cmd/compile: optimize ARM code with MULAF/MULSF/MULAD/MULSD

The go compiler can generate better ARM code with those more
efficient FP instructions. And there is little improvement
in total but big improvement in special cases.

1. The size of pkg/linux_arm/math.a shrinks by 2.4%.

2. there is neither improvement nor regression in compilecmp benchmark.
name        old time/op       new time/op       delta
Template          2.32s ± 2%        2.32s ± 1%    ~     (p=1.000 n=9+10)
Unicode           1.32s ± 4%        1.32s ± 4%    ~     (p=0.912 n=10+10)
GoTypes           7.76s ± 1%        7.79s ± 1%    ~     (p=0.447 n=9+10)
Compiler          37.4s ± 2%        37.2s ± 2%    ~     (p=0.218 n=10+10)
SSA               84.8s ± 2%        85.0s ± 1%    ~     (p=0.604 n=10+9)
Flate             1.45s ± 2%        1.44s ± 2%    ~     (p=0.075 n=10+10)
GoParser          1.82s ± 1%        1.81s ± 1%    ~     (p=0.190 n=10+10)
Reflect           5.06s ± 1%        5.05s ± 1%    ~     (p=0.315 n=10+9)
Tar               2.37s ± 1%        2.37s ± 2%    ~     (p=0.912 n=10+10)
XML               2.56s ± 1%        2.58s ± 2%    ~     (p=0.089 n=10+10)
[Geo mean]        4.77s             4.77s       -0.08%

name        old user-time/op  new user-time/op  delta
Template          2.74s ± 2%        2.75s ± 2%    ~     (p=0.856 n=9+10)
Unicode           1.61s ± 4%        1.62s ± 3%    ~     (p=0.693 n=10+10)
GoTypes           9.55s ± 1%        9.49s ± 2%    ~     (p=0.056 n=9+10)
Compiler          45.9s ± 1%        45.8s ± 1%    ~     (p=0.345 n=9+10)
SSA                110s ± 1%         110s ± 1%    ~     (p=0.763 n=9+10)
Flate             1.68s ± 2%        1.68s ± 3%    ~     (p=0.616 n=10+10)
GoParser          2.14s ± 4%        2.14s ± 1%    ~     (p=0.825 n=10+9)
Reflect           5.95s ± 1%        5.97s ± 3%    ~     (p=0.951 n=9+10)
Tar               2.94s ± 3%        2.93s ± 2%    ~     (p=0.359 n=10+10)
XML               3.03s ± 3%        3.07s ± 6%    ~     (p=0.166 n=10+10)
[Geo mean]        5.76s             5.77s       +0.12%

name        old text-bytes    new text-bytes    delta
HelloSize         588kB ± 0%        588kB ± 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)

3. The performance of Mandelbrot200 improves 15%, though little
   improvement in total.
name                     old time/op    new time/op    delta
BinaryTree17-4              41.7s ± 1%     41.7s ± 1%     ~     (p=0.264 n=29+23)
Fannkuch11-4                24.2s ± 0%     24.1s ± 1%   -0.13%  (p=0.050 n=30+30)
FmtFprintfEmpty-4           826ns ± 1%     824ns ± 1%   -0.24%  (p=0.038 n=25+30)
FmtFprintfString-4         1.38µs ± 1%    1.38µs ± 0%   -0.42%  (p=0.000 n=27+25)
FmtFprintfInt-4            1.46µs ± 1%    1.46µs ± 0%     ~     (p=0.060 n=30+23)
FmtFprintfIntInt-4         2.11µs ± 1%    2.08µs ± 0%   -1.04%  (p=0.000 n=30+30)
FmtFprintfPrefixedInt-4    2.23µs ± 1%    2.22µs ± 1%   -0.51%  (p=0.000 n=30+30)
FmtFprintfFloat-4          4.49µs ± 1%    4.48µs ± 1%   -0.22%  (p=0.004 n=26+30)
FmtManyArgs-4              8.06µs ± 1%    8.12µs ± 1%   +0.68%  (p=0.000 n=25+30)
GobDecode-4                 104ms ± 1%     104ms ± 2%     ~     (p=0.362 n=29+29)
GobEncode-4                92.9ms ± 1%    92.8ms ± 2%     ~     (p=0.786 n=30+30)
Gzip-4                      4.12s ± 1%     4.12s ± 1%     ~     (p=0.314 n=30+30)
Gunzip-4                    602ms ± 1%     603ms ± 1%     ~     (p=0.164 n=30+30)
HTTPClientServer-4          659µs ± 1%     655µs ± 2%   -0.64%  (p=0.006 n=25+28)
JSONEncode-4                234ms ± 1%     235ms ± 1%   +0.29%  (p=0.050 n=30+30)
JSONDecode-4                912ms ± 0%     911ms ± 0%     ~     (p=0.385 n=18+24)
Mandelbrot200-4            49.2ms ± 0%    41.7ms ± 0%  -15.35%  (p=0.000 n=25+27)
GoParse-4                  46.3ms ± 1%    46.3ms ± 2%     ~     (p=0.572 n=30+30)
RegexpMatchEasy0_32-4      1.29µs ± 1%    1.27µs ± 0%   -1.59%  (p=0.000 n=30+30)
RegexpMatchEasy0_1K-4      7.62µs ± 4%    7.71µs ± 3%     ~     (p=0.074 n=30+30)
RegexpMatchEasy1_32-4      1.31µs ± 0%    1.30µs ± 1%   -0.71%  (p=0.000 n=23+30)
RegexpMatchEasy1_1K-4      10.3µs ± 3%    10.3µs ± 5%     ~     (p=0.105 n=30+30)
RegexpMatchMedium_32-4     2.06µs ± 1%    2.06µs ± 1%     ~     (p=0.100 n=30+30)
RegexpMatchMedium_1K-4      533µs ± 1%     534µs ± 1%     ~     (p=0.254 n=29+30)
RegexpMatchHard_32-4       28.9µs ± 0%    28.9µs ± 0%     ~     (p=0.154 n=30+30)
RegexpMatchHard_1K-4        868µs ± 1%     867µs ± 0%     ~     (p=0.729 n=30+23)
Revcomp-4                  66.9ms ± 1%    67.2ms ± 2%     ~     (p=0.102 n=28+29)
Template-4                  1.07s ± 1%     1.06s ± 1%   -0.53%  (p=0.000 n=30+30)
TimeParse-4                7.07µs ± 1%    7.01µs ± 0%   -0.85%  (p=0.000 n=30+25)
TimeFormat-4               13.1µs ± 0%    13.2µs ± 1%   +0.77%  (p=0.000 n=27+27)
[Geo mean]                  721µs          716µs        -0.70%

name                     old speed      new speed      delta
GobDecode-4              7.38MB/s ± 1%  7.37MB/s ± 2%     ~     (p=0.399 n=29+29)
GobEncode-4              8.26MB/s ± 1%  8.27MB/s ± 2%     ~     (p=0.790 n=30+30)
Gzip-4                   4.71MB/s ± 1%  4.71MB/s ± 1%     ~     (p=0.885 n=30+30)
Gunzip-4                 32.2MB/s ± 1%  32.2MB/s ± 1%     ~     (p=0.190 n=30+30)
JSONEncode-4             8.28MB/s ± 1%  8.25MB/s ± 1%     ~     (p=0.053 n=30+30)
JSONDecode-4             2.13MB/s ± 0%  2.12MB/s ± 1%     ~     (p=0.072 n=18+30)
GoParse-4                1.25MB/s ± 1%  1.25MB/s ± 2%     ~     (p=0.863 n=30+30)
RegexpMatchEasy0_32-4    24.8MB/s ± 0%  25.2MB/s ± 1%   +1.61%  (p=0.000 n=30+30)
RegexpMatchEasy0_1K-4     134MB/s ± 4%   133MB/s ± 3%     ~     (p=0.074 n=30+30)
RegexpMatchEasy1_32-4    24.5MB/s ± 0%  24.6MB/s ± 1%   +0.72%  (p=0.000 n=23+30)
RegexpMatchEasy1_1K-4    99.1MB/s ± 3%  99.8MB/s ± 5%     ~     (p=0.105 n=30+30)
RegexpMatchMedium_32-4    483kB/s ± 1%   487kB/s ± 1%   +0.83%  (p=0.002 n=30+30)
RegexpMatchMedium_1K-4   1.92MB/s ± 1%  1.92MB/s ± 1%     ~     (p=0.058 n=30+30)
RegexpMatchHard_32-4     1.10MB/s ± 0%  1.11MB/s ± 0%     ~     (p=0.804 n=30+30)
RegexpMatchHard_1K-4     1.18MB/s ± 0%  1.18MB/s ± 0%     ~     (all equal)
Revcomp-4                38.0MB/s ± 1%  37.8MB/s ± 2%     ~     (p=0.098 n=28+29)
Template-4               1.82MB/s ± 1%  1.83MB/s ± 1%   +0.55%  (p=0.000 n=29+29)
[Geo mean]               6.79MB/s       6.79MB/s        +0.09%

Change-Id: Ia91991c2c5c59c5df712de85a83b13a21c0a554b
Reviewed-on: https://go-review.googlesource.com/63770
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/arm/ssa.go b/src/cmd/compile/internal/arm/ssa.go
index 5525197d31..a70df6dd0e 100644
--- a/src/cmd/compile/internal/arm/ssa.go
+++ b/src/cmd/compile/internal/arm/ssa.go
@@ -197,6 +197,20 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		p.Reg = r1
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = r
+	case ssa.OpARMMULAF, ssa.OpARMMULAD, ssa.OpARMMULSF, ssa.OpARMMULSD:
+		r := v.Reg()
+		r0 := v.Args[0].Reg()
+		r1 := v.Args[1].Reg()
+		r2 := v.Args[2].Reg()
+		if r != r0 {
+			v.Fatalf("result and addend are not in the same register: %v", v.LongString())
+		}
+		p := s.Prog(v.Op.Asm())
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = r2
+		p.Reg = r1
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = r
 	case ssa.OpARMADDS,
 		ssa.OpARMSUBS:
 		r := v.Reg0()