# 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=NOPAD
# 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 %s
# This test exercises only the padding via relaxation logic. The interaction
# etween prefix padding and relaxation logic can be seen in align-via-padding.s
.file "test.c"
.text
.section .text
# NOPAD-LABEL: <.text>:
# NOPAD-NEXT: 0: eb 1f jmp 0x21 <foo>
# NOPAD-NEXT: 2: eb 1d jmp 0x21 <foo>
# NOPAD-NEXT: 4: eb 1b jmp 0x21 <foo>
# NOPAD-NEXT: 6: eb 19 jmp 0x21 <foo>
# NOPAD-NEXT: 8: eb 17 jmp 0x21 <foo>
# NOPAD-NEXT: a: eb 15 jmp 0x21 <foo>
# NOPAD-NEXT: c: eb 13 jmp 0x21 <foo>
# NOPAD-NEXT: e: 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax)
# NOPAD-NEXT: 1d: 0f 1f 00 nopl (%rax)
# NOPAD-NEXT: 20: cc int3
# Demonstrate that we can relax instructions to provide padding, not
# just insert nops. jmps are being used for ease of demonstration.
# CHECK: .text
# CHECK: 0: eb 1f jmp 0x21 <foo>
# CHECK: 2: e9 1a 00 00 00 jmp 0x21 <foo>
# CHECK: 7: e9 15 00 00 00 jmp 0x21 <foo>
# CHECK: c: e9 10 00 00 00 jmp 0x21 <foo>
# CHECK: 11: e9 0b 00 00 00 jmp 0x21 <foo>
# CHECK: 16: e9 06 00 00 00 jmp 0x21 <foo>
# CHECK: 1b: e9 01 00 00 00 jmp 0x21 <foo>
# 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
# Check that we're not shifting aroudn the offsets of labels - doing
# that would require a further round of relaxation
# CHECK: <bar>:
# CHECK: 22: eb fe jmp 0x22 <bar>
# CHECK: 24: 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax)
# CHECK: 30: 0f 0b ud2
bar:
jmp bar
nobypass:
.p2align 4
ud2
# 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: 0f 8e 22 00 00 00 jle 0x70 <loop_exit>
# CHECK: 4e: 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax)
# CHECK: 5d: 0f 1f 00 nopl (%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: e9 f2 ff ff ff jmp 0x60 <loop_header>
# CHECK: 6e: 66 90 nop
# 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
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