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7538b1db8e
builtin.go was auto-generated via go generate; all other changes were manual. The new format reduces the export data size by ~65% on average for the std library packages (and there is still quite a bit of room for improvement). The average time to write export data is reduced by (at least) 62% as measured in one run over the std lib, it is likely more. The average time to read import data is reduced by (at least) 37% as measured in one run over the std lib, it is likely more. There is also room to improve this time. The compiler transparently handles both packages using the old and the new format. Comparing the -S output of the go build for each package via the cmp.bash script (added) shows identical assembly code for all packages, but 6 files show file:line differences: The following files have differences because they use cgo and cgo uses different temp. directories for different builds. Harmless. src/crypto/x509 src/net src/os/user src/runtime/cgo The following files have file:line differences that are not yet fully explained; however the differences exist w/ and w/o new export format (pre-existing condition). See issue #15453. src/go/internal/gccgoimporter src/go/internal/gcimporter In summary, switching to the new export format produces the same package files as before for all practical purposes. How can you tell which one you have (if you care): Open a package (.a) file in an editor. Textual export data starts with a $$ after the header and is more or less legible; binary export data starts with a $$B after the header and is mostly unreadable. A stand-alone decoder (for debugging) is in the works. In case of a problem, please first try reverting back to the old textual format to determine if the cause is the new export format: For a stand-alone compiler invocation: - go tool compile -newexport=0 <files> For a single package: - go build -gcflags="-newexport=0" <pkg> For make/all.bash: - (export GO_GCFLAGS="-newexport=0"; sh make.bash) Fixes #13241. Change-Id: I2588cb463be80af22446bf80c225e92ab79878b8 Reviewed-on: https://go-review.googlesource.com/22123 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Robert Griesemer <gri@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
62 lines
1.5 KiB
Bash
62 lines
1.5 KiB
Bash
#!/usr/bin/env bash
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# Copyright 2016 The Go Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style
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# license that can be found in the LICENSE file.
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# A simple script to compare differences between
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# assembly listings for packages built with different
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# compiler flags. It is useful to inspect the impact
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# of a compiler change across all std lib packages.
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#
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# The script builds the std library (make.bash) once
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# with FLAGS1 and once with FLAGS2 and compares the
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# "go build <pkg>" assembly output for each package
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# and lists the packages with differences.
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#
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# It leaves and old.txt and new.txt file in the package
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# directories for the packages with differences.
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FLAGS1="-newexport=0"
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FLAGS2="-newexport=1"
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echo
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echo
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echo "1a) clean build using $FLAGS1"
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(export GO_GCFLAGS="$FLAGS1"; sh make.bash)
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echo
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echo
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echo "1b) save go build output for all packages"
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for pkg in `go list std`; do
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echo $pkg
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DIR=$GOROOT/src/$pkg
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go build -gcflags "$FLAGS1 -S" -o /dev/null $pkg &> $DIR/old.txt
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done
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echo
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echo
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echo "2a) clean build using $FLAGS2"
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(export GO_GCFLAGS="$FLAGS2"; sh make.bash)
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echo
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echo
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echo "2b) save go build output for all packages"
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for pkg in `go list std`; do
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echo $pkg
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DIR=$GOROOT/src/$pkg
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go build -gcflags "$FLAGS2 -S" -o /dev/null $pkg &> $DIR/new.txt
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done
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echo
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echo
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echo "3) compare assembly files"
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for pkg in `go list std`; do
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DIR=$GOROOT/src/$pkg
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if cmp $DIR/old.txt $DIR/new.txt &> /dev/null
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then rm $DIR/old.txt $DIR/new.txt
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else echo "==> $DIR"
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fi
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done
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