# 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 --no-print-imm-hex -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: <loop_preheader>:
# CHECK: 45: 48 85 c0 testq %rax, %rax
# CHECK: 48: 2e 2e 2e 2e 0f 8e 1e 00 00 00 jle 0x70 <loop_exit>
# CHECK: 52: 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax)
# CHECK: <loop_header>:
# CHECK: 60: 48 83 e8 01 subq $1, %rax
# CHECK: 64: 48 85 c0 testq %rax, %rax
# CHECK: 67: 7e 07 jle 0x70 <loop_exit>
# CHECK: 69: 2e 2e e9 f0 ff ff ff jmp
# CHECK: <loop_exit>:
# 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 <loop_exit+0x10>
# CHECK: 100: cc int3
.p2align 5
.L1:
.rept 126
int3
.endr
jmp .L1
.rept 30
int3
.endr
.p2align 5
Codebase Browser
llvm