1 # When trying (and failing) to instrument at the basic block level 2 # I thought up a lot of corner-cases in the rep code. This tries 3 # to catch some of them 4 5 # Performance counters give us 8207 insns 6 # 11 + 8*1024 + 3 = 8206 7 8 .globl _start 9 _start: 10 cld # we want these to happen forward 11 12 mov $0xfeb131978,%rax # value to store 13 14 # test back-to-back rep/stosb's 15 16 mov $1024,%rcx 17 mov $buffer1, %rdi # set destination 18 rep stosb # store 1024 times 19 rep stosb # should store 0 times 20 rep stosb # should store 0 times 21 22 23 # test stosb where cx is 0 24 25 xor %rcx,%rcx 26 mov $buffer1, %rdi # set destination 27 rep stosb # should not load at all 28 29 # test rep inside of a loop 30 31 mov $1024, %rbx 32 rep_loop: 33 34 mov $1024,%rcx 35 mov $buffer1, %rdi # set destination 36 rep stosb 37 38 mov $1024,%rcx 39 mov $buffer1, %rdi # set destination 40 rep stosb 41 42 dec %rbx 43 jnz rep_loop 44 45 46 #================================ 47 # Exit 48 #================================ 49 exit: 50 mov $60,%rax 51 xor %rdi,%rdi # we return 0 52 syscall # and exit 53 54 55 .bss 56 57 .lcomm buffer1, 16384 58 59
