Always support float128 on x86.

In <https://gcc.gnu.org/ml/gcc-bugs/2016-08/msg03233.html>, Nick
reported i386-elf and 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 x86 targets - the only special cases needed being for
targets that use soft-fp for SFmode and DFmode, one of which already
had the support for TFmode as well (so I based the i[34567]86-*-rtems*
configuration on that present for i[34567]86-*-elfiamcu).  The i386
implementation of TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P is then
removed as no longer needed.

I can provide such a patch for ia64 if useful, but am not in a
position to test it (and while I'm reasonably confident that enabling
this support would be right for ia64-elf and ia64-freebsd, I've no
real idea if enabling libgcc support for TFmode, with or without also
enabling it for XFmode, would be safe for ia64-vms).

Bootstrapped with no regressions on x86_64-pc-linux-gnu.

gcc:
	* config/i386/i386.c (ix86_libgcc_floating_mode_supported_p)
	(TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P): Remove.
	* config/i386/i386elf.h (IX86_MAYBE_NO_LIBGCC_TFMODE): Likewise.
	* config/i386/lynx.h (IX86_MAYBE_NO_LIBGCC_TFMODE): Likewise.
	* config/i386/netbsd-elf.h (IX86_MAYBE_NO_LIBGCC_TFMODE):
	Likewise.
	* config/i386/netbsd64.h (IX86_MAYBE_NO_LIBGCC_TFMODE): Likewise.
	* config/i386/nto.h (IX86_MAYBE_NO_LIBGCC_TFMODE): Likewise.
	* config/i386/openbsd.h (IX86_MAYBE_NO_LIBGCC_TFMODE): Likewise.
	* config/i386/rtemself.h (IX86_NO_LIBGCC_TFMODE): Likewise.
	* config/i386/vxworks.h (IX86_MAYBE_NO_LIBGCC_TFMODE): Likewise.

libgcc:
	* config.host (i[34567]86-*-* | x86_64-*-*): Enable TFmode soft-fp
	where not already enabled.

From-SVN: r239775

2 files changed, 10 insertions, 12 deletions

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 99bd2f1..d5ecf77 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,8 @@
+2016-08-26  Joseph Myers  <joseph@codesourcery.com>
+
+	* config.host (i[34567]86-*-* | x86_64-*-*): Enable TFmode soft-fp
+	where not already enabled.
+
 2016-08-25  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	* config/mips/linux-unwind.h: Use sys/syscall.h.
diff --git a/libgcc/config.host b/libgcc/config.host
index 4ccf25d..002f650 100644
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -632,7 +632,7 @@ i[34567]86-*-nto-qnx*)
 	extra_parts=crtbegin.o
 	;;
 i[34567]86-*-rtems*)
-	tmake_file="$tmake_file i386/t-crtstuff t-softfp-sfdf t-softfp"
+	tmake_file="$tmake_file i386/t-crtstuff t-softfp-sfdftf i386/32/t-softfp i386/t-softfp t-softfp"
 	extra_parts="$extra_parts crti.o crtn.o"
 	;;
 i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]*)
@@ -1330,17 +1330,10 @@ i[34567]86-*-linux* | x86_64-*-linux* | \
 esac
 
 case ${host} in
-i[34567]86-*-darwin* | x86_64-*-darwin* | \
-  i[34567]86-*-kfreebsd*-gnu | x86_64-*-kfreebsd*-gnu | \
-  i[34567]86-*-linux* | x86_64-*-linux* | \
-  i[34567]86-*-msdosdjgpp* | \
-  i[34567]86-*-gnu* | \
-  i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]* | \
-  i[34567]86-*-cygwin* | x86_64-*-cygwin* | \
-  i[34567]86-*-mingw* | x86_64-*-mingw* | \
-  i[34567]86-*-dragonfly* | x86_64-*-dragonfly* | \
-  i[34567]86-*-freebsd* | x86_64-*-freebsd* | \
-  i[34567]86-*-openbsd* | x86_64-*-openbsd*)
+i[34567]86-*-elfiamcu | i[34567]86-*-rtems*)
+	# These use soft-fp for SFmode and DFmode, not just TFmode.
+	;;
+i[34567]86-*-* | x86_64-*-*)
   	tmake_file="${tmake_file} t-softfp-tf"
 	if test "${host_address}" = 32; then
 		tmake_file="${tmake_file} i386/${host_address}/t-softfp"