Hi Iain,

> Currently the DSO support for D runtime is generated by the compiler in
> every object, when really it is only required once per shared object.
>
> This patch moves that support logic from the compiler itself to the
> library as part of the drtstuff code.  The object files drtbegin.o and
> drtend.o are now always linked in.
>
> Bootstrapped and tested on x86_64-linux-gnu/-m32/-mx32, with no
> observable regressions.
>
> @Rainer, as you provided the original, would be good to validate this is
> fine for Solaris too.

I did, with mixed success: initially, the patch broke bootstrap on both
i386-pc-solaris2.11 and sparc-sun-solaris2.11 linking libgdruntime.so:

Text relocation remains                        referenced
    against symbol                  offset      in file
__start_minfo                       0x2         gcc/drtbegin.o
_D8drtstuff7dsoSlotPv               0x7         gcc/drtbegin.o
_D8drtstuff7dsoDataS3gcc8sections6common15CompilerDSOData 0x1e          gcc/drtbegin.o
_D8drtstuff7dsoDataS3gcc8sections6common15CompilerDSOData 0x28          gcc/drtbegin.o
__stop_minfo                        0x2c        gcc/drtbegin.o
_D8drtstuff7dsoDataS3gcc8sections6common15CompilerDSOData 0x34          gcc/drtbegin.o
_D8drtstuff7dsoDataS3gcc8sections6common15CompilerDSOData 0x39          gcc/drtbegin.o
_D8drtstuff7dsoDataS3gcc8sections6common15CompilerDSOData 0x7           gcc/drtbegin.o
_d_dso_registry                     0x3e        gcc/drtbegin.o
_d_dso_registry                     0xc         gcc/drtbegin.o
ld: fatal: relocations remain against allocatable but non-writable sections
collect2: error: ld returned 1 exit status
make[5]: *** [Makefile:1943: libgdruntime.la] Error 1

Solaris ld defaults to -z text, and gcc is still non-pic/pie by
default.  The attached patch fixes the issue by building
drtbegin.o/drtend.o as libtool objects.

There are a couple of caveats, though:

* It directs gdc to libdruntime/gcc/.libs instead of libdruntime/gcc.
  I've no idea what happens when configuring with --disable-shared,
  building for targets without PIC support, or on Windows where that
  directory is called _libs instead (I've found no variable to use
  here).

  OTOH, testsuite_flags.in already hardcodes .libs, so this is a
  preexisting problem.

* I haven't checked if the PIC drt*.o files are actually installed,
  otherwise gdc wouldn't be able to create shared objects on Solaris.

* This comment is misleading now that those files are used unconditionally:

# Provide __start_minfo, __stop_minfo if linker doesn't.
DRTSTUFF = gcc/drtbegin.o gcc/drtend.o

At least with this incremental patch, I've been able to successfully
bootstrap and test trunk on i386-pc-solaris2.11 (Solaris 11.3 which
lacks ld support for __start_<section>/__stop_<section) and 11.4 which
has it) and sparc-sun-solaris2.11 (Solaris 11.4 only).

	Rainer

-- 
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Rainer Orth, Center for Biotechnology, Bielefeld University