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target/mips: Set default NaN pattern explicitly

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Set the default NaN pattern explicitly for MIPS. Note that this
is our only target which currently changes the default NaN
at runtime (which it was previously doing indirectly when it
changed the snan_bit_is_one setting).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241202131347.498124-44-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2024-12-11 15:31:06 +00:00
parent 34f73db53d
commit 5c3ba81055
2 changed files with 10 additions and 0 deletions
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7
target/mips/fpu_helper.h
View file

@ -47,6 +47,13 @@ static inline void restore_snan_bit_mode(CPUMIPSState *env)
set_float_infzeronan_rule(izn_rule, &env->active_fpu.fp_status);
nan3_rule = nan2008 ? float_3nan_prop_s_cab : float_3nan_prop_s_abc;
set_float_3nan_prop_rule(nan3_rule, &env->active_fpu.fp_status);
/*
* With nan2008, the default NaN value has the sign bit clear and the
* frac msb set; with the older mode, the sign bit is clear, and all
* frac bits except the msb are set.
*/
set_float_default_nan_pattern(nan2008 ? 0b01000000 : 0b00111111,
&env->active_fpu.fp_status);
}

3
target/mips/msa.c
View file

@ -81,4 +81,7 @@ void msa_reset(CPUMIPSState *env)
/* Inf * 0 + NaN returns the input NaN */
set_float_infzeronan_rule(float_infzeronan_dnan_never,
&env->active_tc.msa_fp_status);
/* Default NaN: sign bit clear, frac msb set */
set_float_default_nan_pattern(0b01000000,
&env->active_tc.msa_fp_status);
}