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target/ppc: Add helpers for fmadds et al

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Use float64r32_muladd.  Fixes a double-rounding issue with performing
the compuation in float64 and then rounding afterward.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211119160502.17432-29-richard.henderson@linaro.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
This commit is contained in:
Richard Henderson 2021-12-17 17:57:16 +01:00 • committed by Cédric Le Goater
parent 42636fb923
commit d04ca895dc
3 changed files with 25 additions and 9 deletions
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17
target/ppc/fpu_helper.c
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@ -705,10 +705,25 @@ static float64 do_fmadd(CPUPPCState *env, float64 a, float64 b,
return ret;
}
static uint64_t do_fmadds(CPUPPCState *env, float64 a, float64 b,
float64 c, int madd_flags, uintptr_t retaddr)
{
float64 ret = float64r32_muladd(a, b, c, madd_flags, &env->fp_status);
int flags = get_float_exception_flags(&env->fp_status);
if (unlikely(flags & float_flag_invalid)) {
float_invalid_op_madd(env, flags, 1, retaddr);
}
return ret;
}
#define FPU_FMADD(op, madd_flags) \
uint64_t helper_##op(CPUPPCState *env, uint64_t arg1, \
uint64_t arg2, uint64_t arg3) \
{ return do_fmadd(env, arg1, arg2, arg3, madd_flags, GETPC()); }
{ return do_fmadd(env, arg1, arg2, arg3, madd_flags, GETPC()); } \
uint64_t helper_##op##s(CPUPPCState *env, uint64_t arg1, \
uint64_t arg2, uint64_t arg3) \
{ return do_fmadds(env, arg1, arg2, arg3, madd_flags, GETPC()); }
#define MADD_FLGS 0
#define MSUB_FLGS float_muladd_negate_c