442de98c14
To compile: m[k] = v instead of: mapassign(maptype, m, &k, &v), do do: *mapassign(maptype, m, &k) = v mapassign returns a pointer to the value slot in the map. It is just like mapaccess except that it will allocate a new slot if k is not already present in the map. This makes map accesses faster but potentially larger (codewise). It is faster because the write into the map is done when the compiler knows the concrete type, so it can be done with a few store instructions instead of calling typedmemmove. We also potentially avoid stack temporaries to hold v. The code can be larger when the map has pointers in its value type, since there is a write barrier call in addition to the mapassign call. That makes the code at the callsite a bit bigger (go binary is 0.3% bigger). This CL is in preparation for doing operations like m[k] += v with only a single runtime call. That will roughly double the speed of such operations. Update #17133 Update #5147 Change-Id: Ia435f032090a2ed905dac9234e693972fe8c2dc5 Reviewed-on: https://go-review.googlesource.com/30815 Run-TryBot: Keith Randall <khr@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> |
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README.md
The Go Programming Language
Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.
For documentation about how to install and use Go, visit https://golang.org/ or load doc/install-source.html in your web browser.
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.
Go is the work of hundreds of contributors. We appreciate your help!
To contribute, please read the contribution guidelines: https://golang.org/doc/contribute.html
Note that we do not accept pull requests and that we use the issue tracker for bug reports and proposals only. Please ask questions on https://forum.golangbridge.org or https://groups.google.com/forum/#!forum/golang-nuts.
Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.
--
Binary Distribution Notes
If you have just untarred a binary Go distribution, you need to set the environment variable $GOROOT to the full path of the go directory (the one containing this file). You can omit the variable if you unpack it into /usr/local/go, or if you rebuild from sources by running all.bash (see doc/install-source.html). You should also add the Go binary directory $GOROOT/bin to your shell's path.
For example, if you extracted the tar file into $HOME/go, you might put the following in your .profile:
export GOROOT=$HOME/go
export PATH=$PATH:$GOROOT/bin
See https://golang.org/doc/install or doc/install.html for more details.