[LLVMdev] [MSan] false positive from Memory Sanitizer?

[Greg Fitzgerald]

In the example below, the Memory Sanitizier (from clang 3.3) reports an error:

#include <math.h>

int main() {
  double x;
  (void) modf(0, &x);
  if (x) {             // Boom
    return 1;
  }
  return 0;
}

I see that modf() is not implemented by compiler-rt.  Is it possible
to make the Memory Sanitizer assume that all un-instrumented functions
initialize any pointers arguments?

Thanks,
Greg