The branch main has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=b49a0db6628e6f953504ebc8712ed582471ccd05
commit b49a0db6628e6f953504ebc8712ed582471ccd05 Author: Mateusz Guzik <[email protected]> AuthorDate: 2021-02-09 15:18:58 +0000 Commit: Mateusz Guzik <[email protected]> CommitDate: 2021-02-09 15:23:18 +0000 Revert "amd64: implement strlen in assembly" This reverts commit af366d353b84bdc4e730f0fc563853abc338271c. Trips over '\xa4' byte and terminates early, as found in lib/libc/gen/setdomainname_test:setdomainname_basic testcase However, keep moving libkern/strlen.c out of conf/files. Reported by: lwhsu --- sys/amd64/amd64/support.S | 66 ----------------------------------------------- sys/conf/files.amd64 | 1 + 2 files changed, 1 insertion(+), 66 deletions(-) diff --git a/sys/amd64/amd64/support.S b/sys/amd64/amd64/support.S index a059b520c5d5..b623fba277db 100644 --- a/sys/amd64/amd64/support.S +++ b/sys/amd64/amd64/support.S @@ -697,72 +697,6 @@ ENTRY(fillw) ret END(fillw) -/* - * strlen(string) - * %rdi - * - * Uses the ((x - 0x01....01) & ~x & 0x80....80) trick. - * - * 0x01....01 is replaced with 0x0 - 0x01....01 so that it can be added - * with leaq. - * - * For a description see either: - * - "Hacker's Delight" by Henry S. Warren, Jr. - * - "Optimizing subroutines in assembly language: An optimization guide for x86 platforms" - * by Agner Fog - * - * The latter contains a 32-bit variant of the same algorithm coded in assembly for i386. - */ -ENTRY(strlen) - PUSH_FRAME_POINTER - movabsq $0xfefefefefefefeff,%r8 - movabsq $0x8080808080808080,%r9 - - movq %rdi,%r10 - movq %rdi,%rcx - testb $7,%dil - jz 2f - - /* - * Handle misaligned reads: align to 8 and fill - * the spurious bytes. - */ - andq $~7,%rdi - movq (%rdi),%r11 - shlq $3,%rcx - movq $-1,%rdx - shlq %cl,%rdx - notq %rdx - orq %rdx,%r11 - - leaq (%r11,%r8),%rcx - notq %r11 - andq %r11,%rcx - andq %r9,%rcx - jnz 3f - - /* - * Main loop. - */ - ALIGN_TEXT -1: - leaq 8(%rdi),%rdi -2: - movq (%rdi),%r11 - leaq (%r11,%r8),%rcx - notq %r11 - andq %rcx,%r11 - andq %r9,%rcx - jz 1b -3: - bsfq %rcx,%rcx - shrq $3,%rcx - leaq (%rcx,%rdi),%rax - subq %r10,%rax - POP_FRAME_POINTER - ret -END(strlen) - /*****************************************************************************/ /* copyout and fubyte family */ /*****************************************************************************/ diff --git a/sys/conf/files.amd64 b/sys/conf/files.amd64 index 395f501198f8..98a78a8b1ef9 100644 --- a/sys/conf/files.amd64 +++ b/sys/conf/files.amd64 @@ -390,6 +390,7 @@ isa/syscons_isa.c optional sc isa/vga_isa.c optional vga kern/imgact_aout.c optional compat_aout kern/link_elf_obj.c standard +libkern/strlen.c standard # # IA32 binary support # _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/dev-commits-src-main To unsubscribe, send any mail to "[email protected]"
