Re: Fastest way to check for int32 overflows

[drkameleon]

Answering my own question:
    
    
    proc int32AddOverflow(a, b: int32, c: var int32): bool {.
        importc: "__builtin_sadd_overflow", nodecl, nosideeffect.}
    
    var rez: int32
    if int32AddOverflow(int32(2147483647),int32(1),rez):
        echo "overflows!"
    else:
        echo rez
    
    if int32AddOverflow(int32(2147483646),int32(1),rez):
        echo "overflows!"
    else:
        echo "did not overflow: ", rez
    
    
    Run

**Output:**
    
    
    overflows!
    did not overflow: 2147483647
    
    
    Run