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hulxv · 2026-04-10T08:41:33Z

Instead of duplicate inv trig helpers for float and double. we can unify them when that is possible and drop inv_trigf_utils after moving helpers to asin_utils and atan_utils. That makes everything clean.

llvmbot · 2026-04-10T08:42:07Z

@llvm/pr-subscribers-libc

Author: hulxv (hulxv)

Changes

Instead of duplicate inv trig helpers for float and double. we can unify them when that is possible and drop inv_trigf_utils after moving helpers to asin_utils and atan_utils. That makes everything clean.

Patch is 43.07 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/191364.diff

15 Files Affected:

(modified) libc/src/__support/math/CMakeLists.txt (+7-16)
(modified) libc/src/__support/math/acos.h (+5-5)
(modified) libc/src/__support/math/acosf.h (+4-4)
(modified) libc/src/__support/math/acospif.h (+5-5)
(modified) libc/src/__support/math/asin.h (+4-3)
(modified) libc/src/__support/math/asin_utils.h (+75-62)
(modified) libc/src/__support/math/asinf.h (+4-4)
(modified) libc/src/__support/math/asinpi.h (+8-4)
(modified) libc/src/__support/math/asinpif.h (+5-5)
(modified) libc/src/__support/math/atan2f.h (+2-2)
(modified) libc/src/__support/math/atan2f16.h (+3-3)
(modified) libc/src/__support/math/atan_utils.h (+137)
(modified) libc/src/__support/math/atanf.h (+2-2)
(removed) libc/src/__support/math/inv_trigf_utils.h (-263)
(modified) utils/bazel/llvm-project-overlay/libc/BUILD.bazel (-13)

diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index 987ecab8c57ef..64fbffc2e0db9 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -21,7 +21,7 @@ add_header_library(
   HDRS
     acosf.h
   DEPENDS
-    .inv_trigf_utils
+    .asin_utils
     libc.src.__support.FPUtil.except_value_utils
     libc.src.__support.FPUtil.fp_bits
     libc.src.__support.FPUtil.multiply_add
@@ -101,7 +101,7 @@ add_header_library(
   HDRS
     acospif.h
   DEPENDS
-    .inv_trigf_utils
+    .asin_utils
     libc.src.__support.FPUtil.fenv_impl
     libc.src.__support.FPUtil.fp_bits
     libc.src.__support.FPUtil.polyeval
@@ -211,7 +211,7 @@ add_header_library(
   HDRS
     asinpif.h
   DEPENDS
-    .inv_trigf_utils
+    .asin_utils
     libc.src.__support.FPUtil.except_value_utils
     libc.src.__support.FPUtil.fp_bits
     libc.src.__support.FPUtil.multiply_add
@@ -267,7 +267,7 @@ add_header_library(
     atan2f_float.h
     atan2f.h
   DEPENDS
-    .inv_trigf_utils
+    .atan_utils
     libc.src.__support.FPUtil.double_double
     libc.src.__support.FPUtil.fenv_impl
     libc.src.__support.FPUtil.fp_bits
@@ -283,7 +283,7 @@ add_header_library(
   HDRS
     atan2f16.h
   DEPENDS
-    .inv_trigf_utils
+    .atan_utils
     libc.src.__support.FPUtil.fenv_impl
     libc.src.__support.FPUtil.fp_bits
     libc.src.__support.FPUtil.cast
@@ -329,7 +329,7 @@ add_header_library(
     atanf_float.h
     atanf.h
   DEPENDS
-    .inv_trigf_utils
+    .atan_utils
     libc.src.__support.FPUtil.except_value_utils
     libc.src.__support.FPUtil.fp_bits
     libc.src.__support.FPUtil.multiply_add
@@ -417,7 +417,7 @@ add_header_library(
   HDRS
     asinf.h
   DEPENDS
-    .inv_trigf_utils
+    .asin_utils
     libc.src.__support.FPUtil.fenv_impl
     libc.src.__support.FPUtil.fp_bits
     libc.src.__support.FPUtil.except_value_utils
@@ -1685,15 +1685,6 @@ add_header_library(
     libc.src.__support.macros.config
 )
 
-add_header_library(
-  inv_trigf_utils
-  HDRS
-    inv_trigf_utils.h
-  DEPENDS
-    libc.src.__support.FPUtil.multiply_add
-    libc.src.__support.FPUtil.polyeval
-    libc.src.__support.common
-)
 
 add_header_library(
   frexpf16
diff --git a/libc/src/__support/math/acos.h b/libc/src/__support/math/acos.h
index 6b419449176fd..cb35f1a24d670 100644
--- a/libc/src/__support/math/acos.h
+++ b/libc/src/__support/math/acos.h
@@ -48,9 +48,10 @@ LIBC_INLINE constexpr double acos(double x) {
 
 #ifdef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
     // acos(x) = pi/2 - asin(x)
-    //         = pi/2 - x * P(x^2)
-    double p = asin_eval(x * x);
-    return PI_OVER_TWO.hi + fputil::multiply_add(-x, p, PI_OVER_TWO.lo);
+    //         = pi/2 - x * (1 + x^2 * P1(x^2))
+    //         = pi/2 - x - x^3 * P1(x^2)
+    double xsq = x * x;
+    return PI_OVER_TWO.hi + fputil::multiply_add(-x * xsq, asinf_eval(xsq), PI_OVER_TWO.lo - x);
 #else
     unsigned idx = 0;
     DoubleDouble x_sq = fputil::exact_mult(x, x);
@@ -177,9 +178,8 @@ LIBC_INLINE constexpr double acos(double x) {
   constexpr DoubleDouble CONST_TERM[2] = {{0.0, 0.0}, PI};
   DoubleDouble const_term = CONST_TERM[xbits.is_neg()];
 
-  double p = asin_eval(u);
   double scale = x_sign * 2.0 * v_hi;
-  double r = const_term.hi + fputil::multiply_add(scale, p, const_term.lo);
+  double r = const_term.hi + fputil::multiply_add(scale * u, asinf_eval(u), const_term.lo + scale);
   return r;
 #else
 
diff --git a/libc/src/__support/math/acosf.h b/libc/src/__support/math/acosf.h
index ae93abe7e716a..b34e89f62a644 100644
--- a/libc/src/__support/math/acosf.h
+++ b/libc/src/__support/math/acosf.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_MATH_ACOSF_H
 #define LLVM_LIBC_SRC___SUPPORT_MATH_ACOSF_H
 
-#include "inv_trigf_utils.h"
+#include "asin_utils.h"
 #include "src/__support/FPUtil/FEnvImpl.h"
 #include "src/__support/FPUtil/FPBits.h"
 #include "src/__support/FPUtil/except_value_utils.h"
@@ -48,7 +48,7 @@ LIBC_INLINE_VAR constexpr fputil::ExceptValues<float, N_EXCEPTS> ACOSF_EXCEPTS =
 
 LIBC_INLINE constexpr float acosf(float x) {
   using namespace acosf_internal;
-  using namespace inv_trigf_utils_internal;
+  using namespace asin_internal;
   using FPBits = typename fputil::FPBits<float>;
 
   FPBits xbits(x);
@@ -84,7 +84,7 @@ LIBC_INLINE constexpr float acosf(float x) {
     double xd = static_cast<double>(x);
     double xsq = xd * xd;
     double x3 = xd * xsq;
-    double r = asin_eval(xsq);
+    double r = asinf_eval(xsq);
     return static_cast<float>(fputil::multiply_add(-x3, r, M_MATH_PI_2 - xd));
   }
 
@@ -136,7 +136,7 @@ LIBC_INLINE constexpr float acosf(float x) {
   double u = fputil::multiply_add(-0.5, xd, 0.5);
   double cv = 2 * fputil::sqrt<double>(u);
 
-  double r3 = asin_eval(u);
+  double r3 = asinf_eval(u);
   double r = fputil::multiply_add(cv * u, r3, cv);
   return static_cast<float>(x_sign ? M_MATH_PI - r : r);
 }
diff --git a/libc/src/__support/math/acospif.h b/libc/src/__support/math/acospif.h
index acf2b9748975b..a9f6aae5ea4f9 100644
--- a/libc/src/__support/math/acospif.h
+++ b/libc/src/__support/math/acospif.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_MATH_ACOSPIF_H
 #define LLVM_LIBC_SRC___SUPPORT_MATH_ACOSPIF_H
 
-#include "inv_trigf_utils.h"
+#include "asin_utils.h"
 #include "src/__support/FPUtil/FEnvImpl.h"
 #include "src/__support/FPUtil/FPBits.h"
 #include "src/__support/FPUtil/PolyEval.h"
@@ -54,8 +54,8 @@ LIBC_INLINE float acospif(float x) {
     double x_d = fputil::cast<double>(x);
     double v2 = x_d * x_d;
     double result = x_d * fputil::multiply_add(
-                              v2, inv_trigf_utils_internal::asinpi_eval(v2),
-                              inv_trigf_utils_internal::ASINPI_COEFFS[0]);
+                              v2, asin_internal::asinpif_eval(v2),
+                              asin_internal::ASINPIF_COEFFS[0]);
     return fputil::cast<float>(0.5 - result);
   }
 
@@ -76,7 +76,7 @@ LIBC_INLINE float acospif(float x) {
   constexpr double ONE_OVER_PI_LO = -0x1.6b01ec5417056p-56;
   // C0_MINUS_1OVERPI = c0 - 1/pi = DELTA_C0 + ONE_OVER_PI_LO
   constexpr double C0_MINUS_1OVERPI =
-      (inv_trigf_utils_internal::ASINPI_COEFFS[0] - ONE_OVER_PI_HI) +
+      (asin_internal::ASINPIF_COEFFS[0] - ONE_OVER_PI_HI) +
       ONE_OVER_PI_LO;
 
   double u = fputil::multiply_add(-0.5, x_abs, 0.5);
@@ -85,7 +85,7 @@ LIBC_INLINE float acospif(float x) {
 
   // tail = (c0 - 1/pi) + u * P1(u)
   double tail = fputil::multiply_add(
-      u, inv_trigf_utils_internal::asinpi_eval(u), C0_MINUS_1OVERPI);
+      u, asin_internal::asinpif_eval(u), C0_MINUS_1OVERPI);
 
   double result_hi = fputil::multiply_add(neg2_sqrt_u, ONE_OVER_PI_HI, 0.5);
   double result = fputil::multiply_add(tail, neg2_sqrt_u, result_hi);
diff --git a/libc/src/__support/math/asin.h b/libc/src/__support/math/asin.h
index 98e77d0b97454..3117d950ed1ea 100644
--- a/libc/src/__support/math/asin.h
+++ b/libc/src/__support/math/asin.h
@@ -72,7 +72,8 @@ LIBC_INLINE double asin(double x) {
     }
 
 #ifdef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-    return x * asin_eval(x * x);
+    double xsq = x * x;
+    return fputil::multiply_add(x * xsq, asinf_eval(xsq), x);
 #else
     using Float128 = fputil::DyadicFloat<128>;
     using DoubleDouble = fputil::DoubleDouble;
@@ -189,8 +190,8 @@ LIBC_INLINE double asin(double x) {
   double v_hi = fputil::sqrt<double>(u);
 
 #ifdef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-  double p = asin_eval(u);
-  double r = x_sign * fputil::multiply_add(-2.0 * v_hi, p, PI_OVER_TWO.hi);
+  double neg2_v = -2.0 * v_hi;
+  double r = x_sign * fputil::multiply_add(neg2_v * u, asinf_eval(u), PI_OVER_TWO.hi + neg2_v);
   return r;
 #else
 
diff --git a/libc/src/__support/math/asin_utils.h b/libc/src/__support/math/asin_utils.h
index 4f64ad5291711..fcad2259e8814 100644
--- a/libc/src/__support/math/asin_utils.h
+++ b/libc/src/__support/math/asin_utils.h
@@ -30,81 +30,96 @@ LIBC_INLINE_VAR constexpr DoubleDouble PI = {0x1.1a62633145c07p-53,
 LIBC_INLINE_VAR constexpr DoubleDouble PI_OVER_TWO = {0x1.1a62633145c07p-54,
                                                       0x1.921fb54442d18p0};
 
-#ifdef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+// Scalar double constants for pi and pi/2, used by float-precision
+// implementations (acosf etc.).
+LIBC_INLINE_VAR constexpr double M_MATH_PI = 0x1.921fb54442d18p+1;
+LIBC_INLINE_VAR constexpr double M_MATH_PI_2 = 0x1.921fb54442d18p+0;
 
-// When correct rounding is not needed, we use a degree-22 minimax polynomial to
-// approximate asin(x)/x on [0, 0.5] using Sollya with:
-// > P = fpminimax(asin(x)/x, [|0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22|],
+// > Q = fpminimax(asin(x)/x, [|0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24|],
 //                 [|1, D...|], [0, 0.5]);
-// > dirtyinfnorm(asin(x)/x - P, [0, 0.5]);
-// 0x1.1a71ef0a0f26a9fb7ed7e41dee788b13d1770db3dp-52
-
-LIBC_INLINE_VAR constexpr double ASIN_COEFFS[12] = {
-    0x1.0000000000000p0,  0x1.5555555556dcfp-3,  0x1.3333333082e11p-4,
-    0x1.6db6dd14099edp-5, 0x1.f1c69b35bf81fp-6,  0x1.6e97194225a67p-6,
-    0x1.1babddb82ce12p-6, 0x1.d55bd078600d6p-7,  0x1.33328959e63d6p-7,
-    0x1.2b5993bda1d9bp-6, -0x1.806aff270bf25p-7, 0x1.02614e5ed3936p-5,
+// > dirtyinfnorm((asin(x) - x*Q)/x, [0, 0.5]);
+//   0x1.feb2fcdba66447ccbe28a1a0f935b51678a718fb1p-59
+// Coefficients for float-precision asin (ASINF_COEFFS excludes the leading 1
+// term; used as: asin(x) ~ x + x^3 * asinf_eval(x^2)).
+LIBC_INLINE_VAR constexpr double ASINF_COEFFS[12] = {
+    0x1.555555555538p-3,  0x1.333333336fd5bp-4,  0x1.6db6db41ce4bcp-5,
+    0x1.f1c72c66896dep-6, 0x1.6e89f0a0ac64bp-6,  0x1.1c6c111de4074p-6,
+    0x1.c6fa84b5699acp-7, 0x1.8ed60a3e6dd19p-7,  0x1.ab3a090750049p-8,
+    0x1.405213cd1ef46p-6, -0x1.0a5a381f73f65p-6, 0x1.05985a32a9045p-5,
 };
 
-LIBC_INLINE double asin_eval(double u) {
-  double u2 = u * u;
-  double c0 = fputil::multiply_add(u, ASIN_COEFFS[1], ASIN_COEFFS[0]);
-  double c1 = fputil::multiply_add(u, ASIN_COEFFS[3], ASIN_COEFFS[2]);
-  double c2 = fputil::multiply_add(u, ASIN_COEFFS[5], ASIN_COEFFS[4]);
-  double c3 = fputil::multiply_add(u, ASIN_COEFFS[7], ASIN_COEFFS[6]);
-  double c4 = fputil::multiply_add(u, ASIN_COEFFS[9], ASIN_COEFFS[8]);
-  double c5 = fputil::multiply_add(u, ASIN_COEFFS[11], ASIN_COEFFS[10]);
-
-  double u4 = u2 * u2;
-  double d0 = fputil::multiply_add(u2, c1, c0);
-  double d1 = fputil::multiply_add(u2, c3, c2);
-  double d2 = fputil::multiply_add(u2, c5, c4);
-
-  return fputil::polyeval(u4, d0, d1, d2);
+// Evaluate P(x^2) - 1, where P(x^2) ~ asin(x)/x, for float-precision asin.
+// Used as: asin(x) ~ x + x^3 * asinf_eval(x^2).
+LIBC_INLINE double asinf_eval(double xsq) {
+  double x4 = xsq * xsq;
+  double c0 = fputil::multiply_add(xsq, ASINF_COEFFS[1], ASINF_COEFFS[0]);
+  double c1 = fputil::multiply_add(xsq, ASINF_COEFFS[3], ASINF_COEFFS[2]);
+  double c2 = fputil::multiply_add(xsq, ASINF_COEFFS[5], ASINF_COEFFS[4]);
+  double c3 = fputil::multiply_add(xsq, ASINF_COEFFS[7], ASINF_COEFFS[6]);
+  double c4 = fputil::multiply_add(xsq, ASINF_COEFFS[9], ASINF_COEFFS[8]);
+  double c5 = fputil::multiply_add(xsq, ASINF_COEFFS[11], ASINF_COEFFS[10]);
+  double x8 = x4 * x4;
+  double d0 = fputil::multiply_add(x4, c1, c0);
+  double d1 = fputil::multiply_add(x4, c3, c2);
+  double d2 = fputil::multiply_add(x4, c5, c4);
+  return fputil::polyeval(x8, d0, d1, d2);
 }
 
-// Coefficients for the polynomial approximation of asin(x)/(pi*x) on [0, 0.5].
-// Generated by Sollya:
+// the coefficients for the polynomial approximation of asin(x)/(pi*x) in the
+// range [0, 0.5] extracted using Sollya, for float-precision asinpi.
+//
+// Sollya code:
 // > prec = 200;
+// > display = hexadecimal;
 // > g = asin(x) / (pi * x);
 // > P = fpminimax(g, [|0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22|],
 // >              [|D...|], [0, 0.5]);
+// > for i from 0 to degree(P) do coeff(P, i);
 // > print("Error:", dirtyinfnorm(P - g, [1e-30; 0.25]));
-// Error : 0x1.a53f84eafa3ea69bb81b6c52b3278872083fca2c757bd778acp-54 ~= 2^-54
-LIBC_INLINE_VAR constexpr double ASINPI_COEFFS[12] = {
-    0x1.45f306dc9c881p-2,  // x^0
-    0x1.b2995e7b7e756p-5,  // x^2
-    0x1.8723a1d12f828p-6,  // x^4
-    0x1.d1a45564b9545p-7,  // x^6
-    0x1.3ce4ceaa0e1e9p-7,  // x^8
-    0x1.d2c305898ea13p-8,  // x^10
-    0x1.692212e27a5f9p-8,  // x^12
-    0x1.2b22cc744d25bp-8,  // x^14
-    0x1.8427b864479ffp-9,  // x^16
-    0x1.815522d7a2bf1p-8,  // x^18
-    -0x1.f6df98438aef4p-9, // x^20
-    0x1.4b50c2eb13708p-7,  // x^22
+// Error : 0x1.6b01ec54170565911f924eb53361de37df00d74e2a10a21d5p-56 ~ 2^−55.496
+//
+// Non-zero coefficients (even powers only):
+LIBC_INLINE_VAR constexpr double ASINPIF_COEFFS[13] = {
+    0x1.45f306dc9c883p-2,  // x^0
+    0x1.b2995e7b7af0fp-5,  // x^2
+    0x1.8723a1d61d2e9p-6,  // x^4
+    0x1.d1a4529a30a69p-7,  // x^6
+    0x1.3ce53861f8f1fp-7,  // x^8
+    0x1.d2b076c914efep-8,  // x^10
+    0x1.6a2b36f9aed68p-8,  // x^12
+    0x1.21604ae2879a2p-8,  // x^14
+    0x1.ff0549b4fd0d6p-9,  // x^16
+    0x1.035d343508f72p-9,  // x^18
+    0x1.a7b91f72b1592p-8,  // x^20
+    -0x1.6a3fb073e97aep-8, // x^22
+    0x1.547a51d51664ap-7   // x^24
 };
 
-// Evaluate P(u) where P(u) ~ asin(sqrt(u))/(pi*sqrt(u)), using Estrin's scheme.
-LIBC_INLINE double asinpi_eval(double u) {
-  double u2 = u * u;
-  double c0 = fputil::multiply_add(u, ASINPI_COEFFS[1], ASINPI_COEFFS[0]);
-  double c1 = fputil::multiply_add(u, ASINPI_COEFFS[3], ASINPI_COEFFS[2]);
-  double c2 = fputil::multiply_add(u, ASINPI_COEFFS[5], ASINPI_COEFFS[4]);
-  double c3 = fputil::multiply_add(u, ASINPI_COEFFS[7], ASINPI_COEFFS[6]);
-  double c4 = fputil::multiply_add(u, ASINPI_COEFFS[9], ASINPI_COEFFS[8]);
-  double c5 = fputil::multiply_add(u, ASINPI_COEFFS[11], ASINPI_COEFFS[10]);
-
-  double u4 = u2 * u2;
-  double d0 = fputil::multiply_add(u2, c1, c0);
-  double d1 = fputil::multiply_add(u2, c3, c2);
-  double d2 = fputil::multiply_add(u2, c5, c4);
-
-  return fputil::polyeval(u4, d0, d1, d2);
+// Evaluates P1(v2) = c1 + c2*v2 + ... + c12*v2^11 (tail of the asinpif
+// polynomial without c0) using Estrin's scheme.
+// Used as: asinpif(x) ~ x * (ASINPIF_COEFFS[0] + v2 * asinpif_eval(v2))
+// where v2 = x^2.
+LIBC_INLINE double asinpif_eval(double v2) {
+  double v4 = v2 * v2;
+  double v8 = v4 * v4;
+  double v16 = v8 * v8;
+
+  double p0 = fputil::multiply_add(v2, ASINPIF_COEFFS[2], ASINPIF_COEFFS[1]);
+  double p1 = fputil::multiply_add(v2, ASINPIF_COEFFS[4], ASINPIF_COEFFS[3]);
+  double p2 = fputil::multiply_add(v2, ASINPIF_COEFFS[6], ASINPIF_COEFFS[5]);
+  double p3 = fputil::multiply_add(v2, ASINPIF_COEFFS[8], ASINPIF_COEFFS[7]);
+  double p4 = fputil::multiply_add(v2, ASINPIF_COEFFS[10], ASINPIF_COEFFS[9]);
+  double p5 = fputil::multiply_add(v2, ASINPIF_COEFFS[12], ASINPIF_COEFFS[11]);
+
+  double q0 = fputil::multiply_add(v4, p1, p0);
+  double q1 = fputil::multiply_add(v4, p3, p2);
+  double q2 = fputil::multiply_add(v4, p5, p4);
+
+  double r0 = fputil::multiply_add(v8, q1, q0);
+
+  return fputil::multiply_add(v16, q2, r0);
 }
 
-#else
 
 // The Taylor expansion of asin(x) around 0 is:
 //   asin(x) = x + x^3/6 + 3x^5/40 + ...
@@ -635,8 +650,6 @@ LIBC_INLINE constexpr Float128 asinpi_eval(const Float128 &u, unsigned idx) {
   return fputil::quick_mul(p, ONE_OVER_PI_F128);
 }
 
-#endif // LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-
 } // namespace asin_internal
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/math/asinf.h b/libc/src/__support/math/asinf.h
index 08cfb192754e4..ceab243581d01 100644
--- a/libc/src/__support/math/asinf.h
+++ b/libc/src/__support/math/asinf.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_MATH_ASINF_H
 #define LLVM_LIBC_SRC___SUPPORT_MATH_ASINF_H
 
-#include "inv_trigf_utils.h"
+#include "asin_utils.h"
 #include "src/__support/FPUtil/FEnvImpl.h"
 #include "src/__support/FPUtil/FPBits.h"
 #include "src/__support/FPUtil/except_value_utils.h"
@@ -24,7 +24,7 @@ namespace LIBC_NAMESPACE_DECL {
 namespace math {
 
 LIBC_INLINE constexpr float asinf(float x) {
-  using namespace inv_trigf_utils_internal;
+  using namespace asin_internal;
   using FPBits = typename fputil::FPBits<float>;
 
   FPBits xbits(x);
@@ -76,7 +76,7 @@ LIBC_INLINE constexpr float asinf(float x) {
     double xd = static_cast<double>(x);
     double xsq = xd * xd;
     double x3 = xd * xsq;
-    double r = asin_eval(xsq);
+    double r = asinf_eval(xsq);
     return static_cast<float>(fputil::multiply_add(x3, r, xd));
   }
 
@@ -128,7 +128,7 @@ LIBC_INLINE constexpr float asinf(float x) {
   double c2 = fputil::multiply_add(sign_two, M_PI_OVER_4, c1);
   double c3 = c1 * u;
 
-  double r = asin_eval(u);
+  double r = asinf_eval(u);
   return static_cast<float>(fputil::multiply_add(c3, r, c2));
 }
 
diff --git a/libc/src/__support/math/asinpi.h b/libc/src/__support/math/asinpi.h
index a088ae322ad79..9284dc3e2d6f8 100644
--- a/libc/src/__support/math/asinpi.h
+++ b/libc/src/__support/math/asinpi.h
@@ -43,12 +43,14 @@ LIBC_INLINE double asinpi(double x) {
       // The relative error of x/pi is:
       //   |asinpi(x) - x/pi| / |asinpi(x)| < x^2/6 < 2^-54.
 #ifdef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-      return x * ASINPI_COEFFS[0];
+      return x * asin_internal::ASINPIF_COEFFS[0];
 #endif // LIBC_MATH_HAS_SKIP_ACCURATE_PASS
     }
 
 #ifdef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-    return x * asinpi_eval(x * x);
+    double xsq = x * x;
+    return x * fputil::multiply_add(xsq, asin_internal::asinpif_eval(xsq),
+                                    asin_internal::ASINPIF_COEFFS[0]);
 #else
     using Float128 = fputil::DyadicFloat<128>;
     using DoubleDouble = fputil::DoubleDouble;
@@ -193,8 +195,10 @@ LIBC_INLINE double asinpi(double x) {
   double v_hi = fputil::sqrt<double>(u);
 
 #ifdef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-  double p = asinpi_eval(u);
-  double r = x_sign * fputil::multiply_add(-2.0 * v_hi, p, 0.5);
+  double neg2_v = -2.0 * v_hi;
+  double r = x_sign * fputil::multiply_add(
+                 neg2_v * u, asin_internal::asinpif_eval(u),
+                 0.5 + neg2_v * asin_internal::ASINPIF_COEFFS[0]);
   return r;
 #else
   using Float128 = fputil::DyadicFloat<128>;
diff --git a/libc/src/__support/math/asinpif.h b/libc/src/__support/math/asinpif.h
index 79d3ebbe63b5b..ad521e025d1fa 100644
--- a/libc/src/__support/math/asinpif.h
+++ b/libc/src/__support/math/asinpif.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_MATH_ASINPIF_H
 #define LLVM_LIBC_SRC___SUPPORT_MATH_ASINPIF_H
 
-#include "inv_trigf_utils.h"
+#include "asin_utils.h"
 #include "src/__support/FPUtil/FEnvImpl.h"
 #include "src/__support/FPUtil/FPBits.h"
 #include "src/__support/FPUtil/PolyEval.h"
@@ -51,8 +51,8 @@ LIBC_INLINE float asinpif(float x) {
     double x_d = fputil::cast<double>(x);
     double v2 = x_d * x_d;
     double result = x_d * fputil::multiply_add(
-                              v2, inv_trigf_utils_internal::asinpi_eval(v2),
-                              inv_trigf_utils_internal::ASINPI_COEFFS[0]);
+                              v2, asin_internal::asinpif_eval(v2),
+                              asin_internal::ASINPIF_COEFFS[0]);
     return fputil::cast<float>(result);
   }
 
@@ -74,7 +74,7 @@ LIBC_INLINE float asinpif(float x) {
   constexpr double ONE_OVER_PI_LO = -0x1.6b01ec5417056p-56;
   // C0_MINUS_1OVERPI = c0 - 1/pi = DELTA_C0 + ONE_OVER_PI_LO
   constexpr double C0_MINUS_1OVERPI =
-      (inv_trigf_utils_internal::ASINPI_COEFFS[0] - ONE_OVER_PI_HI) +
+      (asin_internal::ASINPIF_COEFFS[0] - ONE_OVER_PI_HI) +
       ONE_OVER_PI_LO;
 
   double u = fputil::multiply_add(-0.5, x_abs, 0.5);
@@ -83,7 +83,7 @@ LIBC_INLINE float asinpif(float x) {
 
   // tail = (c0 - 1/pi) + u * P1(u)
   double tail = fputil::multiply_add(
-      u, inv_trigf_utils_internal::asinpi_eval(u), C0_MINUS_1OVERPI);
+      u, asin_internal::asinpif_eval(u), C0_MINUS_1OVERPI);
 
   double result_hi = fputil::multiply_add(neg2_sqrt_u, ONE_OVER_PI_HI, 0.5);
   double result = fputil::multiply_add(tail, neg2_sqrt_u, result_hi);
diff --git a/libc/src/__support/math/atan2f.h b/libc/src/__support/math/atan2f.h
index 15d1fce2b707c..c9314ee28af2d 100644
--- a/libc/src/__support/math/atan2f.h
+++ b/libc/src/__support/math/atan2f.h
@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_MATH_ATAN2F_H
 #define LLVM_LIBC_SRC___SUPPORT_MATH_ATAN2F_H
 
-#include "inv_trigf_utils.h"
+#include "atan_utils.h"
 ...
[truncated]

github-actions · 2026-04-10T08:42:53Z

✅ With the latest revision this PR passed the C/C++ code formatter.

lntue · 2026-04-11T00:22:36Z

-    0x1.1babddb82ce12p-6, 0x1.d55bd078600d6p-7,  0x1.33328959e63d6p-7,
-    0x1.2b5993bda1d9bp-6, -0x1.806aff270bf25p-7, 0x1.02614e5ed3936p-5,
+// > dirtyinfnorm((asin(x) - x*Q)/x, [0, 0.5]);
+//   0x1.feb2fcdba66447ccbe28a1a0f935b51678a718fb1p-59


Now that the degree of approximation and the evaluation scheme for double precision asin, acos, atan are different. Can you retest whether the error bounds are changed for these functions when the accurate paths are skipped?

github-actions · 2026-04-12T21:14:48Z

🐧 Linux x64 Test Results

1702 tests passed

✅ The build succeeded and all tests passed.

hulxv requested review from bassiounix and lntue April 10, 2026 08:41

hulxv requested review from aaronmondal, keith and rupprecht as code owners April 10, 2026 08:41

llvmbot added libc bazel "Peripheral" support tier build system: utils/bazel labels Apr 10, 2026

lntue reviewed Apr 11, 2026

View reviewed changes

Comment thread libc/src/__support/math/asin_utils.h Outdated

lntue reviewed Apr 11, 2026

View reviewed changes

Comment thread libc/src/__support/math/atan_utils.h Outdated

hulxv force-pushed the libc/math/refactor/reduce-duplication branch from 4371faf to c161a2c Compare April 12, 2026 21:07

hulxv requested a review from lntue April 22, 2026 20:10

hulxv added 6 commits April 22, 2026 22:49

[libc][math] reduce duplicated inv trig helpers

82a7cc4

fix ci

7419411

move pi consts to acosf

8af4817

format

1a39aea

fix the ci

7e60173

fix the ci

e546ca3

hulxv force-pushed the libc/math/refactor/reduce-duplication branch from c86399c to e546ca3 Compare April 22, 2026 20:49

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[libc][math] reduce duplicated inv trig helpers#191364

[libc][math] reduce duplicated inv trig helpers#191364
hulxv wants to merge 6 commits intollvm:mainfrom
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