Re: PING: PATCH: PR target/46770: Use .init_array/.fini_array sections

[Jakub Jelinek <jakub@redhat.com>]

On Fri, Jul 22, 2011 at 04:59:28AM -0700, H.J. Lu wrote:
> @@ -2660,6 +2664,7 @@ esac
>  case ${target} in
>  i[34567]86-*-linux* | x86_64-*-linux*)
>  	tmake_file="${tmake_file} i386/t-pmm_malloc i386/t-i386"
> +	use_initfini_array=yes
>  	;;
>  i[34567]86-*-* | x86_64-*-*)
>  	tmake_file="${tmake_file} i386/t-gmm_malloc i386/t-i386"

What is i?86/x86_64 specific on it?  Don't most other glibc targets
want to use it too, perhaps with some arch specific tweaks?

> --- /dev/null
> +++ b/gcc/config/initfini-array.c

This is ugly.  varasm.c already has lots of ELF specific code, simply
put them there as well and only let configury set some macro which will
allow targets to choose which of the implementations in the generic code
they want to use (or if they want their own which e.g. calls the generic
routine and does something additional to it etc.).  The sections probably
can be created only the first time you actually need them.

> --- a/gcc/crtstuff.c
> +++ b/gcc/crtstuff.c
> @@ -189,6 +190,9 @@ typedef void (*func_ptr) (void);
>     refer to only the __CTOR_END__ symbol in crtend.o and the __DTOR_LIST__
>     symbol in crtbegin.o, where they are defined.  */
>  
> +/* No need for .ctors/.dtors section if linker can place them in
> +   .init_array/.fini_array section.  */
> +#ifndef NO_CTORS_DTORS_SECTIONS
>  /* The -1 is a flag to __do_global_[cd]tors indicating that this table
>     does not start with a count of elements.  */
>  #ifdef CTOR_LIST_BEGIN
> @@ -219,6 +223,7 @@ STATIC func_ptr __DTOR_LIST__[1]
>    __attribute__((section(".dtors"), aligned(sizeof(func_ptr))))
>    = { (func_ptr) (-1) };
>  #endif /* __DTOR_LIST__ alternatives */
> +#endif /* NO_CTORS_DTORS_SECTIONS */
>  
>  #ifdef USE_EH_FRAME_REGISTRY
>  /* Stick a label at the beginning of the frame unwind info so we can register
> @@ -489,6 +494,9 @@ __do_global_ctors_1(void)
>  
>  #elif defined(CRT_END) /* ! CRT_BEGIN */
>  
> +/* No need for .ctors/.dtors section if linker can place them in
> +   .init_array/.fini_array section.  */
> +#ifndef NO_CTORS_DTORS_SECTIONS
>  /* Put a word containing zero at the end of each of our two lists of function
>     addresses.  Note that the words defined here go into the .ctors and .dtors
>     sections of the crtend.o file, and since that file is always linked in
> @@ -534,6 +542,7 @@ STATIC func_ptr __DTOR_END__[1]
>    __attribute__((used, section(".dtors"), aligned(sizeof(func_ptr))))
>    = { (func_ptr) 0 };
>  #endif
> +#endif /* NO_CTORS_DTORS_SECTIONS */
>  
>  #ifdef EH_FRAME_SECTION_NAME
>  /* Terminate the frame unwind info section with a 4byte 0 as a sentinel;

I don't see how you can do this.  It would IMO break any time you link code
built by different gcc versions where some code emitted by the older gcc
used .ctors or .dtors.

	Jakub