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Keith Randall 38dee12dea cmd/compile: zero ambiguously live variables at VARKILLs
At VARKILLs, zero a variable if it is ambiguously live.
After the VARKILL anything this variable references
might be collected. If it were to become live again later,
the GC will see references to already-collected objects.

We don't know a variable is ambiguously live until very
late in compilation (after lowering, register allocation, ...),
so it is hard to generate the code in an arch-independent way.
We also have to be careful not to clobber any registers.
Fortunately, this almost never happens so performance is ~irrelevant.

There are only 2 instances where this triggers in the stdlib.

Fixes #20029

Change-Id: Ia9585a91d7b823fad4a9d141d954464cc7af31f4
Reviewed-on: https://go-review.googlesource.com/41076
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2017-04-20 23:47:43 +00:00
.github doc: improve issue template and contribution guidelines 2017-02-11 20:42:06 +00:00
api math/big: define Word as uint instead of uintptr 2017-02-21 19:31:40 +00:00
doc doc: escape some HTML in Effective Go code examples 2017-04-20 16:29:19 +00:00
lib/time *.bash: always use the same string equality operator 2017-03-14 21:46:31 +00:00
misc cmd/cgo: reject references to builtin functions other than calls 2017-04-18 22:14:43 +00:00
src cmd/compile: zero ambiguously live variables at VARKILLs 2017-04-20 23:47:43 +00:00
test cmd/compile: zero ambiguously live variables at VARKILLs 2017-04-20 23:47:43 +00:00
.gitattributes .gitattributes: prevent all magic line ending changes 2014-12-12 23:14:54 +00:00
.gitignore .gitignore: change path to zbootstrap.go 2017-04-19 02:13:58 +00:00
AUTHORS A+C: automated update 2016-12-21 03:22:22 +00:00
CONTRIBUTING.md doc: improve issue template and contribution guidelines 2017-02-11 20:42:06 +00:00
CONTRIBUTORS A+C: automated update 2016-12-21 03:22:22 +00:00
LICENSE doc: revert copyright date to 2009 2016-06-01 22:40:04 +00:00
PATENTS
README.md readme: add attribution for the Gopher image 2017-02-03 19:39:41 +00:00
favicon.ico website: recreate 16px and 32px favicon 2016-08-25 15:43:32 +00:00
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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.

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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://golang.org/dl/.

After downloading a binary release, visit https://golang.org/doc/install or load doc/install.html in your web browser for installation instructions.

Install From Source

If a binary distribution is not available for your combination of operating system and architecture, visit https://golang.org/doc/install/source or load doc/install-source.html in your web browser for source installation instructions.

Contributing

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 the Go project does not use GitHub pull requests, and that we use the issue tracker for bug reports and proposals only. See https://golang.org/wiki/Questions for a list of places to ask questions about the Go language.