[libc] Add implementations of ilogb[f|l].

Depends on D90805.

Reviewed By: lntue

Differential Revision: https://reviews.llvm.org/D90806

5 files changed, 273 insertions, 0 deletions

diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index a90736992f1f..4f8f77e4cf03 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -371,6 +371,48 @@ add_fp_unittest(
 )
 
 add_fp_unittest(
+  ilogb_test
+  SUITE
+    libc_math_unittests
+  SRCS
+    ilogb_test.cpp
+  HDRS
+    ILogbTest.h
+  DEPENDS
+    libc.include.math
+    libc.src.math.ilogb
+    libc.utils.FPUtil.fputil
+)
+
+add_fp_unittest(
+  ilogbf_test
+  SUITE
+    libc_math_unittests
+  SRCS
+    ilogbf_test.cpp
+  HDRS
+    ILogbTest.h
+  DEPENDS
+    libc.include.math
+    libc.src.math.ilogbf
+    libc.utils.FPUtil.fputil
+)
+
+add_fp_unittest(
+  ilogbl_test
+  SUITE
+    libc_math_unittests
+  SRCS
+    ilogbl_test.cpp
+  HDRS
+    ILogbTest.h
+  DEPENDS
+    libc.include.math
+    libc.src.math.ilogbl
+    libc.utils.FPUtil.fputil
+)
+
+add_fp_unittest(
   logb_test
   SUITE
     libc_math_unittests
diff --git a/libc/test/src/math/ILogbTest.h b/libc/test/src/math/ILogbTest.h
new file mode 100644
index 000000000000..001b419de6cd
--- /dev/null
+++ b/libc/test/src/math/ILogbTest.h
@@ -0,0 +1,108 @@
+//===-- Utility class to test different flavors of ilogb --------*- 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_TEST_SRC_MATH_ILOGBTEST_H
+#define LLVM_LIBC_TEST_SRC_MATH_ILOGBTEST_H
+
+#include "include/math.h"
+#include "utils/FPUtil/FPBits.h"
+#include "utils/FPUtil/ManipulationFunctions.h"
+#include "utils/UnitTest/Test.h"
+
+#include <limits.h>
+
+class ILogbTest : public __llvm_libc::testing::Test {
+public:
+  template <typename T> struct ILogbFunc { typedef int (*Func)(T); };
+
+  template <typename T>
+  void testSpecialNumbers(typename ILogbFunc<T>::Func func) {
+    EXPECT_EQ(FP_ILOGB0, func(__llvm_libc::fputil::FPBits<T>::zero()));
+    EXPECT_EQ(FP_ILOGB0, func(__llvm_libc::fputil::FPBits<T>::negZero()));
+
+    EXPECT_EQ(FP_ILOGBNAN, func(__llvm_libc::fputil::FPBits<T>::buildNaN(1)));
+
+    EXPECT_EQ(INT_MAX, func(__llvm_libc::fputil::FPBits<T>::inf()));
+    EXPECT_EQ(INT_MAX, func(__llvm_libc::fputil::FPBits<T>::negInf()));
+  }
+
+  template <typename T> void testPowersOfTwo(typename ILogbFunc<T>::Func func) {
+    EXPECT_EQ(0, func(T(1.0)));
+    EXPECT_EQ(0, func(T(-1.0)));
+
+    EXPECT_EQ(1, func(T(2.0)));
+    EXPECT_EQ(1, func(T(-2.0)));
+
+    EXPECT_EQ(2, func(T(4.0)));
+    EXPECT_EQ(2, func(T(-4.0)));
+
+    EXPECT_EQ(3, func(T(8.0)));
+    EXPECT_EQ(3, func(-8.0));
+
+    EXPECT_EQ(4, func(16.0));
+    EXPECT_EQ(4, func(-16.0));
+
+    EXPECT_EQ(5, func(32.0));
+    EXPECT_EQ(5, func(-32.0));
+  }
+
+  template <typename T>
+  void testSomeIntegers(typename ILogbFunc<T>::Func func) {
+    EXPECT_EQ(1, func(T(3.0)));
+    EXPECT_EQ(1, func(T(-3.0)));
+
+    EXPECT_EQ(2, func(T(7.0)));
+    EXPECT_EQ(2, func(T(-7.0)));
+
+    EXPECT_EQ(3, func(T(10.0)));
+    EXPECT_EQ(3, func(T(-10.0)));
+
+    EXPECT_EQ(4, func(T(31.0)));
+    EXPECT_EQ(4, func(-31.0));
+
+    EXPECT_EQ(5, func(55.0));
+    EXPECT_EQ(5, func(-55.0));
+  }
+
+  template <typename T>
+  void testSubnormalRange(typename ILogbFunc<T>::Func func) {
+    using FPBits = __llvm_libc::fputil::FPBits<T>;
+    using UIntType = typename FPBits::UIntType;
+    constexpr UIntType count = 1000001;
+    constexpr UIntType step =
+        (FPBits::maxSubnormal - FPBits::minSubnormal) / count;
+    for (UIntType v = FPBits::minSubnormal; v <= FPBits::maxSubnormal;
+         v += step) {
+      T x = FPBits(v);
+      if (isnan(x) || isinf(x) || x == 0.0)
+        continue;
+
+      int exponent;
+      __llvm_libc::fputil::frexp(x, exponent);
+      ASSERT_EQ(exponent, func(x) + 1);
+    }
+  }
+
+  template <typename T> void testNormalRange(typename ILogbFunc<T>::Func func) {
+    using FPBits = __llvm_libc::fputil::FPBits<T>;
+    using UIntType = typename FPBits::UIntType;
+    constexpr UIntType count = 1000001;
+    constexpr UIntType step = (FPBits::maxNormal - FPBits::minNormal) / count;
+    for (UIntType v = FPBits::minNormal; v <= FPBits::maxNormal; v += step) {
+      T x = FPBits(v);
+      if (isnan(x) || isinf(x) || x == 0.0)
+        continue;
+
+      int exponent;
+      __llvm_libc::fputil::frexp(x, exponent);
+      ASSERT_EQ(exponent, func(x) + 1);
+    }
+  }
+};
+
+#endif // LLVM_LIBC_TEST_SRC_MATH_ILOGBTEST_H
diff --git a/libc/test/src/math/ilogb_test.cpp b/libc/test/src/math/ilogb_test.cpp
new file mode 100644
index 000000000000..cf71ac07be18
--- /dev/null
+++ b/libc/test/src/math/ilogb_test.cpp
@@ -0,0 +1,41 @@
+//===-- Unittests for ilogb -----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "ILogbTest.h"
+
+#include "include/math.h"
+#include "src/math/ilogb.h"
+#include "utils/CPP/Functional.h"
+#include "utils/FPUtil/FPBits.h"
+#include "utils/FPUtil/ManipulationFunctions.h"
+#include "utils/FPUtil/TestHelpers.h"
+#include "utils/UnitTest/Test.h"
+
+#include <limits.h>
+
+using RunContext = __llvm_libc::testing::RunContext;
+
+TEST_F(ILogbTest, SpecialNumbers_ilogb) {
+  testSpecialNumbers<double>(&__llvm_libc::ilogb);
+}
+
+TEST_F(ILogbTest, PowersOfTwo_ilogb) {
+  testPowersOfTwo<double>(&__llvm_libc::ilogb);
+}
+
+TEST_F(ILogbTest, SomeIntegers_ilogb) {
+  testSomeIntegers<double>(&__llvm_libc::ilogb);
+}
+
+TEST_F(ILogbTest, SubnormalRange_ilogb) {
+  testSubnormalRange<double>(&__llvm_libc::ilogb);
+}
+
+TEST_F(ILogbTest, NormalRange_ilogb) {
+  testNormalRange<double>(&__llvm_libc::ilogb);
+}
diff --git a/libc/test/src/math/ilogbf_test.cpp b/libc/test/src/math/ilogbf_test.cpp
new file mode 100644
index 000000000000..109dddeca7b1
--- /dev/null
+++ b/libc/test/src/math/ilogbf_test.cpp
@@ -0,0 +1,41 @@
+//===-- Unittests for ilogbf ----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "ILogbTest.h"
+
+#include "include/math.h"
+#include "src/math/ilogbf.h"
+#include "utils/CPP/Functional.h"
+#include "utils/FPUtil/FPBits.h"
+#include "utils/FPUtil/ManipulationFunctions.h"
+#include "utils/FPUtil/TestHelpers.h"
+#include "utils/UnitTest/Test.h"
+
+#include <limits.h>
+
+using RunContext = __llvm_libc::testing::RunContext;
+
+TEST_F(ILogbTest, SpecialNumbers_ilogbf) {
+  testSpecialNumbers<float>(&__llvm_libc::ilogbf);
+}
+
+TEST_F(ILogbTest, PowersOfTwo_ilogbf) {
+  testPowersOfTwo<float>(&__llvm_libc::ilogbf);
+}
+
+TEST_F(ILogbTest, SomeIntegers_ilogbf) {
+  testSomeIntegers<float>(&__llvm_libc::ilogbf);
+}
+
+TEST_F(ILogbTest, SubnormalRange_ilogbf) {
+  testSubnormalRange<float>(&__llvm_libc::ilogbf);
+}
+
+TEST_F(ILogbTest, NormalRange_ilogbf) {
+  testNormalRange<float>(&__llvm_libc::ilogbf);
+}
diff --git a/libc/test/src/math/ilogbl_test.cpp b/libc/test/src/math/ilogbl_test.cpp
new file mode 100644
index 000000000000..6404c6b00fd1
--- /dev/null
+++ b/libc/test/src/math/ilogbl_test.cpp
@@ -0,0 +1,41 @@
+//===-- Unittests for ilogbl ----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "ILogbTest.h"
+
+#include "include/math.h"
+#include "src/math/ilogbl.h"
+#include "utils/CPP/Functional.h"
+#include "utils/FPUtil/FPBits.h"
+#include "utils/FPUtil/ManipulationFunctions.h"
+#include "utils/FPUtil/TestHelpers.h"
+#include "utils/UnitTest/Test.h"
+
+#include <limits.h>
+
+using RunContext = __llvm_libc::testing::RunContext;
+
+TEST_F(ILogbTest, SpecialNumbers_ilogbl) {
+  testSpecialNumbers<long double>(&__llvm_libc::ilogbl);
+}
+
+TEST_F(ILogbTest, PowersOfTwo_ilogbl) {
+  testPowersOfTwo<long double>(&__llvm_libc::ilogbl);
+}
+
+TEST_F(ILogbTest, SomeIntegers_ilogbl) {
+  testSomeIntegers<long double>(&__llvm_libc::ilogbl);
+}
+
+TEST_F(ILogbTest, SubnormalRange_ilogbl) {
+  testSubnormalRange<long double>(&__llvm_libc::ilogbl);
+}
+
+TEST_F(ILogbTest, NormalRange_ilogbl) {
+  testNormalRange<long double>(&__llvm_libc::ilogbl);
+}