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go / go / 8e24a98abe464161bc8937a84f78189684aa738d
commit8e24a98abe464161bc8937a84f78189684aa738d[log] [tgz]
authorKevin Burke <kev@inburke.com>Sat Aug 20 22:05:47 2016 -0700
committerJosh Bleecher Snyder <josharian@gmail.com>Tue Aug 23 17:30:55 2016 +0000
tree31f6de169f24e740268652a74e9fe99a62067233
parentd00890b5f3e7846a7b4ab084fe39d279f21aad04 [diff]
cmd/compile: precompute constant square roots

If a program wants to evaluate math.Sqrt for any constant value
(for example, math.Sqrt(3)), we can replace that expression with
its evaluation (1.7320508075688772) at compile time, instead of
generating a SQRT assembly command or equivalent.

Adds tests that math.Sqrt generates the correct values. I also
compiled a short program and verified that the Sqrt expression was
replaced by a constant value in the "after opt" step.

Adds a short doc to the top of generic.rules explaining what the file
does and how other files interact with it.

Fixes #15543.

Change-Id: I6b6e63ac61cec50763a09ba581024adeee03d4fa
Reviewed-on: https://go-review.googlesource.com/27457
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
5 files changed
tree: 31f6de169f24e740268652a74e9fe99a62067233
  1. .github/
  2. api/
  3. doc/
  4. lib/
  5. misc/
  6. src/
  7. test/
  8. .gitattributes
  9. .gitignore
  10. AUTHORS
  11. CONTRIBUTING.md
  12. CONTRIBUTORS
  13. favicon.ico
  14. LICENSE
  15. PATENTS
  16. README.md
  17. robots.txt
README.md

The Go Programming Language

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For example, if you extracted the tar file into $HOME/go, you might put the following in your .profile:

export GOROOT=$HOME/go
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See https://golang.org/doc/install or doc/install.html for more details.