[Issue 5943] New: Power expression optimisation: 2^^unsigned ==> 1<<unsigned

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=5943

           Summary: Power expression optimisation: 2^^unsigned ==>
                    1<<unsigned
           Product: D
           Version: D2
          Platform: All
        OS/Version: Windows
            Status: NEW
          Keywords: performance
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: bearophile_hugs at eml.cc


--- Comment #0 from bearophile_hugs at eml.cc 2011-05-07 05:27:50 PDT ---
Related to bug 5812
I think it's good to have an optimization of 2^^x ==> 1<<x when x is an
unsigned integral or where the compiler can infer x to be a not negative
integral:


import std.math; // currently std.math is needed here
int main(string[] args) {
    return 2 ^^ args.length;
}


Currently it generates:

__Dmain    comdat
L0:        push    EAX
        push    2
        mov    EAX,0Ch[ESP]
        call    near ptr _D3std4math12__T3powTiTkZ3powFNaNbNeikZk
        pop    ECX
        ret

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