glibc/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile

ifeq ($(subdir),string)
sysdep_routines += \
  memcpy \
  memcpy-generic \
  memcpy_noalignment \
  # sysdep_routines

CFLAGS-memcpy_noalignment.c += -mno-strict-align
endif
riscv: Fix alignment-ignorant memcpy implementation 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. Reviewed-by: Evan Green <evan@rivosinc.com> Acked-by: Palmer Dabbelt <palmer@rivosinc.com> 2024-03-05 17:02:57 +00:00			`ifeq ($(subdir),string)`
			`sysdep_routines += \`
			`memcpy \`
			`memcpy-generic \`
			`memcpy_noalignment \`
			`# sysdep_routines`

			`CFLAGS-memcpy_noalignment.c += -mno-strict-align`
			`endif`