481ce36ec4
"x*41" computes the same value as "x*31 + x*7 + x*3" and (when compiled by gc) requires just one multiply instruction instead of three. Alternatively, the expression could be written as "(x<<2+x)<<3 + x" to use shifts instead of multiplies (which is how GCC optimizes "x*41"). But gc currently emits suboptimal instructions for this expression anyway (e.g., separate SHL+ADD instructions rather than LEA on 386/amd64). Also, if such an optimization was worthwhile, it would seem better to implement it as part of gc's strength reduction logic. Change-Id: I7156b793229d723bbc9a52aa9ed6111291335277 Reviewed-on: https://go-review.googlesource.com/1830 Reviewed-by: Minux Ma <minux@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> |
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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.
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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.