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target/ppc: Use helper_todouble/tosingle in helper_xststdcsp

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When computing the predicate "is this value currently formatted
for single precision", we do not want to round the value according
to the current rounding mode, nor perform a floating-point equality.
We want to see if the N bits that make up single-precision are the
only ones set within the register, and then a bitwise equality.

Fixes a bug in which a single-precision NaN is considered !SP,
because float64_eq(nan, nan) is always false.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211119160502.17432-35-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 7d82ea3484
commit a1f1c731c6
1 changed files with 10 additions and 11 deletions
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21
target/ppc/fpu_helper.c
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@ -3163,26 +3163,25 @@ void helper_xststdcsp(CPUPPCState *env, uint32_t opcode, ppc_vsr_t *xb)
{
uint32_t dcmx, sign, exp;
uint32_t cc, match = 0, not_sp = 0;
float64 arg = xb->VsrD(0);
float64 arg_sp;
dcmx = DCMX(opcode);
exp = (xb->VsrD(0) >> 52) & 0x7FF;
exp = (arg >> 52) & 0x7FF;
sign = float64_is_neg(arg);
sign = float64_is_neg(xb->VsrD(0));
if (float64_is_any_nan(xb->VsrD(0))) {
if (float64_is_any_nan(arg)) {
match = extract32(dcmx, 6, 1);
} else if (float64_is_infinity(xb->VsrD(0))) {
} else if (float64_is_infinity(arg)) {
match = extract32(dcmx, 4 + !sign, 1);
} else if (float64_is_zero(xb->VsrD(0))) {
} else if (float64_is_zero(arg)) {
match = extract32(dcmx, 2 + !sign, 1);
} else if (float64_is_zero_or_denormal(xb->VsrD(0)) ||
(exp > 0 && exp < 0x381)) {
} else if (float64_is_zero_or_denormal(arg) || (exp > 0 && exp < 0x381)) {
match = extract32(dcmx, 0 + !sign, 1);
}
not_sp = !float64_eq(xb->VsrD(0),
float32_to_float64(
float64_to_float32(xb->VsrD(0), &env->fp_status),
&env->fp_status), &env->fp_status);
arg_sp = helper_todouble(helper_tosingle(arg));
not_sp = arg != arg_sp;
cc = sign << CRF_LT_BIT | match << CRF_EQ_BIT | not_sp << CRF_SO_BIT;
env->fpscr &= ~FP_FPCC;