Chromium Code Reviews Chromium Code Reviews
Issue 957063002:
Avoid string instructions in x86_64 memset (Closed)
Base URL: https://chromium.googlesource.com/native_client/nacl-newlib.git@master| OLD | NEW |
|---|---|
| 1 /* | 1 /* |
| 2 * ==================================================== | 2 * ==================================================== |
| 3 * Copyright (C) 2007 by Ellips BV. All rights reserved. | 3 * Copyright (C) 2007 by Ellips BV. All rights reserved. |
| 4 * | 4 * |
| 5 * Permission to use, copy, modify, and distribute this | 5 * Permission to use, copy, modify, and distribute this |
| 6 * software is freely granted, provided that this notice | 6 * software is freely granted, provided that this notice |
| 7 * is preserved. | 7 * is preserved. |
| 8 * ==================================================== | 8 * ==================================================== |
| 9 */ | 9 */ |
| 10 | 10 |
| 11 #include "x86_64mach.h" | 11 #include "x86_64mach.h" |
| 12 | 12 |
| 13 .global SYM (memset) | 13 .global SYM (memset) |
| 14 SOTYPE_FUNCTION(memset) | 14 SOTYPE_FUNCTION(memset) |
| 15 | 15 |
| 16 /* | |
| 17 * Avoid revealing the sandbox base address. In particular, we never read from | |
| 18 * r11, and avoid using the string instructions (stos) because they leave the | |
| 19 * full 64 bits in rdi. | |
| 20 */ | |
| 21 | |
| 16 SYM (memset): | 22 SYM (memset): |
| 17 movl edi, r9d /* Save return value */ | 23 movl edi, r9d /* Save return value */ |
| 18 movl esi, eax | 24 movl esi, eax |
| 19 movl edx, ecx | 25 movl edx, ecx |
| 20 cmpl $16, edx | 26 cmpl $16, edx |
| 21 jb byte_set | 27 jb .Lbyte_set |
| 22 | 28 |
| 23 movl edi, r8d /* Align on quad word boundary */ | 29 movl edi, r8d /* Align on quad word boundary */ |
| 24 andl $7, r8d | 30 andl $7, r8d |
| 25 jz quadword_aligned | 31 jz .Lquadword_aligned |
| 26 movl $8, ecx | 32 movl $8, ecx |
| 27 subl r8d, ecx | 33 subl r8d, ecx |
| 28 subl ecx, edx | 34 subl ecx, edx |
| 29 rep stosb al, %nacl:(rdi), r15 | 35 .Lheader_loop: |
| 36 movb al, %nacl:(r15, rdi) | |
| 37 inc edi | |
| 38 dec ecx | |
| 39 jnz .Lheader_loop | |
| 40 | |
| 30 movl edx, ecx | 41 movl edx, ecx |
| 31 | 42 |
| 32 quadword_aligned: | 43 .Lquadword_aligned: |
| 33 movabs $0x0101010101010101, r8 | 44 movabs $0x0101010101010101, r8 |
| 34 movzbl sil, eax | 45 movzbl sil, eax |
| 35 imul r8, rax | 46 imul r8, rax |
| 36 cmpl $256, edx | 47 cmpl $256, edx |
| 37 jb quadword_set | 48 jb .Lquadword_set |
| 38 | 49 |
| 39 shrl $7, ecx /* Store 128 bytes at a time with minimum cach e polution */ | 50 shrl $7, ecx /* Store 128 bytes at a time */ |
| 40 | 51 |
| 52 pushq $0 | |
| 53 movl ebp, (rsp) | |
| 41 .p2align 4 | 54 .p2align 4 |
| 42 loop: | 55 .Lquadword_aligned_loop: |
| 43 movntiq rax, %nacl: (r15,rdi) | 56 naclrestbp edi, r15 |
| 44 movntiq rax, %nacl: 8 (r15,rdi) | 57 movq rax, (rbp) |
| 45 movntiq rax, %nacl: 16 (r15,rdi) | 58 movq rax, 8 (rbp) |
| 46 movntiq rax, %nacl: 24 (r15,rdi) | 59 movq rax, 16 (rbp) |
| 47 movntiq rax, %nacl: 32 (r15,rdi) | 60 movq rax, 24 (rbp) |
| 48 movntiq rax, %nacl: 40 (r15,rdi) | 61 movq rax, 32 (rbp) |
| 49 movntiq rax, %nacl: 48 (r15,rdi) | 62 movq rax, 40 (rbp) |
| 50 movntiq rax, %nacl: 56 (r15,rdi) | 63 movq rax, 48 (rbp) |
| 51 movntiq rax, %nacl: 64 (r15,rdi) | 64 movq rax, 56 (rbp) |
| 52 movntiq rax, %nacl: 72 (r15,rdi) | 65 movq rax, 64 (rbp) |
| 53 movntiq rax, %nacl: 80 (r15,rdi) | 66 movq rax, 72 (rbp) |
| 54 movntiq rax, %nacl: 88 (r15,rdi) | 67 movq rax, 80 (rbp) |
| 55 movntiq rax, %nacl: 96 (r15,rdi) | 68 movq rax, 88 (rbp) |
| 56 movntiq rax, %nacl: 104 (r15,rdi) | 69 movq rax, 96 (rbp) |
| 57 movntiq rax, %nacl: 112 (r15,rdi) | 70 movq rax, 104 (rbp) |
| 58 movntiq rax, %nacl: 120 (r15,rdi) | 71 movq rax, 112 (rbp) |
| 72 movq rax, 120 (rbp) | |
| 59 | 73 |
| 60 leal 128 (rdi), edi | 74 leal 128 (rdi), edi |
|
jvoung (off chromium)
2015/02/27 20:33:52
Might have been able to add to ebp and then restor
Derek Schuff
2015/02/27 21:03:19
I like it. Done.
| |
| 61 | 75 |
| 62 dec ecx | 76 dec ecx |
| 63 jnz loop | 77 jnz .Lquadword_aligned_loop |
| 64 | 78 |
| 65 sfence | 79 popq r8 |
| 80 naclrestbp r8d, r15 | |
| 81 | |
| 66 movl edx, ecx | 82 movl edx, ecx |
| 67 andl $127, ecx | 83 andl $127, ecx |
| 68 rep stosb al, %nacl:(rdi), r15 | 84 jz .Lfooter_loop_end |
| 85 .Lfooter_loop: | |
| 86 movb al, %nacl:(r15, rdi) | |
| 87 inc edi | |
| 88 dec ecx | |
| 89 jnz .Lfooter_loop | |
| 90 .Lfooter_loop_end: | |
| 69 movl r9d, eax | 91 movl r9d, eax |
| 70 pop r11 | 92 pop r11 |
| 71 nacljmp r11d, r15 | 93 nacljmp r11d, r15 |
| 72 | 94 |
| 73 | 95 |
| 74 byte_set: | 96 .Lbyte_set: |
| 75 rep stosb al, %nacl:(rdi), r15 | 97 testl ecx, ecx |
| 98 jz .Lbyte_set_end | |
| 99 .Lbyte_set_loop: | |
| 100 movb al, %nacl:(r15, rdi) | |
| 101 inc edi | |
| 102 dec ecx | |
| 103 jnz .Lbyte_set_loop | |
| 104 .Lbyte_set_end: | |
| 76 movl r9d, eax | 105 movl r9d, eax |
| 77 pop r11 | 106 pop r11 |
| 78 nacljmp r11d, r15 | 107 nacljmp r11d, r15 |
| 79 | 108 |
| 80 | 109 |
| 81 quadword_set: | 110 .Lquadword_set: |
| 82 shrl $3, ecx | 111 shrl $3, ecx |
| 112 jz .Lquadword_loop_end | |
| 83 .p2align 4 | 113 .p2align 4 |
| 84 rep stosq rax, %nacl:(rdi), r15 | 114 .Lquadword_loop: |
| 115 movq rax, %nacl:(r15, rdi) | |
| 116 add $8, edi | |
| 117 dec ecx | |
| 118 jnz .Lquadword_loop | |
| 119 .Lquadword_loop_end: | |
| 85 movl edx, ecx | 120 movl edx, ecx |
| 86 andl $7, ecx | 121 andl $7, ecx |
| 87 rep stosb al, %nacl:(rdi), r15 /* Store the remaining bytes */ | 122 jz .Lquadword_footer_end |
| 123 .Lquadword_footer: | |
| 124 movb al, %nacl:(r15, rdi) | |
| 125 inc edi | |
| 126 dec ecx | |
| 127 jnz .Lquadword_footer | |
| 128 .Lquadword_footer_end: | |
| 88 movl r9d, eax | 129 movl r9d, eax |
| 89 pop r11 | 130 pop r11 |
| 90 nacljmp r11d, r15 | 131 nacljmp r11d, r15 |
| 91 | 132 |
| OLD | NEW |
