From df3436b5188b785e2f1d22e80be0db6282e2afbb Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Sun, 20 May 2018 00:04:18 -0400 Subject: [PATCH] fpu/softfloat: Define floatN_default_nan in terms of parts_default_nan Isolate the target-specific choice to 2 functions instead of 6. The code in float16_default_nan was only correct for ARM, MIPS, and X86. Though float16 support is rare among our targets. The code in float128_default_nan was arguably wrong for Sparc. While QEMU supports the Sparc 128-bit insns, no real cpu enables it. The code in floatx80_default_nan tried to be over-general. There are only two targets that support this format: x86 and m68k. Thus there is no point in inventing a value for snan_bit_is_one. Move routines that no longer have ifdefs out of softfloat-specialize.h. Backports commit 0218a16e540ad416683e19dfbd52f75092507b27 from qemu --- qemu/fpu/softfloat-specialize.h | 105 ++------------------------------ qemu/fpu/softfloat.c | 41 +++++++++++++ 2 files changed, 47 insertions(+), 99 deletions(-) diff --git a/qemu/fpu/softfloat-specialize.h b/qemu/fpu/softfloat-specialize.h index b649a516..a947c441 100644 --- a/qemu/fpu/softfloat-specialize.h +++ b/qemu/fpu/softfloat-specialize.h @@ -179,94 +179,22 @@ static FloatParts parts_silence_nan(FloatParts a, float_status *status) return a; } -/*---------------------------------------------------------------------------- -| The pattern for a default generated half-precision NaN. -*----------------------------------------------------------------------------*/ -float16 float16_default_nan(float_status *status) -{ -#if defined(TARGET_ARM) - return const_float16(0x7E00); -#else - if (snan_bit_is_one(status)) { - return const_float16(0x7DFF); - } else { -#if defined(TARGET_MIPS) - return const_float16(0x7E00); -#else - return const_float16(0xFE00); -#endif - } -#endif -} - -/*---------------------------------------------------------------------------- -| The pattern for a default generated single-precision NaN. -*----------------------------------------------------------------------------*/ -float32 float32_default_nan(float_status *status) -{ -#if defined(TARGET_SPARC) || defined(TARGET_M68K) - return const_float32(0x7FFFFFFF); -#elif defined(TARGET_PPC) || defined(TARGET_ARM) || defined(TARGET_ALPHA) || \ - defined(TARGET_XTENSA) || defined(TARGET_S390X) || \ - defined(TARGET_TRICORE) || defined(TARGET_RISCV) - return const_float32(0x7FC00000); -#elif defined(TARGET_HPPA) - return const_float32(0x7FA00000); -#else - if (snan_bit_is_one(status)) { - return const_float32(0x7FBFFFFF); - } else { -#if defined(TARGET_MIPS) - return const_float32(0x7FC00000); -#else - return const_float32(0xFFC00000); -#endif - } -#endif -} - -/*---------------------------------------------------------------------------- -| The pattern for a default generated double-precision NaN. -*----------------------------------------------------------------------------*/ -float64 float64_default_nan(float_status *status) -{ -#if defined(TARGET_SPARC) || defined(TARGET_M68K) - return const_float64(LIT64(0x7FFFFFFFFFFFFFFF)); -#elif defined(TARGET_PPC) || defined(TARGET_ARM) || defined(TARGET_ALPHA) || \ - defined(TARGET_S390X) || defined(TARGET_RISCV) - return const_float64(LIT64(0x7FF8000000000000)); -#elif defined(TARGET_HPPA) - return const_float64(LIT64(0x7FF4000000000000)); -#else - if (snan_bit_is_one(status)) { - return const_float64(LIT64(0x7FF7FFFFFFFFFFFF)); - } else { -#if defined(TARGET_MIPS) - return const_float64(LIT64(0x7FF8000000000000)); -#else - return const_float64(LIT64(0xFFF8000000000000)); -#endif - } -#endif -} - /*---------------------------------------------------------------------------- | The pattern for a default generated extended double-precision NaN. *----------------------------------------------------------------------------*/ floatx80 floatx80_default_nan(float_status *status) { floatx80 r; + + /* None of the targets that have snan_bit_is_one use floatx80. */ + assert(!snan_bit_is_one(status)); #if defined(TARGET_M68K) r.low = LIT64(0xFFFFFFFFFFFFFFFF); r.high = 0x7FFF; #else - if (snan_bit_is_one(status)) { - r.low = LIT64(0xBFFFFFFFFFFFFFFF); - r.high = 0x7FFF; - } else { - r.low = LIT64(0xC000000000000000); - r.high = 0xFFFF; - } + /* X86 */ + r.low = LIT64(0xC000000000000000); + r.high = 0xFFFF; #endif return r; } @@ -285,27 +213,6 @@ floatx80 floatx80_default_nan(float_status *status) const floatx80 floatx80_infinity = make_floatx80_init(floatx80_infinity_high, floatx80_infinity_low); -/*---------------------------------------------------------------------------- -| The pattern for a default generated quadruple-precision NaN. -*----------------------------------------------------------------------------*/ -float128 float128_default_nan(float_status *status) -{ - float128 r; - - if (snan_bit_is_one(status)) { - r.low = LIT64(0xFFFFFFFFFFFFFFFF); - r.high = LIT64(0x7FFF7FFFFFFFFFFF); - } else { - r.low = LIT64(0x0000000000000000); -#if defined(TARGET_S390X) || defined(TARGET_PPC) || defined(TARGET_RISCV) - r.high = LIT64(0x7FFF800000000000); -#else - r.high = LIT64(0xFFFF800000000000); -#endif - } - return r; -} - /*---------------------------------------------------------------------------- | Raises the exceptions specified by `flags'. Floating-point traps can be | defined here if desired. It is currently not possible for such a trap diff --git a/qemu/fpu/softfloat.c b/qemu/fpu/softfloat.c index ea8f9259..4199579b 100644 --- a/qemu/fpu/softfloat.c +++ b/qemu/fpu/softfloat.c @@ -2093,6 +2093,47 @@ float64 QEMU_FLATTEN float64_sqrt(float64 a, float_status *status) return float64_round_pack_canonical(pr, status); } +/*---------------------------------------------------------------------------- +| The pattern for a default generated NaN. +*----------------------------------------------------------------------------*/ + +float16 float16_default_nan(float_status *status) +{ + FloatParts p = parts_default_nan(status); + p.frac >>= float16_params.frac_shift; + return float16_pack_raw(p); +} + +float32 float32_default_nan(float_status *status) +{ + FloatParts p = parts_default_nan(status); + p.frac >>= float32_params.frac_shift; + return float32_pack_raw(p); +} + +float64 float64_default_nan(float_status *status) +{ + FloatParts p = parts_default_nan(status); + p.frac >>= float64_params.frac_shift; + return float64_pack_raw(p); +} + +float128 float128_default_nan(float_status *status) +{ + FloatParts p = parts_default_nan(status); + float128 r; + + /* Extrapolate from the choices made by parts_default_nan to fill + * in the quad-floating format. If the low bit is set, assume we + * want to set all non-snan bits. + */ + r.low = -(p.frac & 1); + r.high = p.frac >> (DECOMPOSED_BINARY_POINT - 48); + r.high |= LIT64(0x7FFF000000000000); + r.high |= (uint64_t)p.sign << 63; + + return r; +} /*---------------------------------------------------------------------------- | Takes a 64-bit fixed-point value `absZ' with binary point between bits 6