90 lines · plain
1# RUN: llvm-mc -mcpu=skylake -filetype=obj -triple x86_64-pc-linux-gnu -x86-pad-max-prefix-size=0 %s | llvm-objdump --no-print-imm-hex -d - | FileCheck %s --check-prefix=NOPAD2# 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 --no-print-imm-hex -d - | FileCheck %s3 4# This test exercises only the padding via relaxation logic. The interaction5# etween prefix padding and relaxation logic can be seen in align-via-padding.s6 7 .file "test.c"8 .text9 .section .text10 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 int322 23 # Demonstrate that we can relax instructions to provide padding, not24 # just insert nops. jmps are being used for ease of demonstration.25 # CHECK: .text26 # 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 int334 .p2align 435 jmp foo36 jmp foo37 jmp foo38 jmp foo39 jmp foo40 jmp foo41 jmp foo42 .p2align 543 int344foo:45 ret46 47 # Check that we're not shifting aroudn the offsets of labels - doing48 # that would require a further round of relaxation49 # 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 ud253 54bar: 55 jmp bar56nobypass:57 .p2align 458 ud259 60 61 # Canonical toy loop to show benefit - we can align the loop header with62 # fewer nops by relaxing the branch, even though we don't need to63 # CHECK: <loop_preheader>:64 # CHECK: 45: 48 85 c0 testq %rax, %rax65 # 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, %rax70 # CHECK: 64: 48 85 c0 testq %rax, %rax71 # 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 nop74 # CHECK: <loop_exit>:75 # CHECK: 70: c3 retq76 .p2align 577 .skip 578loop_preheader:79 testq %rax, %rax80 jle loop_exit81 .p2align 582loop_header:83 subq $1, %rax84 testq %rax, %rax85 jle loop_exit86 jmp loop_header87 .p2align 488loop_exit:89 ret90