mirror of https://github.com/golang/go.git
7e97d39879
Deferred functions are not run by a call instruction. They are run by
the runtime editing registers to make the call start with a caller PC
returning to a
CALL deferreturn
instruction.
That instruction has always had the line number of the function's
closing brace, but that instruction's line number is irrelevant.
Stack traces show the line number of the instruction before the
return PC, because normally that's what started the call. Not so here.
The instruction before the CALL deferreturn could be almost anywhere
in the function; it's unrelated and its line number is incorrect to show.
Fix the line number by inserting a true hardware no-op with the right
line number before the returned-to CALL instruction. That is, the deferred
calls now appear to start with a caller PC returning to the second instruction
in this sequence:
NOP
CALL deferreturn
The traceback will show the line number of the NOP, which we've set
to be the line number of the function's closing brace.
The NOP here is not the usual pseudo-instruction, which would be
elided by the linker. Instead it is the real hardware instruction:
XCHG AX, AX on 386 and amd64, and AND.EQ R0, R0, R0 on ARM.
Fixes #5856.
R=ken2, ken
CC=golang-dev
https://golang.org/cl/11223043
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README
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.html in your web browser.
After installing Go, you can view a nicely formatted
doc/install.html by running godoc --http=:6060
and then visiting http://localhost:6060/doc/install.html.
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.