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[src/trunk]: src/sys/crypto/aes/arch/arm Invert some loops to save a branch i...



details:   https://anonhg.NetBSD.org/src/rev/a16af0080385
branches:  trunk
changeset: 974150:a16af0080385
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Jul 25 22:32:09 2020 +0000

description:
Invert some loops to save a branch instruction on every iteration.

diffstat:

 sys/crypto/aes/arch/arm/aes_armv8_64.S |  118 ++++++++++++++++----------------
 1 files changed, 59 insertions(+), 59 deletions(-)

diffs (206 lines):

diff -r a41c54fcd755 -r a16af0080385 sys/crypto/aes/arch/arm/aes_armv8_64.S
--- a/sys/crypto/aes/arch/arm/aes_armv8_64.S    Sat Jul 25 22:31:32 2020 +0000
+++ b/sys/crypto/aes/arch/arm/aes_armv8_64.S    Sat Jul 25 22:32:09 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: aes_armv8_64.S,v 1.6 2020/07/22 06:15:21 riastradh Exp $       */
+/*     $NetBSD: aes_armv8_64.S,v 1.7 2020/07/25 22:32:09 riastradh Exp $       */
 
 /*-
  * Copyright (c) 2020 The NetBSD Foundation, Inc.
@@ -437,13 +437,13 @@
  */
 ENTRY(aesarmv8_enctodec)
        ldr     q0, [x0, x2, lsl #4]    /* load last round key */
-1:     str     q0, [x1], #0x10 /* store round key */
+       b       2f
+1:     aesimc  v0.16b, v0.16b  /* convert encryption to decryption */
+2:     str     q0, [x1], #0x10 /* store round key */
        subs    x2, x2, #1      /* count down round */
        ldr     q0, [x0, x2, lsl #4]    /* load previous round key */
-       b.eq    2f              /* stop if this is the last one */
-       aesimc  v0.16b, v0.16b  /* convert encryption to decryption */
-       b       1b
-2:     str     q0, [x1]        /* store first round key verbatim */
+       b.ne    1b              /* repeat if there's more */
+       str     q0, [x1]        /* store first round key verbatim */
        ret
 END(aesarmv8_enctodec)
 
@@ -536,17 +536,17 @@
        add     x2, x2, x3              /* x2 := pointer past end of out */
        ldr     q0, [x1, #-0x10]!       /* q0 := last ciphertext block */
        str     q0, [x4]                /* update iv */
-1:     mov     x0, x9                  /* x0 := enckey */
+       b       2f
+1:     ldr     q31, [x1, #-0x10]!      /* q31 := chaining value */
+       eor     v0.16b, v0.16b, v31.16b /* q0 := plaintext block */
+       str     q0, [x2, #-0x10]!       /* store plaintext block */
+       mov     v0.16b, v31.16b         /* move cv = ciphertext block */
+2:     mov     x0, x9                  /* x0 := enckey */
        mov     x3, x5                  /* x3 := nrounds */
        bl      aesarmv8_dec1           /* q0 := cv ^ ptxt; trash x0/x3/q16 */
        subs    x10, x10, #0x10         /* count down nbytes */
-       b.eq    2f                      /* stop if this is the first block */
-       ldr     q31, [x1, #-0x10]!      /* q31 := chaining value */
-       eor     v0.16b, v0.16b, v31.16b /* q0 := plaintext block */
-       str     q0, [x2, #-0x10]!       /* store plaintext block */
-       mov     v0.16b, v31.16b         /* move cv = ciphertext block */
-       b       1b
-2:     eor     v0.16b, v0.16b, v24.16b /* q0 := first plaintext block */
+       b.ne    1b                      /* repeat if more blocks */
+       eor     v0.16b, v0.16b, v24.16b /* q0 := first plaintext block */
        str     q0, [x2, #-0x10]!       /* store first plaintext block */
        ldp     fp, lr, [sp], #16       /* pop stack frame */
        ret
@@ -573,7 +573,11 @@
        add     x2, x2, x3              /* x2 := pointer past end of out */
        ldp     q6, q7, [x1, #-0x20]!   /* q6, q7 := last ciphertext blocks */
        str     q7, [x4]                /* update iv */
-1:     ldp     q4, q5, [x1, #-0x20]!
+       b       2f
+1:     ldp     q6, q7, [x1, #-0x20]!
+       eor     v0.16b, v0.16b, v7.16b  /* q0 := pt0 */
+       stp     q0, q1, [x2, #-0x20]!
+2:     ldp     q4, q5, [x1, #-0x20]!
        ldp     q2, q3, [x1, #-0x20]!
        ldp     q0, q1, [x1, #-0x20]!
        mov     v31.16b, v6.16b         /* q[24+i] := cv[i], 0<i<8 */
@@ -598,12 +602,8 @@
        stp     q6, q7, [x2, #-0x20]!   /* store plaintext blocks */
        stp     q4, q5, [x2, #-0x20]!
        stp     q2, q3, [x2, #-0x20]!
-       b.eq    2f                      /* stop if this is the first block */
-       ldp     q6, q7, [x1, #-0x20]!
-       eor     v0.16b, v0.16b, v7.16b  /* q0 := pt0 */
-       stp     q0, q1, [x2, #-0x20]!
-       b       1b
-2:     eor     v0.16b, v0.16b, v24.16b /* q0 := pt0 */
+       b.ne    1b                      /* repeat if there's more */
+       eor     v0.16b, v0.16b, v24.16b /* q0 := pt0 */
        stp     q0, q1, [x2, #-0x20]!   /* store first two plaintext blocks */
        ldp     fp, lr, [sp], #16       /* pop stack frame */
        ret
@@ -873,15 +873,15 @@
        .type   aesarmv8_enc1,@function
 aesarmv8_enc1:
        ldr     q16, [x0], #0x10        /* load round key */
-1:     subs    x3, x3, #1
+       b       2f
+1:     /* q0 := MixColumns(q0) */
+       aesmc   v0.16b, v0.16b
+2:     subs    x3, x3, #1
        /* q0 := ShiftRows(SubBytes(AddRoundKey_q16(q0))) */
        aese    v0.16b, v16.16b
        ldr     q16, [x0], #0x10                /* load next round key */
-       b.eq    2f
-       /* q0 := MixColumns(q0) */
-       aesmc   v0.16b, v0.16b
-       b       1b
-2:     eor     v0.16b, v0.16b, v16.16b
+       b.ne    1b
+       eor     v0.16b, v0.16b, v16.16b
        ret
 END(aesarmv8_enc1)
 
@@ -899,7 +899,17 @@
        .type   aesarmv8_enc8,@function
 aesarmv8_enc8:
        ldr     q16, [x0], #0x10        /* load round key */
-1:     subs    x3, x3, #1
+       b       2f
+1:     /* q[i] := MixColumns(q[i]) */
+       aesmc   v0.16b, v0.16b
+       aesmc   v1.16b, v1.16b
+       aesmc   v2.16b, v2.16b
+       aesmc   v3.16b, v3.16b
+       aesmc   v4.16b, v4.16b
+       aesmc   v5.16b, v5.16b
+       aesmc   v6.16b, v6.16b
+       aesmc   v7.16b, v7.16b
+2:     subs    x3, x3, #1
        /* q[i] := ShiftRows(SubBytes(AddRoundKey_q16(q[i]))) */
        aese    v0.16b, v16.16b
        aese    v1.16b, v16.16b
@@ -910,18 +920,8 @@
        aese    v6.16b, v16.16b
        aese    v7.16b, v16.16b
        ldr     q16, [x0], #0x10        /* load next round key */
-       b.eq    2f
-       /* q[i] := MixColumns(q[i]) */
-       aesmc   v0.16b, v0.16b
-       aesmc   v1.16b, v1.16b
-       aesmc   v2.16b, v2.16b
-       aesmc   v3.16b, v3.16b
-       aesmc   v4.16b, v4.16b
-       aesmc   v5.16b, v5.16b
-       aesmc   v6.16b, v6.16b
-       aesmc   v7.16b, v7.16b
-       b       1b
-2:     eor     v0.16b, v0.16b, v16.16b /* AddRoundKey */
+       b.ne    1b
+       eor     v0.16b, v0.16b, v16.16b /* AddRoundKey */
        eor     v1.16b, v1.16b, v16.16b
        eor     v2.16b, v2.16b, v16.16b
        eor     v3.16b, v3.16b, v16.16b
@@ -945,15 +945,15 @@
        .type   aesarmv8_dec1,@function
 aesarmv8_dec1:
        ldr     q16, [x0], #0x10        /* load round key */
-1:     subs    x3, x3, #1
+       b       2f
+1:     /* q0 := InMixColumns(q0) */
+       aesimc  v0.16b, v0.16b
+2:     subs    x3, x3, #1
        /* q0 := InSubBytes(InShiftRows(AddRoundKey_q16(q0))) */
        aesd    v0.16b, v16.16b
        ldr     q16, [x0], #0x10        /* load next round key */
-       b.eq    2f
-       /* q0 := InMixColumns(q0) */
-       aesimc  v0.16b, v0.16b
-       b       1b
-2:     eor     v0.16b, v0.16b, v16.16b
+       b.ne    1b
+       eor     v0.16b, v0.16b, v16.16b
        ret
 END(aesarmv8_dec1)
 
@@ -971,7 +971,17 @@
        .type   aesarmv8_dec8,@function
 aesarmv8_dec8:
        ldr     q16, [x0], #0x10        /* load round key */
-1:     subs    x3, x3, #1
+       b       2f
+1:     /* q[i] := InMixColumns(q[i]) */
+       aesimc  v0.16b, v0.16b
+       aesimc  v1.16b, v1.16b
+       aesimc  v2.16b, v2.16b
+       aesimc  v3.16b, v3.16b
+       aesimc  v4.16b, v4.16b
+       aesimc  v5.16b, v5.16b
+       aesimc  v6.16b, v6.16b
+       aesimc  v7.16b, v7.16b
+2:     subs    x3, x3, #1
        /* q[i] := InSubBytes(InShiftRows(AddRoundKey_q16(q[i]))) */
        aesd    v0.16b, v16.16b
        aesd    v1.16b, v16.16b
@@ -982,18 +992,8 @@
        aesd    v6.16b, v16.16b
        aesd    v7.16b, v16.16b
        ldr     q16, [x0], #0x10        /* load next round key */
-       b.eq    2f
-       /* q[i] := InMixColumns(q[i]) */
-       aesimc  v0.16b, v0.16b
-       aesimc  v1.16b, v1.16b
-       aesimc  v2.16b, v2.16b
-       aesimc  v3.16b, v3.16b
-       aesimc  v4.16b, v4.16b
-       aesimc  v5.16b, v5.16b
-       aesimc  v6.16b, v6.16b
-       aesimc  v7.16b, v7.16b
-       b       1b
-2:     eor     v0.16b, v0.16b, v16.16b /* AddRoundKey */
+       b.ne    1b
+       eor     v0.16b, v0.16b, v16.16b /* AddRoundKey */
        eor     v1.16b, v1.16b, v16.16b
        eor     v2.16b, v2.16b, v16.16b
        eor     v3.16b, v3.16b, v16.16b



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