm6 - vpmovmskb %ymm6, %esi - tzcntl %esi, %ecx + cmpq %rax, %rdx + jbe L(return_page_cross_end_check) +# endif + movl %eax, %OFFSET_REG + addl $(PAGE_SIZE - VEC_SIZE * 4), %eax + + andl %r10d, %ecx + jz L(loop_skip_page_cross_check) + + .p2align 4,, 3 +L(return_page_cross_end): + tzcntl %ecx, %ecx + # ifdef USE_AS_STRNCMP - addq $(VEC_SIZE * 3), %rcx - cmpq %rcx, %r11 - jbe L(zero) -# ifdef USE_AS_WCSCMP - movq %rax, %rsi - xorl %eax, %eax - movl (%rsi, %rcx), %esi - cmpl (%rdx, %rcx), %esi - jne L(wcscmp_return) -# else - movzbl (%rax, %rcx), %eax - movzbl (%rdx, %rcx), %edx - subl %edx, %eax -# endif + leal -VEC_SIZE(%OFFSET_REG64, %rcx), %ecx +L(return_page_cross_cmp_mem): # else -# ifdef USE_AS_WCSCMP - movq %rax, %rsi + addl %OFFSET_REG, %ecx +# endif +# ifdef USE_AS_WCSCMP + movl VEC_OFFSET(%rdi, %rcx), %edx xorl %eax, %eax - movl (VEC_SIZE * 3)(%rsi, %rcx), %esi - cmpl (VEC_SIZE * 3)(%rdx, %rcx), %esi - jne L(wcscmp_return) -# else - movzbl (VEC_SIZE * 3)(%rax, %rcx), %eax - movzbl (VEC_SIZE * 3)(%rdx, %rcx), %edx - subl %edx, %eax -# endif + cmpl VEC_OFFSET(%rsi, %rcx), %edx + je L(ret8) + setl %al + negl %eax + xorl %r8d, %eax +# else + movzbl VEC_OFFSET(%rdi, %rcx), %eax + movzbl VEC_OFFSET(%rsi, %rcx), %ecx + subl %ecx, %eax + xorl %r8d, %eax + subl %r8d, %eax # endif +L(ret8): VZEROUPPER_RETURN - .p2align 4 -L(loop_cross_page): - xorl %r10d, %r10d - movq %rdx, %rcx - /* Align load via RDX. We load the extra ECX bytes which should - be ignored. */ - andl $((VEC_SIZE * 4) - 1), %ecx - /* R10 is -RCX. */ - subq %rcx, %r10 - - /* This works only if VEC_SIZE * 2 == 64. */ -# if (VEC_SIZE * 2) != 64 -# error (VEC_SIZE * 2) != 64 -# endif - - /* Check if the first VEC_SIZE * 2 bytes should be ignored. */ - cmpl $(VEC_SIZE * 2), %ecx - jge L(loop_cross_page_2_vec) - - vmovdqu (%rax, %r10), %ymm2 - vmovdqu VEC_SIZE(%rax, %r10), %ymm3 - VPCMPEQ (%rdx, %r10), %ymm2, %ymm0 - VPCMPEQ VEC_SIZE(%rdx, %r10), %ymm3, %ymm1 - VPMINU %ymm2, %ymm0, %ymm0 - VPMINU %ymm3, %ymm1, %ymm1 - VPCMPEQ %ymm7, %ymm0, %ymm0 - VPCMPEQ %ymm7, %ymm1, %ymm1 - - vpmovmskb %ymm0, %edi - vpmovmskb %ymm1, %esi - - salq $32, %rsi - xorq %rsi, %rdi - - /* Since ECX < VEC_SIZE * 2, simply skip the first ECX bytes. */ - shrq %cl, %rdi - - testq %rdi, %rdi - je L(loop_cross_page_2_vec) - tzcntq %rdi, %rcx # ifdef USE_AS_STRNCMP - cmpq %rcx, %r11 - jbe L(zero) -# ifdef USE_AS_WCSCMP - movq %rax, %rsi + .p2align 4,, 10 +L(return_page_cross_end_check): + tzcntl %ecx, %ecx + leal -VEC_SIZE(%rax, %rcx), %ecx + cmpl %ecx, %edx + ja L(return_page_cross_cmp_mem) xorl %eax, %eax - movl (%rsi, %rcx), %edi - cmpl (%rdx, %rcx), %edi - jne L(wcscmp_return) -# else - movzbl (%rax, %rcx), %eax - movzbl (%rdx, %rcx), %edx - subl %edx, %eax -# endif -# else -# ifdef USE_AS_WCSCMP - movq %rax, %rsi - xorl %eax, %eax - movl (%rsi, %rcx), %edi - cmpl (%rdx, %rcx), %edi - jne L(wcscmp_return) -# else - movzbl (%rax, %rcx), %eax - movzbl (%rdx, %rcx), %edx - subl %edx, %eax -# endif -# endif VZEROUPPER_RETURN +# endif - .p2align 4 -L(loop_cross_page_2_vec): - /* The first VEC_SIZE * 2 bytes match or are ignored. */ - vmovdqu (VEC_SIZE * 2)(%rax, %r10), %ymm2 - vmovdqu (VEC_SIZE * 3)(%rax, %r10), %ymm3 - VPCMPEQ (VEC_SIZE * 2)(%rdx, %r10), %ymm2, %ymm5 - VPMINU %ymm2, %ymm5, %ymm5 - VPCMPEQ (VEC_SIZE * 3)(%rdx, %r10), %ymm3, %ymm6 - VPCMPEQ %ymm7, %ymm5, %ymm5 - VPMINU %ymm3, %ymm6, %ymm6 - VPCMPEQ %ymm7, %ymm6, %ymm6 - - vpmovmskb %ymm5, %edi - vpmovmskb %ymm6, %esi - - salq $32, %rsi - xorq %rsi, %rdi - xorl %r8d, %r8d - /* If ECX > VEC_SIZE * 2, skip ECX - (VEC_SIZE * 2) bytes. */ - subl $(VEC_SIZE * 2), %ecx - jle 1f - /* Skip ECX bytes. */ - shrq %cl, %rdi - /* R8 has number of bytes skipped. */ - movl %ecx, %r8d -1: - /* Before jumping back to the loop, set ESI to the number of - VEC_SIZE * 4 blocks before page crossing. */ - movl $(PAGE_SIZE / (VEC_SIZE * 4) - 1), %esi - - testq %rdi, %rdi + .p2align 4,, 10 +L(more_2x_vec_till_page_cross): + /* If more 2x vec till cross we will complete a full loop + iteration here. */ + + VMOVU VEC_SIZE(%rdi), %ymm0 + VPCMPEQ VEC_SIZE(%rsi), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + incl %ecx + jnz L(return_vec_1_end) + # ifdef USE_AS_STRNCMP - /* At this point, if %rdi value is 0, it already tested - VEC_SIZE*4+%r10 byte starting from %rax. This label - checks whether strncmp maximum offset reached or not. */ - je L(string_nbyte_offset_check) -# else - je L(back_to_loop) + cmpq $(VEC_SIZE * 2), %rdx + jbe L(ret_zero_in_loop_page_cross) # endif - tzcntq %rdi, %rcx - addq %r10, %rcx - /* Adjust for number of bytes skipped. */ - addq %r8, %rcx + + subl $-(VEC_SIZE * 4), %eax + + /* Safe to include comparisons from lower bytes. */ + VMOVU -(VEC_SIZE * 2)(%rdi, %rax), %ymm0 + VPCMPEQ -(VEC_SIZE * 2)(%rsi, %rax), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + incl %ecx + jnz L(return_vec_page_cross_0) + + VMOVU -(VEC_SIZE * 1)(%rdi, %rax), %ymm0 + VPCMPEQ -(VEC_SIZE * 1)(%rsi, %rax), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + incl %ecx + jnz L(return_vec_page_cross_1) + # ifdef USE_AS_STRNCMP - addq $(VEC_SIZE * 2), %rcx - subq %rcx, %r11 - jbe L(zero) -# ifdef USE_AS_WCSCMP - movq %rax, %rsi + /* Must check length here as length might proclude reading next + page. */ + cmpq %rax, %rdx + jbe L(ret_zero_in_loop_page_cross) +# endif + + /* Finish the loop. */ + VMOVA (VEC_SIZE * 2)(%rdi), %ymm4 + VMOVA (VEC_SIZE * 3)(%rdi), %ymm6 + + VPCMPEQ (VEC_SIZE * 2)(%rsi), %ymm4, %ymm5 + VPCMPEQ (VEC_SIZE * 3)(%rsi), %ymm6, %ymm7 + vpand %ymm4, %ymm5, %ymm5 + vpand %ymm6, %ymm7, %ymm7 + VPMINU %ymm5, %ymm7, %ymm7 + VPCMPEQ %ymm7, %ymmZERO, %ymm7 + vpmovmskb %ymm7, %LOOP_REG + testl %LOOP_REG, %LOOP_REG + jnz L(return_vec_2_3_end) + + /* Best for code size to include ucond-jmp here. Would be faster + if this case is hot to duplicate the L(return_vec_2_3_end) code + as fall-through and have jump back to loop on mismatch + comparison. */ + subq $-(VEC_SIZE * 4), %rdi + subq $-(VEC_SIZE * 4), %rsi + addl $(PAGE_SIZE - VEC_SIZE * 8), %eax +# ifdef USE_AS_STRNCMP + subq $(VEC_SIZE * 4), %rdx + ja L(loop_skip_page_cross_check) +L(ret_zero_in_loop_page_cross): xorl %eax, %eax - movl (%rsi, %rcx), %edi - cmpl (%rdx, %rcx), %edi - jne L(wcscmp_return) -# else - movzbl (%rax, %rcx), %eax - movzbl (%rdx, %rcx), %edx - subl %edx, %eax -# endif + VZEROUPPER_RETURN # else -# ifdef USE_AS_WCSCMP - movq %rax, %rsi - xorl %eax, %eax - movl (VEC_SIZE * 2)(%rsi, %rcx), %edi - cmpl (VEC_SIZE * 2)(%rdx, %rcx), %edi - jne L(wcscmp_return) -# else - movzbl (VEC_SIZE * 2)(%rax, %rcx), %eax - movzbl (VEC_SIZE * 2)(%rdx, %rcx), %edx - subl %edx, %eax -# endif + jmp L(loop_skip_page_cross_check) # endif - VZEROUPPER_RETURN + + .p2align 4,, 10 +L(return_vec_page_cross_0): + addl $-VEC_SIZE, %eax +L(return_vec_page_cross_1): + tzcntl %ecx, %ecx # ifdef USE_AS_STRNCMP -L(string_nbyte_offset_check): - leaq (VEC_SIZE * 4)(%r10), %r10 - cmpq %r10, %r11 - jbe L(zero) - jmp L(back_to_loop) + leal -VEC_SIZE(%rax, %rcx), %ecx + cmpq %rcx, %rdx + jbe L(ret_zero_in_loop_page_cross) +# else + addl %eax, %ecx # endif - .p2align 4 -L(cross_page_loop): - /* Check one byte/dword at a time. */ # ifdef USE_AS_WCSCMP - cmpl %ecx, %eax + movl VEC_OFFSET(%rdi, %rcx), %edx + xorl %eax, %eax + cmpl VEC_OFFSET(%rsi, %rcx), %edx + je L(ret9) + setl %al + negl %eax + xorl %r8d, %eax # else + movzbl VEC_OFFSET(%rdi, %rcx), %eax + movzbl VEC_OFFSET(%rsi, %rcx), %ecx subl %ecx, %eax + xorl %r8d, %eax + subl %r8d, %eax # endif - jne L(different) - addl $SIZE_OF_CHAR, %edx - cmpl $(VEC_SIZE * 4), %edx - je L(main_loop_header) -# ifdef USE_AS_STRNCMP - cmpq %r11, %rdx - jae L(zero) +L(ret9): + VZEROUPPER_RETURN + + + .p2align 4,, 10 +L(page_cross): +# ifndef USE_AS_STRNCMP + /* If both are VEC aligned we don't need any special logic here. + Only valid for strcmp where stop condition is guranteed to be + reachable by just reading memory. */ + testl $((VEC_SIZE - 1) << 20), %eax + jz L(no_page_cross) # endif + + movl %edi, %eax + movl %esi, %ecx + andl $(PAGE_SIZE - 1), %eax + andl $(PAGE_SIZE - 1), %ecx + + xorl %OFFSET_REG, %OFFSET_REG + + /* Check which is closer to page cross, s1 or s2. */ + cmpl %eax, %ecx + jg L(page_cross_s2) + + /* The previous page cross check has false positives. Check for + true positive as page cross logic is very expensive. */ + subl $(PAGE_SIZE - VEC_SIZE * 4), %eax + jbe L(no_page_cross) + + /* Set r8 to not interfere with normal return value (rdi and rsi + did not swap). */ # ifdef USE_AS_WCSCMP - movl (%rdi, %rdx), %eax - movl (%rsi, %rdx), %ecx + /* any non-zero positive value that doesn't inference with 0x1. + */ + movl $2, %r8d # else - movzbl (%rdi, %rdx), %eax - movzbl (%rsi, %rdx), %ecx + xorl %r8d, %r8d # endif - /* Check null char. */ - testl %eax, %eax - jne L(cross_page_loop) - /* Since %eax == 0, subtract is OK for both SIGNED and UNSIGNED - comparisons. */ - subl %ecx, %eax -# ifndef USE_AS_WCSCMP -L(different): + + /* Check if less than 1x VEC till page cross. */ + subl $(VEC_SIZE * 3), %eax + jg L(less_1x_vec_till_page) + + /* If more than 1x VEC till page cross, loop throuh safely + loadable memory until within 1x VEC of page cross. */ + + .p2align 4,, 10 +L(page_cross_loop): + + VMOVU (%rdi, %OFFSET_REG64), %ymm0 + VPCMPEQ (%rsi, %OFFSET_REG64), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + incl %ecx + + jnz L(check_ret_vec_page_cross) + addl $VEC_SIZE, %OFFSET_REG +# ifdef USE_AS_STRNCMP + cmpq %OFFSET_REG64, %rdx + jbe L(ret_zero_page_cross) # endif - VZEROUPPER_RETURN + addl $VEC_SIZE, %eax + jl L(page_cross_loop) + + subl %eax, %OFFSET_REG + /* OFFSET_REG has distance to page cross - VEC_SIZE. Guranteed + to not cross page so is safe to load. Since we have already + loaded at least 1 VEC from rsi it is also guranteed to be safe. + */ + + VMOVU (%rdi, %OFFSET_REG64), %ymm0 + VPCMPEQ (%rsi, %OFFSET_REG64), %ymm0, %ymm1 + VPCMPEQ %ymm0, %ymmZERO, %ymm2 + vpandn %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %ecx + +# ifdef USE_AS_STRNCMP + leal VEC_SIZE(%OFFSET_REG64), %eax + cmpq %rax, %rdx + jbe L(check_ret_vec_page_cross2) + addq %rdi, %rdx +# endif + incl %ecx + jz L(prepare_loop_no_len) + .p2align 4,, 4 +L(ret_vec_page_cross): +# ifndef USE_AS_STRNCMP +L(check_ret_vec_page_cross): +# endif + tzcntl %ecx, %ecx + addl %OFFSET_REG, %ecx +L(ret_vec_page_cross_cont): # ifdef USE_AS_WCSCMP - .p2align 4 -L(different): - /* Use movl to avoid modifying EFLAGS. */ - movl $0, %eax + movl (%rdi, %rcx), %edx + xorl %eax, %eax + cmpl (%rsi, %rcx), %edx + je L(ret12) setl %al negl %eax - orl $1, %eax - VZEROUPPER_RETURN + xorl %r8d, %eax +# else + movzbl (%rdi, %rcx), %eax + movzbl (%rsi, %rcx), %ecx + subl %ecx, %eax + xorl %r8d, %eax + subl %r8d, %eax # endif +L(ret12): + VZEROUPPER_RETURN # ifdef USE_AS_STRNCMP - .p2align 4 -L(zero): + .p2align 4,, 10 +L(check_ret_vec_page_cross2): + incl %ecx +L(check_ret_vec_page_cross): + tzcntl %ecx, %ecx + addl %OFFSET_REG, %ecx + cmpq %rcx, %rdx + ja L(ret_vec_page_cross_cont) + .p2align 4,, 2 +L(ret_zero_page_cross): xorl %eax, %eax VZEROUPPER_RETURN +# endif - .p2align 4 -L(char0): -# ifdef USE_AS_WCSCMP - xorl %eax, %eax - movl (%rdi), %ecx - cmpl (%rsi), %ecx - jne L(wcscmp_return) -# else - movzbl (%rsi), %ecx - movzbl (%rdi), %eax - subl %ecx, %eax -# endif - VZEROUPPER_RETURN + .p2align 4,, 4 +L(page_cross_s2): + /* Ensure this is a true page cross. */ + subl $(PAGE_SIZE - VEC_SIZE * 4), %ecx + jbe L(no_page_cross) + + + movl %ecx, %eax + movq %rdi, %rcx + movq %rsi, %rdi + movq %rcx, %rsi + + /* set r8 to negate return value as rdi and rsi swapped. */ +# ifdef USE_AS_WCSCMP + movl $-4, %r8d +# else + movl $-1, %r8d # endif + xorl %OFFSET_REG, %OFFSET_REG - .p2align 4 -L(last_vector): - addq %rdx, %rdi - addq %rdx, %rsi + /* Check if more than 1x VEC till page cross. */ + subl $(VEC_SIZE * 3), %eax + jle L(page_cross_loop) + + .p2align 4,, 6 +L(less_1x_vec_till_page): + /* Find largest load size we can use. */ + cmpl $16, %eax + ja L(less_16_till_page) + + VMOVU (%rdi), %xmm0 + VPCMPEQ (%rsi), %xmm0, %xmm1 + VPCMPEQ %xmm0, %xmmZERO, %xmm2 + vpandn %xmm1, %xmm2, %xmm1 + vpmovmskb %ymm1, %ecx + incw %cx + jnz L(check_ret_vec_page_cross) + movl $16, %OFFSET_REG # ifdef USE_AS_STRNCMP - subq %rdx, %r11 + cmpq %OFFSET_REG64, %rdx + jbe L(ret_zero_page_cross_slow_case0) + subl %eax, %OFFSET_REG +# else + /* Explicit check for 16 byte alignment. */ + subl %eax, %OFFSET_REG + jz L(prepare_loop) # endif - tzcntl %ecx, %edx + + VMOVU (%rdi, %OFFSET_REG64), %xmm0 + VPCMPEQ (%rsi, %OFFSET_REG64), %xmm0, %xmm1 + VPCMPEQ %xmm0, %xmmZERO, %xmm2 + vpandn %xmm1, %xmm2, %xmm1 + vpmovmskb %ymm1, %ecx + incw %cx + jnz L(check_ret_vec_page_cross) + # ifdef USE_AS_STRNCMP - cmpq %r11, %rdx - jae L(zero) + addl $16, %OFFSET_REG + subq %OFFSET_REG64, %rdx + jbe L(ret_zero_page_cross_slow_case0) + subq $-(VEC_SIZE * 4), %rdx + + leaq -(VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi + leaq -(VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi +# else + leaq (16 - VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi + leaq (16 - VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi # endif -# ifdef USE_AS_WCSCMP + jmp L(prepare_loop_aligned) + +# ifdef USE_AS_STRNCMP + .p2align 4,, 2 +L(ret_zero_page_cross_slow_case0): xorl %eax, %eax - movl (%rdi, %rdx), %ecx - cmpl (%rsi, %rdx), %ecx - jne L(wcscmp_return) -# else - movzbl (%rdi, %rdx), %eax - movzbl (%rsi, %rdx), %edx - subl %edx, %eax + ret # endif - VZEROUPPER_RETURN - /* Comparing on page boundary region requires special treatment: - It must done one vector at the time, starting with the wider - ymm vector if possible, if not, with xmm. If fetching 16 bytes - (xmm) still passes the boundary, byte comparison must be done. - */ - .p2align 4 -L(cross_page): - /* Try one ymm vector at a time. */ - cmpl $(PAGE_SIZE - VEC_SIZE), %eax - jg L(cross_page_1_vector) -L(loop_1_vector): - vmovdqu (%rdi, %rdx), %ymm1 - VPCMPEQ (%rsi, %rdx), %ymm1, %ymm0 - VPMINU %ymm1, %ymm0, %ymm0 - VPCMPEQ %ymm7, %ymm0, %ymm0 - vpmovmskb %ymm0, %ecx - testl %ecx, %ecx - jne L(last_vector) - addl $VEC_SIZE, %edx + .p2align 4,, 10 +L(less_16_till_page): + /* Find largest load size we can use. */ + cmpl $24, %eax + ja L(less_8_till_page) - addl $VEC_SIZE, %eax -# ifdef USE_AS_STRNCMP - /* Return 0 if the current offset (%rdx) >= the maximum offset - (%r11). */ - cmpq %r11, %rdx - jae L(zero) -# endif - cmpl $(PAGE_SIZE - VEC_SIZE), %eax - jle L(loop_1_vector) -L(cross_page_1_vector): - /* Less than 32 bytes to check, try one xmm vector. */ - cmpl $(PAGE_SIZE - 16), %eax - jg L(cross_page_1_xmm) - vmovdqu (%rdi, %rdx), %xmm1 - VPCMPEQ (%rsi, %rdx), %xmm1, %xmm0 - VPMINU %xmm1, %xmm0, %xmm0 - VPCMPEQ %xmm7, %xmm0, %xmm0 - vpmovmskb %xmm0, %ecx - testl %ecx, %ecx - jne L(last_vector) + vmovq (%rdi), %xmm0 + vmovq (%rsi), %xmm1 + VPCMPEQ %xmm0, %xmmZERO, %xmm2 + VPCMPEQ %xmm1, %xmm0, %xmm1 + vpandn %xmm1, %xmm2, %xmm1 + vpmovmskb %ymm1, %ecx + incb %cl + jnz L(check_ret_vec_page_cross) - addl $16, %edx -# ifndef USE_AS_WCSCMP - addl $16, %eax + +# ifdef USE_AS_STRNCMP + cmpq $8, %rdx + jbe L(ret_zero_page_cross_slow_case0) # endif + movl $24, %OFFSET_REG + /* Explicit check for 16 byte alignment. */ + subl %eax, %OFFSET_REG + + + + vmovq (%rdi, %OFFSET_REG64), %xmm0 + vmovq (%rsi, %OFFSET_REG64), %xmm1 + VPCMPEQ %xmm0, %xmmZERO, %xmm2 + VPCMPEQ %xmm1, %xmm0, %xmm1 + vpandn %xmm1, %xmm2, %xmm1 + vpmovmskb %ymm1, %ecx + incb %cl + jnz L(check_ret_vec_page_cross) + # ifdef USE_AS_STRNCMP - /* Return 0 if the current offset (%rdx) >= the maximum offset - (%r11). */ - cmpq %r11, %rdx - jae L(zero) -# endif - -L(cross_page_1_xmm): -# ifndef USE_AS_WCSCMP - /* Less than 16 bytes to check, try 8 byte vector. NB: No need - for wcscmp nor wcsncmp since wide char is 4 bytes. */ - cmpl $(PAGE_SIZE - 8), %eax - jg L(cross_page_8bytes) - vmovq (%rdi, %rdx), %xmm1 - vmovq (%rsi, %rdx), %xmm0 - VPCMPEQ %xmm0, %xmm1, %xmm0 - VPMINU %xmm1, %xmm0, %xmm0 - VPCMPEQ %xmm7, %xmm0, %xmm0 - vpmovmskb %xmm0, %ecx - /* Only last 8 bits are valid. */ - andl $0xff, %ecx - testl %ecx, %ecx - jne L(last_vector) + addl $8, %OFFSET_REG + subq %OFFSET_REG64, %rdx + jbe L(ret_zero_page_cross_slow_case0) + subq $-(VEC_SIZE * 4), %rdx - addl $8, %edx - addl $8, %eax + leaq -(VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi + leaq -(VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi +# else + leaq (8 - VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi + leaq (8 - VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi +# endif + jmp L(prepare_loop_aligned) + + + .p2align 4,, 10 +L(less_8_till_page): +# ifdef USE_AS_WCSCMP + /* If using wchar then this is the only check before we reach + the page boundary. */ + movl (%rdi), %eax + movl (%rsi), %ecx + cmpl %ecx, %eax + jnz L(ret_less_8_wcs) # ifdef USE_AS_STRNCMP - /* Return 0 if the current offset (%rdx) >= the maximum offset - (%r11). */ - cmpq %r11, %rdx - jae L(zero) + addq %rdi, %rdx + /* We already checked for len <= 1 so cannot hit that case here. + */ # endif + testl %eax, %eax + jnz L(prepare_loop_no_len) + ret -L(cross_page_8bytes): - /* Less than 8 bytes to check, try 4 byte vector. */ - cmpl $(PAGE_SIZE - 4), %eax - jg L(cross_page_4bytes) - vmovd (%rdi, %rdx), %xmm1 - vmovd (%rsi, %rdx), %xmm0 - VPCMPEQ %xmm0, %xmm1, %xmm0 - VPMINU %xmm1, %xmm0, %xmm0 - VPCMPEQ %xmm7, %xmm0, %xmm0 - vpmovmskb %xmm0, %ecx - /* Only last 4 bits are valid. */ - andl $0xf, %ecx - testl %ecx, %ecx - jne L(last_vector) + .p2align 4,, 8 +L(ret_less_8_wcs): + setl %OFFSET_REG8 + negl %OFFSET_REG + movl %OFFSET_REG, %eax + xorl %r8d, %eax + ret + +# else + + /* Find largest load size we can use. */ + cmpl $28, %eax + ja L(less_4_till_page) + + vmovd (%rdi), %xmm0 + vmovd (%rsi), %xmm1 + VPCMPEQ %xmm0, %xmmZERO, %xmm2 + VPCMPEQ %xmm1, %xmm0, %xmm1 + vpandn %xmm1, %xmm2, %xmm1 + vpmovmskb %ymm1, %ecx + subl $0xf, %ecx + jnz L(check_ret_vec_page_cross) - addl $4, %edx # ifdef USE_AS_STRNCMP - /* Return 0 if the current offset (%rdx) >= the maximum offset - (%r11). */ - cmpq %r11, %rdx - jae L(zero) + cmpq $4, %rdx + jbe L(ret_zero_page_cross_slow_case1) # endif + movl $28, %OFFSET_REG + /* Explicit check for 16 byte alignment. */ + subl %eax, %OFFSET_REG -L(cross_page_4bytes): -# endif - /* Less than 4 bytes to check, try one byte/dword at a time. */ -# ifdef USE_AS_STRNCMP - cmpq %r11, %rdx - jae L(zero) -# endif -# ifdef USE_AS_WCSCMP - movl (%rdi, %rdx), %eax - movl (%rsi, %rdx), %ecx -# else - movzbl (%rdi, %rdx), %eax - movzbl (%rsi, %rdx), %ecx -# endif - testl %eax, %eax - jne L(cross_page_loop) + + + vmovd (%rdi, %OFFSET_REG64), %xmm0 + vmovd (%rsi, %OFFSET_REG64), %xmm1 + VPCMPEQ %xmm0, %xmmZERO, %xmm2 + VPCMPEQ %xmm1, %xmm0, %xmm1 + vpandn %xmm1, %xmm2, %xmm1 + vpmovmskb %ymm1, %ecx + subl $0xf, %ecx + jnz L(check_ret_vec_page_cross) + +# ifdef USE_AS_STRNCMP + addl $4, %OFFSET_REG + subq %OFFSET_REG64, %rdx + jbe L(ret_zero_page_cross_slow_case1) + subq $-(VEC_SIZE * 4), %rdx + + leaq -(VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi + leaq -(VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi +# else + leaq (4 - VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi + leaq (4 - VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi +# endif + jmp L(prepare_loop_aligned) + +# ifdef USE_AS_STRNCMP + .p2align 4,, 2 +L(ret_zero_page_cross_slow_case1): + xorl %eax, %eax + ret +# endif + + .p2align 4,, 10 +L(less_4_till_page): + subq %rdi, %rsi + /* Extremely slow byte comparison loop. */ +L(less_4_loop): + movzbl (%rdi), %eax + movzbl (%rsi, %rdi), %ecx subl %ecx, %eax - VZEROUPPER_RETURN -END (STRCMP) + jnz L(ret_less_4_loop) + testl %ecx, %ecx + jz L(ret_zero_4_loop) +# ifdef USE_AS_STRNCMP + decq %rdx + jz L(ret_zero_4_loop) +# endif + incq %rdi + /* end condition is reach page boundary (rdi is aligned). */ + testl $31, %edi + jnz L(less_4_loop) + leaq -(VEC_SIZE * 4)(%rdi, %rsi), %rsi + addq $-(VEC_SIZE * 4), %rdi +# ifdef USE_AS_STRNCMP + subq $-(VEC_SIZE * 4), %rdx +# endif + jmp L(prepare_loop_aligned) + +L(ret_zero_4_loop): + xorl %eax, %eax + ret +L(ret_less_4_loop): + xorl %r8d, %eax + subl %r8d, %eax + ret +# endif +END(STRCMP) #endif |