• Matthew Dempsky's avatar
    cmd/compile: cache pointer and slice types · 78a267e3
    Matthew Dempsky authored
    Anonymous pointer and slice types are very common and identical
    anyway, so just reuse them rather than allocating new ones everywhere
    they appear.
    
    Turns out to be a small code/stack size win because SSA relies on
    gc.Type identity for reusing temporary stack slots:
    
       text	   data	    bss	    dec	    hex	filename
    6453005	 231643	 146328	6830976	 683b80	go.old
    6446660	 231643	 146328	6824631	 6822b7	go.new
    
    Saves on memory usage during compile time too, and maybe a small CPU
    time win, but the benchmarks are pretty noisy:
    
    name       old time/op     new time/op     delta
    Template       342ms ± 8%      339ms ± 9%    ~           (p=0.332 n=99+99)
    Unicode        183ms ± 9%      181ms ±11%    ~           (p=0.274 n=95+98)
    GoTypes        1.05s ± 4%      1.04s ± 3%  -1.22%        (p=0.000 n=97+95)
    Compiler       4.49s ± 7%      4.46s ± 6%    ~           (p=0.058 n=96+91)
    
    name       old user-ns/op  new user-ns/op  delta
    Template        520M ±17%       522M ±20%    ~          (p=0.544 n=98+100)
    Unicode         331M ±27%       327M ±30%    ~           (p=0.615 n=98+98)
    GoTypes        1.54G ±10%      1.53G ±12%    ~          (p=0.173 n=99+100)
    Compiler       6.33G ±10%      6.33G ±10%    ~           (p=0.682 n=98+98)
    
    name       old alloc/op    new alloc/op    delta
    Template      44.5MB ± 0%     44.1MB ± 0%  -0.80%        (p=0.000 n=97+99)
    Unicode       37.5MB ± 0%     37.3MB ± 0%  -0.44%       (p=0.000 n=98+100)
    GoTypes        126MB ± 0%      124MB ± 0%  -1.41%        (p=0.000 n=98+99)
    Compiler       518MB ± 0%      508MB ± 0%  -1.90%       (p=0.000 n=98+100)
    
    name       old allocs/op   new allocs/op   delta
    Template        441k ± 0%       434k ± 0%  -1.76%       (p=0.000 n=100+97)
    Unicode         368k ± 0%       365k ± 0%  -0.69%        (p=0.000 n=99+99)
    GoTypes        1.26M ± 0%      1.23M ± 0%  -2.27%       (p=0.000 n=100+99)
    Compiler       4.60M ± 0%      4.46M ± 0%  -2.96%       (p=0.000 n=100+99)
    
    Change-Id: I94abce5c57aed0f9c48f567b3ac24c627d4c7c91
    Reviewed-on: https://go-review.googlesource.com/30632
    Run-TryBot: Matthew Dempsky <mdempsky@google.com>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    Reviewed-by: 's avatarBrad Fitzpatrick <bradfitz@golang.org>
    78a267e3
sizeof_test.go 1.17 KB