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. OK to commit? gcc: 2016-08-25 Joseph Myers <jos...@codesourcery.com> * 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: 2016-08-25 Joseph Myers <jos...@codesourcery.com> * config.host (i[34567]86-*-* | x86_64-*-*): Enable TFmode soft-fp where not already enabled. Index: gcc/config/i386/i386.c =================================================================== --- gcc/config/i386/i386.c (revision 239761) +++ gcc/config/i386/i386.c (working copy) @@ -43284,31 +43284,6 @@ return false; } -/* Implement target hook libgcc_floating_mode_supported_p. */ -static bool -ix86_libgcc_floating_mode_supported_p (machine_mode mode) -{ - switch (mode) - { - case SFmode: - case DFmode: - case XFmode: - return true; - - case TFmode: -#ifdef IX86_NO_LIBGCC_TFMODE - return false; -#elif defined IX86_MAYBE_NO_LIBGCC_TFMODE - return TARGET_LONG_DOUBLE_128; -#else - return true; -#endif - - default: - return false; - } -} - /* Target hook for c_mode_for_suffix. */ static machine_mode ix86_c_mode_for_suffix (char suffix) @@ -50568,10 +50543,6 @@ #undef TARGET_VECTOR_MODE_SUPPORTED_P #define TARGET_VECTOR_MODE_SUPPORTED_P ix86_vector_mode_supported_p -#undef TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P -#define TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P \ - ix86_libgcc_floating_mode_supported_p - #undef TARGET_C_MODE_FOR_SUFFIX #define TARGET_C_MODE_FOR_SUFFIX ix86_c_mode_for_suffix Index: gcc/config/i386/i386elf.h =================================================================== --- gcc/config/i386/i386elf.h (revision 239761) +++ gcc/config/i386/i386elf.h (working copy) @@ -101,5 +101,3 @@ #undef ASM_OUTPUT_ALIGNED_BSS #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN) \ asm_output_aligned_bss (FILE, DECL, NAME, SIZE, ALIGN) - -#define IX86_MAYBE_NO_LIBGCC_TFMODE Index: gcc/config/i386/lynx.h =================================================================== --- gcc/config/i386/lynx.h (revision 239761) +++ gcc/config/i386/lynx.h (working copy) @@ -85,5 +85,3 @@ TLS is detected by configure. We undefine it here. */ #undef HAVE_AS_TLS - -#define IX86_MAYBE_NO_LIBGCC_TFMODE Index: gcc/config/i386/netbsd-elf.h =================================================================== --- gcc/config/i386/netbsd-elf.h (revision 239761) +++ gcc/config/i386/netbsd-elf.h (working copy) @@ -119,5 +119,3 @@ #define DEFAULT_PCC_STRUCT_RETURN 1 #define HAVE_ENABLE_EXECUTE_STACK - -#define IX86_MAYBE_NO_LIBGCC_TFMODE Index: gcc/config/i386/netbsd64.h =================================================================== --- gcc/config/i386/netbsd64.h (revision 239761) +++ gcc/config/i386/netbsd64.h (working copy) @@ -67,5 +67,3 @@ } #define HAVE_ENABLE_EXECUTE_STACK - -#define IX86_MAYBE_NO_LIBGCC_TFMODE Index: gcc/config/i386/nto.h =================================================================== --- gcc/config/i386/nto.h (revision 239761) +++ gcc/config/i386/nto.h (working copy) @@ -103,5 +103,3 @@ #define TARGET_POSIX_IO #undef DBX_REGISTER_NUMBER - -#define IX86_MAYBE_NO_LIBGCC_TFMODE Index: gcc/config/i386/openbsd.h =================================================================== --- gcc/config/i386/openbsd.h (revision 239761) +++ gcc/config/i386/openbsd.h (working copy) @@ -99,5 +99,3 @@ #undef ASM_QUAD #define TARGET_HAVE_NAMED_SECTIONS false - -#define IX86_MAYBE_NO_LIBGCC_TFMODE Index: gcc/config/i386/rtemself.h =================================================================== --- gcc/config/i386/rtemself.h (revision 239761) +++ gcc/config/i386/rtemself.h (working copy) @@ -31,5 +31,3 @@ #undef LONG_DOUBLE_TYPE_SIZE #define LONG_DOUBLE_TYPE_SIZE (TARGET_80387 ? 80 : 64) - -#define IX86_NO_LIBGCC_TFMODE Index: gcc/config/i386/vxworks.h =================================================================== --- gcc/config/i386/vxworks.h (revision 239761) +++ gcc/config/i386/vxworks.h (working copy) @@ -87,8 +87,6 @@ fixed gap between segments. */ #undef ASM_PREFERRED_EH_DATA_FORMAT -#define IX86_MAYBE_NO_LIBGCC_TFMODE - /* Define this to be nonzero if static stack checking is supported. */ #define STACK_CHECK_STATIC_BUILTIN 1 Index: libgcc/config.host =================================================================== --- libgcc/config.host (revision 239761) +++ libgcc/config.host (working copy) @@ -632,7 +632,7 @@ 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 @@ 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" -- Joseph S. Myers jos...@codesourcery.com