[libc][math] Refactor expm1f16 implementation to header-only in src/__support/math folder.

libc/shared/math.h

@@ -56,6 +56,7 @@
 #include "math/expf16.h"
 #include "math/expm1.h"
 #include "math/expm1f.h"
+#include "math/expm1f16.h"
 #include "math/frexpf.h"
 #include "math/frexpf128.h"
 #include "math/frexpf16.h"

libc/shared/math/expm1f16.h

@@ -0,0 +1,29 @@
+//===-- Shared expm1f16 function --------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SHARED_MATH_EXPM1F16_H
+#define LLVM_LIBC_SHARED_MATH_EXPM1F16_H
+
+#include "include/llvm-libc-macros/float16-macros.h"
+#include "shared/libc_common.h"
+
+#ifdef LIBC_TYPES_HAS_FLOAT16
+
+#include "src/__support/math/expm1f16.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::expm1f16;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_HAS_FLOAT16
+
+#endif // LLVM_LIBC_SHARED_MATH_EXPM1F16_H

libc/src/__support/math/CMakeLists.txt

@@ -923,6 +923,22 @@ add_header_library(
     libc.src.errno.errno
 )
 
+add_header_library(
+  expm1f16
+  HDRS
+    expm1f16.h
+  DEPENDS
+    .expxf16_utils
+    libc.src.__support.FPUtil.cast
+    libc.src.__support.FPUtil.except_value_utils
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.multiply_add
+    libc.src.__support.FPUtil.polyeval
+    libc.src.__support.FPUtil.rounding_mode
+    libc.src.__support.macros.optimization
+)
+
 add_header_library(
   range_reduction_double
   HDRS

libc/src/__support/math/expm1f16.h

@@ -0,0 +1,153 @@
+//===-- Implementation header for expm1f16 ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_MATH_EXPM1F16_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_EXPM1F16_H
+
+#include "include/llvm-libc-macros/float16-macros.h"
+
+#ifdef LIBC_TYPES_HAS_FLOAT16
+
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/PolyEval.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/except_value_utils.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/FPUtil/rounding_mode.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h"
+#include "src/__support/math/expxf16_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+LIBC_INLINE static constexpr float16 expm1f16(float16 x) {
+#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+  constexpr fputil::ExceptValues<float16, 1> EXPM1F16_EXCEPTS_LO = {{
+      // (input, RZ output, RU offset, RD offset, RN offset)
+      // x = 0x1.564p-5, expm1f16(x) = 0x1.5d4p-5 (RZ)
+      {0x2959U, 0x2975U, 1U, 0U, 1U},
+  }};
+
+#ifdef LIBC_TARGET_CPU_HAS_FMA_FLOAT
+  constexpr size_t N_EXPM1F16_EXCEPTS_HI = 2;
+#else
+  constexpr size_t N_EXPM1F16_EXCEPTS_HI = 3;
+#endif
+
+  constexpr fputil::ExceptValues<float16, N_EXPM1F16_EXCEPTS_HI>
+      EXPM1F16_EXCEPTS_HI = {{
+          // (input, RZ output, RU offset, RD offset, RN offset)
+          // x = 0x1.c34p+0, expm1f16(x) = 0x1.34cp+2 (RZ)
+          {0x3f0dU, 0x44d3U, 1U, 0U, 1U},
+          // x = -0x1.e28p-3, expm1f16(x) = -0x1.adcp-3 (RZ)
+          {0xb38aU, 0xb2b7U, 0U, 1U, 1U},
+#ifndef LIBC_TARGET_CPU_HAS_FMA_FLOAT
+          // x = 0x1.a08p-3, exp10m1f(x) = 0x1.cdcp-3 (RZ)
+          {0x3282U, 0x3337U, 1U, 0U, 0U},
+#endif
+      }};
+#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+
+  using namespace math::expxf16_internal;
+  using FPBits = fputil::FPBits<float16>;
+  FPBits x_bits(x);
+
+  uint16_t x_u = x_bits.uintval();
+  uint16_t x_abs = x_u & 0x7fffU;
+
+  // When |x| <= 2^(-3), or |x| >= -11 * log(2), or x is NaN.
+  if (LIBC_UNLIKELY(x_abs <= 0x3000U || x_abs >= 0x47a0U)) {
+    // expm1(NaN) = NaN
+    if (x_bits.is_nan()) {
+      if (x_bits.is_signaling_nan()) {
+        fputil::raise_except_if_required(FE_INVALID);
+        return FPBits::quiet_nan().get_val();
+      }
+
+      return x;
+    }
+
+    // expm1(+/-0) = +/-0
+    if (x_abs == 0)
+      return x;
+
+    // When x >= 16 * log(2).
+    if (x_bits.is_pos() && x_abs >= 0x498cU) {
+      // expm1(+inf) = +inf
+      if (x_bits.is_inf())
+        return FPBits::inf().get_val();
+
+      switch (fputil::quick_get_round()) {
+      case FE_TONEAREST:
+      case FE_UPWARD:
+        fputil::set_errno_if_required(ERANGE);
+        fputil::raise_except_if_required(FE_OVERFLOW | FE_INEXACT);
+        return FPBits::inf().get_val();
+      default:
+        return FPBits::max_normal().get_val();
+      }
+    }
+
+    // When x <= -11 * log(2).
+    if (x_u >= 0xc7a0U) {
+      // expm1(-inf) = -1
+      if (x_bits.is_inf())
+        return FPBits::one(Sign::NEG).get_val();
+
+      // When x > -0x1.0ap+3, round(expm1(x), HP, RN) = -1.
+      if (x_u > 0xc828U)
+        return fputil::round_result_slightly_up(
+            FPBits::one(Sign::NEG).get_val());
+      // When x <= -0x1.0ap+3, round(expm1(x), HP, RN) = -0x1.ffcp-1.
+      return fputil::round_result_slightly_down(
+          fputil::cast<float16>(-0x1.ffcp-1));
+    }
+
+    // When 0 < |x| <= 2^(-3).
+    if (x_abs <= 0x3000U && !x_bits.is_zero()) {
+
+#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+      if (auto r = EXPM1F16_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
+      // commands:
+      //   > display = hexadecimal;
+      //   > P = fpminimax(expm1(x)/x, 4, [|SG...|], [-2^-3, 2^-3]);
+      //   > x * P;
+      return fputil::cast<float16>(
+          xf * fputil::polyeval(xf, 0x1p+0f, 0x1.fffff8p-2f, 0x1.555556p-3f,
+                                0x1.55905ep-5f, 0x1.1124c2p-7f));
+    }
+  }
+
+#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+  if (auto r = EXPM1F16_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
+    return r.value();
+#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+
+  // exp(x) = exp(hi + mid) * exp(lo)
+  auto [exp_hi_mid, exp_lo] = exp_range_reduction(x);
+  // expm1(x) = exp(hi + mid) * exp(lo) - 1
+  return fputil::cast<float16>(fputil::multiply_add(exp_hi_mid, exp_lo, -1.0f));
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_HAS_FLOAT16
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_EXPM1F16_H

libc/src/math/generic/CMakeLists.txt

@@ -1571,17 +1571,7 @@ add_entrypoint_object(
   HDRS
     ../expm1f16.h
   DEPENDS
-    libc.hdr.errno_macros
-    libc.hdr.fenv_macros
-    libc.src.__support.FPUtil.cast
-    libc.src.__support.FPUtil.except_value_utils
-    libc.src.__support.FPUtil.fenv_impl
-    libc.src.__support.FPUtil.fp_bits
-    libc.src.__support.FPUtil.multiply_add
-    libc.src.__support.FPUtil.polyeval
-    libc.src.__support.FPUtil.rounding_mode
-    libc.src.__support.macros.optimization
-    libc.src.__support.math.expxf16_utils
+    libc.src.__support.math.expm1f16
 )
 
 add_entrypoint_object(

libc/src/math/generic/expm1f16.cpp

@@ -7,135 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/math/expm1f16.h"
-#include "hdr/errno_macros.h"
-#include "hdr/fenv_macros.h"
-#include "src/__support/FPUtil/FEnvImpl.h"
-#include "src/__support/FPUtil/FPBits.h"
-#include "src/__support/FPUtil/PolyEval.h"
-#include "src/__support/FPUtil/cast.h"
-#include "src/__support/FPUtil/except_value_utils.h"
-#include "src/__support/FPUtil/multiply_add.h"
-#include "src/__support/FPUtil/rounding_mode.h"
-#include "src/__support/common.h"
-#include "src/__support/macros/config.h"
-#include "src/__support/macros/optimization.h"
-#include "src/__support/math/expxf16_utils.h"
+#include "src/__support/math/expm1f16.h"
 
 namespace LIBC_NAMESPACE_DECL {
-
-#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-static constexpr fputil::ExceptValues<float16, 1> EXPM1F16_EXCEPTS_LO = {{
-    // (input, RZ output, RU offset, RD offset, RN offset)
-    // x = 0x1.564p-5, expm1f16(x) = 0x1.5d4p-5 (RZ)
-    {0x2959U, 0x2975U, 1U, 0U, 1U},
-}};
-
-#ifdef LIBC_TARGET_CPU_HAS_FMA_FLOAT
-static constexpr size_t N_EXPM1F16_EXCEPTS_HI = 2;
-#else
-static constexpr size_t N_EXPM1F16_EXCEPTS_HI = 3;
-#endif
-
-static constexpr fputil::ExceptValues<float16, N_EXPM1F16_EXCEPTS_HI>
-    EXPM1F16_EXCEPTS_HI = {{
-        // (input, RZ output, RU offset, RD offset, RN offset)
-        // x = 0x1.c34p+0, expm1f16(x) = 0x1.34cp+2 (RZ)
-        {0x3f0dU, 0x44d3U, 1U, 0U, 1U},
-        // x = -0x1.e28p-3, expm1f16(x) = -0x1.adcp-3 (RZ)
-        {0xb38aU, 0xb2b7U, 0U, 1U, 1U},
-#ifndef LIBC_TARGET_CPU_HAS_FMA_FLOAT
-        // x = 0x1.a08p-3, exp10m1f(x) = 0x1.cdcp-3 (RZ)
-        {0x3282U, 0x3337U, 1U, 0U, 0U},
-#endif
-    }};
-#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-
-LLVM_LIBC_FUNCTION(float16, expm1f16, (float16 x)) {
-  using namespace math::expxf16_internal;
-  using FPBits = fputil::FPBits<float16>;
-  FPBits x_bits(x);
-
-  uint16_t x_u = x_bits.uintval();
-  uint16_t x_abs = x_u & 0x7fffU;
-
-  // When |x| <= 2^(-3), or |x| >= -11 * log(2), or x is NaN.
-  if (LIBC_UNLIKELY(x_abs <= 0x3000U || x_abs >= 0x47a0U)) {
-    // expm1(NaN) = NaN
-    if (x_bits.is_nan()) {
-      if (x_bits.is_signaling_nan()) {
-        fputil::raise_except_if_required(FE_INVALID);
-        return FPBits::quiet_nan().get_val();
-      }
-
-      return x;
-    }
-
-    // expm1(+/-0) = +/-0
-    if (x_abs == 0)
-      return x;
-
-    // When x >= 16 * log(2).
-    if (x_bits.is_pos() && x_abs >= 0x498cU) {
-      // expm1(+inf) = +inf
-      if (x_bits.is_inf())
-        return FPBits::inf().get_val();
-
-      switch (fputil::quick_get_round()) {
-      case FE_TONEAREST:
-      case FE_UPWARD:
-        fputil::set_errno_if_required(ERANGE);
-        fputil::raise_except_if_required(FE_OVERFLOW | FE_INEXACT);
-        return FPBits::inf().get_val();
-      default:
-        return FPBits::max_normal().get_val();
-      }
-    }
-
-    // When x <= -11 * log(2).
-    if (x_u >= 0xc7a0U) {
-      // expm1(-inf) = -1
-      if (x_bits.is_inf())
-        return FPBits::one(Sign::NEG).get_val();
-
-      // When x > -0x1.0ap+3, round(expm1(x), HP, RN) = -1.
-      if (x_u > 0xc828U)
-        return fputil::round_result_slightly_up(
-            FPBits::one(Sign::NEG).get_val());
-      // When x <= -0x1.0ap+3, round(expm1(x), HP, RN) = -0x1.ffcp-1.
-      return fputil::round_result_slightly_down(
-          fputil::cast<float16>(-0x1.ffcp-1));
-    }
-
-    // When 0 < |x| <= 2^(-3).
-    if (x_abs <= 0x3000U && !x_bits.is_zero()) {
-
-#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-      if (auto r = EXPM1F16_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
-      // commands:
-      //   > display = hexadecimal;
-      //   > P = fpminimax(expm1(x)/x, 4, [|SG...|], [-2^-3, 2^-3]);
-      //   > x * P;
-      return fputil::cast<float16>(
-          xf * fputil::polyeval(xf, 0x1p+0f, 0x1.fffff8p-2f, 0x1.555556p-3f,
-                                0x1.55905ep-5f, 0x1.1124c2p-7f));
-    }
-  }
-
-#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-  if (auto r = EXPM1F16_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
-    return r.value();
-#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-
-  // exp(x) = exp(hi + mid) * exp(lo)
-  auto [exp_hi_mid, exp_lo] = exp_range_reduction(x);
-  // expm1(x) = exp(hi + mid) * exp(lo) - 1
-  return fputil::cast<float16>(fputil::multiply_add(exp_hi_mid, exp_lo, -1.0f));
-}
+LLVM_LIBC_FUNCTION(float16, expm1f16, (float16 x)) { return math::expm1f16(x); }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/test/shared/CMakeLists.txt

@@ -47,6 +47,7 @@ add_fp_unittest(
     libc.src.__support.math.exp2m1f16
     libc.src.__support.math.expm1
     libc.src.__support.math.expm1f
+    libc.src.__support.math.expm1f16
     libc.src.__support.math.exp10
     libc.src.__support.math.exp10f
     libc.src.__support.math.exp10f16

libc/test/shared/shared_math_test.cpp

@@ -31,6 +31,7 @@ TEST(LlvmLibcSharedMathTest, AllFloat16) {
   EXPECT_FP_EQ(0x1p+0f16, LIBC_NAMESPACE::shared::exp2f16(0.0f16));
   EXPECT_FP_EQ(0x0p+0f16, LIBC_NAMESPACE::shared::exp2m1f16(0.0f16));
   EXPECT_FP_EQ(0x1p+0f16, LIBC_NAMESPACE::shared::expf16(0.0f16));
+  EXPECT_FP_EQ(0x0p+0f16, LIBC_NAMESPACE::shared::expm1f16(0.0f16));
 
   ASSERT_FP_EQ(float16(8 << 5), LIBC_NAMESPACE::shared::ldexpf16(8.0f16, 5));
   ASSERT_FP_EQ(float16(-1 * (8 << 5)),