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powerpc: use float64 for frsqrte

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Remove the code that reduce the result to float32 as the frsqrte
instruction is defined to return a double-precision estimate of
the reciprocal square root.

Although reducing the fractional part is harmless (as the estimation
must have at least 12 bits of precision according to the old PEM),
reducing the exponent range is not correct.

Signed-off-by: Tristan Gingold <gingold@adacore.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Tristan Gingold 2014-06-03 11:14:20 +02:00 committed by Alexander Graf
parent 23825581d7
commit e223bcad6e
1 changed files with 0 additions and 3 deletions
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3
target-ppc/fpu_helper.c
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@ -977,7 +977,6 @@ uint64_t helper_fres(CPUPPCState *env, uint64_t arg)
uint64_t helper_frsqrte(CPUPPCState *env, uint64_t arg)
{
CPU_DoubleU farg;
float32 f32;
farg.ll = arg;
@ -991,8 +990,6 @@ uint64_t helper_frsqrte(CPUPPCState *env, uint64_t arg)
}
farg.d = float64_sqrt(farg.d, &env->fp_status);
farg.d = float64_div(float64_one, farg.d, &env->fp_status);
f32 = float64_to_float32(farg.d, &env->fp_status);
farg.d = float32_to_float64(f32, &env->fp_status);
}
return farg.ll;
}