Terribly suboptimal code generated for Linux kernel arch/powerpc/lib/xor_vmx.c

[chleroy]

Generated code with GCC, seems properly optimised, doesn't use stack.
With CLANG huge amount of stack use.

Dumping only __xor_altivec_2() but same problem with the 4 functions.

GCC 12.2:

arch/powerpc/lib/xor_vmx.o:     file format elf32-powerpc


Disassembly of section .text:

00000000 <__xor_altivec_2>:
   0:    54 69 d1 be     rlwinm  r9,r3,26,6,31
   4:    38 e4 00 10     addi    r7,r4,16
   8:    7d 29 03 a6     mtctr   r9
   c:    39 04 00 20     addi    r8,r4,32
  10:    39 44 00 30     addi    r10,r4,48
  14:    39 65 00 10     addi    r11,r5,16
  18:    38 65 00 20     addi    r3,r5,32
  1c:    38 c5 00 30     addi    r6,r5,48
  20:    39 20 00 00     li      r9,0
  24:    7c 24 48 ce     lvx     v1,r4,r9
  28:    7d a7 48 ce     lvx     v13,r7,r9
  2c:    7c 05 48 ce     lvx     v0,r5,r9
  30:    11 80 0c c4     vxor    v12,v0,v1
  34:    7c 28 48 ce     lvx     v1,r8,r9
  38:    7c 0a 48 ce     lvx     v0,r10,r9
  3c:    7d 84 49 ce     stvx    v12,r4,r9
  40:    7d 8b 48 ce     lvx     v12,r11,r9
  44:    11 ad 64 c4     vxor    v13,v13,v12
  48:    7d a7 49 ce     stvx    v13,r7,r9
  4c:    7d a3 48 ce     lvx     v13,r3,r9
  50:    10 21 6c c4     vxor    v1,v1,v13
  54:    7c 28 49 ce     stvx    v1,r8,r9
  58:    7c 26 48 ce     lvx     v1,r6,r9
  5c:    10 00 0c c4     vxor    v0,v0,v1
  60:    7c 0a 49 ce     stvx    v0,r10,r9
  64:    39 29 00 40     addi    r9,r9,64
  68:    42 00 ff bc     bdnz    24 <__xor_altivec_2+0x24>
  6c:    4e 80 00 20     blr

CLANG 14:

arch/powerpc/lib/xor_vmx.o:     file format elf32-powerpc


Disassembly of section .text:

00000000 <__xor_altivec_2>:
       0:    94 21 ff 70     stwu    r1,-144(r1)
       4:    91 c1 00 48     stw     r14,72(r1)
       8:    54 66 d1 be     rlwinm  r6,r3,26,6,31
       c:    91 e1 00 4c     stw     r15,76(r1)
      10:    38 64 ff c0     addi    r3,r4,-64
      14:    92 01 00 50     stw     r16,80(r1)
      18:    38 85 ff c0     addi    r4,r5,-64
      1c:    92 21 00 54     stw     r17,84(r1)
      20:    92 41 00 58     stw     r18,88(r1)
      24:    92 61 00 5c     stw     r19,92(r1)
      28:    92 81 00 60     stw     r20,96(r1)
      2c:    92 a1 00 64     stw     r21,100(r1)
      30:    92 c1 00 68     stw     r22,104(r1)
      34:    92 e1 00 6c     stw     r23,108(r1)
      38:    93 01 00 70     stw     r24,112(r1)
      3c:    93 21 00 74     stw     r25,116(r1)
      40:    93 41 00 78     stw     r26,120(r1)
      44:    93 61 00 7c     stw     r27,124(r1)
      48:    93 81 00 80     stw     r28,128(r1)
      4c:    93 a1 00 84     stw     r29,132(r1)
      50:    93 c1 00 88     stw     r30,136(r1)
      54:    93 e1 00 8c     stw     r31,140(r1)
      58:    7c c9 03 a6     mtctr   r6
      5c:    8c e3 00 40     lbzu    r7,64(r3)
      60:    8c c4 00 40     lbzu    r6,64(r4)
      64:    88 a3 00 15     lbz     r5,21(r3)
      68:    89 03 00 0f     lbz     r8,15(r3)
      6c:    7c c6 3a 78     xor     r6,r6,r7
      70:    90 a1 00 38     stw     r5,56(r1)
      74:    88 a3 00 14     lbz     r5,20(r3)
      78:    8b e3 00 0e     lbz     r31,14(r3)
      7c:    90 a1 00 3c     stw     r5,60(r1)
      80:    88 a3 00 13     lbz     r5,19(r3)
      84:    89 c3 00 0d     lbz     r14,13(r3)
      88:    90 a1 00 40     stw     r5,64(r1)
      8c:    88 a3 00 12     lbz     r5,18(r3)
      90:    88 e4 00 0e     lbz     r7,14(r4)
      94:    90 a1 00 44     stw     r5,68(r1)
      98:    88 a4 00 0f     lbz     r5,15(r4)
      9c:    7c e7 fa 78     xor     r7,r7,r31
      a0:    89 e3 00 0b     lbz     r15,11(r3)
      a4:    7c a5 42 78     xor     r5,r5,r8
      a8:    89 04 00 0d     lbz     r8,13(r4)
      ac:    8a 03 00 0a     lbz     r16,10(r3)
      b0:    98 a3 00 0f     stb     r5,15(r3)
      b4:    7d 08 72 78     xor     r8,r8,r14
      b8:    88 a3 00 10     lbz     r5,16(r3)
      bc:    8b e4 00 0b     lbz     r31,11(r4)
      c0:    89 c4 00 0a     lbz     r14,10(r4)
      c4:    8a 23 00 09     lbz     r17,9(r3)
      c8:    7f ef 7a 78     xor     r15,r31,r15
      cc:    8a 43 00 08     lbz     r18,8(r3)
      d0:    7d d0 82 78     xor     r16,r14,r16
      d4:    90 a1 00 30     stw     r5,48(r1)
      d8:    88 a3 00 1c     lbz     r5,28(r3)
      dc:    8b e4 00 09     lbz     r31,9(r4)
      e0:    89 c4 00 08     lbz     r14,8(r4)
      e4:    8a 63 00 07     lbz     r19,7(r3)
      e8:    7f f1 8a 78     xor     r17,r31,r17
      ec:    8a 83 00 06     lbz     r20,6(r3)
      f0:    7d d2 92 78     xor     r18,r14,r18
      f4:    90 a1 00 2c     stw     r5,44(r1)
      f8:    88 a3 00 2e     lbz     r5,46(r3)
      fc:    8b e4 00 07     lbz     r31,7(r4)
     100:    89 c4 00 06     lbz     r14,6(r4)
     104:    8a a3 00 05     lbz     r21,5(r3)
     108:    7f f3 9a 78     xor     r19,r31,r19
     10c:    8a c3 00 04     lbz     r22,4(r3)
     110:    7d d4 a2 78     xor     r20,r14,r20
     114:    90 a1 00 28     stw     r5,40(r1)
     118:    88 a3 00 2d     lbz     r5,45(r3)
     11c:    8b e4 00 05     lbz     r31,5(r4)
     120:    89 c4 00 04     lbz     r14,4(r4)
     124:    8a e3 00 03     lbz     r23,3(r3)
     128:    7f f5 aa 78     xor     r21,r31,r21
     12c:    8b 03 00 02     lbz     r24,2(r3)
     130:    7d d6 b2 78     xor     r22,r14,r22
     134:    90 a1 00 24     stw     r5,36(r1)
     138:    88 a3 00 2b     lbz     r5,43(r3)
     13c:    8b e4 00 03     lbz     r31,3(r4)
     140:    89 c4 00 02     lbz     r14,2(r4)
     144:    8b 23 00 01     lbz     r25,1(r3)
     148:    7f f7 ba 78     xor     r23,r31,r23
     14c:    8b 43 00 0c     lbz     r26,12(r3)
     150:    7d d8 c2 78     xor     r24,r14,r24
     154:    90 a1 00 20     stw     r5,32(r1)
     158:    88 a3 00 2a     lbz     r5,42(r3)
     15c:    8b e4 00 01     lbz     r31,1(r4)
     160:    89 c4 00 0c     lbz     r14,12(r4)
     164:    8b 63 00 1f     lbz     r27,31(r3)
     168:    7f f9 ca 78     xor     r25,r31,r25
     16c:    8b 83 00 1e     lbz     r28,30(r3)
     170:    7d da d2 78     xor     r26,r14,r26
     174:    90 a1 00 1c     stw     r5,28(r1)
     178:    88 a3 00 29     lbz     r5,41(r3)
     17c:    8b e4 00 1f     lbz     r31,31(r4)
     180:    89 c4 00 1e     lbz     r14,30(r4)
     184:    8b a3 00 1d     lbz     r29,29(r3)
     188:    7f fb da 78     xor     r27,r31,r27
     18c:    8b c3 00 1b     lbz     r30,27(r3)
     190:    7d dc e2 78     xor     r28,r14,r28
     194:    90 a1 00 18     stw     r5,24(r1)
     198:    88 a3 00 28     lbz     r5,40(r3)
     19c:    8b e4 00 1d     lbz     r31,29(r4)
     1a0:    89 c4 00 1b     lbz     r14,27(r4)
     1a4:    88 03 00 1a     lbz     r0,26(r3)
     1a8:    7f fd ea 78     xor     r29,r31,r29
     1ac:    89 83 00 19     lbz     r12,25(r3)
     1b0:    7d de f2 78     xor     r30,r14,r30
     1b4:    90 a1 00 14     stw     r5,20(r1)
     1b8:    88 a3 00 27     lbz     r5,39(r3)
     1bc:    8b e4 00 1a     lbz     r31,26(r4)
     1c0:    89 c4 00 19     lbz     r14,25(r4)
     1c4:    89 63 00 18     lbz     r11,24(r3)
     1c8:    7f e0 02 78     xor     r0,r31,r0
     1cc:    89 43 00 17     lbz     r10,23(r3)
     1d0:    7d cc 62 78     xor     r12,r14,r12
     1d4:    90 a1 00 10     stw     r5,16(r1)
     1d8:    88 a3 00 26     lbz     r5,38(r3)
     1dc:    8b e4 00 18     lbz     r31,24(r4)
     1e0:    89 c4 00 17     lbz     r14,23(r4)
     1e4:    89 23 00 16     lbz     r9,22(r3)
     1e8:    7f eb 5a 78     xor     r11,r31,r11
     1ec:    98 c3 00 00     stb     r6,0(r3)
     1f0:    7d ca 52 78     xor     r10,r14,r10
     1f4:    88 c3 00 11     lbz     r6,17(r3)
     1f8:    90 a1 00 0c     stw     r5,12(r1)
     1fc:    8b e4 00 16     lbz     r31,22(r4)
     200:    89 c4 00 15     lbz     r14,21(r4)
     204:    80 a1 00 38     lwz     r5,56(r1)
     208:    7f e9 4a 78     xor     r9,r31,r9
     20c:    90 c1 00 34     stw     r6,52(r1)
     210:    98 e3 00 0e     stb     r7,14(r3)
     214:    7d ce 2a 78     xor     r14,r14,r5
     218:    8b e4 00 14     lbz     r31,20(r4)
     21c:    88 a4 00 13     lbz     r5,19(r4)
     220:    80 c1 00 3c     lwz     r6,60(r1)
     224:    80 e1 00 40     lwz     r7,64(r1)
     228:    7f ff 32 78     xor     r31,r31,r6
     22c:    88 c4 00 12     lbz     r6,18(r4)
     230:    7c a5 3a 78     xor     r5,r5,r7
     234:    80 e1 00 44     lwz     r7,68(r1)
     238:    98 a3 00 13     stb     r5,19(r3)
     23c:    88 a4 00 11     lbz     r5,17(r4)
     240:    7c c6 3a 78     xor     r6,r6,r7
     244:    80 e1 00 34     lwz     r7,52(r1)
     248:    98 c3 00 12     stb     r6,18(r3)
     24c:    88 c4 00 10     lbz     r6,16(r4)
     250:    7c a5 3a 78     xor     r5,r5,r7
     254:    80 e1 00 30     lwz     r7,48(r1)
     258:    98 a3 00 11     stb     r5,17(r3)
     25c:    88 a4 00 1c     lbz     r5,28(r4)
     260:    7c c6 3a 78     xor     r6,r6,r7
     264:    80 e1 00 2c     lwz     r7,44(r1)
     268:    99 03 00 0d     stb     r8,13(r3)
     26c:    89 03 00 2f     lbz     r8,47(r3)
     270:    7c a5 3a 78     xor     r5,r5,r7
     274:    98 c3 00 10     stb     r6,16(r3)
     278:    88 c4 00 2f     lbz     r6,47(r4)
     27c:    98 a3 00 1c     stb     r5,28(r3)
     280:    88 a4 00 2e     lbz     r5,46(r4)
     284:    7c c6 42 78     xor     r6,r6,r8
     288:    80 e1 00 28     lwz     r7,40(r1)
     28c:    98 c3 00 2f     stb     r6,47(r3)
     290:    88 c4 00 2d     lbz     r6,45(r4)
     294:    7c a5 3a 78     xor     r5,r5,r7
     298:    80 e1 00 24     lwz     r7,36(r1)
     29c:    98 a3 00 2e     stb     r5,46(r3)
     2a0:    88 a4 00 2b     lbz     r5,43(r4)
     2a4:    7c c6 3a 78     xor     r6,r6,r7
     2a8:    80 e1 00 20     lwz     r7,32(r1)
     2ac:    99 e3 00 0b     stb     r15,11(r3)
     2b0:    98 c3 00 2d     stb     r6,45(r3)
     2b4:    7c a5 3a 78     xor     r5,r5,r7
     2b8:    88 c4 00 2a     lbz     r6,42(r4)
     2bc:    81 e1 00 1c     lwz     r15,28(r1)
     2c0:    98 a3 00 2b     stb     r5,43(r3)
     2c4:    88 a4 00 29     lbz     r5,41(r4)
     2c8:    7c c6 7a 78     xor     r6,r6,r15
     2cc:    81 e1 00 18     lwz     r15,24(r1)
     2d0:    88 e4 00 28     lbz     r7,40(r4)
     2d4:    7c a5 7a 78     xor     r5,r5,r15
     2d8:    81 e1 00 14     lwz     r15,20(r1)
     2dc:    98 c3 00 2a     stb     r6,42(r3)
     2e0:    88 c4 00 27     lbz     r6,39(r4)
     2e4:    7c e7 7a 78     xor     r7,r7,r15
     2e8:    81 e1 00 10     lwz     r15,16(r1)
     2ec:    98 a3 00 29     stb     r5,41(r3)
     2f0:    88 a4 00 26     lbz     r5,38(r4)
     2f4:    7c c6 7a 78     xor     r6,r6,r15
     2f8:    81 e1 00 0c     lwz     r15,12(r1)
     2fc:    9a 03 00 0a     stb     r16,10(r3)
     300:    8a 03 00 25     lbz     r16,37(r3)
     304:    7c a5 7a 78     xor     r5,r5,r15
     308:    98 e3 00 28     stb     r7,40(r3)
     30c:    88 e4 00 25     lbz     r7,37(r4)
     310:    9a 23 00 09     stb     r17,9(r3)
     314:    8a 23 00 24     lbz     r17,36(r3)
     318:    7c e7 82 78     xor     r7,r7,r16
     31c:    98 c3 00 27     stb     r6,39(r3)
     320:    88 c4 00 24     lbz     r6,36(r4)
     324:    9a 43 00 08     stb     r18,8(r3)
     328:    8a 43 00 23     lbz     r18,35(r3)
     32c:    7c c6 8a 78     xor     r6,r6,r17
     330:    98 a3 00 26     stb     r5,38(r3)
     334:    88 a4 00 23     lbz     r5,35(r4)
     338:    9a 63 00 07     stb     r19,7(r3)
     33c:    8a 63 00 22     lbz     r19,34(r3)
     340:    7c a5 92 78     xor     r5,r5,r18
     344:    98 e3 00 25     stb     r7,37(r3)
     348:    88 e4 00 22     lbz     r7,34(r4)
     34c:    9a 83 00 06     stb     r20,6(r3)
     350:    8a 83 00 21     lbz     r20,33(r3)
     354:    7c e7 9a 78     xor     r7,r7,r19
     358:    98 c3 00 24     stb     r6,36(r3)
     35c:    88 c4 00 21     lbz     r6,33(r4)
     360:    9a a3 00 05     stb     r21,5(r3)
     364:    8a a3 00 20     lbz     r21,32(r3)
     368:    7c c6 a2 78     xor     r6,r6,r20
     36c:    98 a3 00 23     stb     r5,35(r3)
     370:    88 a4 00 20     lbz     r5,32(r4)
     374:    9a c3 00 04     stb     r22,4(r3)
     378:    8a c3 00 2c     lbz     r22,44(r3)
     37c:    7c a5 aa 78     xor     r5,r5,r21
     380:    98 e3 00 22     stb     r7,34(r3)
     384:    88 e4 00 2c     lbz     r7,44(r4)
     388:    9a e3 00 03     stb     r23,3(r3)
     38c:    8a e3 00 3f     lbz     r23,63(r3)
     390:    7c e7 b2 78     xor     r7,r7,r22
     394:    98 c3 00 21     stb     r6,33(r3)
     398:    88 c4 00 3f     lbz     r6,63(r4)
     39c:    9b 03 00 02     stb     r24,2(r3)
     3a0:    8b 03 00 3e     lbz     r24,62(r3)
     3a4:    7c c6 ba 78     xor     r6,r6,r23
     3a8:    98 a3 00 20     stb     r5,32(r3)
     3ac:    88 a4 00 3e     lbz     r5,62(r4)
     3b0:    9b 23 00 01     stb     r25,1(r3)
     3b4:    8b 23 00 3d     lbz     r25,61(r3)
     3b8:    7c a5 c2 78     xor     r5,r5,r24
     3bc:    98 e3 00 2c     stb     r7,44(r3)
     3c0:    88 e4 00 3d     lbz     r7,61(r4)
     3c4:    9b 43 00 0c     stb     r26,12(r3)
     3c8:    8b 43 00 3b     lbz     r26,59(r3)
     3cc:    7c e7 ca 78     xor     r7,r7,r25
     3d0:    98 c3 00 3f     stb     r6,63(r3)
     3d4:    88 c4 00 3b     lbz     r6,59(r4)
     3d8:    9b 63 00 1f     stb     r27,31(r3)
     3dc:    8b 63 00 3a     lbz     r27,58(r3)
     3e0:    7c c6 d2 78     xor     r6,r6,r26
     3e4:    98 a3 00 3e     stb     r5,62(r3)
     3e8:    88 a4 00 3a     lbz     r5,58(r4)
     3ec:    9b 83 00 1e     stb     r28,30(r3)
     3f0:    8b 83 00 39     lbz     r28,57(r3)
     3f4:    7c a5 da 78     xor     r5,r5,r27
     3f8:    98 e3 00 3d     stb     r7,61(r3)
     3fc:    88 e4 00 39     lbz     r7,57(r4)
     400:    99 c3 00 15     stb     r14,21(r3)
     404:    89 c3 00 38     lbz     r14,56(r3)
     408:    7c e7 e2 78     xor     r7,r7,r28
     40c:    98 c3 00 3b     stb     r6,59(r3)
     410:    88 c4 00 38     lbz     r6,56(r4)
     414:    9b e3 00 14     stb     r31,20(r3)
     418:    8b e3 00 37     lbz     r31,55(r3)
     41c:    7c c6 72 78     xor     r6,r6,r14
     420:    98 a3 00 3a     stb     r5,58(r3)
     424:    88 a4 00 37     lbz     r5,55(r4)
     428:    9b a3 00 1d     stb     r29,29(r3)
     42c:    8b a3 00 36     lbz     r29,54(r3)
     430:    7c a5 fa 78     xor     r5,r5,r31
     434:    98 e3 00 39     stb     r7,57(r3)
     438:    88 e4 00 36     lbz     r7,54(r4)
     43c:    9b c3 00 1b     stb     r30,27(r3)
     440:    8b c3 00 35     lbz     r30,53(r3)
     444:    7c e7 ea 78     xor     r7,r7,r29
     448:    98 c3 00 38     stb     r6,56(r3)
     44c:    88 c4 00 35     lbz     r6,53(r4)
     450:    98 03 00 1a     stb     r0,26(r3)
     454:    88 03 00 34     lbz     r0,52(r3)
     458:    7c c6 f2 78     xor     r6,r6,r30
     45c:    98 a3 00 37     stb     r5,55(r3)
     460:    88 a4 00 34     lbz     r5,52(r4)
     464:    99 83 00 19     stb     r12,25(r3)
     468:    89 83 00 33     lbz     r12,51(r3)
     46c:    7c a5 02 78     xor     r5,r5,r0
     470:    98 e3 00 36     stb     r7,54(r3)
     474:    88 e4 00 33     lbz     r7,51(r4)
     478:    99 63 00 18     stb     r11,24(r3)
     47c:    89 63 00 32     lbz     r11,50(r3)
     480:    7c e7 62 78     xor     r7,r7,r12
     484:    98 c3 00 35     stb     r6,53(r3)
     488:    88 c4 00 32     lbz     r6,50(r4)
     48c:    99 43 00 17     stb     r10,23(r3)
     490:    89 43 00 31     lbz     r10,49(r3)
     494:    7c c6 5a 78     xor     r6,r6,r11
     498:    98 a3 00 34     stb     r5,52(r3)
     49c:    88 a4 00 31     lbz     r5,49(r4)
     4a0:    99 23 00 16     stb     r9,22(r3)
     4a4:    89 23 00 30     lbz     r9,48(r3)
     4a8:    7c a5 52 78     xor     r5,r5,r10
     4ac:    98 e3 00 33     stb     r7,51(r3)
     4b0:    88 e4 00 30     lbz     r7,48(r4)
     4b4:    89 03 00 3c     lbz     r8,60(r3)
     4b8:    98 c3 00 32     stb     r6,50(r3)
     4bc:    88 c4 00 3c     lbz     r6,60(r4)
     4c0:    98 a3 00 31     stb     r5,49(r3)
     4c4:    7c e5 4a 78     xor     r5,r7,r9
     4c8:    98 a3 00 30     stb     r5,48(r3)
     4cc:    7c c5 42 78     xor     r5,r6,r8
     4d0:    98 a3 00 3c     stb     r5,60(r3)
     4d4:    42 00 fb 88     bdnz    5c <__xor_altivec_2+0x5c>
     4d8:    83 e1 00 8c     lwz     r31,140(r1)
     4dc:    83 c1 00 88     lwz     r30,136(r1)
     4e0:    83 a1 00 84     lwz     r29,132(r1)
     4e4:    83 81 00 80     lwz     r28,128(r1)
     4e8:    83 61 00 7c     lwz     r27,124(r1)
     4ec:    83 41 00 78     lwz     r26,120(r1)
     4f0:    83 21 00 74     lwz     r25,116(r1)
     4f4:    83 01 00 70     lwz     r24,112(r1)
     4f8:    82 e1 00 6c     lwz     r23,108(r1)
     4fc:    82 c1 00 68     lwz     r22,104(r1)
     500:    82 a1 00 64     lwz     r21,100(r1)
     504:    82 81 00 60     lwz     r20,96(r1)
     508:    82 61 00 5c     lwz     r19,92(r1)
     50c:    82 41 00 58     lwz     r18,88(r1)
     510:    82 21 00 54     lwz     r17,84(r1)
     514:    82 01 00 50     lwz     r16,80(r1)
     518:    81 e1 00 4c     lwz     r15,76(r1)
     51c:    81 c1 00 48     lwz     r14,72(r1)
     520:    38 21 00 90     addi    r1,r1,144
     524:    4e 80 00 20     blr

[nickdesaulniers]

Thanks for the report. I'm immediately reminded of:

• commit 297565a ("lib/xor: make xor prototypes more friendly to compiler vectorization")
• commit a69cb44 ("crypto: arm/xor - make vectorized C code Clang-friendly")
• arch/arm/lib/xor-neon.c -Wwarning #496
• Clang may not be vectorizing xor_8regs_* in arch/arm/lib/xor-neon.c  #503
• ppc32/CONFIG_ALTIVEC=y: frame-larger-than in arch/powerpc/lib/xor_vmx.c #563

[nathanchance]

Is this with KASAN?

https://lore.kernel.org/7cb1285a-42e6-2b67-664f-7d206bc9fd80@csgroup.eu/

[chleroy]

No, that's without KASAN, you can see in the generated code that there is no call to kasan functions.

[ernsteiswuerfel]

Same on ppc64 (PowerMac G5 build).

GCC 12.2.1_p20221126:

gcc12_xor_vmx.o:     file format elf64-powerpc


Disassembly of section .text:

0000000000000000 <__xor_altivec_2>:
   0:   78 6a d1 82     srdi    r10,r3,6
   4:   39 20 00 00     li      r9,0
   8:   38 e4 00 10     addi    r7,r4,16
   c:   39 04 00 20     addi    r8,r4,32
  10:   7d 49 03 a6     mtctr   r10
  14:   39 65 00 10     addi    r11,r5,16
  18:   39 44 00 30     addi    r10,r4,48
  1c:   38 65 00 20     addi    r3,r5,32
  20:   38 c5 00 30     addi    r6,r5,48
  24:   60 00 00 00     nop
  28:   60 00 00 00     nop
  2c:   60 42 00 00     ori     r2,r2,0
  30:   7d 04 48 ce     lvx     v8,r4,r9
  34:   7d a7 48 ce     lvx     v13,r7,r9
  38:   7c 28 48 ce     lvx     v1,r8,r9
  3c:   7c 0a 48 ce     lvx     v0,r10,r9
  40:   7d 85 48 ce     lvx     v12,r5,r9
  44:   7d 2b 48 ce     lvx     v9,r11,r9
  48:   7d 43 48 ce     lvx     v10,r3,r9
  4c:   7d 66 48 ce     lvx     v11,r6,r9
  50:   11 8c 44 c4     vxor    v12,v12,v8
  54:   11 ad 4c c4     vxor    v13,v13,v9
  58:   10 21 54 c4     vxor    v1,v1,v10
  5c:   10 00 5c c4     vxor    v0,v0,v11
  60:   7d 84 49 ce     stvx    v12,r4,r9
  64:   7d a7 49 ce     stvx    v13,r7,r9
  68:   7c 28 49 ce     stvx    v1,r8,r9
  6c:   7c 0a 49 ce     stvx    v0,r10,r9
  70:   39 29 00 40     addi    r9,r9,64
  74:   42 00 ff bc     bdnz    30 <__xor_altivec_2+0x30>
  78:   4e 80 00 20     blr
  7c:   60 42 00 00     ori     r2,r2,0

CLANG 15.0.6:

clang15_xor_vmx.o:     file format elf64-powerpc


Disassembly of section .text:

0000000000000000 <__xor_altivec_2>:
       0:       3c 4c 00 00     addis   r2,r12,0
       4:       38 42 00 00     addi    r2,r2,0
       8:       f9 c1 ff 70     std     r14,-144(r1)
       c:       78 66 d1 82     srdi    r6,r3,6
      10:       38 64 ff c0     addi    r3,r4,-64
      14:       38 85 ff c0     addi    r4,r5,-64
      18:       f9 e1 ff 78     std     r15,-136(r1)
      1c:       fa 01 ff 80     std     r16,-128(r1)
      20:       fa 21 ff 88     std     r17,-120(r1)
      24:       fa 41 ff 90     std     r18,-112(r1)
      28:       fa 61 ff 98     std     r19,-104(r1)
      2c:       fa 81 ff a0     std     r20,-96(r1)
      30:       fa a1 ff a8     std     r21,-88(r1)
      34:       fa c1 ff b0     std     r22,-80(r1)
      38:       fa e1 ff b8     std     r23,-72(r1)
      3c:       fb 01 ff c0     std     r24,-64(r1)
      40:       fb 21 ff c8     std     r25,-56(r1)
      44:       fb 41 ff d0     std     r26,-48(r1)
      48:       fb 61 ff d8     std     r27,-40(r1)
      4c:       fb 81 ff e0     std     r28,-32(r1)
      50:       fb a1 ff e8     std     r29,-24(r1)
      54:       fb c1 ff f0     std     r30,-16(r1)
      58:       fb e1 ff f8     std     r31,-8(r1)
      5c:       f8 41 ff 68     std     r2,-152(r1)
      60:       7c c9 03 a6     mtctr   r6
      64:       60 00 00 00     nop
      68:       60 00 00 00     nop
      6c:       60 00 00 00     nop
      70:       8c c4 00 40     lbzu    r6,64(r4)
      74:       8c a3 00 40     lbzu    r5,64(r3)
      78:       7c c5 2a 78     xor     r5,r6,r5
      7c:       88 e3 00 0f     lbz     r7,15(r3)
      80:       98 a3 00 00     stb     r5,0(r3)
      84:       88 a4 00 0f     lbz     r5,15(r4)
      88:       7c a5 3a 78     xor     r5,r5,r7
      8c:       89 03 00 0e     lbz     r8,14(r3)
      90:       98 a3 00 0f     stb     r5,15(r3)
      94:       88 a4 00 0e     lbz     r5,14(r4)
      98:       7c a5 42 78     xor     r5,r5,r8
      9c:       88 43 00 0d     lbz     r2,13(r3)
      a0:       98 a3 00 0e     stb     r5,14(r3)
      a4:       88 a4 00 0d     lbz     r5,13(r4)
      a8:       7c a5 12 78     xor     r5,r5,r2
      ac:       8b e3 00 0b     lbz     r31,11(r3)
      b0:       98 a3 00 0d     stb     r5,13(r3)
      b4:       88 a4 00 0b     lbz     r5,11(r4)
      b8:       7c a5 fa 78     xor     r5,r5,r31
      bc:       89 c3 00 0a     lbz     r14,10(r3)
      c0:       98 a3 00 0b     stb     r5,11(r3)
      c4:       88 a4 00 0a     lbz     r5,10(r4)
      c8:       7c a5 72 78     xor     r5,r5,r14
      cc:       89 e3 00 09     lbz     r15,9(r3)
      d0:       98 a3 00 0a     stb     r5,10(r3)
      d4:       88 a4 00 09     lbz     r5,9(r4)
      d8:       7c a5 7a 78     xor     r5,r5,r15
      dc:       8a 03 00 08     lbz     r16,8(r3)
      e0:       98 a3 00 09     stb     r5,9(r3)
      e4:       88 a4 00 08     lbz     r5,8(r4)
      e8:       7c a5 82 78     xor     r5,r5,r16
      ec:       8a 23 00 07     lbz     r17,7(r3)
      f0:       98 a3 00 08     stb     r5,8(r3)
      f4:       88 a4 00 07     lbz     r5,7(r4)
      f8:       7c a5 8a 78     xor     r5,r5,r17
      fc:       8a 43 00 06     lbz     r18,6(r3)
     100:       98 a3 00 07     stb     r5,7(r3)
     104:       88 a4 00 06     lbz     r5,6(r4)
     108:       7c a5 92 78     xor     r5,r5,r18
     10c:       8a 63 00 05     lbz     r19,5(r3)
     110:       98 a3 00 06     stb     r5,6(r3)
     114:       88 a4 00 05     lbz     r5,5(r4)
     118:       7c a5 9a 78     xor     r5,r5,r19
     11c:       8a 83 00 04     lbz     r20,4(r3)
     120:       98 a3 00 05     stb     r5,5(r3)
     124:       88 a4 00 04     lbz     r5,4(r4)
     128:       7c a5 a2 78     xor     r5,r5,r20
     12c:       8a a3 00 03     lbz     r21,3(r3)
     130:       98 a3 00 04     stb     r5,4(r3)
     134:       88 a4 00 03     lbz     r5,3(r4)
     138:       7c a5 aa 78     xor     r5,r5,r21
     13c:       8a c3 00 02     lbz     r22,2(r3)
     140:       98 a3 00 03     stb     r5,3(r3)
     144:       88 a4 00 02     lbz     r5,2(r4)
     148:       7c a5 b2 78     xor     r5,r5,r22
     14c:       8a e3 00 01     lbz     r23,1(r3)
     150:       98 a3 00 02     stb     r5,2(r3)
     154:       88 a4 00 01     lbz     r5,1(r4)
     158:       7c a5 ba 78     xor     r5,r5,r23
     15c:       8b 03 00 0c     lbz     r24,12(r3)
     160:       98 a3 00 01     stb     r5,1(r3)
     164:       88 a4 00 0c     lbz     r5,12(r4)
     168:       7c a5 c2 78     xor     r5,r5,r24
     16c:       8b 23 00 1f     lbz     r25,31(r3)
     170:       98 a3 00 0c     stb     r5,12(r3)
     174:       88 a4 00 1f     lbz     r5,31(r4)
     178:       7c a5 ca 78     xor     r5,r5,r25
     17c:       8b 43 00 1e     lbz     r26,30(r3)
     180:       98 a3 00 1f     stb     r5,31(r3)
     184:       88 a4 00 1e     lbz     r5,30(r4)
     188:       7c a5 d2 78     xor     r5,r5,r26
     18c:       8b 63 00 1d     lbz     r27,29(r3)
     190:       98 a3 00 1e     stb     r5,30(r3)
     194:       88 a4 00 1d     lbz     r5,29(r4)
     198:       7c a5 da 78     xor     r5,r5,r27
     19c:       8b 83 00 1b     lbz     r28,27(r3)
     1a0:       98 a3 00 1d     stb     r5,29(r3)
     1a4:       88 a4 00 1b     lbz     r5,27(r4)
     1a8:       7c a5 e2 78     xor     r5,r5,r28
     1ac:       8b a3 00 1a     lbz     r29,26(r3)
     1b0:       98 a3 00 1b     stb     r5,27(r3)
     1b4:       88 a4 00 1a     lbz     r5,26(r4)
     1b8:       88 c3 00 1c     lbz     r6,28(r3)
     1bc:       7c a5 ea 78     xor     r5,r5,r29
     1c0:       8b c3 00 19     lbz     r30,25(r3)
     1c4:       98 a3 00 1a     stb     r5,26(r3)
     1c8:       88 a4 00 19     lbz     r5,25(r4)
     1cc:       90 c1 ff 50     stw     r6,-176(r1)
     1d0:       7c a5 f2 78     xor     r5,r5,r30
     1d4:       88 c3 00 2e     lbz     r6,46(r3)
     1d8:       88 03 00 18     lbz     r0,24(r3)
     1dc:       98 a3 00 19     stb     r5,25(r3)
     1e0:       88 a4 00 18     lbz     r5,24(r4)
     1e4:       90 c1 ff 4c     stw     r6,-180(r1)
     1e8:       7c a5 02 78     xor     r5,r5,r0
     1ec:       88 c3 00 2d     lbz     r6,45(r3)
     1f0:       89 83 00 17     lbz     r12,23(r3)
     1f4:       90 c1 ff 48     stw     r6,-184(r1)
     1f8:       88 c3 00 2b     lbz     r6,43(r3)
     1fc:       98 a3 00 18     stb     r5,24(r3)
     200:       88 a4 00 17     lbz     r5,23(r4)
     204:       90 c1 ff 44     stw     r6,-188(r1)
     208:       7c a5 62 78     xor     r5,r5,r12
     20c:       88 c3 00 2a     lbz     r6,42(r3)
     210:       89 63 00 16     lbz     r11,22(r3)
     214:       98 a3 00 17     stb     r5,23(r3)
     218:       88 a4 00 16     lbz     r5,22(r4)
     21c:       90 c1 ff 40     stw     r6,-192(r1)
     220:       7c a5 5a 78     xor     r5,r5,r11
     224:       88 c3 00 29     lbz     r6,41(r3)
     228:       89 43 00 15     lbz     r10,21(r3)
     22c:       89 23 00 14     lbz     r9,20(r3)
     230:       98 a3 00 16     stb     r5,22(r3)
     234:       88 a4 00 15     lbz     r5,21(r4)
     238:       90 c1 ff 3c     stw     r6,-196(r1)
     23c:       7c a5 52 78     xor     r5,r5,r10
     240:       88 c3 00 28     lbz     r6,40(r3)
     244:       91 21 ff 54     stw     r9,-172(r1)
     248:       89 23 00 13     lbz     r9,19(r3)
     24c:       90 c1 ff 38     stw     r6,-200(r1)
     250:       98 a3 00 15     stb     r5,21(r3)
     254:       88 a4 00 14     lbz     r5,20(r4)
     258:       80 c1 ff 54     lwz     r6,-172(r1)
     25c:       91 21 ff 58     stw     r9,-168(r1)
     260:       7c a5 32 78     xor     r5,r5,r6
     264:       89 23 00 12     lbz     r9,18(r3)
     268:       98 a3 00 14     stb     r5,20(r3)
     26c:       88 a4 00 13     lbz     r5,19(r4)
     270:       80 c1 ff 58     lwz     r6,-168(r1)
     274:       91 21 ff 5c     stw     r9,-164(r1)
     278:       7c a5 32 78     xor     r5,r5,r6
     27c:       89 23 00 11     lbz     r9,17(r3)
     280:       98 a3 00 13     stb     r5,19(r3)
     284:       88 a4 00 12     lbz     r5,18(r4)
     288:       80 c1 ff 5c     lwz     r6,-164(r1)
     28c:       91 21 ff 60     stw     r9,-160(r1)
     290:       7c a5 32 78     xor     r5,r5,r6
     294:       89 23 00 10     lbz     r9,16(r3)
     298:       98 a3 00 12     stb     r5,18(r3)
     29c:       88 a4 00 11     lbz     r5,17(r4)
     2a0:       80 c1 ff 60     lwz     r6,-160(r1)
     2a4:       91 21 ff 64     stw     r9,-156(r1)
     2a8:       7c a5 32 78     xor     r5,r5,r6
     2ac:       98 a3 00 11     stb     r5,17(r3)
     2b0:       88 a4 00 10     lbz     r5,16(r4)
     2b4:       80 c1 ff 64     lwz     r6,-156(r1)
     2b8:       7c a5 32 78     xor     r5,r5,r6
     2bc:       80 c1 ff 50     lwz     r6,-176(r1)
     2c0:       98 a3 00 10     stb     r5,16(r3)
     2c4:       88 a4 00 1c     lbz     r5,28(r4)
     2c8:       7c a5 32 78     xor     r5,r5,r6
     2cc:       88 e3 00 2f     lbz     r7,47(r3)
     2d0:       98 a3 00 1c     stb     r5,28(r3)
     2d4:       88 a4 00 2f     lbz     r5,47(r4)
     2d8:       7c a5 3a 78     xor     r5,r5,r7
     2dc:       80 c1 ff 4c     lwz     r6,-180(r1)
     2e0:       98 a3 00 2f     stb     r5,47(r3)
     2e4:       88 a4 00 2e     lbz     r5,46(r4)
     2e8:       7c a5 32 78     xor     r5,r5,r6
     2ec:       80 41 ff 48     lwz     r2,-184(r1)
     2f0:       98 a3 00 2e     stb     r5,46(r3)
     2f4:       88 a4 00 2d     lbz     r5,45(r4)
     2f8:       88 c4 00 2b     lbz     r6,43(r4)
     2fc:       7c a5 12 78     xor     r5,r5,r2
     300:       80 41 ff 44     lwz     r2,-188(r1)
     304:       98 a3 00 2d     stb     r5,45(r3)
     308:       7c c6 12 78     xor     r6,r6,r2
     30c:       88 a4 00 2a     lbz     r5,42(r4)
     310:       80 41 ff 40     lwz     r2,-192(r1)
     314:       98 c3 00 2b     stb     r6,43(r3)
     318:       7c a5 12 78     xor     r5,r5,r2
     31c:       88 c4 00 29     lbz     r6,41(r4)
     320:       80 41 ff 3c     lwz     r2,-196(r1)
     324:       98 a3 00 2a     stb     r5,42(r3)
     328:       7c c6 12 78     xor     r6,r6,r2
     32c:       88 a4 00 28     lbz     r5,40(r4)
     330:       80 41 ff 38     lwz     r2,-200(r1)
     334:       8b e3 00 27     lbz     r31,39(r3)
     338:       7c a5 12 78     xor     r5,r5,r2
     33c:       98 c3 00 29     stb     r6,41(r3)
     340:       88 c4 00 27     lbz     r6,39(r4)
     344:       89 c3 00 26     lbz     r14,38(r3)
     348:       7c c6 fa 78     xor     r6,r6,r31
     34c:       98 a3 00 28     stb     r5,40(r3)
     350:       88 a4 00 26     lbz     r5,38(r4)
     354:       89 e3 00 25     lbz     r15,37(r3)
     358:       7c a5 72 78     xor     r5,r5,r14
     35c:       98 c3 00 27     stb     r6,39(r3)
     360:       88 c4 00 25     lbz     r6,37(r4)
     364:       8a 03 00 24     lbz     r16,36(r3)
     368:       7c c6 7a 78     xor     r6,r6,r15
     36c:       98 a3 00 26     stb     r5,38(r3)
     370:       88 a4 00 24     lbz     r5,36(r4)
     374:       8a 23 00 23     lbz     r17,35(r3)
     378:       7c a5 82 78     xor     r5,r5,r16
     37c:       98 c3 00 25     stb     r6,37(r3)
     380:       88 c4 00 23     lbz     r6,35(r4)
     384:       8a 43 00 22     lbz     r18,34(r3)
     388:       7c c6 8a 78     xor     r6,r6,r17
     38c:       98 a3 00 24     stb     r5,36(r3)
     390:       88 a4 00 22     lbz     r5,34(r4)
     394:       8a 63 00 21     lbz     r19,33(r3)
     398:       7c a5 92 78     xor     r5,r5,r18
     39c:       98 c3 00 23     stb     r6,35(r3)
     3a0:       88 c4 00 21     lbz     r6,33(r4)
     3a4:       8a 83 00 20     lbz     r20,32(r3)
     3a8:       7c c6 9a 78     xor     r6,r6,r19
     3ac:       98 a3 00 22     stb     r5,34(r3)
     3b0:       88 a4 00 20     lbz     r5,32(r4)
     3b4:       8a a3 00 2c     lbz     r21,44(r3)
     3b8:       7c a5 a2 78     xor     r5,r5,r20
     3bc:       98 c3 00 21     stb     r6,33(r3)
     3c0:       88 c4 00 2c     lbz     r6,44(r4)
     3c4:       8a c3 00 3f     lbz     r22,63(r3)
     3c8:       7c c6 aa 78     xor     r6,r6,r21
     3cc:       98 a3 00 20     stb     r5,32(r3)
     3d0:       88 a4 00 3f     lbz     r5,63(r4)
     3d4:       8a e3 00 3e     lbz     r23,62(r3)
     3d8:       7c a5 b2 78     xor     r5,r5,r22
     3dc:       98 c3 00 2c     stb     r6,44(r3)
     3e0:       88 c4 00 3e     lbz     r6,62(r4)
     3e4:       8b 03 00 3d     lbz     r24,61(r3)
     3e8:       7c c6 ba 78     xor     r6,r6,r23
     3ec:       98 a3 00 3f     stb     r5,63(r3)
     3f0:       88 a4 00 3d     lbz     r5,61(r4)
     3f4:       8b 23 00 3b     lbz     r25,59(r3)
     3f8:       7c a5 c2 78     xor     r5,r5,r24
     3fc:       98 c3 00 3e     stb     r6,62(r3)
     400:       88 c4 00 3b     lbz     r6,59(r4)
     404:       8b 43 00 3a     lbz     r26,58(r3)
     408:       7c c6 ca 78     xor     r6,r6,r25
     40c:       98 a3 00 3d     stb     r5,61(r3)
     410:       88 a4 00 3a     lbz     r5,58(r4)
     414:       8b 63 00 39     lbz     r27,57(r3)
     418:       7c a5 d2 78     xor     r5,r5,r26
     41c:       98 c3 00 3b     stb     r6,59(r3)
     420:       88 c4 00 39     lbz     r6,57(r4)
     424:       8b 83 00 38     lbz     r28,56(r3)
     428:       7c c6 da 78     xor     r6,r6,r27
     42c:       98 a3 00 3a     stb     r5,58(r3)
     430:       88 a4 00 38     lbz     r5,56(r4)
     434:       8b a3 00 37     lbz     r29,55(r3)
     438:       7c a5 e2 78     xor     r5,r5,r28
     43c:       98 c3 00 39     stb     r6,57(r3)
     440:       88 c4 00 37     lbz     r6,55(r4)
     444:       8b c3 00 36     lbz     r30,54(r3)
     448:       7c c6 ea 78     xor     r6,r6,r29
     44c:       98 a3 00 38     stb     r5,56(r3)
     450:       88 a4 00 36     lbz     r5,54(r4)
     454:       88 03 00 35     lbz     r0,53(r3)
     458:       7c a5 f2 78     xor     r5,r5,r30
     45c:       98 c3 00 37     stb     r6,55(r3)
     460:       88 c4 00 35     lbz     r6,53(r4)
     464:       89 83 00 34     lbz     r12,52(r3)
     468:       7c c6 02 78     xor     r6,r6,r0
     46c:       98 a3 00 36     stb     r5,54(r3)
     470:       88 a4 00 34     lbz     r5,52(r4)
     474:       89 63 00 33     lbz     r11,51(r3)
     478:       7c a5 62 78     xor     r5,r5,r12
     47c:       98 c3 00 35     stb     r6,53(r3)
     480:       88 c4 00 33     lbz     r6,51(r4)
     484:       89 43 00 32     lbz     r10,50(r3)
     488:       7c c6 5a 78     xor     r6,r6,r11
     48c:       98 a3 00 34     stb     r5,52(r3)
     490:       88 a4 00 32     lbz     r5,50(r4)
     494:       89 23 00 31     lbz     r9,49(r3)
     498:       7c a5 52 78     xor     r5,r5,r10
     49c:       98 c3 00 33     stb     r6,51(r3)
     4a0:       88 c4 00 31     lbz     r6,49(r4)
     4a4:       89 03 00 30     lbz     r8,48(r3)
     4a8:       7c c6 4a 78     xor     r6,r6,r9
     4ac:       98 a3 00 32     stb     r5,50(r3)
     4b0:       88 a4 00 30     lbz     r5,48(r4)
     4b4:       88 e3 00 3c     lbz     r7,60(r3)
     4b8:       7c a5 42 78     xor     r5,r5,r8
     4bc:       98 c3 00 31     stb     r6,49(r3)
     4c0:       88 c4 00 3c     lbz     r6,60(r4)
     4c4:       98 a3 00 30     stb     r5,48(r3)
     4c8:       7c c5 3a 78     xor     r5,r6,r7
     4cc:       98 a3 00 3c     stb     r5,60(r3)
     4d0:       42 00 fb a0     bdnz    70 <__xor_altivec_2+0x70>
     4d4:       e8 41 ff 68     ld      r2,-152(r1)
     4d8:       eb e1 ff f8     ld      r31,-8(r1)
     4dc:       eb c1 ff f0     ld      r30,-16(r1)
     4e0:       eb a1 ff e8     ld      r29,-24(r1)
     4e4:       eb 81 ff e0     ld      r28,-32(r1)
     4e8:       eb 61 ff d8     ld      r27,-40(r1)
     4ec:       eb 41 ff d0     ld      r26,-48(r1)
     4f0:       eb 21 ff c8     ld      r25,-56(r1)
     4f4:       eb 01 ff c0     ld      r24,-64(r1)
     4f8:       ea e1 ff b8     ld      r23,-72(r1)
     4fc:       ea c1 ff b0     ld      r22,-80(r1)
     500:       ea a1 ff a8     ld      r21,-88(r1)
     504:       ea 81 ff a0     ld      r20,-96(r1)
     508:       ea 61 ff 98     ld      r19,-104(r1)
     50c:       ea 41 ff 90     ld      r18,-112(r1)
     510:       ea 21 ff 88     ld      r17,-120(r1)
     514:       ea 01 ff 80     ld      r16,-128(r1)
     518:       e9 e1 ff 78     ld      r15,-136(r1)
     51c:       e9 c1 ff 70     ld      r14,-144(r1)
     520:       4e 80 00 20     blr

gcc12_xor_vmx.o.gz
clang15_xor_vmx.o.gz

[ernsteiswuerfel]

Seems even a bit worse with CLANG 16.0.4 (Talos II build).

GCC 12.2.1_p20230428:

/usr/src/linux-stable/arch/powerpc/lib/xor_vmx.o:     file format elf64-powerpc

Disassembly of section .text:

0000000000000000 <__xor_altivec_2>:
   0:	78 6a d1 82 	srdi    r10,r3,6
   4:	39 20 00 00 	li      r9,0
   8:	38 e4 00 10 	addi    r7,r4,16
   c:	39 04 00 20 	addi    r8,r4,32
  10:	39 65 00 10 	addi    r11,r5,16
  14:	38 65 00 20 	addi    r3,r5,32
  18:	38 c5 00 30 	addi    r6,r5,48
  1c:	7d 49 03 a6 	mtctr   r10
  20:	39 44 00 30 	addi    r10,r4,48
  24:	60 00 00 00 	nop
  28:	60 00 00 00 	nop
  2c:	60 00 00 00 	nop
  30:	7d 04 48 ce 	lvx     v8,r4,r9
  34:	7d a7 48 ce 	lvx     v13,r7,r9
  38:	7c 28 48 ce 	lvx     v1,r8,r9
  3c:	7c 0a 48 ce 	lvx     v0,r10,r9
  40:	7d 85 48 ce 	lvx     v12,r5,r9
  44:	7d 2b 48 ce 	lvx     v9,r11,r9
  48:	7d 43 48 ce 	lvx     v10,r3,r9
  4c:	7d 66 48 ce 	lvx     v11,r6,r9
  50:	11 8c 44 c4 	vxor    v12,v12,v8
  54:	11 ad 4c c4 	vxor    v13,v13,v9
  58:	10 21 54 c4 	vxor    v1,v1,v10
  5c:	10 00 5c c4 	vxor    v0,v0,v11
  60:	7d 84 49 ce 	stvx    v12,r4,r9
  64:	7d a7 49 ce 	stvx    v13,r7,r9
  68:	7c 28 49 ce 	stvx    v1,r8,r9
  6c:	7c 0a 49 ce 	stvx    v0,r10,r9
  70:	39 29 00 40 	addi    r9,r9,64
  74:	42 00 ff bc 	bdnz    30 <__xor_altivec_2+0x30>
  78:	4e 80 00 20 	blr
  7c:	60 00 00 00 	nop

CLANG 16.0.4

/usr/src/linux-stable/arch/powerpc/lib/xor_vmx.o:    file format elf64-powerpc

Disassembly of section .text:

0000000000000000 <__xor_altivec_2>:
       0:	3c 4c 00 00 	addis   r2,r12,0
       4:	38 42 00 00 	addi    r2,r2,0
       8:	f8 21 fe b1 	stdu    r1,-336(r1)
       c:	78 66 d1 82 	srdi    r6,r3,6
      10:	f9 c1 00 c0 	std     r14,192(r1)
      14:	38 64 ff c0 	addi    r3,r4,-64
      18:	38 85 ff c0 	addi    r4,r5,-64
      1c:	f9 e1 00 c8 	std     r15,200(r1)
      20:	fa 01 00 d0 	std     r16,208(r1)
      24:	fa 21 00 d8 	std     r17,216(r1)
      28:	fa 41 00 e0 	std     r18,224(r1)
      2c:	fa 61 00 e8 	std     r19,232(r1)
      30:	fa 81 00 f0 	std     r20,240(r1)
      34:	fa a1 00 f8 	std     r21,248(r1)
      38:	fa c1 01 00 	std     r22,256(r1)
      3c:	fa e1 01 08 	std     r23,264(r1)
      40:	fb 01 01 10 	std     r24,272(r1)
      44:	fb 21 01 18 	std     r25,280(r1)
      48:	fb 41 01 20 	std     r26,288(r1)
      4c:	fb 61 01 28 	std     r27,296(r1)
      50:	fb 81 01 30 	std     r28,304(r1)
      54:	fb a1 01 38 	std     r29,312(r1)
      58:	fb c1 01 40 	std     r30,320(r1)
      5c:	fb e1 01 48 	std     r31,328(r1)
      60:	f8 41 00 b8 	std     r2,184(r1)
      64:	7c c9 03 a6 	mtctr   r6
      68:	60 00 00 00 	nop
      6c:	60 00 00 00 	nop
      70:	8c a3 00 40 	lbzu    r5,64(r3)
      74:	8a 83 00 0c 	lbz     r20,12(r3)
      78:	8d 44 00 40 	lbzu    r10,64(r4)
      7c:	88 44 00 0c 	lbz     r2,12(r4)
      80:	8a a3 00 01 	lbz     r21,1(r3)
      84:	8b e4 00 01 	lbz     r31,1(r4)
      88:	8a c3 00 02 	lbz     r22,2(r3)
      8c:	89 c4 00 02 	lbz     r14,2(r4)
      90:	8a e3 00 03 	lbz     r23,3(r3)
      94:	89 e4 00 03 	lbz     r15,3(r4)
      98:	8b 03 00 04 	lbz     r24,4(r3)
      9c:	8a 04 00 04 	lbz     r16,4(r4)
      a0:	8b 23 00 05 	lbz     r25,5(r3)
      a4:	8a 24 00 05 	lbz     r17,5(r4)
      a8:	8b 43 00 06 	lbz     r26,6(r3)
      ac:	8a 44 00 06 	lbz     r18,6(r4)
      b0:	8b 63 00 07 	lbz     r27,7(r3)
      b4:	8a 64 00 07 	lbz     r19,7(r4)
      b8:	8b 83 00 08 	lbz     r28,8(r3)
      bc:	89 03 00 0e 	lbz     r8,14(r3)
      c0:	89 63 00 0f 	lbz     r11,15(r3)
      c4:	8b a3 00 09 	lbz     r29,9(r3)
      c8:	8b c3 00 0a 	lbz     r30,10(r3)
      cc:	88 03 00 0b 	lbz     r0,11(r3)
      d0:	89 83 00 0d 	lbz     r12,13(r3)
      d4:	88 c3 00 19 	lbz     r6,25(r3)
      d8:	88 e3 00 1a 	lbz     r7,26(r3)
      dc:	89 23 00 1b 	lbz     r9,27(r3)
      e0:	90 a1 00 b4 	stw     r5,180(r1)
      e4:	88 a3 00 1d 	lbz     r5,29(r3)
      e8:	90 a1 00 b0 	stw     r5,176(r1)
      ec:	7c 45 a2 78 	xor     r5,r2,r20
      f0:	88 44 00 36 	lbz     r2,54(r4)
      f4:	8a 84 00 37 	lbz     r20,55(r4)
      f8:	90 a1 00 ac 	stw     r5,172(r1)
      fc:	7f e5 aa 78 	xor     r5,r31,r21
     100:	8b e4 00 33 	lbz     r31,51(r4)
     104:	8a a4 00 3a 	lbz     r21,58(r4)
     108:	90 a1 00 a8 	stw     r5,168(r1)
     10c:	7d c5 b2 78 	xor     r5,r14,r22
     110:	8a c4 00 1c 	lbz     r22,28(r4)
     114:	89 c4 00 32 	lbz     r14,50(r4)
     118:	90 a1 00 a4 	stw     r5,164(r1)
     11c:	7d e5 ba 78 	xor     r5,r15,r23
     120:	89 e4 00 31 	lbz     r15,49(r4)
     124:	8a e4 00 3e 	lbz     r23,62(r4)
     128:	90 a1 00 a0 	stw     r5,160(r1)
     12c:	7e 05 c2 78 	xor     r5,r16,r24
     130:	8b 04 00 0e 	lbz     r24,14(r4)
     134:	8a 04 00 30 	lbz     r16,48(r4)
     138:	90 a1 00 9c 	stw     r5,156(r1)
     13c:	7e 25 ca 78 	xor     r5,r17,r25
     140:	8a 24 00 34 	lbz     r17,52(r4)
     144:	8b 24 00 3f 	lbz     r25,63(r4)
     148:	90 a1 00 98 	stw     r5,152(r1)
     14c:	7e 45 d2 78 	xor     r5,r18,r26
     150:	8b 44 00 0f 	lbz     r26,15(r4)
     154:	7f 08 42 78 	xor     r8,r24,r8
     158:	8b 03 00 1c 	lbz     r24,28(r3)
     15c:	8a 44 00 35 	lbz     r18,53(r4)
     160:	90 a1 00 94 	stw     r5,148(r1)
     164:	7e 65 da 78 	xor     r5,r19,r27
     168:	8b 64 00 08 	lbz     r27,8(r4)
     16c:	91 01 00 5c 	stw     r8,92(r1)
     170:	8a 64 00 38 	lbz     r19,56(r4)
     174:	7f 48 5a 78 	xor     r8,r26,r11
     178:	8b 43 00 10 	lbz     r26,16(r3)
     17c:	89 63 00 11 	lbz     r11,17(r3)
     180:	90 a1 00 90 	stw     r5,144(r1)
     184:	88 a3 00 18 	lbz     r5,24(r3)
     188:	7f 7c e2 78 	xor     r28,r27,r28
     18c:	83 61 00 b4 	lwz     r27,180(r1)
     190:	91 01 00 54 	stw     r8,84(r1)
     194:	89 03 00 12 	lbz     r8,18(r3)
     198:	93 81 00 8c 	stw     r28,140(r1)
     19c:	8b 84 00 09 	lbz     r28,9(r4)
     1a0:	7d 4a da 78 	xor     r10,r10,r27
     1a4:	91 41 00 48 	stw     r10,72(r1)
     1a8:	7e ca c2 78 	xor     r10,r22,r24
     1ac:	8b 04 00 10 	lbz     r24,16(r4)
     1b0:	7f 9d ea 78 	xor     r29,r28,r29
     1b4:	8b 84 00 0a 	lbz     r28,10(r4)
     1b8:	8a c4 00 3b 	lbz     r22,59(r4)
     1bc:	91 41 00 b4 	stw     r10,180(r1)
     1c0:	93 a1 00 88 	stw     r29,136(r1)
     1c4:	8b a3 00 17 	lbz     r29,23(r3)
     1c8:	7f 0a d2 78 	xor     r10,r24,r26
     1cc:	8b 44 00 11 	lbz     r26,17(r4)
     1d0:	7f 9e f2 78 	xor     r30,r28,r30
     1d4:	8b 84 00 0b 	lbz     r28,11(r4)
     1d8:	91 41 00 84 	stw     r10,132(r1)
     1dc:	93 c1 00 7c 	stw     r30,124(r1)
     1e0:	8b c3 00 16 	lbz     r30,22(r3)
     1e4:	7f 4a 5a 78 	xor     r10,r26,r11
     1e8:	89 64 00 12 	lbz     r11,18(r4)
     1ec:	7f 80 02 78 	xor     r0,r28,r0
     1f0:	8b 84 00 0d 	lbz     r28,13(r4)
     1f4:	90 01 00 74 	stw     r0,116(r1)
     1f8:	88 03 00 15 	lbz     r0,21(r3)
     1fc:	91 41 00 80 	stw     r10,128(r1)
     200:	7d 68 42 78 	xor     r8,r11,r8
     204:	7f 8c 62 78 	xor     r12,r28,r12
     208:	8b 83 00 13 	lbz     r28,19(r3)
     20c:	91 01 00 78 	stw     r8,120(r1)
     210:	89 04 00 13 	lbz     r8,19(r4)
     214:	91 81 00 6c 	stw     r12,108(r1)
     218:	89 83 00 14 	lbz     r12,20(r3)
     21c:	7d 08 e2 78 	xor     r8,r8,r28
     220:	91 01 00 70 	stw     r8,112(r1)
     224:	89 04 00 14 	lbz     r8,20(r4)
     228:	7d 08 62 78 	xor     r8,r8,r12
     22c:	89 84 00 24 	lbz     r12,36(r4)
     230:	91 01 00 68 	stw     r8,104(r1)
     234:	89 04 00 15 	lbz     r8,21(r4)
     238:	7d 08 02 78 	xor     r8,r8,r0
     23c:	91 01 00 64 	stw     r8,100(r1)
     240:	89 04 00 16 	lbz     r8,22(r4)
     244:	7d 08 f2 78 	xor     r8,r8,r30
     248:	91 01 00 58 	stw     r8,88(r1)
     24c:	89 04 00 17 	lbz     r8,23(r4)
     250:	7d 08 ea 78 	xor     r8,r8,r29
     254:	91 01 00 50 	stw     r8,80(r1)
     258:	89 04 00 18 	lbz     r8,24(r4)
     25c:	7d 05 2a 78 	xor     r5,r8,r5
     260:	89 04 00 1e 	lbz     r8,30(r4)
     264:	90 a1 00 44 	stw     r5,68(r1)
     268:	88 a4 00 19 	lbz     r5,25(r4)
     26c:	7c a5 32 78 	xor     r5,r5,r6
     270:	88 c4 00 1d 	lbz     r6,29(r4)
     274:	90 a1 00 40 	stw     r5,64(r1)
     278:	88 a4 00 1a 	lbz     r5,26(r4)
     27c:	7c a5 3a 78 	xor     r5,r5,r7
     280:	90 a1 00 34 	stw     r5,52(r1)
     284:	88 a4 00 1b 	lbz     r5,27(r4)
     288:	7c a5 4a 78 	xor     r5,r5,r9
     28c:	90 a1 00 2c 	stw     r5,44(r1)
     290:	80 a1 00 b0 	lwz     r5,176(r1)
     294:	7c d8 2a 78 	xor     r24,r6,r5
     298:	88 c3 00 1e 	lbz     r6,30(r3)
     29c:	9b 03 00 1d 	stb     r24,29(r3)
     2a0:	7d 1b 32 78 	xor     r27,r8,r6
     2a4:	88 c3 00 1f 	lbz     r6,31(r3)
     2a8:	89 04 00 1f 	lbz     r8,31(r4)
     2ac:	9b 63 00 1e 	stb     r27,30(r3)
     2b0:	7d 1d 32 78 	xor     r29,r8,r6
     2b4:	88 c3 00 2c 	lbz     r6,44(r3)
     2b8:	89 04 00 2c 	lbz     r8,44(r4)
     2bc:	9b a3 00 1f 	stb     r29,31(r3)
     2c0:	83 a1 00 2c 	lwz     r29,44(r1)
     2c4:	7d 05 32 78 	xor     r5,r8,r6
     2c8:	88 c3 00 20 	lbz     r6,32(r3)
     2cc:	89 04 00 20 	lbz     r8,32(r4)
     2d0:	90 a1 00 b0 	stw     r5,176(r1)
     2d4:	9b a3 00 1b 	stb     r29,27(r3)
     2d8:	83 a1 00 34 	lwz     r29,52(r1)
     2dc:	7d 05 32 78 	xor     r5,r8,r6
     2e0:	88 c3 00 21 	lbz     r6,33(r3)
     2e4:	89 04 00 21 	lbz     r8,33(r4)
     2e8:	90 a1 00 60 	stw     r5,96(r1)
     2ec:	9b a3 00 1a 	stb     r29,26(r3)
     2f0:	83 a1 00 40 	lwz     r29,64(r1)
     2f4:	7d 05 32 78 	xor     r5,r8,r6
     2f8:	88 c3 00 22 	lbz     r6,34(r3)
     2fc:	89 04 00 22 	lbz     r8,34(r4)
     300:	90 a1 00 4c 	stw     r5,76(r1)
     304:	9b a3 00 19 	stb     r29,25(r3)
     308:	83 a1 00 44 	lwz     r29,68(r1)
     30c:	7d 05 32 78 	xor     r5,r8,r6
     310:	88 c3 00 23 	lbz     r6,35(r3)
     314:	89 04 00 23 	lbz     r8,35(r4)
     318:	90 a1 00 3c 	stw     r5,60(r1)
     31c:	9b a3 00 18 	stb     r29,24(r3)
     320:	83 a1 00 50 	lwz     r29,80(r1)
     324:	7d 05 32 78 	xor     r5,r8,r6
     328:	88 c3 00 24 	lbz     r6,36(r3)
     32c:	89 03 00 25 	lbz     r8,37(r3)
     330:	90 a1 00 30 	stw     r5,48(r1)
     334:	9b a3 00 17 	stb     r29,23(r3)
     338:	83 a1 00 58 	lwz     r29,88(r1)
     33c:	7d 85 32 78 	xor     r5,r12,r6
     340:	89 84 00 25 	lbz     r12,37(r4)
     344:	90 a1 00 24 	stw     r5,36(r1)
     348:	9b a3 00 16 	stb     r29,22(r3)
     34c:	83 a1 00 64 	lwz     r29,100(r1)
     350:	7d 9a 42 78 	xor     r26,r12,r8
     354:	89 03 00 26 	lbz     r8,38(r3)
     358:	89 84 00 26 	lbz     r12,38(r4)
     35c:	9b a3 00 15 	stb     r29,21(r3)
     360:	83 a1 00 68 	lwz     r29,104(r1)
     364:	9b 43 00 25 	stb     r26,37(r3)
     368:	7d 9c 42 78 	xor     r28,r12,r8
     36c:	89 03 00 27 	lbz     r8,39(r3)
     370:	89 84 00 27 	lbz     r12,39(r4)
     374:	9b a3 00 14 	stb     r29,20(r3)
     378:	83 a1 00 70 	lwz     r29,112(r1)
     37c:	9b 83 00 26 	stb     r28,38(r3)
     380:	7d 9e 42 78 	xor     r30,r12,r8
     384:	89 03 00 28 	lbz     r8,40(r3)
     388:	89 84 00 28 	lbz     r12,40(r4)
     38c:	9b a3 00 13 	stb     r29,19(r3)
     390:	83 a1 00 78 	lwz     r29,120(r1)
     394:	9b c3 00 27 	stb     r30,39(r3)
     398:	7d 80 42 78 	xor     r0,r12,r8
     39c:	89 03 00 29 	lbz     r8,41(r3)
     3a0:	89 84 00 29 	lbz     r12,41(r4)
     3a4:	9b a3 00 12 	stb     r29,18(r3)
     3a8:	83 a1 00 80 	lwz     r29,128(r1)
     3ac:	98 03 00 28 	stb     r0,40(r3)
     3b0:	7d 8b 42 78 	xor     r11,r12,r8
     3b4:	89 03 00 2a 	lbz     r8,42(r3)
     3b8:	89 84 00 2a 	lbz     r12,42(r4)
     3bc:	9b a3 00 11 	stb     r29,17(r3)
     3c0:	83 a1 00 84 	lwz     r29,132(r1)
     3c4:	99 63 00 29 	stb     r11,41(r3)
     3c8:	7d 8a 42 78 	xor     r10,r12,r8
     3cc:	89 03 00 2b 	lbz     r8,43(r3)
     3d0:	89 84 00 2b 	lbz     r12,43(r4)
     3d4:	9b a3 00 10 	stb     r29,16(r3)
     3d8:	83 a1 00 b4 	lwz     r29,180(r1)
     3dc:	99 43 00 2a 	stb     r10,42(r3)
     3e0:	7d 89 42 78 	xor     r9,r12,r8
     3e4:	89 03 00 2d 	lbz     r8,45(r3)
     3e8:	89 84 00 2d 	lbz     r12,45(r4)
     3ec:	9b a3 00 1c 	stb     r29,28(r3)
     3f0:	99 23 00 2b 	stb     r9,43(r3)
     3f4:	7d 87 42 78 	xor     r7,r12,r8
     3f8:	89 03 00 2e 	lbz     r8,46(r3)
     3fc:	89 84 00 2e 	lbz     r12,46(r4)
     400:	98 e3 00 2d 	stb     r7,45(r3)
     404:	7d 86 42 78 	xor     r6,r12,r8
     408:	89 03 00 2f 	lbz     r8,47(r3)
     40c:	89 84 00 2f 	lbz     r12,47(r4)
     410:	98 c3 00 2e 	stb     r6,46(r3)
     414:	7d 85 42 78 	xor     r5,r12,r8
     418:	89 03 00 3c 	lbz     r8,60(r3)
     41c:	89 84 00 3c 	lbz     r12,60(r4)
     420:	98 a3 00 2f 	stb     r5,47(r3)
     424:	80 a1 00 24 	lwz     r5,36(r1)
     428:	7d 88 42 78 	xor     r8,r12,r8
     42c:	89 84 00 39 	lbz     r12,57(r4)
     430:	91 01 00 38 	stw     r8,56(r1)
     434:	89 03 00 30 	lbz     r8,48(r3)
     438:	98 a3 00 24 	stb     r5,36(r3)
     43c:	80 a1 00 30 	lwz     r5,48(r1)
     440:	7e 08 42 78 	xor     r8,r16,r8
     444:	8a 03 00 31 	lbz     r16,49(r3)
     448:	98 a3 00 23 	stb     r5,35(r3)
     44c:	80 a1 00 3c 	lwz     r5,60(r1)
     450:	91 01 00 28 	stw     r8,40(r1)
     454:	89 04 00 3d 	lbz     r8,61(r4)
     458:	7d f0 82 78 	xor     r16,r15,r16
     45c:	89 e3 00 32 	lbz     r15,50(r3)
     460:	98 a3 00 22 	stb     r5,34(r3)
     464:	80 a1 00 4c 	lwz     r5,76(r1)
     468:	9a 03 00 31 	stb     r16,49(r3)
     46c:	7d cf 7a 78 	xor     r15,r14,r15
     470:	89 c3 00 33 	lbz     r14,51(r3)
     474:	98 a3 00 21 	stb     r5,33(r3)
     478:	80 a1 00 60 	lwz     r5,96(r1)
     47c:	99 e3 00 32 	stb     r15,50(r3)
     480:	7f ee 72 78 	xor     r14,r31,r14
     484:	8b e3 00 34 	lbz     r31,52(r3)
     488:	98 a3 00 20 	stb     r5,32(r3)
     48c:	80 a1 00 b0 	lwz     r5,176(r1)
     490:	99 c3 00 33 	stb     r14,51(r3)
     494:	7e 31 fa 78 	xor     r17,r17,r31
     498:	8b e3 00 35 	lbz     r31,53(r3)
     49c:	98 a3 00 2c 	stb     r5,44(r3)
     4a0:	80 a1 00 28 	lwz     r5,40(r1)
     4a4:	9a 23 00 34 	stb     r17,52(r3)
     4a8:	7e 52 fa 78 	xor     r18,r18,r31
     4ac:	8b e3 00 36 	lbz     r31,54(r3)
     4b0:	98 a3 00 30 	stb     r5,48(r3)
     4b4:	80 a1 00 38 	lwz     r5,56(r1)
     4b8:	9a 43 00 35 	stb     r18,53(r3)
     4bc:	7c 5f fa 78 	xor     r31,r2,r31
     4c0:	88 43 00 37 	lbz     r2,55(r3)
     4c4:	98 a3 00 3c 	stb     r5,60(r3)
     4c8:	9b e3 00 36 	stb     r31,54(r3)
     4cc:	7e 94 12 78 	xor     r20,r20,r2
     4d0:	88 43 00 38 	lbz     r2,56(r3)
     4d4:	9a 83 00 37 	stb     r20,55(r3)
     4d8:	7e 73 12 78 	xor     r19,r19,r2
     4dc:	88 43 00 39 	lbz     r2,57(r3)
     4e0:	9a 63 00 38 	stb     r19,56(r3)
     4e4:	7d 8c 12 78 	xor     r12,r12,r2
     4e8:	88 43 00 3a 	lbz     r2,58(r3)
     4ec:	99 83 00 39 	stb     r12,57(r3)
     4f0:	7e b5 12 78 	xor     r21,r21,r2
     4f4:	88 43 00 3b 	lbz     r2,59(r3)
     4f8:	9a a3 00 3a 	stb     r21,58(r3)
     4fc:	7e d6 12 78 	xor     r22,r22,r2
     500:	88 43 00 3d 	lbz     r2,61(r3)
     504:	9a c3 00 3b 	stb     r22,59(r3)
     508:	7d 08 12 78 	xor     r8,r8,r2
     50c:	88 43 00 3e 	lbz     r2,62(r3)
     510:	99 03 00 3d 	stb     r8,61(r3)
     514:	7e f7 12 78 	xor     r23,r23,r2
     518:	88 43 00 3f 	lbz     r2,63(r3)
     51c:	9a e3 00 3e 	stb     r23,62(r3)
     520:	7f 39 12 78 	xor     r25,r25,r2
     524:	80 41 00 48 	lwz     r2,72(r1)
     528:	9b 23 00 3f 	stb     r25,63(r3)
     52c:	98 43 00 00 	stb     r2,0(r3)
     530:	80 41 00 54 	lwz     r2,84(r1)
     534:	98 43 00 0f 	stb     r2,15(r3)
     538:	80 41 00 5c 	lwz     r2,92(r1)
     53c:	98 43 00 0e 	stb     r2,14(r3)
     540:	80 41 00 6c 	lwz     r2,108(r1)
     544:	98 43 00 0d 	stb     r2,13(r3)
     548:	80 41 00 74 	lwz     r2,116(r1)
     54c:	98 43 00 0b 	stb     r2,11(r3)
     550:	80 41 00 7c 	lwz     r2,124(r1)
     554:	98 43 00 0a 	stb     r2,10(r3)
     558:	80 41 00 88 	lwz     r2,136(r1)
     55c:	98 43 00 09 	stb     r2,9(r3)
     560:	80 41 00 8c 	lwz     r2,140(r1)
     564:	98 43 00 08 	stb     r2,8(r3)
     568:	80 41 00 90 	lwz     r2,144(r1)
     56c:	98 43 00 07 	stb     r2,7(r3)
     570:	80 41 00 94 	lwz     r2,148(r1)
     574:	98 43 00 06 	stb     r2,6(r3)
     578:	80 41 00 98 	lwz     r2,152(r1)
     57c:	98 43 00 05 	stb     r2,5(r3)
     580:	80 41 00 9c 	lwz     r2,156(r1)
     584:	98 43 00 04 	stb     r2,4(r3)
     588:	80 41 00 a0 	lwz     r2,160(r1)
     58c:	98 43 00 03 	stb     r2,3(r3)
     590:	80 41 00 a4 	lwz     r2,164(r1)
     594:	98 43 00 02 	stb     r2,2(r3)
     598:	80 41 00 a8 	lwz     r2,168(r1)
     59c:	98 43 00 01 	stb     r2,1(r3)
     5a0:	80 41 00 ac 	lwz     r2,172(r1)
     5a4:	98 43 00 0c 	stb     r2,12(r3)
     5a8:	42 00 fa c8 	bdnz    70 <__xor_altivec_2+0x70>
     5ac:	e8 41 00 b8 	ld      r2,184(r1)
     5b0:	eb e1 01 48 	ld      r31,328(r1)
     5b4:	eb c1 01 40 	ld      r30,320(r1)
     5b8:	eb a1 01 38 	ld      r29,312(r1)
     5bc:	eb 81 01 30 	ld      r28,304(r1)
     5c0:	eb 61 01 28 	ld      r27,296(r1)
     5c4:	eb 41 01 20 	ld      r26,288(r1)
     5c8:	eb 21 01 18 	ld      r25,280(r1)
     5cc:	eb 01 01 10 	ld      r24,272(r1)
     5d0:	ea e1 01 08 	ld      r23,264(r1)
     5d4:	ea c1 01 00 	ld      r22,256(r1)
     5d8:	ea a1 00 f8 	ld      r21,248(r1)
     5dc:	ea 81 00 f0 	ld      r20,240(r1)
     5e0:	ea 61 00 e8 	ld      r19,232(r1)
     5e4:	ea 41 00 e0 	ld      r18,224(r1)
     5e8:	ea 21 00 d8 	ld      r17,216(r1)
     5ec:	ea 01 00 d0 	ld      r16,208(r1)
     5f0:	e9 e1 00 c8 	ld      r15,200(r1)
     5f4:	e9 c1 00 c0 	ld      r14,192(r1)
     5f8:	38 21 01 50 	addi    r1,r1,336
     5fc:	4e 80 00 20 	blr
	...
     60c:	60 00 00 00 	nop

gcc12-xor_vmx.o.gz
clang16-xor_vmx.o.gz

[ernsteiswuerfel]

In numbers the performance difference of the 2 compilers looks like this (on a Talos II).

GCC 12.2.1_p20221126:

xor: measuring software checksum speed
   8regs           :  7446 MB/sec
   8regs_prefetch  :  5979 MB/sec
   32regs          :  7467 MB/sec
   32regs_prefetch :  5914 MB/sec
   altivec         :  8519 MB/sec
xor: using function: altivec (8519 MB/sec)

CLANG 16.0.4:

xor: measuring software checksum speed
   8regs           :  7204 MB/sec
   8regs_prefetch  :  5670 MB/sec
   32regs          :  7303 MB/sec
   32regs_prefetch :  6180 MB/sec
   altivec         :   700 MB/sec
xor: using function: 32regs (7303 MB/sec)

[ernsteiswuerfel]

Seems this issue has been taken care of in CLANG 18.1.x. 👍 The resulting code is still larger compared to GCC but performance is en par with GCC now (in-kernel xor benchmark is faster with CLANG, raid6 benchmark is faster with GCC).

GCC 13.2.1_p20240210::

0000000000000000 <__xor_altivec_2>:
   0:	78 6a d1 82 	srdi    r10,r3,6
   4:	39 20 00 00 	li      r9,0
   8:	38 e4 00 10 	addi    r7,r4,16
   c:	39 04 00 20 	addi    r8,r4,32
  10:	39 65 00 10 	addi    r11,r5,16
  14:	38 65 00 20 	addi    r3,r5,32
  18:	38 c5 00 30 	addi    r6,r5,48
  1c:	7d 49 03 a6 	mtctr   r10
  20:	39 44 00 30 	addi    r10,r4,48
  24:	60 00 00 00 	nop
  28:	60 00 00 00 	nop
  2c:	60 00 00 00 	nop
  30:	7d 04 48 ce 	lvx     v8,r4,r9
  34:	7d a7 48 ce 	lvx     v13,r7,r9
  38:	7c 28 48 ce 	lvx     v1,r8,r9
  3c:	7c 0a 48 ce 	lvx     v0,r10,r9
  40:	7d 85 48 ce 	lvx     v12,r5,r9
  44:	7d 2b 48 ce 	lvx     v9,r11,r9
  48:	7d 43 48 ce 	lvx     v10,r3,r9
  4c:	7d 66 48 ce 	lvx     v11,r6,r9
  50:	11 8c 44 c4 	vxor    v12,v12,v8
  54:	11 ad 4c c4 	vxor    v13,v13,v9
  58:	10 21 54 c4 	vxor    v1,v1,v10
  5c:	10 00 5c c4 	vxor    v0,v0,v11
  60:	7d 84 49 ce 	stvx    v12,r4,r9
  64:	7d a7 49 ce 	stvx    v13,r7,r9
  68:	7c 28 49 ce 	stvx    v1,r8,r9
  6c:	7c 0a 49 ce 	stvx    v0,r10,r9
  70:	39 29 00 40 	addi    r9,r9,64
  74:	42 00 ff bc 	bdnz    30 <__xor_altivec_2+0x30>
  78:	38 60 00 00 	li      r3,0
  7c:	38 80 00 00 	li      r4,0
  80:	38 a0 00 00 	li      r5,0
  84:	38 c0 00 00 	li      r6,0
  88:	38 e0 00 00 	li      r7,0
  8c:	39 00 00 00 	li      r8,0
  90:	39 20 00 00 	li      r9,0
  94:	39 40 00 00 	li      r10,0
  98:	39 60 00 00 	li      r11,0
  9c:	4e 80 00 20 	blr

CLANG 18.1.3:

0000000000000000 <__xor_altivec_2>:
   0:	78 66 d1 82 	srdi    r6,r3,6
   4:	70 63 00 40 	andi.   r3,r3,64
   8:	40 82 00 0c 	bne     14 <__xor_altivec_2+0x14>
   c:	7c c3 33 78 	mr      r3,r6
  10:	48 00 00 5c 	b       6c <__xor_altivec_2+0x6c>
  14:	7c 40 20 ce 	lvx     v2,0,r4
  18:	7c 00 28 ce 	lvx     v0,0,r5
  1c:	38 60 00 10 	li      r3,16
  20:	38 e0 00 20 	li      r7,32
  24:	39 00 00 30 	li      r8,48
  28:	7c 64 18 ce 	lvx     v3,r4,r3
  2c:	7c 84 38 ce 	lvx     v4,r4,r7
  30:	7c a4 40 ce 	lvx     v5,r4,r8
  34:	7c 25 18 ce 	lvx     v1,r5,r3
  38:	7c c5 40 ce 	lvx     v6,r5,r8
  3c:	10 40 14 c4 	vxor    v2,v0,v2
  40:	7c 05 38 ce 	lvx     v0,r5,r7
  44:	38 a5 00 40 	addi    r5,r5,64
  48:	10 61 1c c4 	vxor    v3,v1,v3
  4c:	10 a6 2c c4 	vxor    v5,v6,v5
  50:	7c 40 21 ce 	stvx    v2,0,r4
  54:	7c 64 19 ce 	stvx    v3,r4,r3
  58:	38 66 ff ff 	addi    r3,r6,-1
  5c:	7c a4 41 ce 	stvx    v5,r4,r8
  60:	10 80 24 c4 	vxor    v4,v0,v4
  64:	7c 84 39 ce 	stvx    v4,r4,r7
  68:	38 84 00 40 	addi    r4,r4,64
  6c:	28 26 00 01 	cmpldi  r6,1
  70:	4d 82 00 20 	beqlr
  74:	38 c0 00 00 	li      r6,0
  78:	38 e0 00 10 	li      r7,16
  7c:	39 00 00 20 	li      r8,32
  80:	39 20 00 30 	li      r9,48
  84:	fb a1 ff e8 	std     r29,-24(r1)
  88:	39 40 00 40 	li      r10,64
  8c:	39 60 00 50 	li      r11,80
  90:	39 80 00 60 	li      r12,96
  94:	38 00 00 70 	li      r0,112
  98:	fb c1 ff f0 	std     r30,-16(r1)
  9c:	60 00 00 00 	nop
  a0:	7c 44 30 ce 	lvx     v2,r4,r6
  a4:	7c 65 30 ce 	lvx     v3,r5,r6
  a8:	7f c4 32 14 	add     r30,r4,r6
  ac:	7f a5 32 14 	add     r29,r5,r6
  b0:	38 63 ff fe 	addi    r3,r3,-2
  b4:	7c 1d 38 ce 	lvx     v0,r29,r7
  b8:	7c fe 50 ce 	lvx     v7,r30,r10
  bc:	7c 9e 40 ce 	lvx     v4,r30,r8
  c0:	7c 3d 40 ce 	lvx     v1,r29,r8
  c4:	7c be 48 ce 	lvx     v5,r30,r9
  c8:	7c dd 48 ce 	lvx     v6,r29,r9
  cc:	28 23 00 00 	cmpldi  r3,0
  d0:	10 43 14 c4 	vxor    v2,v3,v2
  d4:	7c 7e 38 ce 	lvx     v3,r30,r7
  d8:	7c 44 31 ce 	stvx    v2,r4,r6
  dc:	7c 5d 50 ce 	lvx     v2,r29,r10
  e0:	10 81 24 c4 	vxor    v4,v1,v4
  e4:	7c 3e 60 ce 	lvx     v1,r30,r12
  e8:	10 a6 2c c4 	vxor    v5,v6,v5
  ec:	7c de 00 ce 	lvx     v6,r30,r0
  f0:	38 c6 00 80 	addi    r6,r6,128
  f4:	7c 9e 41 ce 	stvx    v4,r30,r8
  f8:	7c be 49 ce 	stvx    v5,r30,r9
  fc:	10 60 1c c4 	vxor    v3,v0,v3
 100:	7c 1e 58 ce 	lvx     v0,r30,r11
 104:	10 42 3c c4 	vxor    v2,v2,v7
 108:	7c fd 58 ce 	lvx     v7,r29,r11
 10c:	7c 7e 39 ce 	stvx    v3,r30,r7
 110:	7c 5e 51 ce 	stvx    v2,r30,r10
 114:	10 07 04 c4 	vxor    v0,v7,v0
 118:	7c fd 60 ce 	lvx     v7,r29,r12
 11c:	7c 1e 59 ce 	stvx    v0,r30,r11
 120:	10 27 0c c4 	vxor    v1,v7,v1
 124:	7c fd 00 ce 	lvx     v7,r29,r0
 128:	7c 3e 61 ce 	stvx    v1,r30,r12
 12c:	10 c7 34 c4 	vxor    v6,v7,v6
 130:	7c de 01 ce 	stvx    v6,r30,r0
 134:	40 82 ff 6c 	bne     a0 <__xor_altivec_2+0xa0>
 138:	eb c1 ff f0 	ld      r30,-16(r1)
 13c:	eb a1 ff e8 	ld      r29,-24(r1)
 140:	4e 80 00 20 	blr

Here again performance comparison on my Talos, kernel v6.9-rc4:

GCC 13.2.1_p20240210:

 xor: measuring software checksum speed
    8regs           :  7384 MB/sec
    8regs_prefetch  :  5888 MB/sec
    32regs          :  7468 MB/sec
    32regs_prefetch :  6010 MB/sec
    altivec         :  8517 MB/sec
 xor: using function: altivec (8517 MB/sec)

CLANG 18.1.3:

 xor: measuring software checksum speed
    8regs           :  7321 MB/sec
    8regs_prefetch  :  5664 MB/sec
    32regs          :  7196 MB/sec
    32regs_prefetch :  6188 MB/sec
    altivec         :  9779 MB/sec
 xor: using function: altivec (9779 MB/sec)

dmesg_69-rc4_p9_clang18.txt
dmesg_69-rc4_p9_gcc13.txt

config_69-rc4_p9_clang18.txt
config_69-rc4_p9_gcc13.txt

[nathanchance]

Ha, so this appears to be fixed by my commit 35f20786c481 ("powerpc: xor_vmx: Add '-mhard-float' to CFLAGS"), which was fixing a new compiler error from clang-19, but I think this is basically pointing out that prior to the compiler error being added, -maltivec was having no effect in combination with -msoft-float. Now that -mhard-float overrides -msoft-float, we get nice vectorized code with -maltivec.

Closing this up for now.