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cmd/gc: allocate non-escaping maps on stack

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Extend escape analysis to make(map[k]v).
If it does not escape, allocate temp buffer for hmap and one bucket on stack.

There are 75 cases of non-escaping maps in std lib.

benchmark                                    old allocs     new allocs     delta
BenchmarkConcurrentStmtQuery                 16161          15161          -6.19%
BenchmarkConcurrentTxQuery                   17658          16658          -5.66%
BenchmarkConcurrentTxStmtQuery               16157          15156          -6.20%
BenchmarkConcurrentRandom                    13637          13114          -3.84%
BenchmarkManyConcurrentQueries               22             20             -9.09%
BenchmarkDecodeComplex128Slice               250            188            -24.80%
BenchmarkDecodeFloat64Slice                  250            188            -24.80%
BenchmarkDecodeInt32Slice                    250            188            -24.80%
BenchmarkDecodeStringSlice                   2250           2188           -2.76%
BenchmarkNewEmptyMap                         1              0              -100.00%
BenchmarkNewSmallMap                         2              0              -100.00%

benchmark                old ns/op     new ns/op     delta
BenchmarkNewEmptyMap     124           55.7          -55.08%
BenchmarkNewSmallMap     317           148           -53.31%

benchmark                old allocs     new allocs     delta
BenchmarkNewEmptyMap     1              0              -100.00%
BenchmarkNewSmallMap     2              0              -100.00%

benchmark                old bytes     new bytes     delta
BenchmarkNewEmptyMap     48            0             -100.00%
BenchmarkNewSmallMap     192           0             -100.00%

Fixes #5449

Change-Id: I24fa66f949d2f138885d9e66a0d160240dc9e8fa
Reviewed-on: https://go-review.googlesource.com/3508
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
This commit is contained in:
Dmitry Vyukov 2015-01-29 19:40:02 +03:00
parent aed88be021
commit b3be360f16
12 changed files with 178 additions and 168 deletions
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4
test/live.go
View file

@ -640,8 +640,8 @@ func bad40() {
func good40() {
ret := T40{}
ret.m = make(map[int]int) // ERROR "live at call to makemap: ret"
ret.m = make(map[int]int) // ERROR "live at call to makemap: autotmp_.* ret"
t := &ret
printnl() // ERROR "live at call to printnl: ret"
printnl() // ERROR "live at call to printnl: autotmp_.* ret"
_ = t
}