public inbox for glibc-cvs@sourceware.org
help / color / mirror / Atom feed
From: Noah Goldstein <nwg@sourceware.org>
To: glibc-cvs@sourceware.org
Subject: [glibc] x86: Small improvements for wcslen
Date: Mon, 28 Mar 2022 20:55:49 +0000 (GMT) [thread overview]
Message-ID: <20220328205549.42C443857811@sourceware.org> (raw)
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=244b415d386487521882debb845a040a4758cb18
commit 244b415d386487521882debb845a040a4758cb18
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Fri Mar 25 17:13:33 2022 -0500
x86: Small improvements for wcslen
Just a few QOL changes.
1. Prefer `add` > `lea` as it has high execution units it can run
on.
2. Don't break macro-fusion between `test` and `jcc`
3. Reduce code size by removing gratuitous padding bytes (-90
bytes).
geometric_mean(N=20) of all benchmarks New / Original: 0.959
All string/memory tests pass.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diff:
---
sysdeps/x86_64/wcslen.S | 86 +++++++++++++++++++++++--------------------------
1 file changed, 41 insertions(+), 45 deletions(-)
diff --git a/sysdeps/x86_64/wcslen.S b/sysdeps/x86_64/wcslen.S
index c9165dbf03..d641141d75 100644
--- a/sysdeps/x86_64/wcslen.S
+++ b/sysdeps/x86_64/wcslen.S
@@ -40,82 +40,82 @@ ENTRY (__wcslen)
pxor %xmm0, %xmm0
lea 32(%rdi), %rax
- lea 16(%rdi), %rcx
+ addq $16, %rdi
and $-16, %rax
pcmpeqd (%rax), %xmm0
pmovmskb %xmm0, %edx
pxor %xmm1, %xmm1
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm1
pmovmskb %xmm1, %edx
pxor %xmm2, %xmm2
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm2
pmovmskb %xmm2, %edx
pxor %xmm3, %xmm3
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm3
pmovmskb %xmm3, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm0
pmovmskb %xmm0, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm1
pmovmskb %xmm1, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm2
pmovmskb %xmm2, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm3
pmovmskb %xmm3, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm0
pmovmskb %xmm0, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm1
pmovmskb %xmm1, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm2
pmovmskb %xmm2, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
pcmpeqd (%rax), %xmm3
pmovmskb %xmm3, %edx
+ addq $16, %rax
test %edx, %edx
- lea 16(%rax), %rax
jnz L(exit)
and $-0x40, %rax
@@ -132,104 +132,100 @@ L(aligned_64_loop):
pminub %xmm0, %xmm2
pcmpeqd %xmm3, %xmm2
pmovmskb %xmm2, %edx
+ addq $64, %rax
test %edx, %edx
- lea 64(%rax), %rax
jz L(aligned_64_loop)
pcmpeqd -64(%rax), %xmm3
pmovmskb %xmm3, %edx
+ addq $48, %rdi
test %edx, %edx
- lea 48(%rcx), %rcx
jnz L(exit)
pcmpeqd %xmm1, %xmm3
pmovmskb %xmm3, %edx
+ addq $-16, %rdi
test %edx, %edx
- lea -16(%rcx), %rcx
jnz L(exit)
pcmpeqd -32(%rax), %xmm3
pmovmskb %xmm3, %edx
+ addq $-16, %rdi
test %edx, %edx
- lea -16(%rcx), %rcx
jnz L(exit)
pcmpeqd %xmm6, %xmm3
pmovmskb %xmm3, %edx
+ addq $-16, %rdi
test %edx, %edx
- lea -16(%rcx), %rcx
- jnz L(exit)
-
- jmp L(aligned_64_loop)
+ jz L(aligned_64_loop)
.p2align 4
L(exit):
- sub %rcx, %rax
+ sub %rdi, %rax
shr $2, %rax
test %dl, %dl
jz L(exit_high)
- mov %dl, %cl
- and $15, %cl
+ andl $15, %edx
jz L(exit_1)
ret
- .p2align 4
+ /* No align here. Naturally aligned % 16 == 1. */
L(exit_high):
- mov %dh, %ch
- and $15, %ch
+ andl $(15 << 8), %edx
jz L(exit_3)
add $2, %rax
ret
- .p2align 4
+ .p2align 3
L(exit_1):
add $1, %rax
ret
- .p2align 4
+ .p2align 3
L(exit_3):
add $3, %rax
ret
- .p2align 4
+ .p2align 3
L(exit_tail0):
- xor %rax, %rax
+ xorl %eax, %eax
ret
- .p2align 4
+ .p2align 3
L(exit_tail1):
- mov $1, %rax
+ movl $1, %eax
ret
- .p2align 4
+ .p2align 3
L(exit_tail2):
- mov $2, %rax
+ movl $2, %eax
ret
- .p2align 4
+ .p2align 3
L(exit_tail3):
- mov $3, %rax
+ movl $3, %eax
ret
- .p2align 4
+ .p2align 3
L(exit_tail4):
- mov $4, %rax
+ movl $4, %eax
ret
- .p2align 4
+ .p2align 3
L(exit_tail5):
- mov $5, %rax
+ movl $5, %eax
ret
- .p2align 4
+ .p2align 3
L(exit_tail6):
- mov $6, %rax
+ movl $6, %eax
ret
- .p2align 4
+ .p2align 3
L(exit_tail7):
- mov $7, %rax
+ movl $7, %eax
ret
END (__wcslen)
reply other threads:[~2022-03-28 20:55 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220328205549.42C443857811@sourceware.org \
--to=nwg@sourceware.org \
--cc=glibc-cvs@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).