src/gromacs/simd/tests/base.h

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  35
  36 #ifndef GMX_SIMD_TESTS_BASE_H
  37 #define GMX_SIMD_TESTS_BASE_H
  38
  39 /*! \internal \file
  40  * \brief
  41  * Declares common base class for testing SIMD and SIMD4.
  42  *
  43  * The base class contains the settings for absolute and ulp tolerances,
  44  * as well as testing ranges used for both SIMD and SIMD4 tests, mainly
  45  * to keep everything symmetric and clean. The class also defines a couple
  46  * of generic tests that compare vectors of elements with arbitrary length for
  47  * either exact or approximate matching (in terms of ulp). These are used in
  48  * derived classes that convert either SIMD or SIMD4 values to
  49  * std::vector<real> and then performs the comparison.
  50  *
  51  * \author Erik Lindahl <erik.lindahl@scilifelab.se>
  52  * \ingroup module_simd
  53  */
  54 #include "config.h"
  55
  56 #include <cstdint>
  57
  58 #include <limits>
  59 #include <vector>
  60
  61 #include <gtest/gtest.h>
  62
  63 #include "gromacs/utility/basedefinitions.h"
  64 #include "gromacs/utility/gmxassert.h"
  65 #include "gromacs/utility/real.h"
  66
  67 namespace gmx
  68 {
  69 namespace test
  70 {
  71
  72 //! \internal \brief Test-time utility macro for current precision accuracy
  73 #define GMX_SIMD_ACCURACY_BITS_REAL (GMX_DOUBLE ? GMX_SIMD_ACCURACY_BITS_DOUBLE : GMX_SIMD_ACCURACY_BITS_SINGLE)
  74
  75 /*! \internal
  76  * \brief
  77  * Base class for SIMD test fixtures.
  78  *
  79  * This class contains settings that are common for SIMD and SIMD4 tests,
  80  * and it is thus not used directly for any tests, but derived separately
  81  * in simd.h and simd4.h.
  82  *
  83  * \ingroup module_simd
  84  */
  85 class SimdBaseTest : public ::testing::Test
  86 {
  87     public:
  88         /*! \brief Return the default ulp tolerance for current precision
  89          */
  90         static constexpr std::int64_t
  91         defaultRealUlpTol()
  92         {
  93             return (1LL << (2 + std::numeric_limits<real>::digits-GMX_SIMD_ACCURACY_BITS_REAL));
  94         }
  95
  96         /*! \brief Initialize new SIMD test fixture with default tolerances.
  97          *
  98          * The default absolute tolerance is set to 0, which means the we always
  99          * check the ulp tolerance by default (passing the absolute tolerance
 100          * test would otherwise mean we approve the test instantly).
 101          *
 102          * The default ulp tolerance is set based on the target number of
 103          * bits requested for single or double precision, depending on what
 104          * the default Gromacs precision is. We add two bits to avoid
 105          * tests failing due to corner cases where compiler optimization might
 106          * cause a slight precision loss e.g. for very small numbers.
 107          *
 108          * Most SIMD math functions actually achieve 2-3 ulp accuracy in single,
 109          * but by being a bit liberal we only catch real errors rather than
 110          * doing compiler-standard-compliance debugging.
 111          *
 112          * The range is used by derived classes to test math functions. The
 113          * default test range will be [1,10], which is intentionally
 114          * conservative so it works with (inverse) square root, division,
 115          * exponentials, logarithms, and error functions.
 116          */
 117         SimdBaseTest() :
 118             ulpTol_(defaultRealUlpTol()), absTol_(0)
 119         {
 120         }
 121
 122         /*! \brief Adjust ulp tolerance from the default 10 (float) or 255 (double). */
 123         void setUlpTol(std::int64_t newTol)   { ulpTol_ = newTol; }
 124
 125         /*! \brief Adjust ulp tolerance for single accuracy functions. */
 126         void setUlpTolSingleAccuracy(std::int64_t newTol)
 127         {
 128             const int realBits   = std::numeric_limits<real>::digits;
 129             const int singleBits = std::numeric_limits<float>::digits;
 130             // In single precision the expression (1LL << 0) evaluates to 1.
 131             setUlpTol(newTol * (1LL << (realBits - singleBits)));
 132         }
 133
 134         /*! \brief Adjust the absolute tolerance from the default 0.
 135          *
 136          * If values are closer than the absolute tolerance, the test will pass
 137          * no matter what their ulp difference is.
 138          */
 139         void setAbsTol(real newTol)          { absTol_ = newTol; }
 140
 141         /*! \brief Number of test points to use, settable on command line.
 142          *
 143          * \note While this has to be a static non-const variable for the
 144          *       command-line option to work, you should never change it
 145          *       manually in any of the tests, because the static storage
 146          *       class will make the value apply to all subsequent tests
 147          *       unless you remember to reset it.
 148          */
 149         static int  s_nPoints;
 150
 151         /*! \brief Compare two std::vector<real> for approximate equality.
 152          *
 153          * This is an internal implementation routine that will be used by
 154          * routines in derived child classes that first convert SIMD or SIMD4
 155          * variables to std::vector<real>. Do not call it directly.
 156          *
 157          * This routine is designed according to the Google test specs, so the char
 158          * strings will describe the arguments to the macro.
 159          *
 160          * The comparison is applied to each element, and it returns true if each element
 161          * in the vector test variable is within the class tolerances of the corresponding
 162          * reference elements.
 163          */
 164         ::testing::AssertionResult
 165         compareVectorRealUlp(const char * refExpr,  const char * tstExpr,
 166                              const std::vector<real> &ref, const std::vector<real> &tst);
 167
 168         /*! \brief Compare std::vectors for exact equality.
 169          *
 170          * The template in this class makes it usable for testing both
 171          * SIMD floating-point and integers variables, after conversion to
 172          * vectors.
 173          * This is an internal implementation routine that will be used by
 174          * routines in derived child classes that first convert SIMD or SIMD4
 175          * variables to std::vector<real>. Do not call it directly.
 176          *
 177          * This routine is designed according to the Google test specs, so the char
 178          * strings will describe the arguments to the macro.
 179          *
 180          * The comparison is applied to each element, and it returns true if each element
 181          * in the vector test variable is within the class tolerances of the corresponding
 182          * reference elements.
 183          */
 184         template <typename T> ::testing::AssertionResult
 185         compareVectorEq(const char * refExpr,  const char * tstExpr,
 186                         const std::vector<T> &ref, const std::vector<T> &tst)
 187         {
 188             if (ref == tst)
 189             {
 190                 return ::testing::AssertionSuccess();
 191             }
 192             else
 193             {
 194                 return ::testing::AssertionFailure()
 195                        << "Failing SIMD comparison between " << refExpr << " and " << tstExpr << std::endl
 196                        << "Ref. values: " << ::testing::PrintToString(ref) << std::endl
 197                        << "Test values: " << ::testing::PrintToString(tst) << std::endl;
 198             }
 199         }
 200
 201     protected:
 202         std::int64_t           ulpTol_;       //!< Current tolerance in units-in-last-position.
 203         real                   absTol_;       //!< Current absolute tolerance.
 204 };
 205
 206 }      // namespace test
 207 }      // namespace gmx
 208
 209 #endif // GMX_SIMD_TESTS_BASE_H