[OpenMP][Offloading] Change the way to compare floating point values in bug49334.cpp

[tianshilei1992]

Summary

bug49334.cpp directly uses != to compare two floating point values,
which is almost wrong.

[jhuber6]

LG

openmp/libomptarget/test/offloading/bug49334.cpp

 // RUN: %libomptarget-compilexx-run-and-check-generic
 
 // Currently hangs on amdgpu
 // UNSUPPORTED: amdgcn-amd-amdhsa
 // UNSUPPORTED: x86_64-pc-linux-gnu
 
 #include <cassert>
+#include <cmath>
 #include <iostream>
+#include <limits>
 #include <memory>
 #include <vector>
 
 class BlockMatrix {
 private:
   const int rowsPerBlock;
   const int colsPerBlock;
   const long nRows;
for (int i = 0; i < nBlocksPerCol; i++)
       for (int j = 0; j < nBlocksPerRow; j++) {
         float *CurrBlock = GetBlock(i, j);
         for (int ii = 0; ii < colsPerBlock; ++ii)
           for (int jj = 0; jj < rowsPerBlock; ++jj) {
             int curri = i * colsPerBlock + ii;
             int currj = j * rowsPerBlock + jj;
             float m_value = matrix[curri + currj * nCols];
             float bm_value = CurrBlock[ii + jj * colsPerBlock];
-            if (bm_value != m_value) {
+            if (std::fabs(bm_value - m_value) >
+                std::numeric_limits<float>::epsilon()) {
               fail++;
             }
           }
       }
     return fail;
   }
 
   float *GetBlock(int i, int j) const {