1# RUN: llvm-mc -mcpu=skylake -filetype=obj -triple x86_64-pc-linux-gnu -x86-pad-max-prefix-size=0 %s | llvm-objdump -d --section=.text - | FileCheck %s 2 3# This test exercises only the padding via relaxation logic. The interaction 4# etween prefix padding and relaxation logic can be seen in align-via-padding.s 5 6 .file "test.c" 7 .text 8 .section .text 9 # Demonstrate that we can relax instructions to provide padding, not 10 # just insert nops. jmps are being used for ease of demonstration. 11 # CHECK: .text 12 # CHECK: 0: eb 1f jmp 0x21 <foo> 13 # CHECK: 2: e9 1a 00 00 00 jmp 0x21 <foo> 14 # CHECK: 7: e9 15 00 00 00 jmp 0x21 <foo> 15 # CHECK: c: e9 10 00 00 00 jmp 0x21 <foo> 16 # CHECK: 11: e9 0b 00 00 00 jmp 0x21 <foo> 17 # CHECK: 16: e9 06 00 00 00 jmp 0x21 <foo> 18 # CHECK: 1b: e9 01 00 00 00 jmp 0x21 <foo> 19 # CHECK: 20: cc int3 20 .p2align 4 21 jmp foo 22 jmp foo 23 jmp foo 24 jmp foo 25 jmp foo 26 jmp foo 27 jmp foo 28 .p2align 5 29 int3 30foo: 31 ret 32 33 # Check that we're not shifting aroudn the offsets of labels - doing 34 # that would require a further round of relaxation 35 # CHECK: <bar>: 36 # CHECK: 22: eb fe jmp 0x22 <bar> 37 # CHECK: 24: 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax) 38 # CHECK: 30: 0f 0b ud2 39 40bar: 41 jmp bar 42nobypass: 43 .p2align 4 44 ud2 45 46 47 # Canonical toy loop to show benefit - we can align the loop header with 48 # fewer nops by relaxing the branch, even though we don't need to 49 # CHECK: <loop_preheader>: 50 # CHECK: 45: 48 85 c0 testq %rax, %rax 51 # CHECK: 48: 0f 8e 22 00 00 00 jle 0x70 <loop_exit> 52 # CHECK: 4e: 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax) 53 # CHECK: 5d: 0f 1f 00 nopl (%rax) 54 # CHECK: <loop_header>: 55 # CHECK: 60: 48 83 e8 01 subq $1, %rax 56 # CHECK: 64: 48 85 c0 testq %rax, %rax 57 # CHECK: 67: 7e 07 jle 0x70 <loop_exit> 58 # CHECK: 69: e9 f2 ff ff ff jmp 0x60 <loop_header> 59 # CHECK: 6e: 66 90 nop 60 # CHECK: <loop_exit>: 61 # CHECK: 70: c3 retq 62 .p2align 5 63 .skip 5 64loop_preheader: 65 testq %rax, %rax 66 jle loop_exit 67 .p2align 5 68loop_header: 69 subq $1, %rax 70 testq %rax, %rax 71 jle loop_exit 72 jmp loop_header 73 .p2align 4 74loop_exit: 75 ret 76