Proposal Details

We propose adding a new directive to skip bound checks in the compile toolchain. The new directive will allow the unnecessary bound check to be eliminated if the flag AllowBCSkip is turned on. The current bound check elimination passes (BCE and CSE) are relatively simple and leave many redundant bound checks unremoved. Such unnecessary checks bring extra performance overhead. Improving compiler optimization pass is another solution but it can be time consuming and requires sophisticated analysis. This proposal aims for a straightforward optimization if users know the bound check is always unnecessary but unremoved.

Specifically,
-allowbcskip flag from the command line during compilation will enable this new feature.
//go:noboundcheck directive at the function level will allow the bound check to be skipped for the specific function if the check is always redundant. It works similarly as go:noinline directive.
boundsCheck within ssagen will check the new flag and directive to optionally skipping bound check code generation.

Grit link: https://go-review.googlesource.com/c/go/+/571539. Filing a new issue to make it clearer what we are proposing.
Thanks.

cc
@jinlin-bayarea