deleted file mode 100644
@@ -1,136 +0,0 @@
-/* memcpy for RISC-V, ignoring buffer alignment
- Copyright (C) 2024 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/>. */
-
-#include <sysdep.h>
-#include <sys/asm.h>
-
-/* void *memcpy(void *, const void *, size_t) */
-ENTRY (__memcpy_noalignment)
- move t6, a0 /* Preserve return value */
-
- /* Bail if 0 */
- beqz a2, 7f
-
- /* Jump to byte copy if size < SZREG */
- li a4, SZREG
- bltu a2, a4, 5f
-
- /* Round down to the nearest "page" size */
- andi a4, a2, ~((16*SZREG)-1)
- beqz a4, 2f
- add a3, a1, a4
-
- /* Copy the first word to get dest word aligned */
- andi a5, t6, SZREG-1
- beqz a5, 1f
- REG_L a6, (a1)
- REG_S a6, (t6)
-
- /* Align dst up to a word, move src and size as well. */
- addi t6, t6, SZREG-1
- andi t6, t6, ~(SZREG-1)
- sub a5, t6, a0
- add a1, a1, a5
- sub a2, a2, a5
-
- /* Recompute page count */
- andi a4, a2, ~((16*SZREG)-1)
- beqz a4, 2f
-
-1:
- /* Copy "pages" (chunks of 16 registers) */
- REG_L a4, 0(a1)
- REG_L a5, SZREG(a1)
- REG_L a6, 2*SZREG(a1)
- REG_L a7, 3*SZREG(a1)
- REG_L t0, 4*SZREG(a1)
- REG_L t1, 5*SZREG(a1)
- REG_L t2, 6*SZREG(a1)
- REG_L t3, 7*SZREG(a1)
- REG_L t4, 8*SZREG(a1)
- REG_L t5, 9*SZREG(a1)
- REG_S a4, 0(t6)
- REG_S a5, SZREG(t6)
- REG_S a6, 2*SZREG(t6)
- REG_S a7, 3*SZREG(t6)
- REG_S t0, 4*SZREG(t6)
- REG_S t1, 5*SZREG(t6)
- REG_S t2, 6*SZREG(t6)
- REG_S t3, 7*SZREG(t6)
- REG_S t4, 8*SZREG(t6)
- REG_S t5, 9*SZREG(t6)
- REG_L a4, 10*SZREG(a1)
- REG_L a5, 11*SZREG(a1)
- REG_L a6, 12*SZREG(a1)
- REG_L a7, 13*SZREG(a1)
- REG_L t0, 14*SZREG(a1)
- REG_L t1, 15*SZREG(a1)
- addi a1, a1, 16*SZREG
- REG_S a4, 10*SZREG(t6)
- REG_S a5, 11*SZREG(t6)
- REG_S a6, 12*SZREG(t6)
- REG_S a7, 13*SZREG(t6)
- REG_S t0, 14*SZREG(t6)
- REG_S t1, 15*SZREG(t6)
- addi t6, t6, 16*SZREG
- bltu a1, a3, 1b
- andi a2, a2, (16*SZREG)-1 /* Update count */
-
-2:
- /* Remainder is smaller than a page, compute native word count */
- beqz a2, 7f
- andi a5, a2, ~(SZREG-1)
- andi a2, a2, (SZREG-1)
- add a3, a1, a5
- /* Jump directly to last word if no words. */
- beqz a5, 4f
-
-3:
- /* Use single native register copy */
- REG_L a4, 0(a1)
- addi a1, a1, SZREG
- REG_S a4, 0(t6)
- addi t6, t6, SZREG
- bltu a1, a3, 3b
-
- /* Jump directly out if no more bytes */
- beqz a2, 7f
-
-4:
- /* Copy the last word unaligned */
- add a3, a1, a2
- add a4, t6, a2
- REG_L a5, -SZREG(a3)
- REG_S a5, -SZREG(a4)
- ret
-
-5:
- /* Copy bytes when the total copy is <SZREG */
- add a3, a1, a2
-
-6:
- lb a4, 0(a1)
- addi a1, a1, 1
- sb a4, 0(t6)
- addi t6, t6, 1
- bltu a1, a3, 6b
-
-7:
- ret
-
-END (__memcpy_noalignment)
similarity index 87%
rename from sysdeps/unix/sysv/linux/riscv/memcpy-generic.c
rename to sysdeps/riscv/multiarch/memcpy-generic.c
@@ -18,7 +18,9 @@
#include <string.h>
-extern __typeof (memcpy) __memcpy_generic;
-hidden_proto (__memcpy_generic)
-
+#if IS_IN(libc)
+# define MEMCPY __memcpy_generic
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(x)
+#endif
#include <string/memcpy.c>
new file mode 100644
@@ -0,0 +1,162 @@
+/* memcpy for RISC-V, ignoring buffer alignment
+ Copyright (C) 2024 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/>. */
+
+#include <sysdep.h>
+#include <sys/asm.h>
+
+/* memcpy optimization for CPUs with fast unaligned support
+ (RISCV_HWPROBE_MISALIGNED_FAST).
+
+ Copies are split into 3 main cases: small copies up to SZREG, copies up to
+ BLOCK_SIZE (128 for 64 bits, 64 for 32 bits), and copies larger than BLOCK_SIZE.
+
+ Large copies use a software pipelined loop processing BLOCK_SIZE bytes per
+ iteration. The destination pointer is SZREG-byte aligned to minimize store
+ unaligned accesses.
+
+ The tail is handled with branchless copies. */
+
+#define BLOCK_SIZE (16 * SZREG)
+
+ .attribute unaligned_access, 1
+ENTRY (__memcpy_noalignment)
+ beq a2, zero, L(ret)
+
+ /* if LEN < SZREG jump to tail handling. */
+ li a5, SZREG-1
+ mv a6, a0
+ bleu a2, a5, L(tail)
+
+ /* Copy the first word, align DEST to word, and adjust DEST/SRC/LEN
+ based on the amount adjusted to align DEST. */
+ REG_L a3, 0(a1)
+ andi a5, a0, SZREG-1
+ addi a2, a2, -SZREG
+ li a4, SZREG
+ sub a4, a4, a5
+ REG_S a3, 0(a0)
+ add a2, a5, a2
+
+ /* If LEN < BLOCK_SIZE jump to word copy. */
+ li a3, BLOCK_SIZE-1
+ add a5, a0, a4
+ add a1, a1, a4
+ bleu a2, a3, L(word_copy_adjust)
+ addi a7, a2, -BLOCK_SIZE
+ andi a7, a7, -BLOCK_SIZE
+ addi a7, a7, BLOCK_SIZE
+ add a3, a5, a7
+ mv a4, a1
+L(block_copy):
+ REG_L a6, 0(a4)
+ REG_L t0, SZREG(a4)
+ REG_L t1, (2*SZREG)(a4)
+ REG_L t2, (3*SZREG)(a4)
+ REG_L t3, (4*SZREG)(a4)
+ REG_L t4, (5*SZREG)(a4)
+ REG_L t5, (6*SZREG)(a4)
+ REG_L t6, (7*SZREG)(a4)
+ REG_S a6, 0(a5)
+ REG_S t0, SZREG(a5)
+ REG_S t1, (2*SZREG)(a5)
+ REG_S t2, (3*SZREG)(a5)
+ REG_S t3, (4*SZREG)(a5)
+ REG_S t4, (5*SZREG)(a5)
+ REG_S t5, (6*SZREG)(a5)
+ REG_S t6, (7*SZREG)(a5)
+ REG_L a6, (8*SZREG)(a4)
+ REG_L t0, (9*SZREG)(a4)
+ REG_L t1, (10*SZREG)(a4)
+ REG_L t2, (11*SZREG)(a4)
+ REG_L t3, (12*SZREG)(a4)
+ REG_L t4, (13*SZREG)(a4)
+ REG_L t5, (14*SZREG)(a4)
+ REG_L t6, (15*SZREG)(a4)
+ addi a4, a4, BLOCK_SIZE
+ REG_S a6, (8*SZREG)(a5)
+ REG_S t0, (9*SZREG)(a5)
+ REG_S t1, (10*SZREG)(a5)
+ REG_S t2, (11*SZREG)(a5)
+ REG_S t3, (12*SZREG)(a5)
+ REG_S t4, (13*SZREG)(a5)
+ REG_S t5, (14*SZREG)(a5)
+ REG_S t6, (15*SZREG)(a5)
+ addi a5, a5, BLOCK_SIZE
+ bne a5, a3, L(block_copy)
+ add a1, a1, a7
+ andi a2, a2, BLOCK_SIZE-1
+
+ /* 0 <= a2/LEN < BLOCK_SIZE. */
+L(word_copy):
+ li a5, SZREG-1
+ /* if LEN < SZREG jump to tail handling. */
+ bleu a2, a5, L(tail_adjust)
+ addi a7, a2, -SZREG
+ andi a7, a7, -SZREG
+ addi a7, a7, SZREG
+ add a6, a3, a7
+ mv a5, a1
+L(word_copy_loop):
+ REG_L a4, 0(a5)
+ addi a3, a3, SZREG
+ addi a5, a5, SZREG
+ REG_S a4, -SZREG(a3)
+ bne a3, a6, L(word_copy_loop)
+ add a1, a1, a7
+ andi a2, a2, SZREG-1
+
+ /* Copy the last word unaligned. */
+ add a3, a1, a2
+ add a4, a6, a2
+ REG_L t0, -SZREG(a3)
+ REG_S t0, -SZREG(a4)
+ ret
+
+L(tail):
+ /* Copy 4-7 bytes. */
+ andi a5, a2, 4
+ add a3, a1, a2
+ add a4, a6, a2
+ beq a5, zero, L(copy_0_3)
+ lw t0, 0(a1)
+ lw t1, -4(a3)
+ sw t0, 0(a6)
+ sw t1, -4(a4)
+ ret
+
+ /* Copy 0-3 bytes. */
+L(copy_0_3):
+ beq a2, zero, L(ret)
+ srli a2, a2, 1
+ add t4, a1, a2
+ add t5, a6, a2
+ lbu t0, 0(a1)
+ lbu t1, -1(a3)
+ lbu t2, 0(t4)
+ sb t0, 0(a6)
+ sb t1, -1(a4)
+ sb t2, 0(t5)
+L(ret):
+ ret
+L(tail_adjust):
+ mv a6, a3
+ j L(tail)
+L(word_copy_adjust):
+ mv a3, a5
+ j L(word_copy)
+END (__memcpy_noalignment)
@@ -15,15 +15,6 @@ ifeq ($(subdir),stdlib)
gen-as-const-headers += ucontext_i.sym
endif
-ifeq ($(subdir),string)
-sysdep_routines += \
- memcpy \
- memcpy-generic \
- memcpy_noalignment \
- # sysdep_routines
-
-endif
-
abi-variants := ilp32 ilp32d lp64 lp64d
ifeq (,$(filter $(default-abi),$(abi-variants)))
@@ -34,3 +34,4 @@ int __riscv_hwprobe (struct riscv_hwprobe *pairs, size_t pair_count,
/* Negate negative errno values to match pthreads API. */
return -r;
}
+libc_hidden_def (__riscv_hwprobe)
new file mode 100644
@@ -0,0 +1,8 @@
+#ifndef _SYS_HWPROBE_H
+# include_next <sys/hwprobe.h>
+
+#ifndef _ISOMAC
+libc_hidden_proto (__riscv_hwprobe)
+#endif
+
+#endif
new file mode 100644
@@ -0,0 +1,9 @@
+ifeq ($(subdir),string)
+sysdep_routines += \
+ memcpy \
+ memcpy-generic \
+ memcpy_noalignment \
+ # sysdep_routines
+
+CFLAGS-memcpy_noalignment.c += -mno-strict-align
+endif
similarity index 51%
rename from sysdeps/riscv/memcopy.h
rename to sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
@@ -1,4 +1,4 @@
-/* memcopy.h -- definitions for memory copy functions. RISC-V version.
+/* Enumerate available IFUNC implementations of a function. RISCV version.
Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
@@ -16,11 +16,28 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <sysdeps/generic/memcopy.h>
+#include <ifunc-impl-list.h>
+#include <string.h>
+#include <sys/hwprobe.h>
-/* Redefine the generic memcpy implementation to __memcpy_generic, so
- the memcpy ifunc can select between generic and special versions.
- In rtld, don't bother with all the ifunciness. */
-#if IS_IN (libc)
-#define MEMCPY __memcpy_generic
-#endif
+size_t
+__libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
+ size_t max)
+{
+ size_t i = max;
+
+ bool fast_unaligned = false;
+
+ struct riscv_hwprobe pair = { .key = RISCV_HWPROBE_KEY_CPUPERF_0 };
+ if (__riscv_hwprobe (&pair, 1, 0, NULL, 0) == 0
+ && (pair.value & RISCV_HWPROBE_MISALIGNED_MASK)
+ == RISCV_HWPROBE_MISALIGNED_FAST)
+ fast_unaligned = true;
+
+ IFUNC_IMPL (i, name, memcpy,
+ IFUNC_IMPL_ADD (array, i, memcpy, fast_unaligned,
+ __memcpy_noalignment)
+ IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_generic))
+
+ return 0;
+}
similarity index 90%
rename from sysdeps/riscv/memcpy.c
rename to sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c
@@ -28,8 +28,6 @@
# include <riscv-ifunc.h>
# include <sys/hwprobe.h>
-# define INIT_ARCH()
-
extern __typeof (__redirect_memcpy) __libc_memcpy;
extern __typeof (__redirect_memcpy) __memcpy_generic attribute_hidden;
@@ -38,14 +36,9 @@ extern __typeof (__redirect_memcpy) __memcpy_noalignment attribute_hidden;
static inline __typeof (__redirect_memcpy) *
select_memcpy_ifunc (uint64_t dl_hwcap, __riscv_hwprobe_t hwprobe_func)
{
- unsigned long long int value;
-
- INIT_ARCH ();
-
- if (__riscv_hwprobe_one (hwprobe_func, RISCV_HWPROBE_KEY_CPUPERF_0, &value) != 0)
- return __memcpy_generic;
-
- if ((value & RISCV_HWPROBE_MISALIGNED_MASK) == RISCV_HWPROBE_MISALIGNED_FAST)
+ unsigned long long int v;
+ if (__riscv_hwprobe_one (hwprobe_func, RISCV_HWPROBE_KEY_CPUPERF_0, &v) == 0
+ && (v & RISCV_HWPROBE_MISALIGNED_MASK) == RISCV_HWPROBE_MISALIGNED_FAST)
return __memcpy_noalignment;
return __memcpy_generic;
@@ -59,5 +52,6 @@ strong_alias (__libc_memcpy, memcpy);
__hidden_ver1 (memcpy, __GI_memcpy, __redirect_memcpy)
__attribute__ ((visibility ("hidden"))) __attribute_copy__ (memcpy);
# endif
-
+#else
+# include <string/memcpy.c>
#endif
The memcpy optimization (commit 587a1290a1af7bee6db) has a series of mistakes: - The implementation is wrong: the chunk size calculation is wrong leading to invalid memory access. - It adds ifunc supports as default, so --disable-multi-arch does not work as expected for riscv. - It mixes Linux files (memcpy ifunc selection which requires the vDSO/syscall mechanism) with generic support (the memcpy optimization itself). - There is no __libc_ifunc_impl_list, which makes testing only check the selected implementation instead of all supported by the system. This patch also simplifies the required bits to enable ifunc: there is no need to memcopy.h; nor to add Linux-specific files. The __memcpy_noalignment tail handling now uses a branchless strategy similar to aarch64 (overlap 32-bits copies for sizes 4..7 and byte copies for size 1..3). Checked on riscv64 and riscv32 by explicitly enabling the function on __libc_ifunc_impl_list on qemu-system. Changes from v1: * Implement the memcpy in assembly to correctly handle RISCV strict-alignment. --- sysdeps/riscv/memcpy_noalignment.S | 136 --------------- .../multiarch}/memcpy-generic.c | 8 +- sysdeps/riscv/multiarch/memcpy_noalignment.S | 162 ++++++++++++++++++ sysdeps/unix/sysv/linux/riscv/Makefile | 9 - sysdeps/unix/sysv/linux/riscv/hwprobe.c | 1 + .../sysv/linux/riscv/include/sys/hwprobe.h | 8 + .../unix/sysv/linux/riscv/multiarch/Makefile | 9 + .../linux/riscv/multiarch/ifunc-impl-list.c} | 33 +++- .../sysv/linux/riscv/multiarch}/memcpy.c | 16 +- 9 files changed, 215 insertions(+), 167 deletions(-) delete mode 100644 sysdeps/riscv/memcpy_noalignment.S rename sysdeps/{unix/sysv/linux/riscv => riscv/multiarch}/memcpy-generic.c (87%) create mode 100644 sysdeps/riscv/multiarch/memcpy_noalignment.S create mode 100644 sysdeps/unix/sysv/linux/riscv/include/sys/hwprobe.h create mode 100644 sysdeps/unix/sysv/linux/riscv/multiarch/Makefile rename sysdeps/{riscv/memcopy.h => unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c} (51%) rename sysdeps/{riscv => unix/sysv/linux/riscv/multiarch}/memcpy.c (90%)