x86: Optimize {str|wcs}rchr-avx2
The new code unrolls the main loop slightly without adding too much overhead and minimizes the comparisons for the search CHAR. Geometric Mean of all benchmarks New / Old: 0.832 See email for all results. Full xcheck passes on x86_64 with and without multiarch enabled. Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Noah Goldstein
parent
5307aa9c18
commit
df7e295d18
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@ -27,9 +27,13 @@
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# ifdef USE_AS_WCSRCHR
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# define VPBROADCAST vpbroadcastd
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# define VPCMPEQ vpcmpeqd
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# define VPMIN vpminud
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# define CHAR_SIZE 4
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# else
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# define VPBROADCAST vpbroadcastb
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# define VPCMPEQ vpcmpeqb
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# define VPMIN vpminub
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# define CHAR_SIZE 1
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# endif
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# ifndef VZEROUPPER
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@ -41,196 +45,304 @@
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# endif
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# define VEC_SIZE 32
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# define PAGE_SIZE 4096
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.section SECTION(.text),"ax",@progbits
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ENTRY (STRRCHR)
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movd %esi, %xmm4
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movl %edi, %ecx
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.section SECTION(.text), "ax", @progbits
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ENTRY(STRRCHR)
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movd %esi, %xmm7
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movl %edi, %eax
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/* Broadcast CHAR to YMM4. */
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VPBROADCAST %xmm4, %ymm4
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VPBROADCAST %xmm7, %ymm7
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vpxor %xmm0, %xmm0, %xmm0
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/* Check if we may cross page boundary with one vector load. */
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andl $(2 * VEC_SIZE - 1), %ecx
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cmpl $VEC_SIZE, %ecx
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ja L(cros_page_boundary)
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/* Shift here instead of `andl` to save code size (saves a fetch
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block). */
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sall $20, %eax
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cmpl $((PAGE_SIZE - VEC_SIZE) << 20), %eax
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ja L(cross_page)
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L(page_cross_continue):
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vmovdqu (%rdi), %ymm1
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VPCMPEQ %ymm1, %ymm0, %ymm2
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VPCMPEQ %ymm1, %ymm4, %ymm3
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vpmovmskb %ymm2, %ecx
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vpmovmskb %ymm3, %eax
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addq $VEC_SIZE, %rdi
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testl %eax, %eax
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jnz L(first_vec)
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/* Check end of string match. */
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VPCMPEQ %ymm1, %ymm0, %ymm6
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vpmovmskb %ymm6, %ecx
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testl %ecx, %ecx
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jnz L(return_null)
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jz L(aligned_more)
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andq $-VEC_SIZE, %rdi
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xorl %edx, %edx
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jmp L(aligned_loop)
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.p2align 4
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L(first_vec):
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/* Check if there is a nul CHAR. */
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testl %ecx, %ecx
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jnz L(char_and_nul_in_first_vec)
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/* Remember the match and keep searching. */
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movl %eax, %edx
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movq %rdi, %rsi
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andq $-VEC_SIZE, %rdi
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jmp L(aligned_loop)
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.p2align 4
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L(cros_page_boundary):
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andl $(VEC_SIZE - 1), %ecx
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andq $-VEC_SIZE, %rdi
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vmovdqa (%rdi), %ymm1
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VPCMPEQ %ymm1, %ymm0, %ymm2
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VPCMPEQ %ymm1, %ymm4, %ymm3
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vpmovmskb %ymm2, %edx
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vpmovmskb %ymm3, %eax
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shrl %cl, %edx
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shrl %cl, %eax
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addq $VEC_SIZE, %rdi
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/* Check if there is a CHAR. */
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testl %eax, %eax
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jnz L(found_char)
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testl %edx, %edx
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jnz L(return_null)
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jmp L(aligned_loop)
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.p2align 4
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L(found_char):
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testl %edx, %edx
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jnz L(char_and_nul)
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/* Remember the match and keep searching. */
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movl %eax, %edx
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leaq (%rdi, %rcx), %rsi
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.p2align 4
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L(aligned_loop):
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vmovdqa (%rdi), %ymm1
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VPCMPEQ %ymm1, %ymm0, %ymm2
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addq $VEC_SIZE, %rdi
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VPCMPEQ %ymm1, %ymm4, %ymm3
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vpmovmskb %ymm2, %ecx
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vpmovmskb %ymm3, %eax
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orl %eax, %ecx
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jnz L(char_nor_null)
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vmovdqa (%rdi), %ymm1
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VPCMPEQ %ymm1, %ymm0, %ymm2
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add $VEC_SIZE, %rdi
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VPCMPEQ %ymm1, %ymm4, %ymm3
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vpmovmskb %ymm2, %ecx
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vpmovmskb %ymm3, %eax
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orl %eax, %ecx
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jnz L(char_nor_null)
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vmovdqa (%rdi), %ymm1
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VPCMPEQ %ymm1, %ymm0, %ymm2
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addq $VEC_SIZE, %rdi
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VPCMPEQ %ymm1, %ymm4, %ymm3
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vpmovmskb %ymm2, %ecx
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vpmovmskb %ymm3, %eax
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orl %eax, %ecx
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jnz L(char_nor_null)
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vmovdqa (%rdi), %ymm1
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VPCMPEQ %ymm1, %ymm0, %ymm2
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addq $VEC_SIZE, %rdi
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VPCMPEQ %ymm1, %ymm4, %ymm3
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vpmovmskb %ymm2, %ecx
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vpmovmskb %ymm3, %eax
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orl %eax, %ecx
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jz L(aligned_loop)
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.p2align 4
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L(char_nor_null):
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/* Find a CHAR or a nul CHAR in a loop. */
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testl %eax, %eax
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jnz L(match)
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L(return_value):
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testl %edx, %edx
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jz L(return_null)
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movl %edx, %eax
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movq %rsi, %rdi
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# ifdef USE_AS_WCSRCHR
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/* Keep the first bit for each matching CHAR for bsr. */
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andl $0x11111111, %eax
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# endif
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/* Only check match with search CHAR if needed. */
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VPCMPEQ %ymm1, %ymm7, %ymm1
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vpmovmskb %ymm1, %eax
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/* Check if match before first zero. */
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blsmskl %ecx, %ecx
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andl %ecx, %eax
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jz L(ret0)
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bsrl %eax, %eax
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leaq -VEC_SIZE(%rdi, %rax), %rax
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addq %rdi, %rax
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/* We are off by 3 for wcsrchr if search CHAR is non-zero. If
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search CHAR is zero we are correct. Either way `andq
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-CHAR_SIZE, %rax` gets the correct result. */
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# ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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# endif
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L(ret0):
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L(return_vzeroupper):
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ZERO_UPPER_VEC_REGISTERS_RETURN
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/* Returns for first vec x1/x2 have hard coded backward search
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path for earlier matches. */
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.p2align 4,, 10
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L(first_vec_x1):
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VPCMPEQ %ymm2, %ymm7, %ymm6
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vpmovmskb %ymm6, %eax
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blsmskl %ecx, %ecx
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andl %ecx, %eax
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jnz L(first_vec_x1_return)
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.p2align 4,, 4
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L(first_vec_x0_test):
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VPCMPEQ %ymm1, %ymm7, %ymm6
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vpmovmskb %ymm6, %eax
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testl %eax, %eax
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jz L(ret1)
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bsrl %eax, %eax
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addq %r8, %rax
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# ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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# endif
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L(ret1):
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VZEROUPPER_RETURN
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.p2align 4,, 10
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L(first_vec_x0_x1_test):
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VPCMPEQ %ymm2, %ymm7, %ymm6
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vpmovmskb %ymm6, %eax
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/* Check ymm2 for search CHAR match. If no match then check ymm1
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before returning. */
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testl %eax, %eax
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jz L(first_vec_x0_test)
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.p2align 4,, 4
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L(first_vec_x1_return):
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bsrl %eax, %eax
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leaq 1(%rdi, %rax), %rax
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# ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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# endif
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VZEROUPPER_RETURN
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.p2align 4,, 10
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L(first_vec_x2):
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VPCMPEQ %ymm3, %ymm7, %ymm6
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vpmovmskb %ymm6, %eax
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blsmskl %ecx, %ecx
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/* If no in-range search CHAR match in ymm3 then need to check
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ymm1/ymm2 for an earlier match (we delay checking search
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CHAR matches until needed). */
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andl %ecx, %eax
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jz L(first_vec_x0_x1_test)
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bsrl %eax, %eax
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leaq (VEC_SIZE + 1)(%rdi, %rax), %rax
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# ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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# endif
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VZEROUPPER_RETURN
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.p2align 4
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L(match):
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/* Find a CHAR. Check if there is a nul CHAR. */
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vpmovmskb %ymm2, %ecx
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L(aligned_more):
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/* Save original pointer if match was in VEC 0. */
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movq %rdi, %r8
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/* Align src. */
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orq $(VEC_SIZE - 1), %rdi
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vmovdqu 1(%rdi), %ymm2
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VPCMPEQ %ymm2, %ymm0, %ymm6
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vpmovmskb %ymm6, %ecx
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testl %ecx, %ecx
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jnz L(find_nul)
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jnz L(first_vec_x1)
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/* Remember the match and keep searching. */
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movl %eax, %edx
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vmovdqu (VEC_SIZE + 1)(%rdi), %ymm3
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VPCMPEQ %ymm3, %ymm0, %ymm6
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vpmovmskb %ymm6, %ecx
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testl %ecx, %ecx
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jnz L(first_vec_x2)
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/* Save pointer again before realigning. */
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movq %rdi, %rsi
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jmp L(aligned_loop)
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addq $(VEC_SIZE + 1), %rdi
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andq $-(VEC_SIZE * 2), %rdi
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.p2align 4
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L(find_nul):
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# ifdef USE_AS_WCSRCHR
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/* Keep the first bit for each matching CHAR for bsr. */
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andl $0x11111111, %ecx
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andl $0x11111111, %eax
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# endif
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/* Mask out any matching bits after the nul CHAR. */
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movl %ecx, %r8d
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subl $1, %r8d
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xorl %ecx, %r8d
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andl %r8d, %eax
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L(first_aligned_loop):
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/* Do 2x VEC at a time. Any more and the cost of finding the
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match outweights loop benefit. */
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vmovdqa (VEC_SIZE * 0)(%rdi), %ymm4
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vmovdqa (VEC_SIZE * 1)(%rdi), %ymm5
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VPCMPEQ %ymm4, %ymm7, %ymm6
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VPMIN %ymm4, %ymm5, %ymm8
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VPCMPEQ %ymm5, %ymm7, %ymm10
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vpor %ymm6, %ymm10, %ymm5
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VPCMPEQ %ymm8, %ymm0, %ymm8
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vpor %ymm5, %ymm8, %ymm9
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vpmovmskb %ymm9, %eax
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addq $(VEC_SIZE * 2), %rdi
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/* No zero or search CHAR. */
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testl %eax, %eax
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/* If there is no CHAR here, return the remembered one. */
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jz L(return_value)
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bsrl %eax, %eax
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leaq -VEC_SIZE(%rdi, %rax), %rax
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VZEROUPPER_RETURN
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jz L(first_aligned_loop)
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.p2align 4
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L(char_and_nul):
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/* Find both a CHAR and a nul CHAR. */
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addq %rcx, %rdi
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movl %edx, %ecx
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L(char_and_nul_in_first_vec):
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# ifdef USE_AS_WCSRCHR
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/* Keep the first bit for each matching CHAR for bsr. */
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andl $0x11111111, %ecx
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andl $0x11111111, %eax
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# endif
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/* Mask out any matching bits after the nul CHAR. */
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movl %ecx, %r8d
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subl $1, %r8d
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xorl %ecx, %r8d
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andl %r8d, %eax
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/* If no zero CHAR then go to second loop (this allows us to
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throw away all prior work). */
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vpmovmskb %ymm8, %ecx
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testl %ecx, %ecx
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jz L(second_aligned_loop_prep)
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/* Search char could be zero so we need to get the true match.
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*/
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vpmovmskb %ymm5, %eax
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testl %eax, %eax
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/* Return null pointer if the nul CHAR comes first. */
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jz L(return_null)
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bsrl %eax, %eax
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leaq -VEC_SIZE(%rdi, %rax), %rax
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jnz L(first_aligned_loop_return)
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.p2align 4,, 4
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L(first_vec_x1_or_x2):
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VPCMPEQ %ymm3, %ymm7, %ymm3
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VPCMPEQ %ymm2, %ymm7, %ymm2
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vpmovmskb %ymm3, %eax
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vpmovmskb %ymm2, %edx
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/* Use add for macro-fusion. */
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addq %rax, %rdx
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jz L(first_vec_x0_test)
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/* NB: We could move this shift to before the branch and save a
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bit of code size / performance on the fall through. The
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branch leads to the null case which generally seems hotter
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than char in first 3x VEC. */
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salq $32, %rax
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addq %rdx, %rax
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bsrq %rax, %rax
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leaq 1(%rsi, %rax), %rax
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# ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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# endif
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VZEROUPPER_RETURN
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.p2align 4,, 8
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L(first_aligned_loop_return):
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VPCMPEQ %ymm4, %ymm0, %ymm4
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vpmovmskb %ymm4, %edx
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salq $32, %rcx
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orq %rdx, %rcx
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vpmovmskb %ymm10, %eax
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vpmovmskb %ymm6, %edx
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salq $32, %rax
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orq %rdx, %rax
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blsmskq %rcx, %rcx
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andq %rcx, %rax
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jz L(first_vec_x1_or_x2)
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bsrq %rax, %rax
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leaq -(VEC_SIZE * 2)(%rdi, %rax), %rax
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# ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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# endif
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VZEROUPPER_RETURN
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/* Search char cannot be zero. */
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.p2align 4
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L(second_aligned_loop_set_furthest_match):
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/* Save VEC and pointer from most recent match. */
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L(second_aligned_loop_prep):
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movq %rdi, %rsi
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vmovdqu %ymm6, %ymm2
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vmovdqu %ymm10, %ymm3
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.p2align 4
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L(return_null):
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xorl %eax, %eax
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L(second_aligned_loop):
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/* Search 2x at at time. */
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vmovdqa (VEC_SIZE * 0)(%rdi), %ymm4
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vmovdqa (VEC_SIZE * 1)(%rdi), %ymm5
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VPCMPEQ %ymm4, %ymm7, %ymm6
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VPMIN %ymm4, %ymm5, %ymm1
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VPCMPEQ %ymm5, %ymm7, %ymm10
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vpor %ymm6, %ymm10, %ymm5
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VPCMPEQ %ymm1, %ymm0, %ymm1
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vpor %ymm5, %ymm1, %ymm9
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vpmovmskb %ymm9, %eax
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addq $(VEC_SIZE * 2), %rdi
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testl %eax, %eax
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jz L(second_aligned_loop)
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vpmovmskb %ymm1, %ecx
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testl %ecx, %ecx
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jz L(second_aligned_loop_set_furthest_match)
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vpmovmskb %ymm5, %eax
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testl %eax, %eax
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jnz L(return_new_match)
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/* This is the hot patch. We know CHAR is inbounds and that
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ymm3/ymm2 have latest match. */
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.p2align 4,, 4
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L(return_old_match):
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vpmovmskb %ymm3, %eax
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vpmovmskb %ymm2, %edx
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salq $32, %rax
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orq %rdx, %rax
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bsrq %rax, %rax
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/* Search char cannot be zero so safe to just use lea for
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wcsrchr. */
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leaq (VEC_SIZE * -2 -(CHAR_SIZE - 1))(%rsi, %rax), %rax
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VZEROUPPER_RETURN
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END (STRRCHR)
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/* Last iteration also potentially has a match. */
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.p2align 4,, 8
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L(return_new_match):
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VPCMPEQ %ymm4, %ymm0, %ymm4
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vpmovmskb %ymm4, %edx
|
||||
salq $32, %rcx
|
||||
orq %rdx, %rcx
|
||||
|
||||
vpmovmskb %ymm10, %eax
|
||||
vpmovmskb %ymm6, %edx
|
||||
salq $32, %rax
|
||||
orq %rdx, %rax
|
||||
blsmskq %rcx, %rcx
|
||||
andq %rcx, %rax
|
||||
jz L(return_old_match)
|
||||
bsrq %rax, %rax
|
||||
/* Search char cannot be zero so safe to just use lea for
|
||||
wcsrchr. */
|
||||
leaq (VEC_SIZE * -2 -(CHAR_SIZE - 1))(%rdi, %rax), %rax
|
||||
VZEROUPPER_RETURN
|
||||
|
||||
.p2align 4,, 4
|
||||
L(cross_page):
|
||||
movq %rdi, %rsi
|
||||
andq $-VEC_SIZE, %rsi
|
||||
vmovdqu (%rsi), %ymm1
|
||||
VPCMPEQ %ymm1, %ymm0, %ymm6
|
||||
vpmovmskb %ymm6, %ecx
|
||||
/* Shift out zero CHAR matches that are before the begining of
|
||||
src (rdi). */
|
||||
shrxl %edi, %ecx, %ecx
|
||||
testl %ecx, %ecx
|
||||
jz L(page_cross_continue)
|
||||
VPCMPEQ %ymm1, %ymm7, %ymm1
|
||||
vpmovmskb %ymm1, %eax
|
||||
|
||||
/* Shift out search CHAR matches that are before the begining of
|
||||
src (rdi). */
|
||||
shrxl %edi, %eax, %eax
|
||||
blsmskl %ecx, %ecx
|
||||
/* Check if any search CHAR match in range. */
|
||||
andl %ecx, %eax
|
||||
jz L(ret2)
|
||||
bsrl %eax, %eax
|
||||
addq %rdi, %rax
|
||||
# ifdef USE_AS_WCSRCHR
|
||||
andq $-CHAR_SIZE, %rax
|
||||
# endif
|
||||
L(ret2):
|
||||
VZEROUPPER_RETURN
|
||||
END(STRRCHR)
|
||||
#endif
|
||||
|
|
|
|||
Loading…
Reference in New Issue