+ .quad memset
+ .quad memset_c
+ .byte X86_FEATURE_REP_GOOD
+ .byte memset_c_end-memset_c
+ .byte memset_c_end-memset_c
+ .previous
+
+ .section .altinstr_replacement,"ax"
+ /* rdi destination
+ * rsi value
+ * rdx count
+ */
+memset_c:
+ movq %rdi,%r9
+ movl %edx,%r8d
+ andl $7,%r8d
+ movl %edx,%ecx
+ shrl $3,%ecx
+ /* expand byte value */
+ movzbl %sil,%esi
+ movabs $0x0101010101010101,%rax
+ mulq %rsi /* with rax, clobbers rdx */
+ rep
+ stosq
+ movl %r8d,%ecx
+ rep
+ stosb
+ movq %r9,%rax
+ ret
+memset_c_end: