code review 12311046: gc: get rid of redundant slice bound check.

cmd/gc: get rid of redundant slice bound check.

For normal slices a[i:j] we're generating 3 bounds
checks: j<={len(string),cap(slice)}, j<=j (!), and i<=j.
Somehow snuck in as part of the [i:j:k] implementation
where the second check does something.
Remove the second check when we don't need it.

[khr, 2013-08-05 05:50:17]

Hello rsc@golang.org (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go/

[r, 2013-08-05 05:55:33]

LGTM but in CL s/snunk/snuck/, much as I like the coinage.

[rsc, 2013-08-05 18:28:33]

LGTM

[rsc, 2013-08-05 18:28:44]

Change description to say "cmd/gc" not "gc"

[khr, 2013-08-05 20:24:36]

*** Submitted as https://code.google.com/p/go/source/detail?r=0aee4b3eb910 ***

cmd/gc: get rid of redundant slice bound check.

For normal slices a[i:j] we're generating 3 bounds
checks: j<={len(string),cap(slice)}, j<=j (!), and i<=j.
Somehow snuck in as part of the [i:j:k] implementation
where the second check does something.
Remove the second check when we don't need it.

R=rsc, r
CC=golang-dev
https://codereview.appspot.com/12311046

[khr, 2013-09-10 16:08:05]

*** Abandoned ***