Re: Integer overflow checking

[Walter Bright via Digitalmars-d]

On 4/12/2016 5:06 AM, Andrei Alexandrescu wrote:

Interesting: http://blog.regehr.org/archives/1384 -- Andrei

Curiously never mentioned is the following optimization:

    return a+b*2+27;

becomes:

    LEA EAX,27[ESI][EDI*2]

To overflow check:

    ADD EDI,EDI
    JO overflow
    ADD EDI,27
    JO overflow
    MOV EAX,ESI
    ADD EAX,EDI
    JO overflow

I don't see efficiency there, even with the JO's being free.