cmd/compile: optimize ARM with MULS

cmd/compile: optimize ARM with MULS

MULS was introduced in ARMv7 and corresponding to MULA. This patch
duplicated all MULA related SSA rules with MULS.

Here was the contrast test result against the original go compiler.
There was no improvement in total, but big improvement in special cases.

1. A specific test case accelerated 18.62%.
(https://github.com/benshi001/ugo1/blob/master/mulsub_test.go)
name                     old time/op    new time/op    delta
MulSub-4                    270µs ± 0%     219µs ± 0%  -18.62%  (p=0.000 n=35+40)

2. Total size of all .a files in pkg/ shrank by 0.002%.

3. The compilecmp benchmark showed no decline.
name        old time/op       new time/op       delta
Template          2.37s ± 3%        2.36s ± 1%    ~     (p=0.233 n=19+18)
Unicode           1.32s ± 2%        1.34s ± 5%  +1.32%  (p=0.011 n=20+18)
GoTypes           7.88s ± 1%        7.87s ± 1%    ~     (p=0.758 n=20+20)
Compiler          37.5s ± 1%        37.6s ± 1%    ~     (p=0.194 n=20+19)
SSA               83.7s ± 2%        83.5s ± 2%    ~     (p=0.569 n=20+19)
Flate             1.46s ± 3%        1.45s ± 1%    ~     (p=0.619 n=20+17)
GoParser          1.87s ± 2%        1.85s ± 1%  -0.58%  (p=0.048 n=20+18)
Reflect           5.10s ± 2%        5.11s ± 2%    ~     (p=0.365 n=19+20)
Tar               1.78s ± 2%        1.78s ± 2%    ~     (p=0.531 n=19+20)
XML               2.62s ± 1%        2.61s ± 2%    ~     (p=0.057 n=17+19)
[Geo mean]        4.68s             4.67s       -0.07%

name        old user-time/op  new user-time/op  delta
Template          2.80s ± 1%        2.79s ± 2%    ~     (p=0.686 n=17+20)
Unicode           1.61s ± 4%        1.63s ± 6%    ~     (p=0.222 n=20+20)
GoTypes           9.59s ± 1%        9.60s ± 1%    ~     (p=0.482 n=17+20)
Compiler          46.1s ± 1%        46.2s ± 1%    ~     (p=0.373 n=20+18)
SSA                108s ± 1%         108s ± 2%    ~     (p=0.784 n=20+20)
Flate             1.68s ± 3%        1.69s ± 3%    ~     (p=0.335 n=20+19)
GoParser          2.20s ± 4%        2.19s ± 2%    ~     (p=0.844 n=20+18)
Reflect           5.97s ± 3%        6.01s ± 2%    ~     (p=0.184 n=20+20)
Tar               2.11s ± 2%        2.11s ± 4%    ~     (p=0.961 n=19+20)
XML               3.07s ± 1%        3.07s ± 3%    ~     (p=0.786 n=16+19)
[Geo mean]        5.61s             5.62s       +0.19%

name        old text-bytes    new text-bytes    delta
HelloSize         586kB ± 0%        586kB ± 0%    ~     (all equal)

name        old data-bytes    new data-bytes    delta
HelloSize        5.46kB ± 0%       5.46kB ± 0%    ~     (all equal)

name        old bss-bytes     new bss-bytes     delta
HelloSize        72.9kB ± 0%       72.9kB ± 0%    ~     (all equal)

name        old exe-bytes     new exe-bytes     delta
HelloSize        1.03MB ± 0%       1.03MB ± 0%    ~     (all equal)

4. The go1 benchmark showed no decline in total.
name                     old time/op    new time/op    delta
BinaryTree17-4              41.7s ± 1%     41.7s ± 1%    ~     (p=0.966 n=40+40)
Fannkuch11-4                23.6s ± 0%     23.6s ± 1%  -0.23%  (p=0.000 n=40+40)
FmtFprintfEmpty-4           844ns ± 1%     834ns ± 1%  -1.23%  (p=0.000 n=40+40)
FmtFprintfString-4         1.39µs ± 1%    1.40µs ± 1%  +0.71%  (p=0.000 n=40+40)
FmtFprintfInt-4            1.44µs ± 1%    1.45µs ± 1%  +0.70%  (p=0.000 n=40+40)
FmtFprintfIntInt-4         2.10µs ± 1%    2.10µs ± 1%  +0.30%  (p=0.000 n=40+40)
FmtFprintfPrefixedInt-4    2.49µs ± 0%    2.50µs ± 1%  +0.66%  (p=0.000 n=32+40)
FmtFprintfFloat-4          4.42µs ± 1%    4.46µs ± 2%  +0.94%  (p=0.000 n=40+40)
FmtManyArgs-4              8.31µs ± 1%    8.22µs ± 1%  -1.09%  (p=0.000 n=40+40)
GobDecode-4                 105ms ± 1%     102ms ± 1%  -2.30%  (p=0.000 n=39+39)
GobEncode-4                90.2ms ± 1%    88.7ms ± 1%  -1.66%  (p=0.000 n=40+39)
Gzip-4                      4.17s ± 1%     4.16s ± 1%    ~     (p=0.785 n=40+40)
Gunzip-4                    608ms ± 1%     608ms ± 1%    ~     (p=0.481 n=40+40)
HTTPClientServer-4          697µs ± 2%     684µs ± 3%  -1.89%  (p=0.000 n=37+40)
JSONEncode-4                255ms ± 1%     256ms ± 1%  +0.35%  (p=0.000 n=40+40)
JSONDecode-4                920ms ± 1%     926ms ± 1%  +0.64%  (p=0.000 n=40+39)
Mandelbrot200-4            49.3ms ± 1%    49.3ms ± 0%  +0.07%  (p=0.005 n=40+40)
GoParse-4                  46.8ms ± 2%    46.7ms ± 1%    ~     (p=1.000 n=40+40)
RegexpMatchEasy0_32-4      1.27µs ± 0%    1.27µs ± 1%    ~     (p=0.057 n=40+40)
RegexpMatchEasy0_1K-4      7.97µs ± 7%    7.92µs ± 5%    ~     (p=0.094 n=40+40)
RegexpMatchEasy1_32-4      1.28µs ± 1%    1.28µs ± 1%    ~     (p=0.406 n=40+40)
RegexpMatchEasy1_1K-4      10.5µs ± 4%    10.5µs ± 3%    ~     (p=0.855 n=40+40)
RegexpMatchMedium_32-4     2.04µs ± 0%    2.04µs ± 1%  -0.22%  (p=0.000 n=39+40)
RegexpMatchMedium_1K-4      541µs ± 0%     540µs ± 1%  -0.25%  (p=0.000 n=40+38)
RegexpMatchHard_32-4       29.3µs ± 1%    29.3µs ± 0%    ~     (p=0.149 n=40+40)
RegexpMatchHard_1K-4        878µs ± 1%     880µs ± 0%  +0.14%  (p=0.005 n=36+35)
Revcomp-4                  81.8ms ± 2%    81.4ms ± 2%  -0.43%  (p=0.015 n=38+39)
Template-4                  1.05s ± 1%     1.05s ± 1%    ~     (p=0.302 n=40+35)
TimeParse-4                7.18µs ± 1%    7.26µs ± 1%  +1.05%  (p=0.000 n=40+36)
TimeFormat-4               13.1µs ± 1%    13.1µs ± 1%    ~     (p=0.698 n=37+40)
[Geo mean]                  733µs          732µs       -0.16%

name                     old speed      new speed      delta
GobDecode-4              7.34MB/s ± 1%  7.51MB/s ± 1%  +2.36%  (p=0.000 n=39+39)
GobEncode-4              8.51MB/s ± 1%  8.65MB/s ± 1%  +1.69%  (p=0.000 n=40+39)
Gzip-4                   4.66MB/s ± 1%  4.66MB/s ± 1%    ~     (p=0.783 n=40+40)
Gunzip-4                 31.9MB/s ± 1%  31.9MB/s ± 1%    ~     (p=0.466 n=40+40)
JSONEncode-4             7.61MB/s ± 1%  7.58MB/s ± 1%  -0.35%  (p=0.001 n=40+40)
JSONDecode-4             2.11MB/s ± 1%  2.10MB/s ± 1%  -0.52%  (p=0.000 n=38+39)
GoParse-4                1.24MB/s ± 2%  1.24MB/s ± 1%    ~     (p=0.556 n=40+39)
RegexpMatchEasy0_32-4    25.1MB/s ± 0%  25.1MB/s ± 1%    ~     (p=0.064 n=40+40)
RegexpMatchEasy0_1K-4     129MB/s ± 8%   129MB/s ± 5%    ~     (p=0.094 n=40+40)
RegexpMatchEasy1_32-4    25.0MB/s ± 1%  25.1MB/s ± 1%    ~     (p=0.331 n=40+40)
RegexpMatchEasy1_1K-4    97.7MB/s ± 4%  97.8MB/s ± 3%    ~     (p=0.851 n=40+40)
RegexpMatchMedium_32-4    490kB/s ± 0%   490kB/s ± 0%    ~     (all equal)
RegexpMatchMedium_1K-4   1.89MB/s ± 0%  1.90MB/s ± 1%  +0.12%  (p=0.031 n=40+40)
RegexpMatchHard_32-4     1.09MB/s ± 1%  1.09MB/s ± 1%    ~     (p=0.597 n=40+40)
RegexpMatchHard_1K-4     1.16MB/s ± 1%  1.16MB/s ± 1%    ~     (p=0.565 n=40+35)
Revcomp-4                31.1MB/s ± 2%  31.2MB/s ± 2%  +0.44%  (p=0.018 n=38+39)
Template-4               1.85MB/s ± 1%  1.85MB/s ± 1%    ~     (p=0.873 n=40+40)
[Geo mean]               6.66MB/s       6.67MB/s       +0.26%

Change-Id: Icc972d8a78ea06c32c3aa15733ff0537c82c2dc7
Reviewed-on: https://go-review.googlesource.com/58950
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>