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target/ppc: Add helper for frsqrtes

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There is no double-rounding bug here, because the result is
merely an estimate to within 1 part in 32, but perform the
operation with float64r32_div for consistency.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211119160502.17432-33-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 7f87214e3b
commit dedbfda765
3 changed files with 21 additions and 2 deletions
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19
target/ppc/fpu_helper.c
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@ -896,6 +896,25 @@ float64 helper_frsqrte(CPUPPCState *env, float64 arg)
return retd;
}
/* frsqrtes - frsqrtes. */
float64 helper_frsqrtes(CPUPPCState *env, float64 arg)
{
/* "Estimate" the reciprocal with actual division. */
float64 rets = float64_sqrt(arg, &env->fp_status);
float64 retd = float64r32_div(float64_one, rets, &env->fp_status);
int flags = get_float_exception_flags(&env->fp_status);
if (unlikely(flags & float_flag_invalid)) {
float_invalid_op_sqrt(env, flags, 1, GETPC());
}
if (unlikely(flags & float_flag_divbyzero)) {
/* Reciprocal of (square root of) zero. */
float_zero_divide_excp(env, GETPC());
}
return retd;
}
/* fsel - fsel. */
uint64_t helper_fsel(CPUPPCState *env, uint64_t arg1, uint64_t arg2,
uint64_t arg3)

1
target/ppc/helper.h
View File

@ -114,6 +114,7 @@ DEF_HELPER_2(fsqrts, f64, env, f64)
DEF_HELPER_2(fre, i64, env, i64)
DEF_HELPER_2(fres, i64, env, i64)
DEF_HELPER_2(frsqrte, i64, env, i64)
DEF_HELPER_2(frsqrtes, i64, env, i64)
DEF_HELPER_4(fsel, i64, env, i64, i64, i64)
DEF_HELPER_FLAGS_2(ftdiv, TCG_CALL_NO_RWG_SE, i32, i64, i64)

3
target/ppc/translate/fp-impl.c.inc
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@ -212,8 +212,7 @@ static void gen_frsqrtes(DisasContext *ctx)
t1 = tcg_temp_new_i64();
gen_reset_fpstatus();
get_fpr(t0, rB(ctx->opcode));
gen_helper_frsqrte(t1, cpu_env, t0);
gen_helper_frsp(t1, cpu_env, t1);
gen_helper_frsqrtes(t1, cpu_env, t0);
set_fpr(rD(ctx->opcode), t1);
gen_compute_fprf_float64(t1);
if (unlikely(Rc(ctx->opcode) != 0)) {