--- /dev/null
+/* Placeholder function, not used by any processor at the moment.
+ Copyright (C) 2022 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+/* UNUSED. Exists purely as reference implementation. */
+
+#include <isa-level.h>
+
+#if ISA_SHOULD_BUILD (4)
+
+# include <sysdep.h>
+
+# ifdef USE_AS_WCSRCHR
+# define CHAR_SIZE 4
+# define VPBROADCAST vpbroadcastd
+# define VPCMPEQ vpcmpeqd
+# define VPMINU vpminud
+# define VPTESTN vptestnmd
+# else
+# define CHAR_SIZE 1
+# define VPBROADCAST vpbroadcastb
+# define VPCMPEQ vpcmpeqb
+# define VPMINU vpminub
+# define VPTESTN vptestnmb
+# endif
+
+# define PAGE_SIZE 4096
+# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
+
+ .section SECTION(.text), "ax", @progbits
+/* Aligning entry point to 64 byte, provides better performance for
+ one vector length string. */
+ENTRY_P2ALIGN (STRRCHR, 6)
+
+ /* Broadcast CHAR to VMM(0). */
+ VPBROADCAST %esi, %VMM(0)
+ movl %edi, %eax
+ sall $20, %eax
+ cmpl $((PAGE_SIZE - VEC_SIZE) << 20), %eax
+ ja L(page_cross)
+
+L(page_cross_continue):
+ /* Compare [w]char for null, mask bit will be set for match. */
+ VMOVU (%rdi), %VMM(1)
+
+ VPTESTN %VMM(1), %VMM(1), %k1
+ KMOV %k1, %VRCX
+ test %VRCX, %VRCX
+ jz L(align_more)
+
+ VPCMPEQ %VMM(1), %VMM(0), %k0
+ KMOV %k0, %VRAX
+ BLSMSK %VRCX, %VRCX
+ and %VRCX, %VRAX
+ jz L(ret)
+
+ BSR %VRAX, %VRAX
+# ifdef USE_AS_WCSRCHR
+ leaq (%rdi, %rax, CHAR_SIZE), %rax
+# else
+ add %rdi, %rax
+# endif
+L(ret):
+ ret
+
+L(vector_x2_end):
+ VPCMPEQ %VMM(2), %VMM(0), %k2
+ KMOV %k2, %VRAX
+ BLSMSK %VRCX, %VRCX
+ and %VRCX, %VRAX
+ jz L(vector_x1_ret)
+
+ BSR %VRAX, %VRAX
+ leaq (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %rax
+ ret
+
+ /* Check the first vector at very last to look for match. */
+L(vector_x1_ret):
+ VPCMPEQ %VMM(1), %VMM(0), %k2
+ KMOV %k2, %VRAX
+ test %VRAX, %VRAX
+ jz L(ret)
+
+ BSR %VRAX, %VRAX
+# ifdef USE_AS_WCSRCHR
+ leaq (%rsi, %rax, CHAR_SIZE), %rax
+# else
+ add %rsi, %rax
+# endif
+ ret
+
+L(align_more):
+ /* Zero r8 to store match result. */
+ xorl %r8d, %r8d
+ /* Save pointer of first vector, in case if no match found. */
+ movq %rdi, %rsi
+ /* Align pointer to vector size. */
+ andq $-VEC_SIZE, %rdi
+ /* Loop unroll for 2 vector loop. */
+ VMOVA (VEC_SIZE)(%rdi), %VMM(2)
+ VPTESTN %VMM(2), %VMM(2), %k0
+ KMOV %k0, %VRCX
+ test %VRCX, %VRCX
+ jnz L(vector_x2_end)
+
+ /* Save pointer of second vector, in case if no match
+ found. */
+ movq %rdi, %r9
+ /* Align address to VEC_SIZE * 2 for loop. */
+ andq $-(VEC_SIZE * 2), %rdi
+
+ .p2align 4,,11
+L(loop):
+ /* 2 vector loop, as it provide better performance as compared
+ to 4 vector loop. */
+ VMOVA (VEC_SIZE * 2)(%rdi), %VMM(3)
+ VMOVA (VEC_SIZE * 3)(%rdi), %VMM(4)
+ VPCMPEQ %VMM(3), %VMM(0), %k1
+ VPCMPEQ %VMM(4), %VMM(0), %k2
+ VPMINU %VMM(3), %VMM(4), %VMM(5)
+ VPTESTN %VMM(5), %VMM(5), %k0
+ KOR %k1, %k2, %k3
+ subq $-(VEC_SIZE * 2), %rdi
+ /* If k0 and k3 zero, match and end of string not found. */
+ KORTEST %k0, %k3
+ jz L(loop)
+
+ /* If k0 is non zero, end of string found. */
+ KORTEST %k0, %k0
+ jnz L(endloop)
+
+ lea VEC_SIZE(%rdi), %r8
+ /* A match found, it need to be stored in r8 before loop
+ continue. */
+ /* Check second vector first. */
+ KMOV %k2, %VRDX
+ test %VRDX, %VRDX
+ jnz L(loop_vec_x2_match)
+
+ KMOV %k1, %VRDX
+ /* Match is in first vector, rdi offset need to be substracted
+ by VEC_SIZE. */
+ sub $VEC_SIZE, %r8
+
+ /* If second vector doesn't have match, first vector must
+ have match. */
+L(loop_vec_x2_match):
+ BSR %VRDX, %VRDX
+# ifdef USE_AS_WCSRCHR
+ sal $2, %rdx
+# endif
+ add %rdx, %r8
+ jmp L(loop)
+
+L(endloop):
+ /* Check if string end in first loop vector. */
+ VPTESTN %VMM(3), %VMM(3), %k0
+ KMOV %k0, %VRCX
+ test %VRCX, %VRCX
+ jnz L(loop_vector_x1_end)
+
+ /* Check if it has match in first loop vector. */
+ KMOV %k1, %VRAX
+ test %VRAX, %VRAX
+ jz L(loop_vector_x2_end)
+
+ BSR %VRAX, %VRAX
+ leaq (%rdi, %rax, CHAR_SIZE), %r8
+
+ /* String must end in second loop vector. */
+L(loop_vector_x2_end):
+ VPTESTN %VMM(4), %VMM(4), %k0
+ KMOV %k0, %VRCX
+ KMOV %k2, %VRAX
+ BLSMSK %VRCX, %VRCX
+ /* Check if it has match in second loop vector. */
+ and %VRCX, %VRAX
+ jz L(check_last_match)
+
+ BSR %VRAX, %VRAX
+ leaq (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %rax
+ ret
+
+ /* String end in first loop vector. */
+L(loop_vector_x1_end):
+ KMOV %k1, %VRAX
+ BLSMSK %VRCX, %VRCX
+ /* Check if it has match in second loop vector. */
+ and %VRCX, %VRAX
+ jz L(check_last_match)
+
+ BSR %VRAX, %VRAX
+ leaq (%rdi, %rax, CHAR_SIZE), %rax
+ ret
+
+ /* No match in first and second loop vector. */
+L(check_last_match):
+ /* Check if any match recorded in r8. */
+ test %r8, %r8
+ jz L(vector_x2_ret)
+ movq %r8, %rax
+ ret
+
+ /* No match recorded in r8. Check the second saved vector
+ in begining. */
+L(vector_x2_ret):
+ VPCMPEQ %VMM(2), %VMM(0), %k2
+ KMOV %k2, %VRAX
+ test %VRAX, %VRAX
+ jz L(vector_x1_ret)
+
+ /* Match found in the second saved vector. */
+ BSR %VRAX, %VRAX
+ leaq (VEC_SIZE)(%r9, %rax, CHAR_SIZE), %rax
+ ret
+
+L(page_cross):
+ mov %rdi, %rax
+ movl %edi, %ecx
+
+# ifdef USE_AS_WCSRCHR
+ /* Calculate number of compare result bits to be skipped for
+ wide string alignment adjustment. */
+ andl $(VEC_SIZE - 1), %ecx
+ sarl $2, %ecx
+# endif
+ /* ecx contains number of w[char] to be skipped as a result
+ of address alignment. */
+ andq $-VEC_SIZE, %rax
+ VMOVA (%rax), %VMM(1)
+ VPTESTN %VMM(1), %VMM(1), %k1
+ KMOV %k1, %VRAX
+ SHR %cl, %VRAX
+ jz L(page_cross_continue)
+ VPCMPEQ %VMM(1), %VMM(0), %k0
+ KMOV %k0, %VRDX
+ SHR %cl, %VRDX
+ BLSMSK %VRAX, %VRAX
+ and %VRDX, %VRAX
+ jz L(ret)
+ BSR %VRAX, %VRAX
+# ifdef USE_AS_WCSRCHR
+ leaq (%rdi, %rax, CHAR_SIZE), %rax
+# else
+ add %rdi, %rax
+# endif
+
+ ret
+END (STRRCHR)
+#endif
projects / thirdparty / glibc.git / commitdiff
