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fix(libc): asin(|x| > 1) returns the x86 default NaN and leaves errno unchanged 

On main asin(2.0) returns 0x7ff8000000000000 and sets errno to 33;
FreeBSD msun (lib/msun/src/e_asin.c) returns 0xfff8000000000000 and
never sets errno. asin now handles |x| > 1 itself with quiet
comparisons, so a NaN input still raises no exception. For |x| <= 1
and for NaN the host function is still called.

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
This commit is contained in:
Alex 2026-10-11 10:07:47 -04:00
parent a11c8f7f70
commit fba96d6422
2 changed files with 39 additions and 1 deletions
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8
core/libs/prx/libc/src/Math.cpp
View File

@ -70,7 +70,13 @@ int APS5_VABI __isnormalf_nid_postfix(float x) { return std::isnormal(x) ? 1 : 0
int APS5_VABI __isinff_nid_postfix(float x) { return std::isinf(x) ? 1 : 0; }
double APS5_VABI cbrt_nid_postfix(double x) { return std::cbrt(x); }
double APS5_VABI asin_nid_postfix(double x) { return std::asin(x); }
double APS5_VABI asin_nid_postfix(double x) {
if (std::isgreater(x, 1.0) || std::isless(x, -1.0)) {
std::feraiseexcept(FE_INVALID);
return -std::numeric_limits<double>::quiet_NaN();
}
return std::asin(x);
}
double APS5_VABI acos_nid_postfix(double x) { return std::acos(x); }
double APS5_VABI sqrt_nid_postfix(double x) { return std::sqrt(x); }
float APS5_VABI sqrtf_nid_postfix(float x) { return std::sqrt(x); }

32
core/libs/tests/GuestMath.cpp
View File

@ -40,6 +40,7 @@ int APS5_VABI __fpclassifyf_nid_postfix(float);
float APS5_VABI fmodf_nid_postfix(float, float);
float APS5_VABI asinf_nid_postfix(float);
float APS5_VABI acosf_nid_postfix(float);
double APS5_VABI asin_nid_postfix(double);
float APS5_VABI atan2f_nid_postfix(float, float);
float APS5_VABI hypotf_nid_postfix(float, float);
double APS5_VABI hypot_nid_postfix(double, double);
@ -281,6 +282,36 @@ static void CheckIntegerConversions() {
static bool Near(double value, double expected, double tolerance) { return std::abs(value - expected) <= tolerance * std::abs(expected); }
static void CheckAsin() {
const double pi = 3.14159265358979323846;
const double pi_2 = pi / 2;
const double nan = std::numeric_limits<double>::quiet_NaN();
const double infinity = std::numeric_limits<double>::infinity();
Require(asin_nid_postfix(0.) == 0.);
Require(std::signbit(asin_nid_postfix(-0.)));
Require(Near(asin_nid_postfix(1.), pi_2, 1e-15));
Require(Near(asin_nid_postfix(-1.), -pi_2, 1e-15));
Require(std::isnan(asin_nid_postfix(2.0)) && std::signbit(asin_nid_postfix(2.0)));
Require(std::isnan(asin_nid_postfix(-2.0)) && std::signbit(asin_nid_postfix(-2.0)));
Require(std::isnan(asin_nid_postfix(infinity)) && std::signbit(asin_nid_postfix(infinity)));
Require(std::isnan(asin_nid_postfix(-infinity)) && std::signbit(asin_nid_postfix(-infinity)));
Require(std::isnan(asin_nid_postfix(nan)));
Require(Near(asin_nid_postfix(0.5), pi/6, 1e-15));
Require(Near(asin_nid_postfix(-0.5), -pi/6, 1e-15));
Require(Near(asin_nid_postfix(1./std::sqrt(2)), pi/4, 1e-15));
Require(asin_nid_postfix(1e-300) == 1e-300);
Require(asin_nid_postfix(-1e-300) == -1e-300);
std::feclearexcept(FE_ALL_EXCEPT);
errno = 0;
asin_nid_postfix(2.0);
Require(std::fetestexcept(FE_INVALID));
Require(errno == 0);
std::feclearexcept(FE_ALL_EXCEPT);
asin_nid_postfix(nan);
Require(!std::fetestexcept(FE_INVALID));
}
static void CheckHyperbolic() {
const double infinity = std::numeric_limits<double>::infinity();
Require(sinh_nid_postfix(0.) == 0. && std::signbit(sinh_nid_postfix(-0.)));
@ -478,6 +509,7 @@ int main() {
Require(__isnormalf_nid_postfix(std::numeric_limits<float>::denorm_min()) == 0);
Require(__isnormal_nid_postfix(1.) == 1 && __isnormal_nid_postfix(0.) == 0);
Require(__isnormal_nid_postfix(std::numeric_limits<double>::denorm_min()) == 0);
CheckAsin();
const auto quotient = div_nid_postfix(7, 2);
Require(quotient.quot == 3 && quotient.rem == 1);
const auto negativeNumerator = div_nid_postfix(-7, 2);