ARM + gcc：在 main() returns 之后不调用全局析构函数，但构造函数是
ARM + gcc: global destructors not called after main() returns, but constructors are
我正在尝试编写一个简单的“Hello, World!” Cortex-M0 的固件 CPU。目标是正确初始化和关闭 C++ 运行time，以便在 main() 之前调用全局构造函数，在 main()[ 之后调用全局析构函数=52=]。
到目前为止，我成功地完成了其中一半的工作——全局 ctors 运行 正确，但全局析构函数没有。我在 Windows 上使用 gcc 和 Newlib，它应该初始化 运行time.
struct Test {
Test() // This is invoked correctly.
{}
~Test() // This is not invoked at all.
{}
};
Test test;
int main()
{
return 0;
}
extern void __libc_init_array();
extern void __libc_fini_array();
void reset_handler() // This is the entry point.
{
__libc_init_array(); // Test::Test().
asm volatile( "bl main" ); // Invoke 'main'.
__libc_fini_array(); // Expect Test::~Test() but nothing happens.
}
我已经做了很多研究，似乎对于 ARM 编译器应该为全局构造函数生成一个名为 .init_array 的部分，并且 .fini_array，对于全局析构函数，它将指针指向要调用的函数。然后，链接器会将所有单元的部分合并在一起，__libc_init_array 将“遍历”该部分并调用相应的函数。
这是链接描述文件的相关部分：
/* Initialization functions which run before main(),
such as global constructors. */
.init_array : ALIGN( 4 ) {
/* preinit data */
PROVIDE_HIDDEN ( __preinit_array_start = . );
KEEP( *( .preinit_array ) )
PROVIDE_HIDDEN( __preinit_array_end = . );
. = ALIGN(4);
/* init data */
PROVIDE_HIDDEN ( __init_array_start = . );
KEEP( *( SORT( .init_array.* ) ) )
KEEP(*(.init_array))
PROVIDE_HIDDEN ( __init_array_end = . );
} > flash
/* Finalization functions which run after main(),
such as global destructors. */
.fini_array : ALIGN( 4 ) {
/* finit data */
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP ( *( .fini_array.* ) )
KEEP ( *( .fini_array ) )
PROVIDE_HIDDEN (__fini_array_end = .);
} > flash
但是，让我担心的是，当我转储 目标文件 、main.o 时，甚至连可执行文件都没有，我只能看到 .init_array 部分，但看不到 .fini_array:
Sections:
Idx Name Size VMA LMA File off Algn
0 .group 00000008 00000000 00000000 00000034 2**2
CONTENTS, READONLY, GROUP, LINK_ONCE_DISCARD
1 .group 00000008 00000000 00000000 0000003c 2**2
CONTENTS, READONLY, GROUP, LINK_ONCE_DISCARD
2 .text 0000022c 00000000 00000000 00000044 2**2
CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
3 .data 00000000 00000000 00000000 00000270 2**0
CONTENTS, ALLOC, LOAD, DATA
4 .bss 00000001 00000000 00000000 00000270 2**2
ALLOC
5 .text._ZN4TestC2Ev 00000012 00000000 00000000 00000270 2**1 << Test::Test()
CONTENTS, ALLOC, LOAD, READONLY, CODE
6 .text._ZN4TestD2Ev 00000012 00000000 00000000 00000282 2**1 << Test::~Test()
CONTENTS, ALLOC, LOAD, READONLY, CODE
7 .init_array 00000004 00000000 00000000 00000294 2**2 << WHERE IS .fini_array???
CONTENTS, ALLOC, LOAD, RELOC, DATA
8 .debug_info 000012d9 00000000 00000000 00000298 2**0
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
9 .debug_abbrev 000003a1 00000000 00000000 00001571 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
10 .debug_aranges 00000030 00000000 00000000 00001912 2**0
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
11 .debug_ranges 00000020 00000000 00000000 00001942 2**0
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
12 .debug_line 000002d2 00000000 00000000 00001962 2**0
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
13 .debug_str 000009e4 00000000 00000000 00001c34 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
14 .comment 0000004d 00000000 00000000 00002618 2**0
CONTENTS, READONLY
15 .debug_frame 0000054c 00000000 00000000 00002668 2**2
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
16 .ARM.attributes 0000002c 00000000 00000000 00002bb4 2**0
CONTENTS, READONLY
这是我调用编译器的方式：
arm-none-eabi-c++.exe -o main.elf --verbose -mcpu=cortex-m0 -mthumb --specs=nano.specs --entry reset_handler -T./../src/firmware.ld -ggdb -O0 -Wall -Wextra -Wpedantic -Werror ../src/main.cpp
这是日志：
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 7a1ab17ae8404f635d46188cccacd8be
COLLECT_GCC_OPTIONS='-o' 'main.elf' '-v' '-mcpu=cortex-m0' '-mthumb' '-specs=nano.specs' '-e' 'reset_handler' '-T' './../src/firmware.ld' '-ggdb' '-O0' '-Wall' '-Wextra' '-Wpedantic' '-Werror' '-mfloat-abi=soft' '-march=armv6s-m'
c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/bin/as.exe -v -march=armv6s-m -mfloat-abi=soft -meabi=5
GNU assembler version 2.34.0 (arm-none-eabi) using BFD version (GNU Arm Embedded Toolchain 9-2020-q2-update) 2.34.0.20200428
COMPILER_PATH=c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/;c:/id/gcc/bin/../lib/gcc/;c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/bin/
LIBRARY_PATH=c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/;c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/;c:/id/gcc/bin/../arm-none-eabi/lib/thumb/v6-m/nofp/;c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/;c:/id/gcc/bin/../lib/gcc/;c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib/;c:/id/gcc/bin/../arm-none-eabi/lib/
COLLECT_GCC_OPTIONS='-o' 'main.elf' '-v' '-mcpu=cortex-m0' '-mthumb' '-specs=nano.specs' '-e' 'reset_handler' '-T' './../src/firmware.ld' '-ggdb' '-O0' '-Wall' '-Wextra' '-Wpedantic' '-Werror' '-mfloat-abi=soft' '-march=armv6s-m'
c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/collect2.exe -plugin c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/liblto_plugin-0.dll -plugin-opt=c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/lto-wrapper.exe -plugin-opt=-fresolution=C:\Users\MAXID~1\AppData\Local\Temp\ccpOTkFN.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lg_nano -plugin-opt=-pass-through=-lc_nano -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc_nano --sysroot=c:\id\gcc\bin\../arm-none-eabi -X -o main.elf -e reset_handler c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/crti.o c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/crtbegin.o c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/crt0.o -Lc:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp -Lc:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib/thumb/v6-m/nofp -Lc:/id/gcc/bin/../arm-none-eabi/lib/thumb/v6-m/nofp -Lc:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1 -Lc:/id/gcc/bin/../lib/gcc -Lc:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib -Lc:/id/gcc/bin/../arm-none-eabi/lib C:\Users\MAXID~1\AppData\Local\Temp\cc1lU5Gg.o -lstdc++_nano -lm --start-group -lgcc -lg_nano -lc_nano --end-group --start-group -lgcc -lc_nano --end-group c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/crtend.o c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/crtn.o -T ./../src/firmware.ld
COLLECT_GCC_OPTIONS='-o' 'main.elf' '-v' '-mcpu=cortex-m0' '-mthumb' '-specs=nano.specs' '-e' 'reset_handler' '-T' './../src/firmware.ld' '-ggdb' '-O0' '-Wall' '-Wextra' '-Wpedantic' '-Werror' '-mfloat-abi=soft' '-march=armv6s-m'
公平地说，我对可能出现的问题一无所知——我尝试了默认的链接描述文件，.fini_array 没有出现。
我想到的唯一想法是我的编译器是用某种标志构建的，该标志禁用了 .fini_array 部分???
任何想法将不胜感激！
更新：经过进一步调查，析构函数似乎与 __cxa_atexit 更多有关...将进一步调查。
更新 2：感谢这里 https://forum.osdev.org/viewtopic.php?f=13&t=36728 的精彩讨论，我添加了 -fno-use-cxa-atexit，以及 .fini_array栏目出现了！
好的，对于那些有兴趣的人，gcc 有两种方法来生成对全局析构函数的调用。一种方法是通过 __cxa_atexit。编译器会在全局构造函数中注入一段代码，使用__cxa_atexit注册析构函数该对象。 这样，当调用 exit 时，运行时“知道”要调用哪些析构函数。处理 loading/unloading 个共享库需要这种复杂性。
然而，也可以传递一个 -fno-cxa-atexit 标志，编译器会将对全局析构函数的调用放入 .fini_array。 Newlib 然后使用此部分调用析构函数。
更多信息可以在这里找到：https://forum.osdev.org/viewtopic.php?f=13&t=36728
我正在尝试编写一个简单的“Hello, World!” Cortex-M0 的固件 CPU。目标是正确初始化和关闭 C++ 运行time，以便在 main() 之前调用全局构造函数，在 main()[ 之后调用全局析构函数=52=]。 到目前为止，我成功地完成了其中一半的工作——全局 ctors 运行 正确，但全局析构函数没有。我在 Windows 上使用 gcc 和 Newlib，它应该初始化 运行time.
struct Test {
Test() // This is invoked correctly.
{}
~Test() // This is not invoked at all.
{}
};
Test test;
int main()
{
return 0;
}
extern void __libc_init_array();
extern void __libc_fini_array();
void reset_handler() // This is the entry point.
{
__libc_init_array(); // Test::Test().
asm volatile( "bl main" ); // Invoke 'main'.
__libc_fini_array(); // Expect Test::~Test() but nothing happens.
}
我已经做了很多研究，似乎对于 ARM 编译器应该为全局构造函数生成一个名为 .init_array 的部分，并且 .fini_array，对于全局析构函数，它将指针指向要调用的函数。然后，链接器会将所有单元的部分合并在一起，__libc_init_array 将“遍历”该部分并调用相应的函数。
这是链接描述文件的相关部分：
/* Initialization functions which run before main(),
such as global constructors. */
.init_array : ALIGN( 4 ) {
/* preinit data */
PROVIDE_HIDDEN ( __preinit_array_start = . );
KEEP( *( .preinit_array ) )
PROVIDE_HIDDEN( __preinit_array_end = . );
. = ALIGN(4);
/* init data */
PROVIDE_HIDDEN ( __init_array_start = . );
KEEP( *( SORT( .init_array.* ) ) )
KEEP(*(.init_array))
PROVIDE_HIDDEN ( __init_array_end = . );
} > flash
/* Finalization functions which run after main(),
such as global destructors. */
.fini_array : ALIGN( 4 ) {
/* finit data */
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP ( *( .fini_array.* ) )
KEEP ( *( .fini_array ) )
PROVIDE_HIDDEN (__fini_array_end = .);
} > flash
但是，让我担心的是，当我转储 目标文件 、main.o 时，甚至连可执行文件都没有，我只能看到 .init_array 部分，但看不到 .fini_array:
Sections:
Idx Name Size VMA LMA File off Algn
0 .group 00000008 00000000 00000000 00000034 2**2
CONTENTS, READONLY, GROUP, LINK_ONCE_DISCARD
1 .group 00000008 00000000 00000000 0000003c 2**2
CONTENTS, READONLY, GROUP, LINK_ONCE_DISCARD
2 .text 0000022c 00000000 00000000 00000044 2**2
CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
3 .data 00000000 00000000 00000000 00000270 2**0
CONTENTS, ALLOC, LOAD, DATA
4 .bss 00000001 00000000 00000000 00000270 2**2
ALLOC
5 .text._ZN4TestC2Ev 00000012 00000000 00000000 00000270 2**1 << Test::Test()
CONTENTS, ALLOC, LOAD, READONLY, CODE
6 .text._ZN4TestD2Ev 00000012 00000000 00000000 00000282 2**1 << Test::~Test()
CONTENTS, ALLOC, LOAD, READONLY, CODE
7 .init_array 00000004 00000000 00000000 00000294 2**2 << WHERE IS .fini_array???
CONTENTS, ALLOC, LOAD, RELOC, DATA
8 .debug_info 000012d9 00000000 00000000 00000298 2**0
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
9 .debug_abbrev 000003a1 00000000 00000000 00001571 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
10 .debug_aranges 00000030 00000000 00000000 00001912 2**0
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
11 .debug_ranges 00000020 00000000 00000000 00001942 2**0
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
12 .debug_line 000002d2 00000000 00000000 00001962 2**0
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
13 .debug_str 000009e4 00000000 00000000 00001c34 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
14 .comment 0000004d 00000000 00000000 00002618 2**0
CONTENTS, READONLY
15 .debug_frame 0000054c 00000000 00000000 00002668 2**2
CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
16 .ARM.attributes 0000002c 00000000 00000000 00002bb4 2**0
CONTENTS, READONLY
这是我调用编译器的方式：
arm-none-eabi-c++.exe -o main.elf --verbose -mcpu=cortex-m0 -mthumb --specs=nano.specs --entry reset_handler -T./../src/firmware.ld -ggdb -O0 -Wall -Wextra -Wpedantic -Werror ../src/main.cpp
这是日志：
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 7a1ab17ae8404f635d46188cccacd8be
COLLECT_GCC_OPTIONS='-o' 'main.elf' '-v' '-mcpu=cortex-m0' '-mthumb' '-specs=nano.specs' '-e' 'reset_handler' '-T' './../src/firmware.ld' '-ggdb' '-O0' '-Wall' '-Wextra' '-Wpedantic' '-Werror' '-mfloat-abi=soft' '-march=armv6s-m'
c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/bin/as.exe -v -march=armv6s-m -mfloat-abi=soft -meabi=5
GNU assembler version 2.34.0 (arm-none-eabi) using BFD version (GNU Arm Embedded Toolchain 9-2020-q2-update) 2.34.0.20200428
COMPILER_PATH=c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/;c:/id/gcc/bin/../lib/gcc/;c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/bin/
LIBRARY_PATH=c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/;c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/;c:/id/gcc/bin/../arm-none-eabi/lib/thumb/v6-m/nofp/;c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/;c:/id/gcc/bin/../lib/gcc/;c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib/;c:/id/gcc/bin/../arm-none-eabi/lib/
COLLECT_GCC_OPTIONS='-o' 'main.elf' '-v' '-mcpu=cortex-m0' '-mthumb' '-specs=nano.specs' '-e' 'reset_handler' '-T' './../src/firmware.ld' '-ggdb' '-O0' '-Wall' '-Wextra' '-Wpedantic' '-Werror' '-mfloat-abi=soft' '-march=armv6s-m'
c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/collect2.exe -plugin c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/liblto_plugin-0.dll -plugin-opt=c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/lto-wrapper.exe -plugin-opt=-fresolution=C:\Users\MAXID~1\AppData\Local\Temp\ccpOTkFN.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lg_nano -plugin-opt=-pass-through=-lc_nano -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc_nano --sysroot=c:\id\gcc\bin\../arm-none-eabi -X -o main.elf -e reset_handler c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/crti.o c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/crtbegin.o c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/crt0.o -Lc:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp -Lc:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib/thumb/v6-m/nofp -Lc:/id/gcc/bin/../arm-none-eabi/lib/thumb/v6-m/nofp -Lc:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1 -Lc:/id/gcc/bin/../lib/gcc -Lc:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/lib -Lc:/id/gcc/bin/../arm-none-eabi/lib C:\Users\MAXID~1\AppData\Local\Temp\cc1lU5Gg.o -lstdc++_nano -lm --start-group -lgcc -lg_nano -lc_nano --end-group --start-group -lgcc -lc_nano --end-group c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/crtend.o c:/id/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/thumb/v6-m/nofp/crtn.o -T ./../src/firmware.ld
COLLECT_GCC_OPTIONS='-o' 'main.elf' '-v' '-mcpu=cortex-m0' '-mthumb' '-specs=nano.specs' '-e' 'reset_handler' '-T' './../src/firmware.ld' '-ggdb' '-O0' '-Wall' '-Wextra' '-Wpedantic' '-Werror' '-mfloat-abi=soft' '-march=armv6s-m'
公平地说，我对可能出现的问题一无所知——我尝试了默认的链接描述文件，.fini_array 没有出现。 我想到的唯一想法是我的编译器是用某种标志构建的，该标志禁用了 .fini_array 部分???
任何想法将不胜感激！
更新：经过进一步调查，析构函数似乎与 __cxa_atexit 更多有关...将进一步调查。
更新 2：感谢这里 https://forum.osdev.org/viewtopic.php?f=13&t=36728 的精彩讨论，我添加了 -fno-use-cxa-atexit，以及 .fini_array栏目出现了！
好的，对于那些有兴趣的人，gcc 有两种方法来生成对全局析构函数的调用。一种方法是通过 __cxa_atexit。编译器会在全局构造函数中注入一段代码，使用__cxa_atexit注册析构函数该对象。 这样，当调用 exit 时，运行时“知道”要调用哪些析构函数。处理 loading/unloading 个共享库需要这种复杂性。
然而，也可以传递一个 -fno-cxa-atexit 标志，编译器会将对全局析构函数的调用放入 .fini_array。 Newlib 然后使用此部分调用析构函数。 更多信息可以在这里找到：https://forum.osdev.org/viewtopic.php?f=13&t=36728