go/test/fixedbugs/bug206.go

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// run
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import "go/ast";
func g(list []ast.Expr) {
n := len(list)-1;
go/ast: use token.Pos instead of token.Position; adjust all dependent code Specifically: * lib/godoc: - provide file set (FSet) argument to formatters where needed * src/cmd: - cgo, ebnflint, godoc, gofmt, goinstall: provide file set (fset) where needed - godoc: remove local binary search with sort.Search (change by rsc), extract file set for formatters * src/pkg: - exp/eval: remove embedded token.Position fields from nodes and replace with named token.Pos fields; add corresponding Pos() accessor methods - go/token: added file.Line(), changed signature of File.Position() * test/fixedbugs/: - bug206.go: change test to not rely on token.Pos details * added various extra comments * Runs all.bash * gofmt formats all of src, misc w/o changes * godoc runs * performance: - The new version of godoc consumes about the same space after indexing has completed, but indexing is half the speed. Significant space savings are expected from smaller ASTs, but since they are thrown away after a file has been indexed, this is not visible anymore. The slower indexing time is due to the much more expensive computation of line information. However, with the new compressed position information, indexing can be rewritten and simplified. Furthermore, computing the line info can be done more efficiently. New godoc, immediately after indexing completed (best of three runs): PID COMMAND %CPU TIME #TH #PRTS #MREGS RPRVT RSHRD RSIZE VSIZE 44381 godoc 0.0% 0:38.00 4 19 149 145M 184K 148M 176M 2010/12/03 17:58:35 index updated (39.231s, 18505 unique words, 386387 spots) 2010/12/03 17:58:35 bytes=90858456 footprint=199182584 2010/12/03 17:58:36 bytes=47858568 footprint=167295224 Old godoc, immediately after indexing completed (best of three runs): PID COMMAND %CPU TIME #TH #PRTS #MREGS RPRVT RSHRD RSIZE VSIZE 23167 godoc 0.0% 0:22.02 4 17 132 129M 184K 132M 173M 2010/12/03 14:51:32 index updated (24.892s, 18765 unique words, 393830 spots) 2010/12/03 14:51:32 bytes=66404528 footprint=163907832 2010/12/03 14:51:32 bytes=46282224 footprint=163907832 The different numbers for unique words/spots stem from the fact the the two workspaces are not exactly identical. The new godoc maintains a large file set data structure during indexing which (probably) is the reason for the larger heap (90858456 vs 66404528) before garbage collection. R=rsc, r CC=golang-dev https://golang.org/cl/3050041
2010-12-06 22:23:18 +00:00
println(list[n].Pos());
}
// f is the same as g except that the expression assigned to n is inlined.
func f(list []ast.Expr) {
// n := len(list)-1;
go/ast: use token.Pos instead of token.Position; adjust all dependent code Specifically: * lib/godoc: - provide file set (FSet) argument to formatters where needed * src/cmd: - cgo, ebnflint, godoc, gofmt, goinstall: provide file set (fset) where needed - godoc: remove local binary search with sort.Search (change by rsc), extract file set for formatters * src/pkg: - exp/eval: remove embedded token.Position fields from nodes and replace with named token.Pos fields; add corresponding Pos() accessor methods - go/token: added file.Line(), changed signature of File.Position() * test/fixedbugs/: - bug206.go: change test to not rely on token.Pos details * added various extra comments * Runs all.bash * gofmt formats all of src, misc w/o changes * godoc runs * performance: - The new version of godoc consumes about the same space after indexing has completed, but indexing is half the speed. Significant space savings are expected from smaller ASTs, but since they are thrown away after a file has been indexed, this is not visible anymore. The slower indexing time is due to the much more expensive computation of line information. However, with the new compressed position information, indexing can be rewritten and simplified. Furthermore, computing the line info can be done more efficiently. New godoc, immediately after indexing completed (best of three runs): PID COMMAND %CPU TIME #TH #PRTS #MREGS RPRVT RSHRD RSIZE VSIZE 44381 godoc 0.0% 0:38.00 4 19 149 145M 184K 148M 176M 2010/12/03 17:58:35 index updated (39.231s, 18505 unique words, 386387 spots) 2010/12/03 17:58:35 bytes=90858456 footprint=199182584 2010/12/03 17:58:36 bytes=47858568 footprint=167295224 Old godoc, immediately after indexing completed (best of three runs): PID COMMAND %CPU TIME #TH #PRTS #MREGS RPRVT RSHRD RSIZE VSIZE 23167 godoc 0.0% 0:22.02 4 17 132 129M 184K 132M 173M 2010/12/03 14:51:32 index updated (24.892s, 18765 unique words, 393830 spots) 2010/12/03 14:51:32 bytes=66404528 footprint=163907832 2010/12/03 14:51:32 bytes=46282224 footprint=163907832 The different numbers for unique words/spots stem from the fact the the two workspaces are not exactly identical. The new godoc maintains a large file set data structure during indexing which (probably) is the reason for the larger heap (90858456 vs 66404528) before garbage collection. R=rsc, r CC=golang-dev https://golang.org/cl/3050041
2010-12-06 22:23:18 +00:00
println(list[len(list)-1 /* n */].Pos());
}
func main() {
list := []ast.Expr{&ast.Ident{}};
g(list); // this works
f(list); // this doesn't
}
/*
0
throw: index out of range
panic PC=0x2bcf10
throw+0x33 /home/gri/go/src/pkg/runtime/runtime.c:71
throw(0x470f8, 0x0)
sys·throwindex+0x1c /home/gri/go/src/pkg/runtime/runtime.c:45
sys·throwindex()
main·f+0x26 /home/gri/go/test/bugs/bug206.go:16
main·f(0x2b9560, 0x0)
main·main+0xc3 /home/gri/go/test/bugs/bug206.go:23
main·main()
mainstart+0xf /home/gri/go/src/pkg/runtime/amd64/asm.s:55
mainstart()
goexit /home/gri/go/src/pkg/runtime/proc.c:133
goexit()
*/