1# RUN: llvm-mc -mcpu=skylake -filetype=obj -triple x86_64-pc-linux-gnu -x86-pad-max-prefix-size=0 %s | llvm-objdump -d - | FileCheck %s --check-prefix=NOPAD 2# RUN: llvm-mc -mcpu=skylake -filetype=obj -triple x86_64-pc-linux-gnu -x86-pad-max-prefix-size=0 -x86-pad-for-align=1 %s | llvm-objdump -d - | FileCheck %s 3 4# This test exercises only the padding via relaxation logic. The interaction 5# etween prefix padding and relaxation logic can be seen in align-via-padding.s 6 7 .file "test.c" 8 .text 9 .section .text 10 11# NOPAD-LABEL: <.text>: 12# NOPAD-NEXT: 0: eb 1f jmp 0x21 <foo> 13# NOPAD-NEXT: 2: eb 1d jmp 0x21 <foo> 14# NOPAD-NEXT: 4: eb 1b jmp 0x21 <foo> 15# NOPAD-NEXT: 6: eb 19 jmp 0x21 <foo> 16# NOPAD-NEXT: 8: eb 17 jmp 0x21 <foo> 17# NOPAD-NEXT: a: eb 15 jmp 0x21 <foo> 18# NOPAD-NEXT: c: eb 13 jmp 0x21 <foo> 19# NOPAD-NEXT: e: 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax) 20# NOPAD-NEXT: 1d: 0f 1f 00 nopl (%rax) 21# NOPAD-NEXT: 20: cc int3 22 23 # Demonstrate that we can relax instructions to provide padding, not 24 # just insert nops. jmps are being used for ease of demonstration. 25 # CHECK: .text 26 # CHECK: 0: eb 1f jmp 0x21 <foo> 27 # CHECK: 2: e9 1a 00 00 00 jmp 0x21 <foo> 28 # CHECK: 7: e9 15 00 00 00 jmp 0x21 <foo> 29 # CHECK: c: e9 10 00 00 00 jmp 0x21 <foo> 30 # CHECK: 11: e9 0b 00 00 00 jmp 0x21 <foo> 31 # CHECK: 16: e9 06 00 00 00 jmp 0x21 <foo> 32 # CHECK: 1b: e9 01 00 00 00 jmp 0x21 <foo> 33 # CHECK: 20: cc int3 34 .p2align 4 35 jmp foo 36 jmp foo 37 jmp foo 38 jmp foo 39 jmp foo 40 jmp foo 41 jmp foo 42 .p2align 5 43 int3 44foo: 45 ret 46 47 # Check that we're not shifting aroudn the offsets of labels - doing 48 # that would require a further round of relaxation 49 # CHECK: <bar>: 50 # CHECK: 22: eb fe jmp 0x22 <bar> 51 # CHECK: 24: 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax) 52 # CHECK: 30: 0f 0b ud2 53 54bar: 55 jmp bar 56nobypass: 57 .p2align 4 58 ud2 59 60 61 # Canonical toy loop to show benefit - we can align the loop header with 62 # fewer nops by relaxing the branch, even though we don't need to 63 # CHECK: <loop_preheader>: 64 # CHECK: 45: 48 85 c0 testq %rax, %rax 65 # CHECK: 48: 0f 8e 22 00 00 00 jle 0x70 <loop_exit> 66 # CHECK: 4e: 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax) 67 # CHECK: 5d: 0f 1f 00 nopl (%rax) 68 # CHECK: <loop_header>: 69 # CHECK: 60: 48 83 e8 01 subq $1, %rax 70 # CHECK: 64: 48 85 c0 testq %rax, %rax 71 # CHECK: 67: 7e 07 jle 0x70 <loop_exit> 72 # CHECK: 69: e9 f2 ff ff ff jmp 0x60 <loop_header> 73 # CHECK: 6e: 66 90 nop 74 # CHECK: <loop_exit>: 75 # CHECK: 70: c3 retq 76 .p2align 5 77 .skip 5 78loop_preheader: 79 testq %rax, %rax 80 jle loop_exit 81 .p2align 5 82loop_header: 83 subq $1, %rax 84 testq %rax, %rax 85 jle loop_exit 86 jmp loop_header 87 .p2align 4 88loop_exit: 89 ret 90