RFC PATCH: Enable dl_iterate_phdr inside libgcc_s.so.1 on *-*-freebsd*

[Loren James Rittle]

This proposed mainline patch enables dl_iterate_phdr support inside
libgcc_s.so.1 (on FreeBSD 7 or later) on *-*-freebsd* to match the
configuration of the FreeBSD 7 system compiler.  Yes, the system
compiler configuration actually defines __GLIBC__ (in a similar yet
more hard-coded fashion since they don't run configure) to enable the
code paths in crtstuff.c and unwind-dw2-fde-glibc.c ...

I have not committed this patch since the better alternative appears
to properly patch both crtstuff.c and unwind-dw2-fde-glibc.c, and
perhaps even rename unwind-dw2-fde-glibc.c to a more general name (now
that the same mechanism is properly supported outside of glibc hosts).

Comments?

Regards,
Loren

Index: config/t-freebsd
===================================================================
--- config/t-freebsd	(revision 151644)
+++ config/t-freebsd	(working copy)
@@ -1,3 +1,5 @@
+CRTSTUFF_T_CFLAGS = -D__GLIBC__="((__FreeBSD__>=7)*3)"
+
 # Compile crtbeginS.o and crtendS.o with pic.
 CRTSTUFF_T_CFLAGS_S = $(CRTSTUFF_T_CFLAGS) -fPIC
 
@@ -2,2 +4,7 @@
 # Compile libgcc.a with pic.
-TARGET_LIBGCC2_CFLAGS += -fPIC
+TARGET_LIBGCC2_CFLAGS += -fPIC -D__GLIBC__="((__FreeBSD__>=7)*3)" -DElfW=__ElfN
+
+# Use unwind-dw2-fde-glibc
+LIB2ADDEH = $(srcdir)/unwind-dw2.c $(srcdir)/unwind-dw2-fde-glibc.c \
+  $(srcdir)/unwind-sjlj.c $(srcdir)/gthr-gnat.c $(srcdir)/unwind-c.c
+LIB2ADDEHDEP = unwind.inc unwind-dw2-fde.h unwind-dw2-fde.c
Index: config/freebsd-spec.h
===================================================================
--- config/freebsd-spec.h	(revision 151644)
+++ config/freebsd-spec.h	(working copy)
@@ -148,3 +148,12 @@
 #else
 #define FBSD_DYNAMIC_LINKER "/libexec/ld-elf.so.1"
 #endif
+
+#if defined(HAVE_LD_EH_FRAME_HDR)
+#define LINK_EH_SPEC "%{!static:--eh-frame-hdr} "
+#endif
+
+/* Use --as-needed -lgcc_s for eh support.  */
+#ifdef HAVE_LD_AS_NEEDED
+#define USE_LD_AS_NEEDED 1
+#endif