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x86: Optimize memchr-avx2.S

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No bug. This commit optimizes memchr-avx2.S. The optimizations include
replacing some branches with cmovcc, avoiding some branches entirely
in the less_4x_vec case, making the page cross logic less strict,
asaving a few instructions the in loop return loop. test-memchr,
test-rawmemchr, and test-wmemchr are all passing.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Noah Goldstein 2021-05-03 03:01:58 -04:00
parent 77c1573dbc
commit acfd088a19
1 changed files with 311 additions and 242 deletions
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553
sysdeps/x86_64/multiarch/memchr-avx2.S
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@ -26,8 +26,22 @@
# ifdef USE_AS_WMEMCHR # ifdef USE_AS_WMEMCHR
# define VPCMPEQ vpcmpeqd # define VPCMPEQ vpcmpeqd
# define VPBROADCAST vpbroadcastd
# define CHAR_SIZE 4
# else # else
# define VPCMPEQ vpcmpeqb # define VPCMPEQ vpcmpeqb
# define VPBROADCAST vpbroadcastb
# define CHAR_SIZE 1
# endif
# ifdef USE_AS_RAWMEMCHR
# define ERAW_PTR_REG ecx
# define RRAW_PTR_REG rcx
# define ALGN_PTR_REG rdi
# else
# define ERAW_PTR_REG edi
# define RRAW_PTR_REG rdi
# define ALGN_PTR_REG rcx
# endif # endif
# ifndef VZEROUPPER # ifndef VZEROUPPER
@ -39,6 +53,7 @@
# endif # endif
# define VEC_SIZE 32 # define VEC_SIZE 32
# define PAGE_SIZE 4096
.section SECTION(.text),"ax",@progbits .section SECTION(.text),"ax",@progbits
ENTRY (MEMCHR) ENTRY (MEMCHR)
@ -47,295 +62,349 @@ ENTRY (MEMCHR)
test %RDX_LP, %RDX_LP test %RDX_LP, %RDX_LP
jz L(null) jz L(null)
# endif # endif
movl %edi, %ecx
/* Broadcast CHAR to YMM0. */
vmovd %esi, %xmm0
# ifdef USE_AS_WMEMCHR # ifdef USE_AS_WMEMCHR
shl $2, %RDX_LP shl $2, %RDX_LP
vpbroadcastd %xmm0, %ymm0
# else # else
# ifdef __ILP32__ # ifdef __ILP32__
/* Clear the upper 32 bits. */ /* Clear the upper 32 bits. */
movl %edx, %edx movl %edx, %edx
# endif # endif
vpbroadcastb %xmm0, %ymm0
# endif # endif
/* Broadcast CHAR to YMMMATCH. */
vmovd %esi, %xmm0
VPBROADCAST %xmm0, %ymm0
/* Check if we may cross page boundary with one vector load. */ /* Check if we may cross page boundary with one vector load. */
andl $(2 * VEC_SIZE - 1), %ecx movl %edi, %eax
cmpl $VEC_SIZE, %ecx andl $(PAGE_SIZE - 1), %eax
ja L(cros_page_boundary) cmpl $(PAGE_SIZE - VEC_SIZE), %eax
ja L(cross_page_boundary)
/* Check the first VEC_SIZE bytes. */ /* Check the first VEC_SIZE bytes. */
VPCMPEQ (%rdi), %ymm0, %ymm1 VPCMPEQ (%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax vpmovmskb %ymm1, %eax
testl %eax, %eax
# ifndef USE_AS_RAWMEMCHR # ifndef USE_AS_RAWMEMCHR
jnz L(first_vec_x0_check) /* If length < CHAR_PER_VEC handle special. */
/* Adjust length and check the end of data. */ cmpq $VEC_SIZE, %rdx
subq $VEC_SIZE, %rdx jbe L(first_vec_x0)
jbe L(zero)
# else
jnz L(first_vec_x0)
# endif # endif
/* Align data for aligned loads in the loop. */
addq $VEC_SIZE, %rdi
andl $(VEC_SIZE - 1), %ecx
andq $-VEC_SIZE, %rdi
# ifndef USE_AS_RAWMEMCHR
/* Adjust length. */
addq %rcx, %rdx
subq $(VEC_SIZE * 4), %rdx
jbe L(last_4x_vec_or_less)
# endif
jmp L(more_4x_vec)
.p2align 4
L(cros_page_boundary):
andl $(VEC_SIZE - 1), %ecx
andq $-VEC_SIZE, %rdi
VPCMPEQ (%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
/* Remove the leading bytes. */
sarl %cl, %eax
testl %eax, %eax testl %eax, %eax
jz L(aligned_more) jz L(aligned_more)
tzcntl %eax, %eax tzcntl %eax, %eax
# ifndef USE_AS_RAWMEMCHR
/* Check the end of data. */
cmpq %rax, %rdx
jbe L(zero)
# endif
addq %rdi, %rax addq %rdi, %rax
addq %rcx, %rax
L(return_vzeroupper):
ZERO_UPPER_VEC_REGISTERS_RETURN
.p2align 4
L(aligned_more):
# ifndef USE_AS_RAWMEMCHR
/* Calculate "rdx + rcx - VEC_SIZE" with "rdx - (VEC_SIZE - rcx)"
instead of "(rdx + rcx) - VEC_SIZE" to void possible addition
overflow. */
negq %rcx
addq $VEC_SIZE, %rcx
/* Check the end of data. */
subq %rcx, %rdx
jbe L(zero)
# endif
addq $VEC_SIZE, %rdi
# ifndef USE_AS_RAWMEMCHR
subq $(VEC_SIZE * 4), %rdx
jbe L(last_4x_vec_or_less)
# endif
L(more_4x_vec):
/* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time
since data is only aligned to VEC_SIZE. */
VPCMPEQ (%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x0)
VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x1)
VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x2)
VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x3)
addq $(VEC_SIZE * 4), %rdi
# ifndef USE_AS_RAWMEMCHR
subq $(VEC_SIZE * 4), %rdx
jbe L(last_4x_vec_or_less)
# endif
/* Align data to 4 * VEC_SIZE. */
movq %rdi, %rcx
andl $(4 * VEC_SIZE - 1), %ecx
andq $-(4 * VEC_SIZE), %rdi
# ifndef USE_AS_RAWMEMCHR
/* Adjust length. */
addq %rcx, %rdx
# endif
.p2align 4
L(loop_4x_vec):
/* Compare 4 * VEC at a time forward. */
VPCMPEQ (%rdi), %ymm0, %ymm1
VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm2
VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm0, %ymm3
VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm0, %ymm4
vpor %ymm1, %ymm2, %ymm5
vpor %ymm3, %ymm4, %ymm6
vpor %ymm5, %ymm6, %ymm5
vpmovmskb %ymm5, %eax
testl %eax, %eax
jnz L(4x_vec_end)
addq $(VEC_SIZE * 4), %rdi
# ifdef USE_AS_RAWMEMCHR
jmp L(loop_4x_vec)
# else
subq $(VEC_SIZE * 4), %rdx
ja L(loop_4x_vec)
L(last_4x_vec_or_less):
/* Less than 4 * VEC and aligned to VEC_SIZE. */
addl $(VEC_SIZE * 2), %edx
jle L(last_2x_vec)
VPCMPEQ (%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x0)
VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x1)
VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x2_check)
subl $VEC_SIZE, %edx
jle L(zero)
VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x3_check)
xorl %eax, %eax
VZEROUPPER_RETURN VZEROUPPER_RETURN
.p2align 4 # ifndef USE_AS_RAWMEMCHR
L(last_2x_vec): .p2align 5
addl $(VEC_SIZE * 2), %edx L(first_vec_x0):
VPCMPEQ (%rdi), %ymm0, %ymm1 /* Check if first match was before length. */
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x0_check)
subl $VEC_SIZE, %edx
jle L(zero)
VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x1_check)
xorl %eax, %eax
VZEROUPPER_RETURN
.p2align 4
L(first_vec_x0_check):
tzcntl %eax, %eax tzcntl %eax, %eax
/* Check the end of data. */ xorl %ecx, %ecx
cmpq %rax, %rdx cmpl %eax, %edx
jbe L(zero) leaq (%rdi, %rax), %rax
addq %rdi, %rax cmovle %rcx, %rax
VZEROUPPER_RETURN VZEROUPPER_RETURN
.p2align 4
L(first_vec_x1_check):
tzcntl %eax, %eax
/* Check the end of data. */
cmpq %rax, %rdx
jbe L(zero)
addq $VEC_SIZE, %rax
addq %rdi, %rax
VZEROUPPER_RETURN
.p2align 4
L(first_vec_x2_check):
tzcntl %eax, %eax
/* Check the end of data. */
cmpq %rax, %rdx
jbe L(zero)
addq $(VEC_SIZE * 2), %rax
addq %rdi, %rax
VZEROUPPER_RETURN
.p2align 4
L(first_vec_x3_check):
tzcntl %eax, %eax
/* Check the end of data. */
cmpq %rax, %rdx
jbe L(zero)
addq $(VEC_SIZE * 3), %rax
addq %rdi, %rax
VZEROUPPER_RETURN
.p2align 4
L(zero):
xorl %eax, %eax
jmp L(return_vzeroupper)
.p2align 4
L(null): L(null):
xorl %eax, %eax xorl %eax, %eax
ret ret
# endif # endif
.p2align 4 .p2align 4
L(first_vec_x0): L(cross_page_boundary):
/* Save pointer before aligning as its original value is necessary
for computer return address if byte is found or adjusting length
if it is not and this is memchr. */
movq %rdi, %rcx
/* Align data to VEC_SIZE - 1. ALGN_PTR_REG is rcx for memchr and
rdi for rawmemchr. */
orq $(VEC_SIZE - 1), %ALGN_PTR_REG
VPCMPEQ -(VEC_SIZE - 1)(%ALGN_PTR_REG), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
# ifndef USE_AS_RAWMEMCHR
/* Calculate length until end of page (length checked for a
match). */
leaq 1(%ALGN_PTR_REG), %rsi
subq %RRAW_PTR_REG, %rsi
# endif
/* Remove the leading bytes. */
sarxl %ERAW_PTR_REG, %eax, %eax
# ifndef USE_AS_RAWMEMCHR
/* Check the end of data. */
cmpq %rsi, %rdx
jbe L(first_vec_x0)
# endif
testl %eax, %eax
jz L(cross_page_continue)
tzcntl %eax, %eax tzcntl %eax, %eax
addq %rdi, %rax addq %RRAW_PTR_REG, %rax
VZEROUPPER_RETURN L(return_vzeroupper):
ZERO_UPPER_VEC_REGISTERS_RETURN
.p2align 4 .p2align 4
L(first_vec_x1): L(first_vec_x1):
tzcntl %eax, %eax tzcntl %eax, %eax
addq $VEC_SIZE, %rax incq %rdi
addq %rdi, %rax addq %rdi, %rax
VZEROUPPER_RETURN VZEROUPPER_RETURN
.p2align 4 .p2align 4
L(first_vec_x2): L(first_vec_x2):
tzcntl %eax, %eax tzcntl %eax, %eax
addq $(VEC_SIZE * 2), %rax addq $(VEC_SIZE + 1), %rdi
addq %rdi, %rax addq %rdi, %rax
VZEROUPPER_RETURN VZEROUPPER_RETURN
.p2align 4 .p2align 4
L(4x_vec_end):
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x0)
vpmovmskb %ymm2, %eax
testl %eax, %eax
jnz L(first_vec_x1)
vpmovmskb %ymm3, %eax
testl %eax, %eax
jnz L(first_vec_x2)
vpmovmskb %ymm4, %eax
testl %eax, %eax
L(first_vec_x3): L(first_vec_x3):
tzcntl %eax, %eax tzcntl %eax, %eax
addq $(VEC_SIZE * 3), %rax addq $(VEC_SIZE * 2 + 1), %rdi
addq %rdi, %rax addq %rdi, %rax
VZEROUPPER_RETURN VZEROUPPER_RETURN
.p2align 4
L(first_vec_x4):
tzcntl %eax, %eax
addq $(VEC_SIZE * 3 + 1), %rdi
addq %rdi, %rax
VZEROUPPER_RETURN
.p2align 4
L(aligned_more):
/* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time
since data is only aligned to VEC_SIZE. */
# ifndef USE_AS_RAWMEMCHR
L(cross_page_continue):
/* Align data to VEC_SIZE - 1. */
xorl %ecx, %ecx
subl %edi, %ecx
orq $(VEC_SIZE - 1), %rdi
/* esi is for adjusting length to see if near the end. */
leal (VEC_SIZE * 4 + 1)(%rdi, %rcx), %esi
# else
orq $(VEC_SIZE - 1), %rdi
L(cross_page_continue):
# endif
/* Load first VEC regardless. */
VPCMPEQ 1(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
# ifndef USE_AS_RAWMEMCHR
/* Adjust length. If near end handle specially. */
subq %rsi, %rdx
jbe L(last_4x_vec_or_less)
# endif
testl %eax, %eax
jnz L(first_vec_x1)
VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x2)
VPCMPEQ (VEC_SIZE * 2 + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x3)
VPCMPEQ (VEC_SIZE * 3 + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(first_vec_x4)
# ifndef USE_AS_RAWMEMCHR
/* Check if at last VEC_SIZE * 4 length. */
subq $(VEC_SIZE * 4), %rdx
jbe L(last_4x_vec_or_less_cmpeq)
/* Align data to VEC_SIZE * 4 - 1 for the loop and readjust
length. */
incq %rdi
movl %edi, %ecx
orq $(VEC_SIZE * 4 - 1), %rdi
andl $(VEC_SIZE * 4 - 1), %ecx
addq %rcx, %rdx
# else
/* Align data to VEC_SIZE * 4 - 1 for loop. */
incq %rdi
orq $(VEC_SIZE * 4 - 1), %rdi
# endif
/* Compare 4 * VEC at a time forward. */
.p2align 4
L(loop_4x_vec):
VPCMPEQ 1(%rdi), %ymm0, %ymm1
VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm2
VPCMPEQ (VEC_SIZE * 2 + 1)(%rdi), %ymm0, %ymm3
VPCMPEQ (VEC_SIZE * 3 + 1)(%rdi), %ymm0, %ymm4
vpor %ymm1, %ymm2, %ymm5
vpor %ymm3, %ymm4, %ymm6
vpor %ymm5, %ymm6, %ymm5
vpmovmskb %ymm5, %ecx
# ifdef USE_AS_RAWMEMCHR
subq $-(VEC_SIZE * 4), %rdi
testl %ecx, %ecx
jz L(loop_4x_vec)
# else
testl %ecx, %ecx
jnz L(loop_4x_vec_end)
subq $-(VEC_SIZE * 4), %rdi
subq $(VEC_SIZE * 4), %rdx
ja L(loop_4x_vec)
/* Fall through into less than 4 remaining vectors of length case.
*/
VPCMPEQ (VEC_SIZE * 0 + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
.p2align 4
L(last_4x_vec_or_less):
/* Check if first VEC contained match. */
testl %eax, %eax
jnz L(first_vec_x1_check)
/* If remaining length > VEC_SIZE * 2. */
addl $(VEC_SIZE * 2), %edx
jg L(last_4x_vec)
L(last_2x_vec):
/* If remaining length < VEC_SIZE. */
addl $VEC_SIZE, %edx
jle L(zero_end)
/* Check VEC2 and compare any match with remaining length. */
VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
tzcntl %eax, %eax
cmpl %eax, %edx
jbe L(set_zero_end)
addq $(VEC_SIZE + 1), %rdi
addq %rdi, %rax
L(zero_end):
VZEROUPPER_RETURN
.p2align 4
L(loop_4x_vec_end):
# endif
/* rawmemchr will fall through into this if match was found in
loop. */
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(last_vec_x1_return)
vpmovmskb %ymm2, %eax
testl %eax, %eax
jnz L(last_vec_x2_return)
vpmovmskb %ymm3, %eax
/* Combine VEC3 matches (eax) with VEC4 matches (ecx). */
salq $32, %rcx
orq %rcx, %rax
tzcntq %rax, %rax
# ifdef USE_AS_RAWMEMCHR
subq $(VEC_SIZE * 2 - 1), %rdi
# else
subq $-(VEC_SIZE * 2 + 1), %rdi
# endif
addq %rdi, %rax
VZEROUPPER_RETURN
# ifndef USE_AS_RAWMEMCHR
.p2align 4
L(first_vec_x1_check):
tzcntl %eax, %eax
/* Adjust length. */
subl $-(VEC_SIZE * 4), %edx
/* Check if match within remaining length. */
cmpl %eax, %edx
jbe L(set_zero_end)
incq %rdi
addq %rdi, %rax
VZEROUPPER_RETURN
.p2align 4
L(set_zero_end):
xorl %eax, %eax
VZEROUPPER_RETURN
# endif
.p2align 4
L(last_vec_x1_return):
tzcntl %eax, %eax
# ifdef USE_AS_RAWMEMCHR
subq $(VEC_SIZE * 4 - 1), %rdi
# else
incq %rdi
# endif
addq %rdi, %rax
VZEROUPPER_RETURN
.p2align 4
L(last_vec_x2_return):
tzcntl %eax, %eax
# ifdef USE_AS_RAWMEMCHR
subq $(VEC_SIZE * 3 - 1), %rdi
# else
subq $-(VEC_SIZE + 1), %rdi
# endif
addq %rdi, %rax
VZEROUPPER_RETURN
# ifndef USE_AS_RAWMEMCHR
.p2align 4
L(last_4x_vec_or_less_cmpeq):
VPCMPEQ (VEC_SIZE * 4 + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
subq $-(VEC_SIZE * 4), %rdi
/* Check first VEC regardless. */
testl %eax, %eax
jnz L(first_vec_x1_check)
/* If remaining length <= CHAR_PER_VEC * 2. */
addl $(VEC_SIZE * 2), %edx
jle L(last_2x_vec)
.p2align 4
L(last_4x_vec):
VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
testl %eax, %eax
jnz L(last_vec_x2_return)
VPCMPEQ (VEC_SIZE * 2 + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
/* Create mask for possible matches within remaining length. */
movq $-1, %rcx
bzhiq %rdx, %rcx, %rcx
/* Test matches in data against length match. */
andl %ecx, %eax
jnz L(last_vec_x3)
/* if remaining length <= VEC_SIZE * 3 (Note this is after
remaining length was found to be > VEC_SIZE * 2. */
subl $VEC_SIZE, %edx
jbe L(zero_end2)
VPCMPEQ (VEC_SIZE * 3 + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
/* Shift remaining length mask for last VEC. */
shrq $32, %rcx
andl %ecx, %eax
jz L(zero_end2)
tzcntl %eax, %eax
addq $(VEC_SIZE * 3 + 1), %rdi
addq %rdi, %rax
L(zero_end2):
VZEROUPPER_RETURN
.p2align 4
L(last_vec_x3):
tzcntl %eax, %eax
subq $-(VEC_SIZE * 2 + 1), %rdi
addq %rdi, %rax
VZEROUPPER_RETURN
# endif
END (MEMCHR) END (MEMCHR)
#endif #endif