[libc] Add differential quality and perf analysis targets for sinf and cosf.

[sivachandra]

Summary

Infrastructure needed for setting up the diff binaries has been added.
Along the way, an exhaustive test for sinf and cosf have also been added.

[sivachandra]

• Fix a typo.
• Add similar targets for cosf as well.

libc/test/src/math/CMakeLists.txt

add_fp_unittest(
   DEPENDS
     libc.include.math
     libc.src.math.fma
     libc.utils.FPUtil.fputil
 )
 
 add_subdirectory(generic)
 add_subdirectory(exhaustive)
+add_subdirectory(differential_testing)

libc/test/src/math/differential_testing/CMakeLists.txt

+
+function(add_diff_binary target_name)
+  cmake_parse_arguments(
+    "DIFF"
+    "" # No optional arguments
+    "SUITE" # Single value arguments
+    "SRCS;HDRS;DEPENDS;COMPILE_OPTIONS" # Multi-value arguments
+    ${ARGN}
+  )
+  if(NOT DIFF_SRCS)
+    message(FATAL_ERROR "'add_diff_binary' target requires a SRCS list of .cpp "
+                        "files.")
+  endif()
+  if(NOT DIFF_DEPENDS)
+    message(FATAL_ERROR "'add_diff_binary' target requires a DEPENDS list of "
+                        "'add_entrypoint_object' targets.")
+  endif()
+
+  get_fq_target_name(${target_name} fq_target_name)
+  get_fq_deps_list(fq_deps_list ${DIFF_DEPENDS})
+  get_object_files_for_test(
+      link_object_files skipped_entrypoints_list ${fq_deps_list})
+  if(skipped_entrypoints_list)
+    set(msg "Will not build ${fq_target_name} as it has missing deps: "
+            "${skipped_entrypoints_list}.")
+    message(STATUS ${msg})
+    return()
+  endif()
+
+  add_executable(
+    ${fq_target_name}
+    EXCLUDE_FROM_ALL
+    ${DIFF_SRCS}
+    ${DIFF_HDRS}
+  )
+  target_include_directories(
+    ${fq_target_name}
+    PRIVATE
+      ${LIBC_SOURCE_DIR}
+      ${LIBC_BUILD_DIR}
+      ${LIBC_BUILD_DIR}/include
+  )
+  if(DIFF_COMPILE_OPTIONS)
+    target_compile_options(
+      ${fq_target_name}
+      PRIVATE ${DIFF_COMPILE_OPTIONS}
+    )
+  endif()
+
+  target_link_libraries(
+      ${fq_target_name}
+      PRIVATE ${link_object_files} libc_test_utils)
+
+  set_target_properties(${fq_target_name}
+    PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
+  add_dependencies(
+    ${fq_target_name}
+    libc.utils.FPUtil.fputil
+    ${fq_deps_list}
+  )
+endfunction()
+
+add_header_library(
+  single_input_single_output_diff
+  HDRS
+    SingleInputSingleOutputDiff.h
+)
+
+add_diff_binary(
+  sinf_diff
+  SRCS
+    sinf_diff.cpp
+  DEPENDS
+    .single_input_single_output_diff
+    libc.src.math.sinf
+)
+
+add_diff_binary(
+  sinf_perf
+  SRCS
+    sinf_perf.cpp
+  DEPENDS
+    .single_input_single_output_diff
+    libc.src.math.sinf
+  COMPILE_OPTIONS
+    -fno-builtin
+)
+
+add_diff_binary(
+  cosf_diff
+  SRCS
+    cosf_diff.cpp
+  DEPENDS
+    .single_input_single_output_diff
+    libc.src.math.cosf
+)
+
+add_diff_binary(
+  cosf_perf
+  SRCS
+    cosf_perf.cpp
+  DEPENDS
+    .single_input_single_output_diff
+    libc.src.math.cosf
+  COMPILE_OPTIONS
+    -fno-builtin
+)

libc/test/src/math/differential_testing/SingleInputSingleOutputDiff.h

+//===-- Common utility class for differential analysis --------------------===//
+//
+// 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 "utils/FPUtil/FPBits.h"
+#include "utils/testutils/StreamWrapper.h"
+#include "utils/testutils/Timer.h"
+
+namespace __llvm_libc {
+namespace testing {
+
+template <typename T> class SingleInputSingleOutputDiff {
+  using FPBits = fputil::FPBits<T>;
+  using UIntType = typename FPBits::UIntType;
+  static constexpr UIntType MSBit = UIntType(1) << (8 * sizeof(UIntType) - 1);
+  static constexpr UIntType UIntMax = (MSBit - 1) + MSBit;
+
+public:
+  typedef T Func(T);
+
+  static void runDiff(Func myFunc, Func otherFunc, const char *logFile) {
+    UIntType diffCount = 0;
+    testutils::OutputFileStream log(logFile);
+    log << "Starting diff for values from 0 to " << UIntMax << '\n'
+        << "Only differing results will be logged.\n\n";
+    for (UIntType bits = 0;; ++bits) {
+      T x = T(FPBits(bits));
+      T myResult = myFunc(x);
+      T otherResult = otherFunc(x);
+      UIntType myBits = FPBits(myResult).uintval();
+      UIntType otherBits = FPBits(otherResult).uintval();
+      if (myBits != otherBits) {
+        ++diffCount;
+        log << "       Input: " << bits << " (" << x << ")\n"
+            << "   My result: " << myBits << " (" << myResult << ")\n"
+            << "Other result: " << otherBits << " (" << otherResult << ")\n"
+            << '\n';
+      }
+      if (bits == UIntMax)
+        break;
+    }
+    log << "Total number of differing results: " << diffCount << '\n';
+  }
+
+  static void runPerf(Func myFunc, Func otherFunc, const char *logFile) {
+    auto runner = [](Func func) {
+      volatile T result;
+      for (UIntType bits = 0;; ++bits) {
+        T x = T(FPBits(bits));
+        result = func(x);
+        if (bits == UIntMax)
+          break;
+      }
+    };
+
+    testutils::OutputFileStream log(logFile);
+    Timer timer;
+    timer.start();
+    runner(myFunc);
+    timer.stop();
+    log << "   Run time of my function: " << timer.nanoseconds() << " ns \n";
+
+    timer.start();
+    runner(otherFunc);
+    timer.stop();
+    log << "Run time of other function: " << timer.nanoseconds() << " ns \n";
+  }
+};
+
+} // namespace testing
+} // namespace __llvm_libc
+
+#define SINGLE_INPUT_SINGLE_OUTPUT_DIFF(T, myFunc, otherFunc, filename)        \
+  int main() {                                                                 \
+    __llvm_libc::testing::SingleInputSingleOutputDiff<T>::runDiff(             \
+        &myFunc, &otherFunc, filename);                                        \
+    return 0;                                                                  \
+  }
+
+#define SINGLE_INPUT_SINGLE_OUTPUT_PERF(T, myFunc, otherFunc, filename)        \
+  int main() {                                                                 \
+    __llvm_libc::testing::SingleInputSingleOutputDiff<T>::runPerf(             \
+        &myFunc, &otherFunc, filename);                                        \
+    return 0;                                                                  \
+  }

libc/test/src/math/differential_testing/cosf_diff.cpp

+//===-- Differential test for cosf ----------------------------------------===//
+//
+// 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 "SingleInputSingleOutputDiff.h"
+
+#include "src/math/cosf.h"
+
+#include <math.h>
+
+SINGLE_INPUT_SINGLE_OUTPUT_DIFF(float, __llvm_libc::cosf, ::cosf,
+                                "cosf_diff.log")

libc/test/src/math/differential_testing/cosf_perf.cpp

+//===-- Differential test for cosf ----------------------------------------===//
+//
+// 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 "SingleInputSingleOutputDiff.h"
+
+#include "src/math/cosf.h"
+
+#include <math.h>
+
+SINGLE_INPUT_SINGLE_OUTPUT_PERF(float, __llvm_libc::cosf, ::cosf,
+                                "cosf_perf.log")

libc/test/src/math/differential_testing/sinf_diff.cpp

+//===-- Differential test for sinf ----------------------------------------===//
+//
+// 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 "SingleInputSingleOutputDiff.h"
+
+#include "src/math/sinf.h"
+
+#include <math.h>
+
+SINGLE_INPUT_SINGLE_OUTPUT_DIFF(float, __llvm_libc::sinf, ::sinf,
+                                "sinf_diff.log")

libc/test/src/math/differential_testing/sinf_perf.cpp

+//===-- Differential test for sinf ----------------------------------------===//
+//
+// 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 "SingleInputSingleOutputDiff.h"
+
+#include "src/math/sinf.h"
+
+#include <math.h>
+
+SINGLE_INPUT_SINGLE_OUTPUT_PERF(float, __llvm_libc::sinf, ::sinf,
+                                "sinf_perf.log")

libc/test/src/math/exhaustive/CMakeLists.txt

 add_libc_exhaustive_testsuite(libc_math_exhaustive_tests)
 
 add_fp_unittest(
   sqrtf_test
   NEED_MPFR
   SUITE
     libc_math_exhaustive_tests
   SRCS
     sqrtf_test.cpp
   DEPENDS
     libc.include.math
     libc.src.math.sqrtf
     libc.utils.FPUtil.fputil
 )
+
+add_fp_unittest(
+  sinf_test
+  NEED_MPFR
+  SUITE
+    libc_math_exhaustive_tests
+  SRCS
+    sinf_test.cpp
+  DEPENDS
+    libc.include.math
+    libc.src.math.sinf
+    libc.utils.FPUtil.fputil
+)
+
+add_fp_unittest(
+  cosf_test
+  NEED_MPFR
+  SUITE
+    libc_math_exhaustive_tests
+  SRCS
+    cosf_test.cpp
+  DEPENDS
+    libc.include.math
+    libc.src.math.cosf
+    libc.utils.FPUtil.fputil
+)

libc/test/src/math/exhaustive/cosf_test.cpp

-//===-- Exhaustive test for sqrtf -----------------------------------------===//
+//===-- Exhaustive test for cosf ------------------------------------------===//
 //
 // 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 "src/math/sqrtf.h"
+#include "src/math/cosf.h"
 #include "utils/FPUtil/FPBits.h"
 #include "utils/FPUtil/TestHelpers.h"
 #include "utils/MPFRWrapper/MPFRUtils.h"
 #include <math.h>
 
 using FPBits = __llvm_libc::fputil::FPBits<float>;
 
 namespace mpfr = __llvm_libc::testing::mpfr;
 
-TEST(LlvmLibcSqrtfExhaustiveTest, AllValues) {
+TEST(LlvmLibccosffExhaustiveTest, AllValues) {
   uint32_t bits = 0;
   do {
-    FPBits x(bits);
-    ASSERT_MPFR_MATCH(mpfr::Operation::Sqrt, float(x), __llvm_libc::sqrtf(x),
-                      0.5);
+    FPBits xbits(bits);
+    float x = float(xbits);
+    ASSERT_MPFR_MATCH(mpfr::Operation::Cos, x, __llvm_libc::cosf(x), 1.0);
   } while (bits++ < 0xffff'ffffU);
 }

libc/test/src/math/exhaustive/sinf_test.cpp

-//===-- Exhaustive test for sqrtf -----------------------------------------===//
+//===-- Exhaustive test for sinf ------------------------------------------===//
 //
 // 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 "src/math/sqrtf.h"
+#include "src/math/sinf.h"
 #include "utils/FPUtil/FPBits.h"
 #include "utils/FPUtil/TestHelpers.h"
 #include "utils/MPFRWrapper/MPFRUtils.h"
 #include <math.h>
 
 using FPBits = __llvm_libc::fputil::FPBits<float>;
 
 namespace mpfr = __llvm_libc::testing::mpfr;
 
-TEST(LlvmLibcSqrtfExhaustiveTest, AllValues) {
+TEST(LlvmLibcsinffExhaustiveTest, AllValues) {
   uint32_t bits = 0;
   do {
-    FPBits x(bits);
-    ASSERT_MPFR_MATCH(mpfr::Operation::Sqrt, float(x), __llvm_libc::sqrtf(x),
-                      0.5);
+    FPBits xbits(bits);
+    float x = float(xbits);
+    ASSERT_MPFR_MATCH(mpfr::Operation::Sin, x, __llvm_libc::sinf(x), 1.0);
   } while (bits++ < 0xffff'ffffU);
 }

libc/test/src/math/exhaustive/sqrtf_test.cpp

 
 using FPBits = __llvm_libc::fputil::FPBits<float>;
 
 namespace mpfr = __llvm_libc::testing::mpfr;
 
 TEST(LlvmLibcSqrtfExhaustiveTest, AllValues) {
   uint32_t bits = 0;
   do {
-    FPBits x(bits);
-    ASSERT_MPFR_MATCH(mpfr::Operation::Sqrt, float(x), __llvm_libc::sqrtf(x),
-                      0.5);
+    FPBits xbits(bits);
+    float x = float(xbits);
+    ASSERT_MPFR_MATCH(mpfr::Operation::Sqrt, x, __llvm_libc::sqrtf(x), 0.5);
   } while (bits++ < 0xffff'ffffU);
 }

libc/utils/testutils/CMakeLists.txt

 if(CMAKE_HOST_UNIX)
   set(EFFile ExecuteFunctionUnix.cpp)
   set(FDReaderFile FDReaderUnix.cpp)
 endif()
 
 add_llvm_library(
   libc_test_utils
   RandUtils.cpp
   RandUtils.h
   StreamWrapper.cpp
   StreamWrapper.h
   ${EFFile}
   ExecuteFunction.h
   ${FDReaderFile}
   FDReader.h
+  Timer.h
+  Timer.cpp
 )

libc/utils/testutils/StreamWrapper.h

 
 namespace __llvm_libc {
 namespace testutils {
 
 // StreamWrapper is necessary because llvm/Support/raw_ostream.h includes
 // standard headers so we must provide streams through indirection to not
 // expose the system libc headers.
 class StreamWrapper {
+protected:
   void *OS;
 
 public:
   StreamWrapper(void *OS) : OS(OS) {}
 
   template <typename T> StreamWrapper &operator<<(T t);
 };
 
 StreamWrapper outs();
 
+class OutputFileStream : public StreamWrapper {
+public:
+  explicit OutputFileStream(const char *FN);
+  ~OutputFileStream();
+};
+
 } // namespace testutils
 } // namespace __llvm_libc
 
 #endif // LLVM_LIBC_UTILS_TESTUTILS_STREAMWRAPPER_H

libc/utils/testutils/StreamWrapper.cpp

 //===-- StreamWrapper.cpp -------------------------------------------------===//
 //
 // 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 "StreamWrapper.h"
 #include <cassert>
+#include <fstream>
 #include <iostream>
 #include <memory>
 #include <string>
 
 namespace __llvm_libc {
 namespace testutils {
 
 StreamWrapper outs() { return {std::addressof(std::cout)}; }
 
 template <typename T> StreamWrapper &StreamWrapper::operator<<(T t) {
   assert(OS);
   std::ostream &Stream = *reinterpret_cast<std::ostream *>(OS);
   Stream << t;
+  Stream.flush();
   return *this;
 }
 
 template StreamWrapper &StreamWrapper::operator<<<void *>(void *t);
 template StreamWrapper &StreamWrapper::operator<<<const char *>(const char *t);
 template StreamWrapper &StreamWrapper::operator<<<char *>(char *t);
 template StreamWrapper &StreamWrapper::operator<<<char>(char t);
 template StreamWrapper &StreamWrapper::operator<<<short>(short t);
 template StreamWrapper &StreamWrapper::operator<<<int>(int t);
 template StreamWrapper &StreamWrapper::operator<<<long>(long t);
 template StreamWrapper &StreamWrapper::operator<<<long long>(long long t);
 template StreamWrapper &
     StreamWrapper::operator<<<unsigned char>(unsigned char t);
 template StreamWrapper &
     StreamWrapper::operator<<<unsigned short>(unsigned short t);
 template StreamWrapper &StreamWrapper::operator<<<unsigned int>(unsigned int t);
 template StreamWrapper &
     StreamWrapper::operator<<<unsigned long>(unsigned long t);
 template StreamWrapper &
     StreamWrapper::operator<<<unsigned long long>(unsigned long long t);
 template StreamWrapper &StreamWrapper::operator<<<bool>(bool t);
 template StreamWrapper &StreamWrapper::operator<<<std::string>(std::string t);
+template StreamWrapper &StreamWrapper::operator<<<float>(float t);
+template StreamWrapper &StreamWrapper::operator<<<double>(double t);
+
+OutputFileStream::OutputFileStream(const char *FN)
+    : StreamWrapper(new std::ofstream(FN)) {}
+
+OutputFileStream::~OutputFileStream() {
+  delete reinterpret_cast<std::ofstream *>(OS);
+}
 
 } // namespace testutils
 } // namespace __llvm_libc

libc/utils/testutils/Timer.h

+//===-- Timer.h -------------------------------------------------*- 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_UTILS_TESTUTILS_TIMER_H
+#define LLVM_LIBC_UTILS_TESTUTILS_TIMER_H
+
+#include <stdint.h>
+
+namespace __llvm_libc {
+namespace testing {
+
+class Timer {
+  void *Impl;
+
+public:
+  Timer();
+  ~Timer();
+
+  void start();
+  void stop();
+
+  uint64_t nanoseconds() const;
+};
+
+} // namespace testing
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_UTILS_TESTUTILS_TIMER_H

libc/utils/testutils/Timer.cpp

+//===-- Timer.cpp --------------------------------------------------------===//
+//
+// 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 "Timer.h"
+
+#include <chrono>
+#include <fstream>
+
+namespace __llvm_libc {
+namespace testing {
+
+struct TimerImplementation {
+  std::chrono::high_resolution_clock::time_point Start;
+  std::chrono::high_resolution_clock::time_point End;
+};
+
+Timer::Timer() : Impl(new TimerImplementation) {}
+
+Timer::~Timer() { delete reinterpret_cast<TimerImplementation *>(Impl); }
+
+void Timer::start() {
+  auto T = reinterpret_cast<TimerImplementation *>(Impl);
+  T->Start = std::chrono::high_resolution_clock::now();
+}
+
+void Timer::stop() {
+  auto T = reinterpret_cast<TimerImplementation *>(Impl);
+  T->End = std::chrono::high_resolution_clock::now();
+}
+
+uint64_t Timer::nanoseconds() const {
+  auto T = reinterpret_cast<TimerImplementation *>(Impl);
+  return std::chrono::nanoseconds(T->End - T->Start).count();
+}
+
+} // namespace testing
+} // namespace __llvm_libc