3ebc191975
Currently, a method Value (aquired from e.g. Value.Method(i)) is represented with its receiver and the index of the method, with a special flag, instead of a regular func Value (as a method value is a function). When the func value is needed (e.g. with Value.Interface), it is lazily converted to the func Value representation. The lazy conversion has a bad escape behavior: it flows the Value to the a heap-allocated methodValue structure, which causes the Value to escape. This in turn causes operations like Value.Interface or Value.Convert escape its receiver to heap, as they have a code path to handle the lazy conversion of method Value, even if this code path is not taken. To avoid the unnecessary escape, this CL changes the method Value representation to eagerly creating the func Value. This eliminates the code path with bad escape behavior in operations like Value.Interface. The lazy representation does have an advantage: Call on the method Value is simple, as the method's code expects the receiver as the first parameter, instead of a closure with the receiver pre-bound. Keeping the receiver and the method index in the Value allows Call to find the code pointer and pass the receiver directly. With the func Value representation, Call has to unmarshal and re-marshal the arguments in order to shift them by one. To avoid this problem, we save the receiver and the method index in the closure structure (i.e. methodValue structure), and set a special flag, so Call on such a Value can still take the fast path, instead of going through the closure. Benchmark result shows that Call on such a Value is as fast as before, but creating the method Value is slower as it involes an allocation. Creating a method Value and then doing operations like Interface/Convert/Set is mostly unchanged, as it just moves a lazy operation earlier. Change-Id: I70beab0b816c8b0587a1b414e804ec3061c39e43 Reviewed-on: https://go-review.googlesource.com/c/go/+/799760 LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: David Chase <drchase@google.com>
The Go Programming Language
Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.
Gopher image by Renee French, licensed under Creative Commons 4.0 Attribution license.
Our canonical Git repository is located at https://go.googlesource.com/go. There is a mirror of the repository at https://github.com/golang/go.
Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.
Download and Install
Binary Distributions
Official binary distributions are available at https://go.dev/dl/.
After downloading a binary release, visit https://go.dev/doc/install for installation instructions.
Install From Source
If a binary distribution is not available for your combination of operating system and architecture, visit https://go.dev/doc/install/source for source installation instructions.
Contributing
Go is the work of thousands of contributors. We appreciate your help!
To contribute, please read the contribution guidelines at https://go.dev/doc/contribute.
Note that the Go project uses the issue tracker for bug reports and proposals only. See https://go.dev/wiki/Questions for a list of places to ask questions about the Go language.