[llvm-bugs] [Bug 24585] New: Constant folding disagrees with GCC and FPU on result of 0./0.

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=24585

            Bug ID: 24585
           Summary: Constant folding disagrees with GCC and FPU on result
                    of 0./0.
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Global Analyses
          Assignee: unassignedbugs at nondot.org
          Reporter: schaub.johannes at googlemail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

The following testcase outputs "1 -1" instead of the same value two times

   #include <iostream>
   #include <math.h>

   int main() { 
     double zero = 0.0;
     volatile double zerov = 0.0;
     std::cout << copysign(1., zero/zero) << " " << copysign(1., zerov/zerov); 
   }

GCC outputs "-1 -1" (it has the sign bit set to 1).

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