src/gromacs/simd/tests/simd4_math.cpp

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  35 #include "gmxpre.h"
  36
  37 #include "config.h"
  38
  39 #include <cmath>
  40 #include <cstdint>
  41
  42 #include <vector>
  43
  44 #include "gromacs/math/utilities.h"
  45 #include "gromacs/options/basicoptions.h"
  46 #include "gromacs/simd/simd.h"
  47 #include "gromacs/simd/simd_math.h"
  48
  49 #include "simd4.h"
  50
  51 #if GMX_SIMD
  52
  53 namespace gmx
  54 {
  55 namespace test
  56 {
  57
  58 /*! \cond internal */
  59 /*! \addtogroup module_simd */
  60 /*! \{ */
  61
  62 #if GMX_SIMD4_HAVE_REAL
  63
  64 class Simd4MathTest : public Simd4Test
  65 {
  66     public:
  67         ::testing::AssertionResult
  68                              compareSimd4MathFunction(const char * refFuncExpr, const char *simd4FuncExpr,
  69                                                       real refFunc(real x),     Simd4Real gmx_simdcall simd4Func(Simd4Real x));
  70 };
  71
  72 /*! \brief Test approximate equality of SIMD4 vs reference version of a function.
  73  *
  74  * This macro takes vanilla C and SIMD flavors of a function and tests it with
  75  * the number of points, range, and tolerances specified by the test fixture class.
  76  */
  77 #define GMX_EXPECT_SIMD4_FUNC_NEAR(refFunc, tstFunc) \
  78     EXPECT_PRED_FORMAT2(compareSimd4MathFunction, refFunc, tstFunc)
  79
  80
  81 /*! \brief Implementation routine to compare SIMD4 vs reference functions.
  82  *
  83  * \param refFuncExpr    Description of reference function expression
  84  * \param simd4FuncExpr  Description of SIMD function expression
  85  * \param refFunc        Reference math function pointer
  86  * \param simd4Func      SIMD math function pointer
  87  *
  88  * The function will be tested with the range and tolerances specified in
  89  * the SimdBaseTest class. You should not never call this function directly,
  90  * but use the macro GMX_EXPECT_SIMD4_FUNC_NEAR(refFunc,tstFunc) instead.
  91  */
  92 ::testing::AssertionResult
  93 Simd4MathTest::compareSimd4MathFunction(const char * refFuncExpr, const char *simd4FuncExpr,
  94                                         real refFunc(real x),     Simd4Real gmx_simdcall simd4Func(Simd4Real x))
  95 {
  96     std::vector<real>            vx(GMX_SIMD4_WIDTH);
  97     std::vector<real>            vref(GMX_SIMD4_WIDTH);
  98     std::vector<real>            vtst(GMX_SIMD4_WIDTH);
  99     real                         dx;
 100     std::int64_t                 ulpDiff, maxUlpDiff;
 101     real                         maxUlpDiffPos;
 102     real                         refValMaxUlpDiff, simdValMaxUlpDiff;
 103     int                          niter   = s_nPoints/GMX_SIMD4_WIDTH;
 104     int                          npoints = niter*GMX_SIMD4_WIDTH;
 105 #    if GMX_DOUBLE
 106     union {
 107         double r; std::int64_t i;
 108     } conv0, conv1;
 109 #    else
 110     union {
 111         float  r; std::int32_t i;
 112     } conv0, conv1;
 113 #    endif
 114
 115     maxUlpDiff = 0;
 116     dx         = (range_.second-range_.first)/npoints;
 117
 118     for (int iter = 0; iter < niter; iter++)
 119     {
 120         for (int i = 0; i < GMX_SIMD4_WIDTH; i++)
 121         {
 122             vx[i]   = range_.first+dx*(iter*GMX_SIMD4_WIDTH+i);
 123             vref[i] = refFunc(vx[i]);
 124         }
 125         vtst  = simd4Real2Vector(simd4Func(vector2Simd4Real(vx)));
 126
 127         bool eq = true, signOk = true;
 128         for (int i = 0; i < GMX_SIMD4_WIDTH && eq; i++)
 129         {
 130             eq     = eq && ( std::abs(vref[i]-vtst[i]) < absTol_ );
 131             signOk = signOk && ( vref[i]*vtst[i] >= 0 );
 132         }
 133         if (eq)
 134         {
 135             // Go to next point if everything within absolute tolerance
 136             continue;
 137         }
 138         else if (!signOk)
 139         {
 140             return ::testing::AssertionFailure()
 141                    << "Failing SIMD4 math function comparison due to sign differences." << std::endl
 142                    << "Reference function: " << refFuncExpr << std::endl
 143                    << "Simd function:      " << simd4FuncExpr << std::endl
 144                    << "Test range is ( " << range_.first << " , " << range_.second << " ) " << std::endl
 145                    << "First sign difference around x=" << std::setprecision(20) << ::testing::PrintToString(vx) << std::endl
 146                    << "Ref values:   " << std::setprecision(20) << ::testing::PrintToString(vref) << std::endl
 147                    << "SIMD4 values: " << std::setprecision(20) << ::testing::PrintToString(vtst) << std::endl;
 148         }
 149         /* We replicate the trivial ulp differences comparison here rather than
 150          * calling the lower-level routine for comparing them, since this enables
 151          * us to run through the entire test range and report the largest deviation
 152          * without lots of extra glue routines.
 153          */
 154         for (int i = 0; i < GMX_SIMD4_WIDTH; i++)
 155         {
 156             conv0.r = vref[i];
 157             conv1.r = vtst[i];
 158             ulpDiff = llabs(conv0.i-conv1.i);
 159             if (ulpDiff > maxUlpDiff)
 160             {
 161                 maxUlpDiff        = ulpDiff;
 162                 maxUlpDiffPos     = vx[i];
 163                 refValMaxUlpDiff  = vref[i];
 164                 simdValMaxUlpDiff = vtst[i];
 165             }
 166         }
 167     }
 168     GMX_RELEASE_ASSERT(ulpTol_ >= 0, "Invalid ulp value.");
 169     if (maxUlpDiff <= ulpTol_)
 170     {
 171         return ::testing::AssertionSuccess();
 172     }
 173     else
 174     {
 175         return ::testing::AssertionFailure()
 176                << "Failing SIMD4 math function ulp comparison between " << refFuncExpr << " and " << simd4FuncExpr << std::endl
 177                << "Requested ulp tolerance: " << ulpTol_ << std::endl
 178                << "Requested abs tolerance: " << absTol_ << std::endl
 179                << "Largest Ulp difference occurs for x=" << std::setprecision(20) << maxUlpDiffPos << std::endl
 180                << "Ref  values:  " << std::setprecision(20) << refValMaxUlpDiff << std::endl
 181                << "SIMD4 values: " << std::setprecision(20) << simdValMaxUlpDiff << std::endl
 182                << "Ulp diff.:   " << std::setprecision(20) << maxUlpDiff << std::endl;
 183     }
 184 }
 185
 186 /*! \} */
 187 /*! \endcond */
 188
 189 // Actual math function tests below
 190
 191 namespace
 192 {
 193
 194 /*! \cond internal */
 195 /*! \addtogroup module_simd */
 196 /*! \{ */
 197
 198 /*! \brief Function wrapper to evaluate reference 1/sqrt(x) */
 199 real
 200 refInvsqrt(real x)
 201 {
 202     return 1.0/std::sqrt(x);
 203 }
 204
 205 TEST_F(Simd4MathTest, invsqrt)
 206 {
 207     setRange(1e-10, 1e10);
 208     GMX_EXPECT_SIMD4_FUNC_NEAR(refInvsqrt, invsqrt);
 209 }
 210
 211 TEST_F(Simd4MathTest, invsqrtSingleaccuracy)
 212 {
 213     setRange(1e-10, 1e10);
 214     /* Increase the allowed error by the difference between the actual precision and single */
 215     setUlpTolSingleAccuracy(ulpTol_);
 216     GMX_EXPECT_SIMD4_FUNC_NEAR(refInvsqrt, invsqrtSingleAccuracy);
 217 }
 218
 219 }      // namespace
 220
 221 #endif // GMX_SIMD4_HAVE_REAL
 222
 223 /*! \} */
 224 /*! \endcond */
 225
 226 }      // namespace test
 227 }      // namespace gmx
 228
 229 #endif // GMX_SIMD