Always support float128 on x86.

Programming / Compilers / GCC - jsm28 [138bc75d-0d04-0410-961f-82ee72b054a4] - 26 August 2016 06:13 UTC

In , 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.

ac34f4b Always support float128 on x86.
gcc/ChangeLog | 14 ++++++++++++++
gcc/config/i386/i386.c | 29 -----------------------------
gcc/config/i386/i386elf.h | 2 --
gcc/config/i386/lynx.h | 2 --
gcc/config/i386/netbsd-elf.h | 2 --
gcc/config/i386/netbsd64.h | 2 --
gcc/config/i386/nto.h | 2 --
gcc/config/i386/openbsd.h | 2 --
gcc/config/i386/rtemself.h | 2 --
gcc/config/i386/vxworks.h | 2 --
libgcc/ChangeLog | 5 +++++
libgcc/config.host | 17 +++++------------
12 files changed, 24 insertions(+), 57 deletions(-)

Upstream: gcc.gnu.org


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