# RUN: llvm-mc -mcpu=skylake -filetype=obj -triple x86_64-pc-linux-gnu %s -x86-pad-max-prefix-size=5 -x86-pad-for-align=1 | llvm-objdump -d - | FileCheck %s # This test file highlights the interactions between prefix padding and # relaxation padding. .file "test.c" .text .section .text # We can both relax and prefix for padding purposes, but the moment, we # can't prefix without first having relaxed. # CHECK: .text # CHECK: 0: eb 1f jmp # CHECK: 2: eb 1d jmp # CHECK: 4: eb 1b jmp # CHECK: 6: eb 19 jmp # CHECK: 8: eb 17 jmp # CHECK: a: 2e 2e 2e 2e 2e e9 0d 00 00 00 jmp # CHECK: 14: 2e 2e 2e 2e 2e e9 03 00 00 00 jmp # CHECK: 1e: 66 90 nop # CHECK: 20: cc int3 .p2align 4 jmp foo jmp foo jmp foo jmp foo jmp foo jmp foo jmp foo .p2align 5 int3 foo: ret # Canonical toy loop to show benefit - we can align the loop header with # fewer nops by relaxing the branch, even though we don't need to # CHECK: : # CHECK: 45: 48 85 c0 testq %rax, %rax # CHECK: 48: 2e 2e 2e 2e 0f 8e 1e 00 00 00 jle 0x70 # CHECK: 52: 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax) # CHECK: : # CHECK: 60: 48 83 e8 01 subq $1, %rax # CHECK: 64: 48 85 c0 testq %rax, %rax # CHECK: 67: 7e 07 jle 0x70 # CHECK: 69: 2e 2e e9 f0 ff ff ff jmp # CHECK: : # CHECK: 70: c3 retq .p2align 5 .skip 5 loop_preheader: testq %rax, %rax jle loop_exit .p2align 5 loop_header: subq $1, %rax testq %rax, %rax jle loop_exit jmp loop_header .p2align 4 loop_exit: ret # Correctness cornercase - can't prefix pad jmp without having relaxed it # first as doing so would make the relative offset too large # CHECK: fd: cc int3 # CHECK: fe: eb 80 jmp 0x80 # CHECK: 100: cc int3 .p2align 5 .L1: .rept 126 int3 .endr jmp .L1 .rept 30 int3 .endr .p2align 5