code review 121000045: runtime: fix 32 bit build.

runtime: fix 32 bit build.

int(maxMem) is negative on 32 bits.  Need to use
unsigned arithmetic.

[khr, 2014-07-31 20:07:14]

Hello bradfitz (cc: golang-codereviews@googlegroups.com),

I'd like you to review this change to
https://khr%40golang.org@code.google.com/p/go/

[khr, 2014-07-31 20:07:29]

*** Submitted as https://code.google.com/p/go/source/detail?r=b55df4e0da18 ***

runtime: fix 32 bit build.

int(maxMem) is negative on 32 bits.  Need to use
unsigned arithmetic.

TBR=bradfitz
CC=golang-codereviews
https://codereview.appspot.com/121000045

[bradfitz, 2014-07-31 20:18:04]

LGTM
 On Jul 31, 2014 1:07 PM, <khr@golang.org> wrote:

> Reviewers: bradfitz,
>
> Message:
> Hello bradfitz (cc: golang-codereviews@googlegroups.com),
>
> I'd like you to review this change to
> https://khr%40golang.org@code.google.com/p/go/
>
>
> Description:
> runtime: fix 32 bit build.
>
> int(maxMem) is negative on 32 bits.  Need to use
> unsigned arithmetic.
>
> Please review this at https://codereview.appspot.com/121000045/
>
> Affected files (+4, -4 lines):
>   M src/pkg/runtime/slice.go
>
>
> Index: src/pkg/runtime/slice.go
> ===================================================================
> --- a/src/pkg/runtime/slice.go
> +++ b/src/pkg/runtime/slice.go
> @@ -22,11 +22,11 @@
>         // but since the cap is only being supplied implicitly, saying len
> is clearer.
>         // See issue 4085.
>         len := int(len64)
> -       if len64 < 0 || int64(len) != len64 || t.elem.size > 0 && len >
> int(maxMem/uintptr(t.elem.size)) {
> +       if len64 < 0 || int64(len) != len64 || t.elem.size > 0 &&
> uintptr(len) > maxMem/uintptr(t.elem.size) {
>                 panic(errorString("makeslice: len out of range"))
>         }
>         cap := int(cap64)
> -       if cap < len || int64(cap) != cap64 || t.elem.size > 0 && cap >
> int(maxMem/uintptr(t.elem.size)) {
> +       if cap < len || int64(cap) != cap64 || t.elem.size > 0 &&
> uintptr(cap) > maxMem/uintptr(t.elem.size) {
>                 panic(errorString("makeslice: cap out of range"))
>         }
>         p := newarray(t.elem, uintptr(cap))
> @@ -42,7 +42,7 @@
>         cap64 := int64(old.cap) + n
>         cap := int(cap64)
>
> -       if int64(cap) != cap64 || cap < old.cap || t.elem.size > 0 && cap
> > int(maxMem/uintptr(t.elem.size)) {
> +       if int64(cap) != cap64 || cap < old.cap || t.elem.size > 0 &&
> uintptr(cap) > maxMem/uintptr(t.elem.size) {
>                 panic(errorString("growslice: cap out of range"))
>         }
>
> @@ -74,7 +74,7 @@
>                 }
>         }
>
> -       if newcap >= int(maxMem/uintptr(et.size)) {
> +       if uintptr(newcap) >= maxMem/uintptr(et.size) {
>                 panic(errorString("growslice: cap out of range"))
>         }
>         lenmem := uintptr(old.len) * uintptr(et.size)
>
>
>