Always support float128 on ia64 (PR target/77586).

Bug 77586, and previously
<https://gcc.gnu.org/ml/gcc-bugs/2016-08/msg03233.html>, reports
ia64-elf failing to build because of float128_type_node being NULL,
but being used by the back end for __float128.

The global float128_type_node is only available conditionally, if
target hooks indicate TFmode is not only available as a scalar mode
and of the right format, but also supported in libgcc.  The back-end
support, however, expects the type always to be available for
__float128 even if the libgcc support is missing.

Although a target-specific node could be restored in the case where
libgcc support is missing, it seems better to address the missing
libgcc support.  Thus, this patch enables TFmode soft-fp in libgcc
globally for all ia64 targets.  Support for XFmode in libgcc (that is,
for libgcc2.c XFmode functions, not soft-fp) is also enabled for all
ia64 targets so that ia64 no longer needs to define the
TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P hook.

I've confirmed that ia64-elf builds cc1 with this patch and it passes
-fself-test.  I have not otherwise tested the patch.  It's plausible
that ia64-elf and ia64-freebsd might work as-is, but ia64-vms probably
needs further changes, by someone familiar with VMS shared libraries,
to implement an equivalent of ia64/t-softfp-compat in that case
(avoiding conflicts between __divtf3 from soft-fp and the old alias
for __divxf3).

	PR target/77586
gcc:
	* config/ia64/ia64.c (ia64_libgcc_floating_mode_supported_p)
	(TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P): Remove.
	* config/ia64/elf.h (IA64_NO_LIBGCC_TFMODE): Likewise.
	* config/ia64/freebsd.h (IA64_NO_LIBGCC_TFMODE): Likewise.
	* config/ia64/vms.h (IA64_NO_LIBGCC_XFMODE)
	(IA64_NO_LIBGCC_TFMODE): Likewise.

libgcc:
	* config.host (ia64*-*-elf*, ia64*-*-freebsd*, ia64-hp-*vms*): Use
	soft-fp.

From-SVN: r240955

2 files changed, 9 insertions, 3 deletions

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index f627591..d9949a1 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-10-10  Joseph Myers  <joseph@codesourcery.com>
+
+	PR target/77586
+	* config.host (ia64*-*-elf*, ia64*-*-freebsd*, ia64-hp-*vms*): Use
+	soft-fp.
+
 2016-10-10  Andreas Tobler  <andreast@gcc.gnu.org>
 
 	* config.host: Add support for aarch64-*-freebsd*.
diff --git a/libgcc/config.host b/libgcc/config.host
index 1c90e23..ab61d63 100644
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -751,11 +751,11 @@ x86_64-*-mingw*)
 	;;
 ia64*-*-elf*)
 	extra_parts="$extra_parts crtbeginS.o crtendS.o crtfastmath.o"
-	tmake_file="ia64/t-ia64 ia64/t-ia64-elf ia64/t-eh-ia64 t-crtfm"
+	tmake_file="ia64/t-ia64 ia64/t-ia64-elf ia64/t-eh-ia64 t-crtfm t-softfp-tf ia64/t-softfp t-softfp ia64/t-softfp-compat"
 	;;
 ia64*-*-freebsd*)
 	extra_parts="$extra_parts crtfastmath.o"
-	tmake_file="$tmake_file ia64/t-ia64 ia64/t-ia64-elf ia64/t-eh-ia64 t-crtfm"
+	tmake_file="$tmake_file ia64/t-ia64 ia64/t-ia64-elf ia64/t-eh-ia64 t-crtfm t-softfp-tf ia64/t-softfp t-softfp ia64/t-softfp-compat"
 	;;
 ia64*-*-linux*)
 	# Don't use crtbeginT.o from *-*-linux* default.
@@ -770,7 +770,7 @@ ia64*-*-hpux*)
 	tmake_file="ia64/t-ia64 ia64/t-ia64-elf ia64/t-hpux t-slibgcc ia64/t-slibgcc-hpux t-slibgcc-hpux"
 	;;
 ia64-hp-*vms*)
-	tmake_file="$tmake_file ia64/t-ia64 ia64/t-eh-ia64 ia64/t-vms t-slibgcc-vms"
+	tmake_file="$tmake_file ia64/t-ia64 ia64/t-eh-ia64 ia64/t-vms t-slibgcc-vms t-softfp-tf ia64/t-softfp t-softfp"
 	extra_parts="$extra_parts crtinitS.o"
 	md_unwind_header=ia64/vms-unwind.h
 	;;