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[libc][math] Skip checking for exceptional values when LIBC_MATH_SKIP_ACCURATE_PASS is set. #130811

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Merged
merged 1 commit into from
Mar 11, 2025
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[libc][math] Skip checking for exceptional values when LIBC_MATH_SKIP_ACCURATE_PASS is set. #130811

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4 changes: 4 additions & 0 deletions libc/src/math/generic/acosf.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
static constexpr size_t N_EXCEPTS = 4;

// Exceptional values when |x| <= 0.5
Expand All @@ -34,6 +35,7 @@ static constexpr fputil::ExceptValues<float, N_EXCEPTS> ACOSF_EXCEPTS = {{
// x = -0x1.04c444p-12, acosf(x) = 0x1.923p0 (RZ)
{0xb9826222, 0x3fc91800, 1, 0, 1},
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float, acosf, (float x)) {
using FPBits = typename fputil::FPBits<float>;
Expand All @@ -51,9 +53,11 @@ LLVM_LIBC_FUNCTION(float, acosf, (float x)) {
// acos(x) = pi/2 - asin(x)
// ~ pi/2 - x - x^3 / 6

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
// Check for exceptional values
if (auto r = ACOSF_EXCEPTS.lookup(x_uint); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

double xd = static_cast<double>(x);
return static_cast<float>(fputil::multiply_add(
Expand Down
4 changes: 4 additions & 0 deletions libc/src/math/generic/acosf16.cpp
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Expand Up @@ -27,13 +27,15 @@ namespace LIBC_NAMESPACE_DECL {
static constexpr float PI_OVER_2 = 0x1.921fb6p0f;
static constexpr float PI = 0x1.921fb6p1f;

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
static constexpr size_t N_EXCEPTS = 2;

static constexpr fputil::ExceptValues<float16, N_EXCEPTS> ACOSF16_EXCEPTS{{
// (input, RZ output, RU offset, RD offset, RN offset)
{0xacaf, 0x3e93, 1, 0, 0},
{0xb874, 0x4052, 1, 0, 1},
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float16, acosf16, (float16 x)) {
using FPBits = fputil::FPBits<float16>;
Expand Down Expand Up @@ -64,9 +66,11 @@ LLVM_LIBC_FUNCTION(float16, acosf16, (float16 x)) {

float xf = x;

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
// Handle exceptional values
if (auto r = ACOSF16_EXCEPTS.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// |x| == 0x1p0, x is 1 or -1
// if x is (-)1, return pi, else
Expand Down
7 changes: 6 additions & 1 deletion libc/src/math/generic/acoshf.cpp
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Expand Up @@ -22,7 +22,6 @@ namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(float, acoshf, (float x)) {
using FPBits_t = typename fputil::FPBits<float>;
FPBits_t xbits(x);
uint32_t x_u = xbits.uintval();

if (LIBC_UNLIKELY(x <= 1.0f)) {
if (x == 1.0f)
Expand All @@ -33,6 +32,8 @@ LLVM_LIBC_FUNCTION(float, acoshf, (float x)) {
return FPBits_t::quiet_nan().get_val();
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
uint32_t x_u = xbits.uintval();
if (LIBC_UNLIKELY(x_u >= 0x4f8ffb03)) {
if (LIBC_UNLIKELY(xbits.is_inf_or_nan()))
return x;
Expand Down Expand Up @@ -64,6 +65,10 @@ LLVM_LIBC_FUNCTION(float, acoshf, (float x)) {
return round_result_slightly_up(0x1.451436p6f);
}
}
#else
if (LIBC_UNLIKELY(xbits.is_inf_or_nan()))
return x;
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

double x_d = static_cast<double>(x);
// acosh(x) = log(x + sqrt(x^2 - 1))
Expand Down
6 changes: 6 additions & 0 deletions libc/src/math/generic/asinf.cpp
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Expand Up @@ -21,6 +21,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
static constexpr size_t N_EXCEPTS = 2;

// Exceptional values when |x| <= 0.5
Expand All @@ -40,6 +41,7 @@ static constexpr fputil::ExceptValues<float, N_EXCEPTS> ASINF_EXCEPTS_HI = {{
// x = 0x1.ee836cp-1, asinf(x) = 0x1.4f0654p0 (RZ)
{0x3f7741b6, 0x3fa7832a, 1, 0, 0},
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float, asinf, (float x)) {
using FPBits = typename fputil::FPBits<float>;
Expand Down Expand Up @@ -82,10 +84,12 @@ LLVM_LIBC_FUNCTION(float, asinf, (float x)) {
#endif // LIBC_TARGET_CPU_HAS_FMA_FLOAT
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
// Check for exceptional values
if (auto r = ASINF_EXCEPTS_LO.lookup_odd(x_abs, x_sign);
LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// For |x| <= 0.5, we approximate asinf(x) by:
// asin(x) = x * P(x^2)
Expand All @@ -111,10 +115,12 @@ LLVM_LIBC_FUNCTION(float, asinf, (float x)) {
return FPBits::quiet_nan().get_val();
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
// Check for exceptional values
if (auto r = ASINF_EXCEPTS_HI.lookup_odd(x_abs, x_sign);
LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// When |x| > 0.5, we perform range reduction as follow:
//
Expand Down
5 changes: 5 additions & 0 deletions libc/src/math/generic/asinhf.cpp
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Expand Up @@ -49,6 +49,7 @@ LLVM_LIBC_FUNCTION(float, asinhf, (float x)) {
double x_sign = SIGN[x_u >> 31];
double x_d = x;

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
// Helper functions to set results for exceptional cases.
auto round_result_slightly_down = [x_sign](float r) -> float {
return fputil::multiply_add(static_cast<float>(x_sign), r,
Expand Down Expand Up @@ -95,6 +96,10 @@ LLVM_LIBC_FUNCTION(float, asinhf, (float x)) {
return round_result_slightly_down(0x1.e1b92p3f);
}
}
#else
if (LIBC_UNLIKELY(xbits.is_inf_or_nan()))
return x;
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// asinh(x) = log(x + sqrt(x^2 + 1))
return static_cast<float>(
Expand Down
4 changes: 4 additions & 0 deletions libc/src/math/generic/cosf.cpp
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Expand Up @@ -20,6 +20,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
// Exceptional cases for cosf.
static constexpr size_t N_EXCEPTS = 6;

Expand All @@ -38,6 +39,7 @@ static constexpr fputil::ExceptValues<float, N_EXCEPTS> COSF_EXCEPTS{{
// x = 0x1.ddebdep120, cos(x) = 0x1.114438p-1 (RZ)
{0x7beef5ef, 0x3f08a21c, 1, 0, 0},
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float, cosf, (float x)) {
using FPBits = typename fputil::FPBits<float>;
Expand Down Expand Up @@ -108,8 +110,10 @@ LLVM_LIBC_FUNCTION(float, cosf, (float x)) {
#endif // LIBC_TARGET_CPU_HAS_FMA_FLOAT
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
if (auto r = COSF_EXCEPTS.lookup(x_abs); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// x is inf or nan.
if (LIBC_UNLIKELY(x_abs >= 0x7f80'0000U)) {
Expand Down
4 changes: 4 additions & 0 deletions libc/src/math/generic/cosf16.cpp
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Expand Up @@ -19,6 +19,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
constexpr size_t N_EXCEPTS = 4;

constexpr fputil::ExceptValues<float16, N_EXCEPTS> COSF16_EXCEPTS{{
Expand All @@ -28,6 +29,7 @@ constexpr fputil::ExceptValues<float16, N_EXCEPTS> COSF16_EXCEPTS{{
{0x5c49, 0xb8c6, 0, 1, 0},
{0x7acc, 0xa474, 0, 1, 0},
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float16, cosf16, (float16 x)) {
using FPBits = fputil::FPBits<float16>;
Expand All @@ -53,9 +55,11 @@ LLVM_LIBC_FUNCTION(float16, cosf16, (float16 x)) {
// = cos(k * pi/32) * cos(y * pi/32) -
// sin(k * pi/32) * sin(y * pi/32)

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
// Handle exceptional values
if (auto r = COSF16_EXCEPTS.lookup(x_abs); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// cos(+/-0) = 1
if (LIBC_UNLIKELY(x_abs == 0U))
Expand Down
4 changes: 4 additions & 0 deletions libc/src/math/generic/coshf16.cpp
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Expand Up @@ -20,6 +20,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
static constexpr fputil::ExceptValues<float16, 9> COSHF16_EXCEPTS_POS = {{
// x = 0x1.6ap-5, coshf16(x) = 0x1p+0 (RZ)
{0x29a8U, 0x3c00U, 1U, 0U, 1U},
Expand Down Expand Up @@ -51,6 +52,7 @@ static constexpr fputil::ExceptValues<float16, 4> COSHF16_EXCEPTS_NEG = {{
// x = -0x1.5fp+3, coshf16(x) = 0x1.c54p+14 (RZ)
{0xc97cU, 0x7715U, 1U, 0U, 1U},
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float16, coshf16, (float16 x)) {
using FPBits = fputil::FPBits<float16>;
Expand Down Expand Up @@ -89,13 +91,15 @@ LLVM_LIBC_FUNCTION(float16, coshf16, (float16 x)) {
}
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
if (x_bits.is_pos()) {
if (auto r = COSHF16_EXCEPTS_POS.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
return r.value();
} else {
if (auto r = COSHF16_EXCEPTS_NEG.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
return r.value();
}
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

return eval_sinh_or_cosh</*IsSinh=*/false>(x);
}
Expand Down
2 changes: 2 additions & 0 deletions libc/src/math/generic/erff.cpp
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Expand Up @@ -141,6 +141,7 @@ LLVM_LIBC_FUNCTION(float, erff, (float x)) {
return ONE[sign] + SMALL[sign];
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
// Exceptional mask = common 0 bits of 2 exceptional values.
constexpr uint32_t EXCEPT_MASK = 0x809a'6184U;

Expand All @@ -155,6 +156,7 @@ LLVM_LIBC_FUNCTION(float, erff, (float x)) {
if (x_abs == 0U)
return x;
}
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// Polynomial approximation:
// erf(x) ~ x * (c0 + c1 * x^2 + c2 * x^4 + ... + c7 * x^14)
Expand Down
4 changes: 4 additions & 0 deletions libc/src/math/generic/exp10f16.cpp
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Expand Up @@ -26,6 +26,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
#ifdef LIBC_TARGET_CPU_HAS_FMA_FLOAT
static constexpr size_t N_EXP10F16_EXCEPTS = 5;
#else
Expand Down Expand Up @@ -53,6 +54,7 @@ static constexpr fputil::ExceptValues<float16, N_EXP10F16_EXCEPTS>
{0x446eU, 0x7690U, 1U, 0U, 1U},
#endif
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float16, exp10f16, (float16 x)) {
using FPBits = fputil::FPBits<float16>;
Expand Down Expand Up @@ -119,8 +121,10 @@ LLVM_LIBC_FUNCTION(float16, exp10f16, (float16 x)) {
}
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
if (auto r = EXP10F16_EXCEPTS.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// 10^x = 2^((hi + mid) * log2(10)) * 10^lo
auto [exp2_hi_mid, exp10_lo] = exp10_range_reduction(x);
Expand Down
6 changes: 6 additions & 0 deletions libc/src/math/generic/exp10m1f.cpp
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Expand Up @@ -22,6 +22,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
static constexpr size_t N_EXCEPTS_LO = 11;

static constexpr fputil::ExceptValues<float, N_EXCEPTS_LO> EXP10M1F_EXCEPTS_LO =
Expand Down Expand Up @@ -94,6 +95,7 @@ static constexpr fputil::ExceptValues<float, N_EXCEPTS_HI> EXP10M1F_EXCEPTS_HI =
// x = -0x1.ca4322p-5, exp10m1f(x) = -0x1.ef073p-4 (RZ)
{0xbd65'2191U, 0xbdf7'8398U, 0U, 1U, 1U},
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float, exp10m1f, (float x)) {
using FPBits = fputil::FPBits<float>;
Expand All @@ -119,8 +121,10 @@ LLVM_LIBC_FUNCTION(float, exp10m1f, (float x)) {

// When |x| <= log10(2) * 2^(-6)
if (LIBC_UNLIKELY(x_abs <= 0x3b9a'209bU)) {
#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
if (auto r = EXP10M1F_EXCEPTS_LO.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

double dx = x;
double dx_sq = dx * dx;
Expand Down Expand Up @@ -192,8 +196,10 @@ LLVM_LIBC_FUNCTION(float, exp10m1f, (float x)) {
}
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
if (auto r = EXP10M1F_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// Range reduction: 10^x = 2^(mid + hi) * 10^lo
// rr = (2^(mid + hi), lo)
Expand Down
6 changes: 6 additions & 0 deletions libc/src/math/generic/exp10m1f16.cpp
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Expand Up @@ -24,6 +24,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
static constexpr fputil::ExceptValues<float16, 3> EXP10M1F16_EXCEPTS_LO = {{
// (input, RZ output, RU offset, RD offset, RN offset)
// x = 0x1.5c4p-4, exp10m1f16(x) = 0x1.bacp-3 (RZ)
Expand Down Expand Up @@ -58,6 +59,7 @@ static constexpr fputil::ExceptValues<float16, N_EXP10M1F16_EXCEPTS_HI>
{0x44bdU, 0x7aaeU, 1U, 0U, 1U},
#endif
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float16, exp10m1f16, (float16 x)) {
using FPBits = fputil::FPBits<float16>;
Expand Down Expand Up @@ -122,9 +124,11 @@ LLVM_LIBC_FUNCTION(float16, exp10m1f16, (float16 x)) {
if (LIBC_UNLIKELY(x_abs == 0))
return x;

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
if (auto r = EXP10M1F16_EXCEPTS_LO.lookup(x_u);
LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

float xf = x;
// Degree-5 minimax polynomial generated by Sollya with the following
Expand Down Expand Up @@ -153,8 +157,10 @@ LLVM_LIBC_FUNCTION(float16, exp10m1f16, (float16 x)) {
}
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
if (auto r = EXP10M1F16_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// exp10(x) = exp2((hi + mid) * log2(10)) * exp10(lo)
auto [exp2_hi_mid, exp10_lo] = exp10_range_reduction(x);
Expand Down
4 changes: 4 additions & 0 deletions libc/src/math/generic/exp2f16.cpp
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Expand Up @@ -21,6 +21,7 @@

namespace LIBC_NAMESPACE_DECL {

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
static constexpr fputil::ExceptValues<float16, 3> EXP2F16_EXCEPTS = {{
// (input, RZ output, RU offset, RD offset, RN offset)
// x = 0x1.714p-11, exp2f16(x) = 0x1p+0 (RZ)
Expand All @@ -30,6 +31,7 @@ static constexpr fputil::ExceptValues<float16, 3> EXP2F16_EXCEPTS = {{
// x = -0x1.d5cp-4, exp2f16(x) = 0x1.d8cp-1 (RZ)
{0xaf57U, 0x3b63U, 1U, 0U, 0U},
}};
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

LLVM_LIBC_FUNCTION(float16, exp2f16, (float16 x)) {
using FPBits = fputil::FPBits<float16>;
Expand Down Expand Up @@ -82,8 +84,10 @@ LLVM_LIBC_FUNCTION(float16, exp2f16, (float16 x)) {
}
}

#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
if (auto r = EXP2F16_EXCEPTS.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
return r.value();
#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS

// exp2(x) = exp2(hi + mid) * exp2(lo)
auto [exp2_hi_mid, exp2_lo] = exp2_range_reduction(x);
Expand Down
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