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lib/52214: llround can't handle big but legal values

>Number:         52214
>Category:       lib
>Synopsis:       llround can't handle big but legal values
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri May 05 23:45:00 +0000 2017
>Originator:     Hal Murray
>Release:        7.0.2
NetBSD 7.0.2 NetBSD 7.0.2 (GENERIC.201610210724Z) amd64

llround can't handle values like 0x10000000000000

That's the 53rd bit.

There are 53 bits of precision in a double, but a double
can hold integers (long long) up to 63 bits.
Needs -lm

I've been using:
  cc -O1 -Wall -Wstrict-prototypes -Wmissing-prototypes -g -o ll-bug ll-bug.c -lm

/* test case for llround */

#include <math.h>
#include <stdio.h>

int main(int argc, char *argv[])

  int i;

  for (i=40; i<62; i++) {
    long long op1 = 1LL<<i;
    double op2 = (double)(op1);
    long long int op3 = llround(op2);
    long long int op4 = (long long)op2;
    printf("%16llx %16llx %16llx\n", op1, op3, op4);

  return 0;


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