Tigthen libc_internal and crtstuff for VxWorks shared objects
This change tightens and documents the use of libc_internal, then strengthens the VxWorks crtstuff objects for the support of shared libraries. In particular: - Define __dso_handle, which libstdc++.so requires, - Provide _init and _fini functions to run through the init/fini arrays for shared libs in configurations which HAVE_INITFINI_ARRAY_SUPPORT. The init/fini functions are provided by libc_internal.a for static links but with slightly different names and we don't want to risk dragging other libc_internal contents in the closure accidentally so make sure we don't link with it. As for the !vxworks crtstuff, the new shared libs specific bits are conditioned by a CRTSTUFFS_O macro, for which we provide new Makefile fragment. The bits to actually use the fragment and the shared objects will be added by a forthcoming change, as part of a more general configury update for shared libs. The change also adds guards the eh table registration code in vxcrtstuff so the objects can be used for either init/fini or eh tables independently. 2021-12-07 Fred Konrad <konrad@adacore.com> Olivier Hainque <hainque@adacore.com> gcc/ * config/vxworks.h (VXWORKS_BASE_LIBS_RTP): Guard -lc_internal on !shared+!non-static and document. (VXWORKS_LIB_SPEC): Remove the bits intended to drag the init/fini functions from libc_internal in the shared lib case. (VX_CRTBEGIN_SPEC/VX_CRTEND_SPEC): Use vxcrtstuff objects also in configurations with shared lib and INITFINI_ARRAY support. libgcc/ * config/t-vxcrtstuffS: New Makefile fragment. * config/vxcrtstuff.c: Provide __dso_handle. Provide _init/_fini functions for INITFINI_ARRAY support in shared libs and guard the definition of eh table registration functions on conditions indicating they are needed.
This commit is contained in:
Frederic Konrad
Olivier Hainque
parent
0515c95d5f
commit
4099d6501e
3 changed files with 109 additions and 19 deletions
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@ -101,11 +101,23 @@ along with GCC; see the file COPYING3. If not see
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the default CPP spec for C++ as well. */
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#undef CPLUSPLUS_CPP_SPEC
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/* For VxWorks static rtps, the system provides libc_internal.a, a superset of
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libgcc.a that we need to use e.g. to satisfy references to __init and
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__fini. We still want our libgcc to prevail for symbols it would provide
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(e.g. register save entry points), so re-place it here between libraries
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that might reference it and libc_internal.
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/* For VxWorks static rtps, the system provides libc_internal.a for a variety
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of purposes. Care is needed to include it appropriately.
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- In some configurations, libc_internal fills in possible references from
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the static libc that we don't wouldn't satisfy ourselves, say, with
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libgcc. An example is the __aeabi_memcpy family of functions on arm,
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which have very specific ABI allowances.
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- OTOH, in some configurations the library provides typical libgcc
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services, for example register save/restore entry points on powerpc. We
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want our libgcc to prevail for symbols it would provide, so place
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-lc_internal after -lc -lgcc.
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- libc_internal also contains __init/__fini functions for
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USE_INITFINI_ARRAY support. However, the system expects these in
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every shared lib as well, with slightly different names, and it is
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simpler for us to provide our own versions through vxcrtstuff.
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In addition, some versions of VxWorks rely on explicit extra libraries for
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system calls and the set of base network libraries of common use varies
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@ -120,7 +132,8 @@ along with GCC; see the file COPYING3. If not see
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#define VXWORKS_NET_LIBS_RTP "-lnet -ldsi"
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#endif
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#define VXWORKS_BASE_LIBS_RTP "-lc -lgcc -lc_internal"
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#define VXWORKS_BASE_LIBS_RTP \
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"-lc -lgcc %{!shared:%{!non-static:-lc_internal}}"
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#define VXWORKS_EXTRA_LIBS_RTP
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@ -161,10 +174,9 @@ along with GCC; see the file COPYING3. If not see
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#endif
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#undef VXWORKS_LIB_SPEC
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#define VXWORKS_LIB_SPEC \
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"%{mrtp:%{shared:-u " USER_LABEL_PREFIX "__init -u " USER_LABEL_PREFIX "__fini} \
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%{!shared:%{non-static:-u " USER_LABEL_PREFIX "_STI__6__rtld -ldl} \
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" TLS_SYM " \
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#define VXWORKS_LIB_SPEC \
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"%{mrtp:%{!shared:%{non-static:-u " USER_LABEL_PREFIX "_STI__6__rtld -ldl} \
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" TLS_SYM " \
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--start-group " VXWORKS_LIBS_RTP " --end-group}}"
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/* The no-op spec for "-shared" below is present because otherwise GCC
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@ -196,11 +208,13 @@ along with GCC; see the file COPYING3. If not see
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#define VXWORKS_LIBGCC_SPEC "-lgcc"
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#endif
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/* Setup the crtstuff begin/end we might need for dwarf EH registration. */
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/* Setup the crtstuff begin/end we might need for dwarf EH registration
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and/or INITFINI_ARRAY support for shared libs. */
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#if !defined(CONFIG_SJLJ_EXCEPTIONS) && DWARF2_UNWIND_INFO
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#define VX_CRTBEGIN_SPEC "vx_crtbegin.o%s"
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#define VX_CRTEND_SPEC "-l:vx_crtend.o"
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#if (HAVE_INITFINI_ARRAY_SUPPORT && defined(ENABLE_SHARED_LIBGCC)) \
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|| (DWARF2_UNWIND_INFO && !defined(CONFIG_SJLJ_EXCEPTIONS))
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#define VX_CRTBEGIN_SPEC "%{!shared:vx_crtbegin.o%s;:vx_crtbeginS.o%s}"
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#define VX_CRTEND_SPEC "%{!shared:vx_crtend.o%s;:vx_crtendS.o%s}"
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#else
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#define VX_CRTBEGIN_SPEC ""
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#define VX_CRTEND_SPEC ""
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9
libgcc/config/t-vxcrtstuffS
Normal file
9
libgcc/config/t-vxcrtstuffS
Normal file
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@ -0,0 +1,9 @@
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# Shared versions of vx_crt{begin,end}.o, those one must be compiled only
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# when the shared libraries are available
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vx_crtbeginS.o: $(srcdir)/config/vxcrtstuff.c
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$(crt_compile) $(CRTSTUFF_T_CFLAGS_S) -DCRT_BEGIN -c $< -DCRTSTUFFS_O
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vx_crtendS.o: $(srcdir)/config/vxcrtstuff.c
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$(crt_compile) $(CRTSTUFF_T_CFLAGS_S) -DCRT_END -c $< -DCRTSTUFFS_O
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EXTRA_PARTS += vx_crtbeginS.o vx_crtendS.o
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@ -50,15 +50,25 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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#define USE_CDTORS_SECTIONS
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#endif
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#if DWARF2_UNWIND_INFO && !defined(__USING_SJLJ_EXCEPTIONS__)
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#define USE_EH_FRAME_REGISTRY
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#endif
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/* ------------------------------ crtbegin ------------------------------- */
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#ifdef CRT_BEGIN
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/* Stick a label at the beginning of the frame unwind info so we can register
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and deregister it with the exception handling library code. */
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static const char __EH_FRAME_BEGIN__[]
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__attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
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= { };
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#if DEFAULT_USE_CXA_ATEXIT && defined(__RTP__)
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/* This mimics the crtstuff.c behavior. dso_handle should be NULL for the
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main program (in vx_crtbegin.o) and a unique value for the shared libraries
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(in vx_crtbeginS.o). */
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extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
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#ifdef CRTSTUFFS_O
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void *__dso_handle = &__dso_handle;
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#else
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void *__dso_handle = 0;
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#endif
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#endif /* DEFAULT_USE_CXA_ATEXIT */
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/* Determine what names to use for the constructor/destructor functions. */
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@ -89,6 +99,53 @@ __attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
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#define EH_CTOR_ATTRIBUTE __attribute__((constructor (101)))
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#define EH_DTOR_ATTRIBUTE __attribute__((destructor (101)))
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/* Provide the init/fini array support functions for shared libraries,
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where we don't want to drag libc_internal contents blindly and which
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provides functions with a slightly different name anyway. */
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#if HAVE_INITFINI_ARRAY_SUPPORT && defined(CRTSTUFFS_O)
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/* Run through the .init_array, .fini_array sections. The linker script
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*must* provide __init_array_start, __init_array_end, __fini_array_start,
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__fini_array_end symbols. */
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typedef void (*initfini_ptr) (void);
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extern initfini_ptr __init_array_start[];
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extern initfini_ptr __init_array_end[];
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extern initfini_ptr __fini_array_start[];
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extern initfini_ptr __fini_array_end[];
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/* Provide the actual code through static functions, which don't need
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to be exposed in the shared lib interface. */
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static void __exec_init_array(void)
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{
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initfini_ptr *fn;
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for (fn = __init_array_start; fn < __init_array_end; ++fn)
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(*fn)();
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}
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static void __exec_fini_array(void)
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{
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initfini_ptr *fn;
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for (fn = __fini_array_end - 1; fn >= __fini_array_start; --fn)
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(*fn)();
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}
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/* Reference the two above functions as the init / fini function. */
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void __attribute__ ((__section__ (".init"))) _init()
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{
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__exec_init_array();
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}
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void __attribute__ ((__section__ (".fini"))) _fini()
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{
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__exec_fini_array();
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}
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#endif /* __CRTSTUFFS_O__ */
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#else /* !USE_INITFINI_ARRAY */
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/* Note: Even in case of .ctors/.dtors sections, we can't use the attribute
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@ -100,6 +157,13 @@ __attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
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#endif /* USE_INITFINI_ARRAY */
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#ifdef USE_EH_FRAME_REGISTRY
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/* Stick a label at the beginning of the frame unwind info so we can register
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and deregister it with the exception handling library code. */
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static const char __EH_FRAME_BEGIN__[]
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__attribute__((section(__LIBGCC_EH_FRAME_SECTION_NAME__), aligned(4)))
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= { };
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EH_LINKAGE EH_CTOR_ATTRIBUTE void EH_CTOR_NAME (void)
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{
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static struct object object;
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@ -110,6 +174,7 @@ EH_LINKAGE EH_DTOR_ATTRIBUTE void EH_DTOR_NAME (void)
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{
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__deregister_frame_info (__EH_FRAME_BEGIN__);
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}
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#endif /* USE_EH_FRAME_REGISTRY */
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#ifdef USE_CDTORS_SECTIONS
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/* As explained above, we need to manually build the sections here as the
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@ -126,6 +191,7 @@ static void (* volatile eh_registration_dtors[])()
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#elif defined (CRT_END) /* ! CRT_BEGIN */
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#ifdef USE_EH_FRAME_REGISTRY
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/* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
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this would be the 'length' field in a real FDE. */
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@ -133,6 +199,7 @@ static const char __FRAME_END__[]
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__attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
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aligned(4)))
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= { 0, 0, 0, 0 };
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#endif /* USE_EH_FRAME_REGISTRY */
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#else /* ! CRT_BEGIN & ! CRT_END */
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