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The default sysdeps/ieee754 fma implementations rely on exceptions and rounding modes to achieve correct results through internal use of round-to-odd. Thus, glibc configurations without support for exceptions and rounding modes instead need to use implementations of fma based on soft-fp. At present, this is achieved via having implementation files in soft-fp/ that are #included by sysdeps files for each glibc configuration that needs them. In general this means such a configuration has its own s_fma.c and s_fmaf.c. TS 18661-1 adds functions that do an operation (+ - * / sqrt fma) on arguments wider than the return type, with a single rounding of the infinite-precision result to that return type. These are also naturally implemented using round-to-odd on platforms with hardware support for rounding modes and exceptions but lacking hardware support for these narrowing operations themselves. (Platforms that have direct hardware support for such narrowing operations include at least ia64, and Power ISA 2.07 or later, which I think means POWER8 or later.) So adding the remaining TS 18661-1 functions would mean at least six narrowing function implementations (fadd fsub fmul fdiv ffma fsqrt), with aliases for other types and further implementations in some configurations, that need to be overridden for configurations lacking hardware exceptions and rounding modes. Requiring all such configurations (currently seven of them) to have their own source files for all those functions seems undesirable. Thus, this patch adds a directory sysdeps/ieee754/soft-fp to contain libm function implementations based on soft-fp. This directory is then used via Implies from all the configurations that need it, so no more files need adding to every such configuration when adding more functions with soft-fp implementations. A configuration can still selectively #include a particular file from this directory if desired; thus, the MIPS #include of the fmal implementation is retained, since that's appropriate even for hard float (because long double is always implementated in software for MIPS64, so the soft-fp implementation of fmal is better than the ldbl-128 one). This also provides additional motivation for my recent patch removing --with-fp / --without-fp: previously there was no need for correct use of --without-fp for no-FPU ARM or SH3, and now we have autodetection nofpu/ sysdeps directories can be used by this patch for those configurations without imposing any new requirements on how glibc is configured. (The mips64/*/fpu/s_fma.c files added by this patch are needed to keep the dbl-64 version of fma for double, rather than the ldbl-128 one, used in that case.) Tested with build-many-glibcs.py that installed stripped shared libraries are unchanged by this patch. * soft-fp/fmadf4.c: Move to .... * sysdeps/ieee754/soft-fp/s_fma.c: ... here. * soft-fp/fmasf4.c: Move to .... * sysdeps/ieee754/soft-fp/s_fmaf.c: ... here. * soft-fp/fmatf4.c: Move to .... * sysdeps/ieee754/soft-fp/s_fmal.c: ... here. * sysdeps/ieee754/soft-fp/Makefile: New file. * sysdeps/arm/preconfigure.ac: Define with_fp_cond. * sysdeps/arm/preconfigure: Regenerated. * sysdeps/arm/nofpu/Implies: New file. * sysdeps/arm/s_fma.c: Remove file. * sysdeps/arm/s_fmaf.c: Likewise. * sysdeps/m68k/coldfire/nofpu/Implies: New file. * sysdeps/m68k/coldfire/nofpu/s_fma.c: Remove file. * sysdeps/m68k/coldfire/nofpu/s_fmaf.c: Likewise. * sysdeps/microblaze/Implies: Add ieee754/soft-fp. * sysdeps/microblaze/s_fma.c: Remove file. * sysdeps/microblaze/s_fmaf.c: Likewise. * sysdeps/mips/mips32/nofpu/Implies: New file. * sysdeps/mips/mips64/n32/fpu/s_fma.c: Likewise. * sysdeps/mips/mips64/n32/nofpu/Implies: Likewise. * sysdeps/mips/mips64/n64/fpu/s_fma.c: Likewise. * sysdeps/mips/mips64/n64/nofpu/Implies: Likewise. * sysdeps/mips/ieee754/s_fma.c: Remove file. * sysdeps/mips/ieee754/s_fmaf.c: Likewise. * sysdeps/mips/ieee754/s_fmal.c: Update include for move of fmal implementation. * sysdeps/nios2/Implies: Add ieee754/soft-fp. * sysdeps/nios2/s_fma.c: Remove file. * sysdeps/nios2/s_fmaf.c: Likewise. * sysdeps/sh/nofpu/Implies: New file. * sysdeps/sh/s_fma.c: Remove file. * sysdeps/sh/s_fmaf.c: Likewise. * sysdeps/tile/Implies: Add ieee754/soft-fp. * sysdeps/tile/s_fma.c: Remove file. * sysdeps/tile/s_fmaf.c: Likewise.
52 lines
1.5 KiB
Plaintext
52 lines
1.5 KiB
Plaintext
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
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# Local preconfigure fragment for sysdeps/arm
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case "$machine" in
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arm*)
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# If the compiler enables unwind tables by default, this causes
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# problems with undefined symbols in -nostdlib link tests. To
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# avoid this, add -fno-unwind-tables here and remove it in
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# sysdeps/arm/configure.ac after those tests have been run.
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if test "${CFLAGS+set}" != "set"; then
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CFLAGS="-g -O2"
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fi
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CFLAGS="$CFLAGS -fno-unwind-tables"
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base_machine=arm
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# Lets ask the compiler which ARM family we've got
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# Unfortunately it doesn't define any flags for implementations
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# that you might pass to -mcpu or -mtune
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# Note if you add patterns here you must ensure that
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# an appropriate directory exists in sysdeps/arm
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archcppflag=`$CC $CFLAGS $CPPFLAGS -E -dM -xc /dev/null |
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sed -n 's/^#define \(__ARM_ARCH_[0-9].*__\) .*$/\1/p'`
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case "x$archcppflag" in
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x__ARM_ARCH_[89]*__)
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machine=armv7
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AC_MSG_NOTICE([Found compiler is configured for something newer than v7 - using v7])
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;;
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x__ARM_ARCH_7A__)
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machine=armv7
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AC_MSG_NOTICE([Found compiler is configured for $machine])
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;;
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x__ARM_ARCH_6T2__)
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machine=armv6t2
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AC_MSG_NOTICE([Found compiler is configured for $machine])
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;;
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x__ARM_ARCH_6*__)
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machine=armv6
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AC_MSG_NOTICE([Found compiler is configured for $machine])
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;;
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*)
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machine=arm
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AC_MSG_WARN([arm/preconfigure: Did not find ARM architecture type; using default])
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;;
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esac
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machine=arm/$machine
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with_fp_cond="!defined __SOFTFP__"
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esac
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