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cmd/compile: optimize arm's bit operation
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>
This commit is contained in:
Ben Shi
Cherry Zhang
parent
95a11c7381
commit
9f2411894b
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@ -7,6 +7,7 @@ package arm
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import (
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"fmt"
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"math"
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"math/bits"
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"cmd/compile/internal/gc"
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"cmd/compile/internal/ssa"
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@ -119,6 +120,28 @@ func genregshift(s *gc.SSAGenState, as obj.As, r0, r1, r2, r int16, typ int64) *
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return p
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}
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// find a (lsb, width) pair for BFC
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// lsb must be in [0, 31], width must be in [1, 32 - lsb]
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// return (0xffffffff, 0) if v is not a binary like 0...01...10...0
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func getBFC(v uint32) (uint32, uint32) {
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var m, l uint32
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// BFC is not applicable with zero
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if v == 0 {
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return 0xffffffff, 0
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}
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// find the lowest set bit, for example l=2 for 0x3ffffffc
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l = uint32(bits.TrailingZeros32(v))
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// m-1 represents the highest set bit index, for example m=30 for 0x3ffffffc
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m = 32 - uint32(bits.LeadingZeros32(v))
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// check if v is a binary like 0...01...10...0
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if (1<<m)-(1<<l) == v {
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// it must be m > l for non-zero v
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return l, m - l
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}
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// invalid
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return 0xffffffff, 0
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}
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func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
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switch v.Op {
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case ssa.OpCopy, ssa.OpARMMOVWreg:
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@ -267,16 +290,38 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
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p.Reg = v.Args[0].Reg()
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p.To.Type = obj.TYPE_REG
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p.To.Reg = v.Reg()
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case ssa.OpARMANDconst, ssa.OpARMBICconst:
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// try to optimize ANDconst and BICconst to BFC, which saves bytes and ticks
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// BFC is only available on ARMv7, and its result and source are in the same register
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if objabi.GOARM == 7 && v.Reg() == v.Args[0].Reg() {
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var val uint32
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if v.Op == ssa.OpARMANDconst {
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val = ^uint32(v.AuxInt)
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} else { // BICconst
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val = uint32(v.AuxInt)
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}
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lsb, width := getBFC(val)
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// omit BFC for ARM's imm12
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if 8 < width && width < 24 {
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p := s.Prog(arm.ABFC)
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p.From.Type = obj.TYPE_CONST
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p.From.Offset = int64(width)
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p.SetFrom3(obj.Addr{Type: obj.TYPE_CONST, Offset: int64(lsb)})
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p.To.Type = obj.TYPE_REG
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p.To.Reg = v.Reg()
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break
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}
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}
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// fall back to ordinary form
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fallthrough
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case ssa.OpARMADDconst,
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ssa.OpARMADCconst,
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ssa.OpARMSUBconst,
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ssa.OpARMSBCconst,
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ssa.OpARMRSBconst,
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ssa.OpARMRSCconst,
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ssa.OpARMANDconst,
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ssa.OpARMORconst,
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ssa.OpARMXORconst,
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ssa.OpARMBICconst,
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ssa.OpARMSLLconst,
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ssa.OpARMSRLconst,
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ssa.OpARMSRAconst:
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@ -284,9 +284,12 @@ func and_mask_2(a uint64) uint64 {
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return a & (1 << 63)
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}
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func and_mask_3(a uint32) uint32 {
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func and_mask_3(a, b uint32) (uint32, uint32) {
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// arm/7:`BIC`,-`AND`
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return a & 0xffff0000
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a &= 0xffffaaaa
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// arm/7:`BFC`,-`AND`,-`BIC`
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b &= 0xffc003ff
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return a, b
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}
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// Check generation of arm64 BIC/EON/ORN instructions
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