compiler-rt/test/nsan/fcmp.cpp

   1 // RUN: %clangxx_nsan -O2 -g %s -o %t
   2 // RUN: env NSAN_OPTIONS=check_cmp=true,halt_on_error=0 %run %t 2>&1 | FileCheck %s -check-prefix=CMP_ENABLE
   3 // RUN: env NSAN_OPTIONS=check_cmp=false,halt_on_error=0 %run %t 2>&1 | FileCheck %s -check-prefix=CMP_DISABLE
   4
   5 #include <cmath>
   6 #include <cstdio>
   7
   8 // 0.6/0.2 is slightly below 3, so the comparison will fail after a certain
   9 // threshold that depends on the precision of the computation.
  10 __attribute__((noinline))  // To check call stack reporting.
  11 bool DoCmp(double a, double b, double c, double threshold) {
  12   return c - a / b < threshold;
  13   // CMP_ENABLE: WARNING: NumericalStabilitySanitizer: floating-point comparison results depend on precision
  14   // CMP_ENABLE: double    {{ *}}precision dec (native): {{.*}}<{{.*}}
  15   // CMP_ENABLE: __float128{{ *}}precision dec (shadow): {{.*}}<{{.*}}
  16   // CMP_ENABLE: {{#0 .*in DoCmp}}
  17 }
  18
  19 int main() {
  20   double threshold = 1.0;
  21   for (int i = 0; i < 60; ++i) {
  22     threshold /= 2;
  23     // CMP_DISABLE: value at threshold {{.*}}
  24     printf("value at threshold %.20f: %i\n", threshold,
  25            DoCmp(0.6, 0.2, 3.0, threshold));
  26   }
  27   return 0;
  28 }