https://go-review.googlesource.com/#/c/19515/

Improved some sqrt testcases by 10X or more.

Further improvement if this was inlined so that the load of the argument and store of the return value could be avoided.

CL https://golang.org/cl/19515 mentions this issue.

There is an easy to miss hack in cmd/compile/internal/gc/walk.go which inlines the square root function on platforms where it is a single instruction:

if n.Left.Op == ONAME && n.Left.Sym.Name == "Sqrt" && n.Left.Sym.Pkg.Path == "math" {
    switch Thearch.Thechar {
        case '5', '6', '7':
            n.Op = OSQRT
            n.Left = n.List.N
            n.List = nil
            break opswitch
        }
}

It sounds like '9' should be added to the case statement.

Thanks! I'll try it out.

On 02/19/2016 10:04 AM, Michael Munday wrote:

There is an easy to miss hack in cmd/compile/internal/gc/walk.go which
inlines the square root function on platforms where it is a single
instruction:

if n.Left.Op ==ONAME && n.Left.Sym.Name =="Sqrt" && n.Left.Sym.Pkg.Path =="math" {
switch Thearch.Thechar {
case '5','6','7':
n.Op = OSQRT
n.Left = n.List.N
n.List =nil
break opswitch
}
}

It sounds like |'9'| should be added to the case statement.

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#14349 (comment).

I had to change a few files to get the inlining to work for sqrt but I think it is right now. Are these additional files something I can add to my original CL or should I create a new one?

Add to your existing CL.