mirror of https://github.com/golang/go.git
daca06f2e3
1. In functions with heap-allocated result variables or with defer statements, the return sequence requires more than just a single RET instruction. There is an optimization that arranges for all returns to jump to a single copy of the return epilogue in this case. Unfortunately, that optimization is fundamentally incompatible with PC-based liveness information: it takes PCs at many different points in the function and makes them all land at one PC, making the combined liveness information at that target PC a mess. Disable this optimization, so that each return site gets its own copy of the 'call deferreturn' and the copying of result variables back from the heap. This removes quite a few spurious 'ambiguously live' variables. 2. Let orderexpr allocate temporaries that are passed by address to a function call and then die on return, so that we can arrange an appropriate VARKILL. 2a. Do this for ... slices. 2b. Do this for closure structs. 2c. Do this for runtime.concatstring, which is the implementation of large string additions. Change representation of OADDSTR to an explicit list in typecheck to avoid reconstructing list in both walk and order. 3. Let orderexpr allocate the temporary variable copies used for range loops, so that they can be killed when the loop is over. Similarly, let it allocate the temporary holding the map iterator. CL 81940043 reduced the number of ambiguously live temps in the godoc binary from 860 to 711. This CL reduces the number to 121. Still more to do, but another good checkpoint. Update #7345 LGTM=khr R=khr CC=golang-codereviews https://golang.org/cl/83090046 |
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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-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.