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target/i386: force maximum rounding precision for fildl[l]

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The instruction description says "It is loaded without rounding
errors." which implies we should have the widest rounding mode
possible.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/888
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220315121251.2280317-4-alex.bennee@linaro.org>
This commit is contained in:
Alex Bennée 2022-03-07 18:41:59 +00:00
parent 425d6aba99
commit 276de33f3d
1 changed files with 13 additions and 0 deletions
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13
target/i386/tcg/fpu_helper.c
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@ -237,24 +237,37 @@ void helper_fldl_ST0(CPUX86State *env, uint64_t val)
merge_exception_flags(env, old_flags);
}
static FloatX80RoundPrec tmp_maximise_precision(float_status *st)
{
FloatX80RoundPrec old = get_floatx80_rounding_precision(st);
set_floatx80_rounding_precision(floatx80_precision_x, st);
return old;
}
void helper_fildl_ST0(CPUX86State *env, int32_t val)
{
int new_fpstt;
FloatX80RoundPrec old = tmp_maximise_precision(&env->fp_status);
new_fpstt = (env->fpstt - 1) & 7;
env->fpregs[new_fpstt].d = int32_to_floatx80(val, &env->fp_status);
env->fpstt = new_fpstt;
env->fptags[new_fpstt] = 0; /* validate stack entry */
set_floatx80_rounding_precision(old, &env->fp_status);
}
void helper_fildll_ST0(CPUX86State *env, int64_t val)
{
int new_fpstt;
FloatX80RoundPrec old = tmp_maximise_precision(&env->fp_status);
new_fpstt = (env->fpstt - 1) & 7;
env->fpregs[new_fpstt].d = int64_to_floatx80(val, &env->fp_status);
env->fpstt = new_fpstt;
env->fptags[new_fpstt] = 0; /* validate stack entry */
set_floatx80_rounding_precision(old, &env->fp_status);
}
uint32_t helper_fsts_ST0(CPUX86State *env)