0c587f1339
Set the 2-NaN propagation rule explicitly in the float_status words we use. For active_fpu.fp_status, we do this in a new fp_reset() function which mirrors the existing msa_reset() function in doing "first call restore to set the fp status parts that depend on CPU state, then set the fp status parts that are constant". Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Message-id: 20241025141254.2141506-5-peter.maydell@linaro.org
78 lines
2.6 KiB
C
78 lines
2.6 KiB
C
/*
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* MIPS SIMD Architecture Module Instruction emulation helpers for QEMU.
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*
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* Copyright (c) 2014 Imagination Technologies
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "cpu.h"
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#include "internal.h"
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#include "fpu/softfloat.h"
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#include "fpu_helper.h"
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void msa_reset(CPUMIPSState *env)
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{
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if (!ase_msa_available(env)) {
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return;
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}
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#ifdef CONFIG_USER_ONLY
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/* MSA access enabled */
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env->CP0_Config5 |= 1 << CP0C5_MSAEn;
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env->CP0_Status |= (1 << CP0St_CU1) | (1 << CP0St_FR);
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#endif
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/*
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* MSA CSR:
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* - non-signaling floating point exception mode off (NX bit is 0)
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* - Cause, Enables, and Flags are all 0
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* - round to nearest / ties to even (RM bits are 0)
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*/
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env->active_tc.msacsr = 0;
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restore_msa_fp_status(env);
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/* tininess detected after rounding.*/
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set_float_detect_tininess(float_tininess_after_rounding,
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&env->active_tc.msa_fp_status);
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/*
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* According to MIPS specifications, if one of the two operands is
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* a sNaN, a new qNaN has to be generated. This is done in
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* floatXX_silence_nan(). For qNaN inputs the specifications
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* says: "When possible, this QNaN result is one of the operand QNaN
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* values." In practice it seems that most implementations choose
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* the first operand if both operands are qNaN. In short this gives
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* the following rules:
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* 1. A if it is signaling
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* 2. B if it is signaling
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* 3. A (quiet)
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* 4. B (quiet)
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* A signaling NaN is always silenced before returning it.
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*/
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set_float_2nan_prop_rule(float_2nan_prop_s_ab,
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&env->active_tc.msa_fp_status);
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/* clear float_status exception flags */
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set_float_exception_flags(0, &env->active_tc.msa_fp_status);
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/* clear float_status nan mode */
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set_default_nan_mode(0, &env->active_tc.msa_fp_status);
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/* set proper signanling bit meaning ("1" means "quiet") */
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set_snan_bit_is_one(0, &env->active_tc.msa_fp_status);
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}
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