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| author | Josh Bleecher Snyder <josharian@gmail.com> | 2018-04-12 07:42:20 -0700 |
|---|---|---|
| committer | Josh Bleecher Snyder <josharian@gmail.com> | 2018-04-13 19:52:07 +0000 |
| commit | e511f153752ab1f17b2862aa47bb149c0ed79990 (patch) | |
| tree | 46af674ecdbf3349447563006bab705eda0039a4 /src/debug | |
| parent | c0547476f342665514904cf2581a62135d2366c3 (diff) | |
| download | go-e511f153752ab1f17b2862aa47bb149c0ed79990.tar.xz | |
debug/gosym: intern LineTable strings
This cuts the allocated space while executing
go tool objdump -S `go tool -n compile`
by over 10%.
It also speeds it up slightly:
name old time/op new time/op delta
ObjdumpSCompiler 9.03s ± 1% 8.88s ± 1% -1.59% (p=0.000 n=20+20)
Updates #24725
Change-Id: Ic6ef8e273ede589334ab6e07099ac2e5bdf990c9
Reviewed-on: https://go-review.googlesource.com/106798
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Diffstat (limited to 'src/debug')
| -rw-r--r-- | src/debug/gosym/pclntab.go | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/src/debug/gosym/pclntab.go b/src/debug/gosym/pclntab.go index ba1cf8b699..ad99b4dc5a 100644 --- a/src/debug/gosym/pclntab.go +++ b/src/debug/gosym/pclntab.go @@ -9,6 +9,7 @@ package gosym import ( + "bytes" "encoding/binary" "sync" ) @@ -42,6 +43,7 @@ type LineTable struct { filetab []byte nfiletab uint32 fileMap map[string]uint32 + strings map[uint32]string // interned substrings of Data, keyed by offset } // NOTE(rsc): This is wrong for GOARCH=arm, which uses a quantum of 4, @@ -120,7 +122,7 @@ func (t *LineTable) LineToPC(line int, maxpc uint64) uint64 { // Text must be the start address of the // corresponding text segment. func NewLineTable(data []byte, text uint64) *LineTable { - return &LineTable{Data: data, PC: text, Line: 0} + return &LineTable{Data: data, PC: text, Line: 0, strings: make(map[uint32]string)} } // Go 1.2 symbol table format. @@ -266,11 +268,13 @@ func (t *LineTable) readvarint(pp *[]byte) uint32 { // string returns a Go string found at off. func (t *LineTable) string(off uint32) string { - for i := off; ; i++ { - if t.Data[i] == 0 { - return string(t.Data[off:i]) - } + if s, ok := t.strings[off]; ok { + return s } + i := bytes.IndexByte(t.Data[off:], 0) + s := string(t.Data[off : off+uint32(i)]) + t.strings[off] = s + return s } // step advances to the next pc, value pair in the encoded table. |