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The `REVERSE` keyword is described here: https://sourceware.org/bugzilla/show_bug.cgi?id=27565 It complements `SORT` by allowing the order of input sections to be reversed. This is particularly useful for order-dependent sections such as .init_array, where `REVERSE` can be used to either detect static initialization order fiasco issues or as a mechanism to maintain .ctors element order while transitioning to the modern .init_array. Such a transition is described here: https://discourse.llvm.org/t/is-it-possible-to-manually-specify-init-array-order/68649 Differential Revision: https://reviews.llvm.org/D145381
60 lines
1.4 KiB
ArmAsm
60 lines
1.4 KiB
ArmAsm
# REQUIRES: x86
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## Test SORT_BY_INIT_PRIORITY can be used to convert .ctors into .init_array
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# RUN: split-file %s %t
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# RUN: llvm-mc -filetype=obj -triple=x86_64 %t/asm -o %t.o
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# RUN: ld.lld -T %t/lds %t.o -o %t.out
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# RUN: llvm-readelf -x .init_array %t.out | FileCheck %s
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# CHECK: Hex dump of section '.init_array':
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# CHECK-NEXT: 0x00000001 00010203 04050607
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## Test REVERSE can be used to reverse the order of .init_array and .ctors
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# RUN: ld.lld -T %t/reverse.lds %t.o -o %t2.out
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# RUN: llvm-readelf -x .init_array %t2.out | FileCheck %s --check-prefix=CHECK2
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# CHECK2: Hex dump of section '.init_array':
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# CHECK2-NEXT: 0x00000001 04030201 00050706
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#--- asm
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.globl _start
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_start:
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nop
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.section foo, "aw", @init_array
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.byte 5
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.section .ctors.65435, "a"
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.byte 3
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.section .init_array.100, "aw", @init_array
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.byte 4
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.section .init_array.7, "aw", @init_array
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.byte 2
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.section .ctors.65529,"a"
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.byte 1
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.section .init_array.5, "aw", @init_array
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.byte 0
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.section .init_array, "aw", @init_array
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.byte 6
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.section .ctors, "a"
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.byte 7
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#--- lds
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SECTIONS {
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.init_array : {
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*(SORT_BY_INIT_PRIORITY(.init_array.* .ctors.*) SORT_BY_INIT_PRIORITY(foo*))
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*(.init_array .ctors)
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}
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}
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#--- reverse.lds
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SECTIONS {
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.init_array : {
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*(REVERSE(SORT_BY_INIT_PRIORITY(.init_array.* .ctors.*)) SORT_BY_INIT_PRIORITY(foo*))
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*(REVERSE(.init_array .ctors))
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}
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}
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