From 0bcfbcbea548656ff930394f296589728c2a0c5d Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Thu, 10 May 2018 13:32:53 -0700 Subject: [PATCH] fpu/softfloat: Replace float_class_msnan with parts_silence_nan MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit With a canonical representation of NaNs, we can silence an SNaN immediately rather than delay until the final format is known. Tested-by: Alex Bennée Reviewed-by: Alex Bennée Reviewed-by: Peter Maydell Signed-off-by: Richard Henderson --- fpu/softfloat-specialize.h | 23 ++++++++++++++++++++++ fpu/softfloat.c | 40 ++++++++++---------------------------- 2 files changed, 33 insertions(+), 30 deletions(-) diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h index 0d3d81a52b..571d1df378 100644 --- a/fpu/softfloat-specialize.h +++ b/fpu/softfloat-specialize.h @@ -138,6 +138,29 @@ static FloatParts parts_default_nan(float_status *status) }; } +/*---------------------------------------------------------------------------- +| Returns a quiet NaN from a signalling NaN for the deconstructed +| floating-point parts. +*----------------------------------------------------------------------------*/ + +static FloatParts parts_silence_nan(FloatParts a, float_status *status) +{ +#ifdef NO_SIGNALING_NANS + g_assert_not_reached(); +#elif defined(TARGET_HPPA) + a.frac &= ~(1ULL << (DECOMPOSED_BINARY_POINT - 1)); + a.frac |= 1ULL << (DECOMPOSED_BINARY_POINT - 2); +#else + if (status->snan_bit_is_one) { + return parts_default_nan(status); + } else { + a.frac |= 1ULL << (DECOMPOSED_BINARY_POINT - 1); + } +#endif + a.cls = float_class_qnan; + return a; +} + /*---------------------------------------------------------------------------- | The pattern for a default generated half-precision NaN. *----------------------------------------------------------------------------*/ diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 51780b718f..41253c6749 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -188,7 +188,6 @@ typedef enum __attribute__ ((__packed__)) { float_class_inf, float_class_qnan, /* all NaNs from here */ float_class_snan, - float_class_msnan, /* maybe silenced */ } FloatClass; /* @@ -492,14 +491,7 @@ static FloatParts float16_unpack_canonical(float16 f, float_status *s) static float16 float16_round_pack_canonical(FloatParts p, float_status *s) { - switch (p.cls) { - case float_class_msnan: - p.frac >>= float16_params.frac_shift; - return float16_maybe_silence_nan(float16_pack_raw(p), s); - default: - p = round_canonical(p, s, &float16_params); - return float16_pack_raw(p); - } + return float16_pack_raw(round_canonical(p, s, &float16_params)); } static FloatParts float32_unpack_canonical(float32 f, float_status *s) @@ -509,14 +501,7 @@ static FloatParts float32_unpack_canonical(float32 f, float_status *s) static float32 float32_round_pack_canonical(FloatParts p, float_status *s) { - switch (p.cls) { - case float_class_msnan: - p.frac >>= float32_params.frac_shift; - return float32_maybe_silence_nan(float32_pack_raw(p), s); - default: - p = round_canonical(p, s, &float32_params); - return float32_pack_raw(p); - } + return float32_pack_raw(round_canonical(p, s, &float32_params)); } static FloatParts float64_unpack_canonical(float64 f, float_status *s) @@ -526,14 +511,7 @@ static FloatParts float64_unpack_canonical(float64 f, float_status *s) static float64 float64_round_pack_canonical(FloatParts p, float_status *s) { - switch (p.cls) { - case float_class_msnan: - p.frac >>= float64_params.frac_shift; - return float64_maybe_silence_nan(float64_pack_raw(p), s); - default: - p = round_canonical(p, s, &float64_params); - return float64_pack_raw(p); - } + return float64_pack_raw(round_canonical(p, s, &float64_params)); } /* Simple helpers for checking if what NaN we have */ @@ -555,7 +533,7 @@ static FloatParts return_nan(FloatParts a, float_status *s) switch (a.cls) { case float_class_snan: s->float_exception_flags |= float_flag_invalid; - a.cls = float_class_msnan; + a = parts_silence_nan(a, s); /* fall through */ case float_class_qnan: if (s->default_nan_mode) { @@ -584,7 +562,9 @@ static FloatParts pick_nan(FloatParts a, FloatParts b, float_status *s) (a.frac == b.frac && a.sign < b.sign))) { a = b; } - a.cls = float_class_msnan; + if (is_snan(a.cls)) { + return parts_silence_nan(a, s); + } } return a; } @@ -624,8 +604,10 @@ static FloatParts pick_nan_muladd(FloatParts a, FloatParts b, FloatParts c, default: g_assert_not_reached(); } - a.cls = float_class_msnan; + if (is_snan(a.cls)) { + return parts_silence_nan(a, s); + } return a; } @@ -1334,7 +1316,6 @@ static int64_t round_to_int_and_pack(FloatParts in, int rmode, switch (p.cls) { case float_class_snan: case float_class_qnan: - case float_class_msnan: s->float_exception_flags = orig_flags | float_flag_invalid; return max; case float_class_inf: @@ -1425,7 +1406,6 @@ static uint64_t round_to_uint_and_pack(FloatParts in, int rmode, uint64_t max, switch (p.cls) { case float_class_snan: case float_class_qnan: - case float_class_msnan: s->float_exception_flags = orig_flags | float_flag_invalid; return max; case float_class_inf: