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Russ Cox 5a23a7e52c runtime: enable 'bad pointer' check during garbage collection of Go stack frames
This is the same check we use during stack copying.
The check cannot be applied to C stack frames, even
though we do emit pointer bitmaps for the arguments,
because (1) the pointer bitmaps assume all arguments
are always live, not true of outputs during the prologue,
and (2) the pointer bitmaps encode interface values as
pointer pairs, not true of interfaces holding integers.

For the rest of the frames, however, we should hold ourselves
to the rule that a pointer marked live really is initialized.
The interface scanning already implicitly checks this
because it interprets the type word  as a valid type pointer.

This may slow things down a little because of the extra loads.
Or it may speed things up because we don't bother enqueuing
nil pointers anymore. Enough of the rest of the system is slow
right now that we can't measure it meaningfully.
Enable for now, even if it is slow, to shake out bugs in the
liveness bitmaps, and then decide whether to turn it off
for the Go 1.3 release (issue 7650 reminds us to do this).

The new m->traceback field lets us force printing of fp=
values on all goroutine stack traces when we detect a
bad pointer. This makes it easier to understand exactly
where in the frame the bad pointer is, so that we can trace
it back to a specific variable and determine what is wrong.

Update #7650

LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/80860044
2014-03-27 14:06:15 -04:00
api api: update next.txt 2014-03-06 01:44:04 -05:00
doc doc/go1.3.html: explain the change to the memory model 2014-03-27 11:45:51 +11:00
include cmd/ld: clear unused ctxt before morestack 2014-03-04 13:53:08 -05:00
lib codereview: remove unused upload_options.revision 2014-02-24 10:11:37 -05:00
misc misc/bash, misc/zsh: fix completion rules 2014-03-27 00:29:55 -04:00
src runtime: enable 'bad pointer' check during garbage collection of Go stack frames 2014-03-27 14:06:15 -04:00
test cmd/gc: liveness-related bug fixes 2014-03-27 14:05:57 -04:00
.hgignore lib9: enable on Plan 9 2014-02-13 20:06:41 +01:00
.hgtags tag go1.2.1 2014-03-03 13:22:13 +11:00
AUTHORS A+C: Erik Westrup (individual CLA) 2014-03-26 15:23:05 -07:00
CONTRIBUTORS A+C: Erik Westrup (individual CLA) 2014-03-26 15:23:05 -07:00
favicon.ico godoc: update favicon 2012-10-11 17:02:36 +11:00
LICENSE doc: update licensing text one more time 2012-03-27 15:09:13 +11:00
PATENTS
README README: Fix installation instructions 2013-11-20 13:47:37 -08:00
robots.txt godoc: serve robots.txt raw 2011-02-19 05:46:20 +11:00

This is the source code repository for the Go programming language.  

For documentation about how to install and use Go,
visit http://golang.org/ or load doc/install-source.html
in your web browser.

After installing Go, you can view a nicely formatted
doc/install-source.html by running godoc --http=:6060
and then visiting http://localhost:6060/doc/install/source.

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 README).  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.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 doc/install.html for more details.