[src/trunk]: src/sys/crypto/aes/arch/x86 Invert some loops to save a jmp inst...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/83bc6608a4f8
branches:  trunk
changeset: 936303:83bc6608a4f8
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Jul 25 22:11:05 2020 +0000

description:
Invert some loops to save a jmp instruction on each iteration.

No semantic change intended.

diffstat:

 sys/crypto/aes/arch/x86/aes_ni_64.S |  86 ++++++++++++++++++------------------
 1 files changed, 43 insertions(+), 43 deletions(-)

diffs (170 lines):

diff -r 8eb84885eab0 -r 83bc6608a4f8 sys/crypto/aes/arch/x86/aes_ni_64.S
--- a/sys/crypto/aes/arch/x86/aes_ni_64.S       Sat Jul 25 22:10:34 2020 +0000
+++ b/sys/crypto/aes/arch/x86/aes_ni_64.S       Sat Jul 25 22:11:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: aes_ni_64.S,v 1.2 2020/06/30 21:41:04 riastradh Exp $  */
+/*     $NetBSD: aes_ni_64.S,v 1.3 2020/07/25 22:11:05 riastradh Exp $  */
 
 /*-
  * Copyright (c) 2020 The NetBSD Foundation, Inc.
@@ -522,14 +522,14 @@
        shl     $4,%edx         /* rdx := byte offset of last round key */
        movdqa  (%rdi,%rdx),%xmm0       /* load last round key */
        movdqa  %xmm0,(%rsi)    /* store last round key verbatim */
-1:     sub     $0x10,%rdx      /* advance to next round key */
-       lea     0x10(%rsi),%rsi
-       jz      2f              /* stop if this is the last one */
-       movdqa  (%rdi,%rdx),%xmm0       /* load round key */
+       jmp     2f
+1:     movdqa  (%rdi,%rdx),%xmm0       /* load round key */
        aesimc  %xmm0,%xmm0     /* convert encryption to decryption */
        movdqa  %xmm0,(%rsi)    /* store round key */
-       jmp     1b
-2:     movdqa  (%rdi),%xmm0    /* load first round key */
+2:     sub     $0x10,%rdx      /* advance to next round key */
+       lea     0x10(%rsi),%rsi
+       jnz     1b              /* repeat if more rounds */
+       movdqa  (%rdi),%xmm0    /* load first round key */
        movdqa  %xmm0,(%rsi)    /* store first round key verbatim */
        ret
 END(aesni_enctodec)
@@ -614,16 +614,16 @@
        mov     %rcx,%r10               /* r10 := nbytes */
        movdqu  -0x10(%rsi,%r10),%xmm0  /* xmm0 := last ciphertext block */
        movdqu  %xmm0,(%r8)             /* update iv */
-1:     mov     %r9d,%ecx               /* ecx := nrounds */
-       call    aesni_dec1              /* xmm0 := cv ^ ptxt */
-       sub     $0x10,%r10
-       jz      2f                      /* first block if r10 is now zero */
-       movdqu  -0x10(%rsi,%r10),%xmm8  /* xmm8 := chaining value */
+       jmp     2f
+1:     movdqu  -0x10(%rsi,%r10),%xmm8  /* xmm8 := chaining value */
        pxor    %xmm8,%xmm0             /* xmm0 := ptxt */
        movdqu  %xmm0,(%rdx,%r10)       /* store plaintext block */
        movdqa  %xmm8,%xmm0             /* move cv = ciphertext block */
-       jmp     1b
-2:     pxor    (%rsp),%xmm0            /* xmm0 := ptxt */
+2:     mov     %r9d,%ecx               /* ecx := nrounds */
+       call    aesni_dec1              /* xmm0 := cv ^ ptxt */
+       sub     $0x10,%r10
+       jnz     1b                      /* repeat if more blocks */
+       pxor    (%rsp),%xmm0            /* xmm0 := ptxt */
        movdqu  %xmm0,(%rdx)            /* store first plaintext block */
        leave
        ret
@@ -649,7 +649,11 @@
        mov     %rcx,%r10               /* r10 := nbytes */
        movdqu  -0x10(%rsi,%r10),%xmm7  /* xmm7 := ciphertext block[n-1] */
        movdqu  %xmm7,(%r8)             /* update iv */
-1:     movdqu  -0x20(%rsi,%r10),%xmm6  /* xmm6 := ciphertext block[n-2] */
+       jmp     2f
+1:     movdqu  -0x10(%rsi,%r10),%xmm7  /* xmm7 := cv[0] */
+       pxor    %xmm7,%xmm0             /* xmm0 := ptxt[0] */
+       movdqu  %xmm0,(%rdx,%r10)       /* store plaintext block */
+2:     movdqu  -0x20(%rsi,%r10),%xmm6  /* xmm6 := ciphertext block[n-2] */
        movdqu  -0x30(%rsi,%r10),%xmm5  /* xmm5 := ciphertext block[n-3] */
        movdqu  -0x40(%rsi,%r10),%xmm4  /* xmm4 := ciphertext block[n-4] */
        movdqu  -0x50(%rsi,%r10),%xmm3  /* xmm3 := ciphertext block[n-5] */
@@ -680,12 +684,8 @@
        movdqu  %xmm2,-0x60(%rdx,%r10)
        movdqu  %xmm1,-0x70(%rdx,%r10)
        sub     $0x80,%r10
-       jz      2f                      /* first block if r10 is now zero */
-       movdqu  -0x10(%rsi,%r10),%xmm7  /* xmm7 := cv[0] */
-       pxor    %xmm7,%xmm0             /* xmm0 := ptxt[0] */
-       movdqu  %xmm0,(%rdx,%r10)       /* store plaintext block */
-       jmp     1b
-2:     pxor    (%rsp),%xmm0            /* xmm0 := ptxt[0] */
+       jnz     1b                      /* repeat if more blocks */
+       pxor    (%rsp),%xmm0            /* xmm0 := ptxt[0] */
        movdqu  %xmm0,(%rdx)            /* store first plaintext block */
        leave
        ret
@@ -966,12 +966,12 @@
        shl     $4,%ecx         /* ecx := total byte size of round keys */
        lea     0x10(%rdi,%rcx),%rax    /* rax := end of round key array */
        neg     %rcx            /* rcx := byte offset of round key from end */
-1:     movdqa  (%rax,%rcx),%xmm8       /* load round key */
+       jmp     2f
+1:     aesenc  %xmm8,%xmm0
+2:     movdqa  (%rax,%rcx),%xmm8       /* load round key */
        add     $0x10,%rcx
-       jz      2f              /* stop if this is the last one */
-       aesenc  %xmm8,%xmm0
-       jmp     1b
-2:     aesenclast %xmm8,%xmm0
+       jnz     1b              /* repeat if more rounds */
+       aesenclast %xmm8,%xmm0
        ret
 END(aesni_enc1)
 
@@ -999,10 +999,8 @@
        shl     $4,%ecx         /* ecx := total byte size of round keys */
        lea     0x10(%rdi,%rcx),%rax    /* rax := end of round key array */
        neg     %rcx            /* rcx := byte offset of round key from end */
-1:     movdqa  (%rax,%rcx),%xmm8       /* load round key */
-       add     $0x10,%rcx
-       jz      2f              /* stop if this is the last one */
-       aesenc  %xmm8,%xmm0
+       jmp     2f
+1:     aesenc  %xmm8,%xmm0
        aesenc  %xmm8,%xmm1
        aesenc  %xmm8,%xmm2
        aesenc  %xmm8,%xmm3
@@ -1010,8 +1008,10 @@
        aesenc  %xmm8,%xmm5
        aesenc  %xmm8,%xmm6
        aesenc  %xmm8,%xmm7
-       jmp     1b
-2:     aesenclast %xmm8,%xmm0
+2:     movdqa  (%rax,%rcx),%xmm8       /* load round key */
+       add     $0x10,%rcx
+       jnz     1b              /* repeat if more rounds */
+       aesenclast %xmm8,%xmm0
        aesenclast %xmm8,%xmm1
        aesenclast %xmm8,%xmm2
        aesenclast %xmm8,%xmm3
@@ -1038,12 +1038,12 @@
        shl     $4,%ecx         /* ecx := byte offset of round key */
        lea     0x10(%rdi,%rcx),%rax    /* rax := pointer to round key */
        neg     %rcx            /* rcx := byte offset of round key from end */
-1:     movdqa  (%rax,%rcx),%xmm8       /* load round key */
+       jmp     2f
+1:     aesdec  %xmm8,%xmm0
+2:     movdqa  (%rax,%rcx),%xmm8       /* load round key */
        add     $0x10,%rcx
-       jz      2f              /* stop if this is the last one */
-       aesdec  %xmm8,%xmm0
-       jmp     1b
-2:     aesdeclast %xmm8,%xmm0
+       jnz     1b              /* repeat if more rounds */
+       aesdeclast %xmm8,%xmm0
        ret
 END(aesni_dec1)
 
@@ -1071,10 +1071,8 @@
        shl     $4,%ecx         /* ecx := byte offset of round key */
        lea     0x10(%rdi,%rcx),%rax    /* rax := pointer to round key */
        neg     %rcx            /* rcx := byte offset of round key from end */
-1:     movdqa  (%rax,%rcx),%xmm8       /* load round key */
-       add     $0x10,%rcx
-       jz      2f              /* stop if this is the last one */
-       aesdec  %xmm8,%xmm0
+       jmp     2f
+1:     aesdec  %xmm8,%xmm0
        aesdec  %xmm8,%xmm1
        aesdec  %xmm8,%xmm2
        aesdec  %xmm8,%xmm3
@@ -1082,8 +1080,10 @@
        aesdec  %xmm8,%xmm5
        aesdec  %xmm8,%xmm6
        aesdec  %xmm8,%xmm7
-       jmp     1b
-2:     aesdeclast %xmm8,%xmm0
+2:     movdqa  (%rax,%rcx),%xmm8       /* load round key */
+       add     $0x10,%rcx
+       jnz     1b              /* repeat if more rounds */
+       aesdeclast %xmm8,%xmm0
        aesdeclast %xmm8,%xmm1
        aesdeclast %xmm8,%xmm2
        aesdeclast %xmm8,%xmm3