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  1. 29 May, 2012 3 commits
    • Russ Cox's avatar
      cmd/6g, cmd/8g: move panicindex calls out of line · fefae6ee
      Russ Cox authored 
      The old code generated for a bounds check was
                CMP
                JLT ok
                CALL panicindex
        ok:
                ...

The new code is (once the linker finishes with it):
                CMP
                JGE panic
                ...
        panic:
                CALL panicindex

which moves the calls out of line, putting more useful
code in each cache line.  This matters especially in tight
loops, such as in Fannkuch.  The benefit is more modest
elsewhere, but real.

From test/bench/go1, amd64:

benchmark                old ns/op    new ns/op    delta
BenchmarkBinaryTree17   6096092000   6088808000   -0.12%
BenchmarkFannkuch11     6151404000   4020463000  -34.64%
BenchmarkGobDecode        28990050     28894630   -0.33%
BenchmarkGobEncode        12406310     12136730   -2.17%
BenchmarkGzip               179923       179903   -0.01%
BenchmarkGunzip              11219        11130   -0.79%
BenchmarkJSONEncode       86429350     86515900   +0.10%
BenchmarkJSONDecode      334593800    315728400   -5.64%
BenchmarkRevcomp25M     1219763000   1180767000   -3.20%
BenchmarkTemplate        492947600    483646800   -1.89%

And 386:

benchmark                old ns/op    new ns/op    delta
BenchmarkBinaryTree17   6354902000   6243000000   -1.76%
BenchmarkFannkuch11     8043769000   7326965000   -8.91%
BenchmarkGobDecode        19010800     18941230   -0.37%
BenchmarkGobEncode        14077500     13792460   -2.02%
BenchmarkGzip               194087       193619   -0.24%
BenchmarkGunzip              12495        12457   -0.30%
BenchmarkJSONEncode      125636400    125451400   -0.15%
BenchmarkJSONDecode      696648600    685032800   -1.67%
BenchmarkRevcomp25M     2058088000   2052545000   -0.27%
BenchmarkTemplate        602140000    589876800   -2.04%

To implement this, two new instruction forms:

        JLT target      // same as always
        JLT $0, target  // branch expected not taken
        JLT $1, target  // branch expected taken

The linker could also emit the prediction prefixes, but it
does not: expected taken branches are reversed so that the
expected case is not taken (as in example above), and
the default expectaton for such a jump is not taken
already.

R=golang-dev, gri, r, dave
CC=golang-dev
https://golang.org/cl/6248049
      fefae6ee
    • Sameer Ajmani's avatar
      A+C: Peter Kleiweg (individual CLA) · b9918dbf
      Sameer Ajmani authored 
      R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6260049
      b9918dbf
    • Andrew Balholm's avatar
      exp/html: implement Noah's Ark clause · 9c14184e
      Andrew Balholm authored 
      Implement the (3-per-family) Noah's Ark clause (i.e. don't put
more than three identical elements on the list of active formatting
elements.

Also, when running tests, sort attributes by name before dumping
them.

Pass 4 additional tests with Noah's Ark clause (including one
that needs attributes to be sorted).

Pass 5 additional, unrelated tests because of sorting attributes.

R=nigeltao, rsc
CC=golang-dev
https://golang.org/cl/6247056
      9c14184e
  3. 28 May, 2012 7 commits
  5. 27 May, 2012 1 commit
  7. 26 May, 2012 1 commit
  9. 25 May, 2012 6 commits
  11. 24 May, 2012 22 commits
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