77 lines
2.3 KiB
ArmAsm
77 lines
2.3 KiB
ArmAsm
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# 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
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# This test file highlights the interactions between prefix padding and
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# relaxation padding.
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.file "test.c"
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.text
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.section .text
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# We can both relax and prefix for padding purposes, but the moment, we
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# can't prefix without first having relaxed.
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# CHECK: .text
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# CHECK: 0: eb 1f jmp
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# CHECK: 2: eb 1d jmp
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# CHECK: 4: eb 1b jmp
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# CHECK: 6: eb 19 jmp
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# CHECK: 8: eb 17 jmp
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# CHECK: a: 2e 2e 2e 2e 2e e9 0d 00 00 00 jmp
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# CHECK: 14: 2e 2e 2e 2e 2e e9 03 00 00 00 jmp
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# CHECK: 1e: 66 90 nop
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# CHECK: 20: cc int3
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.p2align 4
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jmp foo
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jmp foo
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jmp foo
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jmp foo
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jmp foo
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jmp foo
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jmp foo
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.p2align 5
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int3
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foo:
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ret
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# Canonical toy loop to show benefit - we can align the loop header with
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# fewer nops by relaxing the branch, even though we don't need to
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# CHECK: <loop_preheader>:
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# CHECK: 45: 48 85 c0 testq %rax, %rax
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# CHECK: 48: 2e 2e 2e 2e 0f 8e 1e 00 00 00 jle 0x70 <loop_exit>
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# CHECK: 52: 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:(%rax,%rax)
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# CHECK: <loop_header>:
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# CHECK: 60: 48 83 e8 01 subq $1, %rax
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# CHECK: 64: 48 85 c0 testq %rax, %rax
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# CHECK: 67: 7e 07 jle 0x70 <loop_exit>
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# CHECK: 69: 2e 2e e9 f0 ff ff ff jmp
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# CHECK: <loop_exit>:
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# CHECK: 70: c3 retq
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.p2align 5
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.skip 5
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loop_preheader:
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testq %rax, %rax
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jle loop_exit
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.p2align 5
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loop_header:
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subq $1, %rax
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testq %rax, %rax
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jle loop_exit
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jmp loop_header
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.p2align 4
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loop_exit:
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ret
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# Correctness cornercase - can't prefix pad jmp without having relaxed it
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# first as doing so would make the relative offset too large
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# CHECK: fd: cc int3
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# CHECK: fe: eb 80 jmp 0x80 <loop_exit+0x10>
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# CHECK: 100: cc int3
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.p2align 5
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.L1:
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.rept 126
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int3
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.endr
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jmp .L1
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.rept 30
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int3
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.endr
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.p2align 5
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