BFC (Bit Field Clear) was introduced in ARMv7, which can simplify
ANDconst and BICconst. And this CL implements that optimization.
1. The total size of pkg/android_arm decreases about 3KB, excluding
cmd/compile/.
2. There is no regression in the go1 benchmark result, and some
cases (FmtFprintfEmpty-4 and RegexpMatchMedium_32-4) even get
slight improvement.
name old time/op new time/op delta
BinaryTree17-4 25.3s ± 1% 25.2s ± 1% ~ (p=0.072 n=30+29)
Fannkuch11-4 13.3s ± 0% 13.3s ± 0% +0.13% (p=0.000 n=30+26)
FmtFprintfEmpty-4 407ns ± 0% 394ns ± 0% -3.19% (p=0.000 n=26+28)
FmtFprintfString-4 664ns ± 0% 662ns ± 0% -0.22% (p=0.000 n=30+30)
FmtFprintfInt-4 712ns ± 0% 706ns ± 0% -0.79% (p=0.000 n=30+30)
FmtFprintfIntInt-4 1.06µs ± 0% 1.05µs ± 0% -0.38% (p=0.000 n=30+30)
FmtFprintfPrefixedInt-4 1.16µs ± 0% 1.16µs ± 0% -0.13% (p=0.000 n=30+29)
FmtFprintfFloat-4 2.24µs ± 0% 2.23µs ± 0% -0.51% (p=0.000 n=29+21)
FmtManyArgs-4 4.09µs ± 0% 4.06µs ± 0% -0.83% (p=0.000 n=28+30)
GobDecode-4 55.0ms ± 5% 55.4ms ± 5% ~ (p=0.307 n=30+30)
GobEncode-4 51.2ms ± 1% 51.9ms ± 1% +1.23% (p=0.000 n=29+30)
Gzip-4 2.64s ± 0% 2.60s ± 0% -1.35% (p=0.000 n=30+29)
Gunzip-4 309ms ± 0% 308ms ± 0% -0.27% (p=0.000 n=30+30)
HTTPClientServer-4 1.03ms ± 5% 1.02ms ± 4% ~ (p=0.117 n=30+29)
JSONEncode-4 101ms ± 2% 101ms ± 2% ~ (p=0.338 n=29+29)
JSONDecode-4 383ms ± 2% 382ms ± 2% ~ (p=0.751 n=26+30)
Mandelbrot200-4 18.4ms ± 0% 18.4ms ± 0% -0.10% (p=0.000 n=29+29)
GoParse-4 22.6ms ± 0% 22.5ms ± 0% -0.39% (p=0.000 n=30+30)
RegexpMatchEasy0_32-4 761ns ± 0% 750ns ± 0% -1.47% (p=0.000 n=26+29)
RegexpMatchEasy0_1K-4 4.33µs ± 0% 4.34µs ± 0% +0.27% (p=0.000 n=25+28)
RegexpMatchEasy1_32-4 809ns ± 0% 795ns ± 0% -1.74% (p=0.000 n=27+25)
RegexpMatchEasy1_1K-4 5.54µs ± 0% 5.53µs ± 0% -0.18% (p=0.000 n=29+29)
RegexpMatchMedium_32-4 1.11µs ± 0% 1.08µs ± 0% -2.78% (p=0.000 n=27+29)
RegexpMatchMedium_1K-4 255µs ± 0% 255µs ± 0% -0.02% (p=0.029 n=30+30)
RegexpMatchHard_32-4 14.7µs ± 0% 14.7µs ± 0% -0.28% (p=0.000 n=30+29)
RegexpMatchHard_1K-4 439µs ± 0% 439µs ± 0% ~ (p=0.907 n=23+27)
Revcomp-4 41.9ms ± 1% 41.9ms ± 1% ~ (p=0.230 n=28+30)
Template-4 522ms ± 1% 528ms ± 1% +1.25% (p=0.000 n=30+30)
TimeParse-4 3.34µs ± 0% 3.35µs ± 0% +0.23% (p=0.000 n=30+27)
TimeFormat-4 6.06µs ± 0% 6.13µs ± 0% +1.08% (p=0.000 n=29+29)
[Geo mean] 384µs 382µs -0.37%
name old speed new speed delta
GobDecode-4 14.0MB/s ± 5% 13.9MB/s ± 5% ~ (p=0.308 n=30+30)
GobEncode-4 15.0MB/s ± 1% 14.8MB/s ± 1% -1.22% (p=0.000 n=29+30)
Gzip-4 7.36MB/s ± 0% 7.46MB/s ± 0% +1.35% (p=0.000 n=30+30)
Gunzip-4 62.8MB/s ± 0% 63.0MB/s ± 0% +0.27% (p=0.000 n=30+30)
JSONEncode-4 19.2MB/s ± 2% 19.2MB/s ± 2% ~ (p=0.312 n=29+29)
JSONDecode-4 5.05MB/s ± 3% 5.08MB/s ± 2% ~ (p=0.356 n=29+30)
GoParse-4 2.56MB/s ± 0% 2.57MB/s ± 0% +0.39% (p=0.000 n=23+27)
RegexpMatchEasy0_32-4 42.0MB/s ± 0% 42.6MB/s ± 0% +1.50% (p=0.000 n=26+28)
RegexpMatchEasy0_1K-4 236MB/s ± 0% 236MB/s ± 0% -0.27% (p=0.000 n=25+28)
RegexpMatchEasy1_32-4 39.6MB/s ± 0% 40.2MB/s ± 0% +1.73% (p=0.000 n=27+27)
RegexpMatchEasy1_1K-4 185MB/s ± 0% 185MB/s ± 0% +0.18% (p=0.000 n=29+29)
RegexpMatchMedium_32-4 900kB/s ± 0% 920kB/s ± 0% +2.22% (p=0.000 n=29+29)
RegexpMatchMedium_1K-4 4.02MB/s ± 0% 4.02MB/s ± 0% +0.07% (p=0.004 n=30+27)
RegexpMatchHard_32-4 2.17MB/s ± 0% 2.18MB/s ± 0% +0.46% (p=0.000 n=30+26)
RegexpMatchHard_1K-4 2.33MB/s ± 0% 2.33MB/s ± 0% ~ (all equal)
Revcomp-4 60.6MB/s ± 1% 60.7MB/s ± 1% ~ (p=0.207 n=28+30)
Template-4 3.72MB/s ± 1% 3.67MB/s ± 1% -1.23% (p=0.000 n=30+30)
[Geo mean] 12.9MB/s 12.9MB/s +0.29%
Change-Id: I07f497f8bb476c950dc555491d00c9066fb64a4e
Reviewed-on: https://go-review.googlesource.com/134232
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
import (
"fmt"
"math"
+ "math/bits"
"cmd/compile/internal/gc"
"cmd/compile/internal/ssa"
return p
}
+// find a (lsb, width) pair for BFC
+// lsb must be in [0, 31], width must be in [1, 32 - lsb]
+// return (0xffffffff, 0) if v is not a binary like 0...01...10...0
+func getBFC(v uint32) (uint32, uint32) {
+ var m, l uint32
+ // BFC is not applicable with zero
+ if v == 0 {
+ return 0xffffffff, 0
+ }
+ // find the lowest set bit, for example l=2 for 0x3ffffffc
+ l = uint32(bits.TrailingZeros32(v))
+ // m-1 represents the highest set bit index, for example m=30 for 0x3ffffffc
+ m = 32 - uint32(bits.LeadingZeros32(v))
+ // check if v is a binary like 0...01...10...0
+ if (1<<m)-(1<<l) == v {
+ // it must be m > l for non-zero v
+ return l, m - l
+ }
+ // invalid
+ return 0xffffffff, 0
+}
+
func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
switch v.Op {
case ssa.OpCopy, ssa.OpARMMOVWreg:
p.Reg = v.Args[0].Reg()
p.To.Type = obj.TYPE_REG
p.To.Reg = v.Reg()
+ case ssa.OpARMANDconst, ssa.OpARMBICconst:
+ // try to optimize ANDconst and BICconst to BFC, which saves bytes and ticks
+ // BFC is only available on ARMv7, and its result and source are in the same register
+ if objabi.GOARM == 7 && v.Reg() == v.Args[0].Reg() {
+ var val uint32
+ if v.Op == ssa.OpARMANDconst {
+ val = ^uint32(v.AuxInt)
+ } else { // BICconst
+ val = uint32(v.AuxInt)
+ }
+ lsb, width := getBFC(val)
+ // omit BFC for ARM's imm12
+ if 8 < width && width < 24 {
+ p := s.Prog(arm.ABFC)
+ p.From.Type = obj.TYPE_CONST
+ p.From.Offset = int64(width)
+ p.SetFrom3(obj.Addr{Type: obj.TYPE_CONST, Offset: int64(lsb)})
+ p.To.Type = obj.TYPE_REG
+ p.To.Reg = v.Reg()
+ break
+ }
+ }
+ // fall back to ordinary form
+ fallthrough
case ssa.OpARMADDconst,
ssa.OpARMADCconst,
ssa.OpARMSUBconst,
ssa.OpARMSBCconst,
ssa.OpARMRSBconst,
ssa.OpARMRSCconst,
- ssa.OpARMANDconst,
ssa.OpARMORconst,
ssa.OpARMXORconst,
- ssa.OpARMBICconst,
ssa.OpARMSLLconst,
ssa.OpARMSRLconst,
ssa.OpARMSRAconst:
return a & (1 << 63)
}
-func and_mask_3(a uint32) uint32 {
+func and_mask_3(a, b uint32) (uint32, uint32) {
// arm/7:`BIC`,-`AND`
- return a & 0xffff0000
+ a &= 0xffffaaaa
+ // arm/7:`BFC`,-`AND`,-`BIC`
+ b &= 0xffc003ff
+ return a, b
}
// Check generation of arm64 BIC/EON/ORN instructions