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digitalmars.D.bugs - [Issue 21325] New: Wrong code with -release -inline -O


          Issue ID: 21325
           Summary: Wrong code with -release -inline -O
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: critical
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: thomas.bockman gmail.com

The program below should return 0. On Linux x86_64 it works properly with LDC
or GDC, and even with DMD in debug mode. But, it fails and returns 1 with DMD
-release -inline -O.

(This was reduced from a multi-thousand line program.)
module app;

real f(const real x) pure  safe nothrow  nogc {
    return (x != 0.0L)? x : real.nan; }

int main()  safe {
    ulong x = 0uL;
    while(true) {
        const y = f(x); // should set y to real.nan

        if(y == y)
            return 1; // bad

            return 0; // good

Oct 18 2020