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cmd/compile: prefer to evict a rematerializable register
This resolves a long-standing regalloc TODO: If you must evict a register, choose to evict a register containing a rematerializable value, since that value won't need to be spilled. Provides very minor performance and size improvements. name old time/op new time/op delta BinaryTree17-8 2.20s ± 3% 2.18s ± 2% -0.77% (p=0.000 n=45+49) Fannkuch11-8 2.14s ± 2% 2.15s ± 2% +0.73% (p=0.000 n=43+44) FmtFprintfEmpty-8 30.6ns ± 4% 30.2ns ± 3% -1.14% (p=0.000 n=50+48) FmtFprintfString-8 54.5ns ± 6% 53.6ns ± 5% -1.64% (p=0.001 n=50+48) FmtFprintfInt-8 58.0ns ± 7% 57.6ns ± 4% ~ (p=0.220 n=50+50) FmtFprintfIntInt-8 85.3ns ± 2% 84.8ns ± 3% -0.62% (p=0.001 n=44+47) FmtFprintfPrefixedInt-8 93.9ns ± 6% 93.6ns ± 5% ~ (p=0.706 n=50+48) FmtFprintfFloat-8 178ns ± 4% 177ns ± 4% ~ (p=0.107 n=49+50) FmtManyArgs-8 376ns ± 4% 374ns ± 3% -0.58% (p=0.013 n=45+50) GobDecode-8 4.77ms ± 2% 4.76ms ± 3% ~ (p=0.059 n=47+46) GobEncode-8 4.04ms ± 2% 3.99ms ± 3% -1.13% (p=0.000 n=49+49) Gzip-8 177ms ± 2% 180ms ± 3% +1.43% (p=0.000 n=48+48) Gunzip-8 28.5ms ± 6% 28.3ms ± 5% ~ (p=0.104 n=50+49) HTTPClientServer-8 72.1µs ± 1% 72.0µs ± 1% -0.15% (p=0.042 n=48+42) JSONEncode-8 9.81ms ± 5% 10.03ms ± 6% +2.29% (p=0.000 n=50+49) JSONDecode-8 39.2ms ± 3% 39.3ms ± 2% ~ (p=0.095 n=49+49) Mandelbrot200-8 3.48ms ± 2% 3.46ms ± 2% -0.80% (p=0.000 n=47+48) GoParse-8 2.54ms ± 3% 2.51ms ± 3% -1.35% (p=0.000 n=49+49) RegexpMatchEasy0_32-8 66.0ns ± 7% 65.7ns ± 8% ~ (p=0.331 n=50+50) RegexpMatchEasy0_1K-8 155ns ± 4% 154ns ± 4% ~ (p=0.986 n=49+50) RegexpMatchEasy1_32-8 62.6ns ± 8% 62.2ns ± 5% ~ (p=0.395 n=50+49) RegexpMatchEasy1_1K-8 260ns ± 5% 255ns ± 3% -1.92% (p=0.000 n=49+49) RegexpMatchMedium_32-8 92.9ns ± 2% 91.8ns ± 2% -1.25% (p=0.000 n=46+48) RegexpMatchMedium_1K-8 27.7µs ± 3% 27.0µs ± 2% -2.59% (p=0.000 n=49+49) RegexpMatchHard_32-8 1.23µs ± 4% 1.21µs ± 2% -2.16% (p=0.000 n=49+44) RegexpMatchHard_1K-8 36.4µs ± 2% 35.7µs ± 2% -1.87% (p=0.000 n=48+49) Revcomp-8 274ms ± 2% 276ms ± 3% +0.70% (p=0.034 n=45+48) Template-8 45.1ms ± 8% 45.1ms ± 8% ~ (p=0.643 n=50+50) TimeParse-8 223ns ± 2% 223ns ± 2% ~ (p=0.401 n=47+47) TimeFormat-8 245ns ± 2% 246ns ± 3% ~ (p=0.758 n=49+50) [Geo mean] 36.5µs 36.3µs -0.54% name old object-bytes new object-bytes delta Template 480kB ± 0% 480kB ± 0% ~ (all equal) Unicode 214kB ± 0% 214kB ± 0% ~ (all equal) GoTypes 1.54MB ± 0% 1.54MB ± 0% -0.03% (p=0.008 n=5+5) Compiler 5.75MB ± 0% 5.75MB ± 0% ~ (all equal) SSA 14.6MB ± 0% 14.6MB ± 0% -0.01% (p=0.008 n=5+5) Flate 300kB ± 0% 300kB ± 0% -0.01% (p=0.008 n=5+5) GoParser 366kB ± 0% 366kB ± 0% ~ (all equal) Reflect 1.20MB ± 0% 1.20MB ± 0% ~ (all equal) Tar 413kB ± 0% 413kB ± 0% ~ (all equal) XML 529kB ± 0% 528kB ± 0% -0.13% (p=0.008 n=5+5) [Geo mean] 909kB 909kB -0.02% Change-Id: I46d37a55197683a98913f35801dc2b0d609653c8 Reviewed-on: https://go-review.googlesource.com/103240 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Josh Bleecher Snyder
parent
5d8d3d52b0
commit
014a9048d4
@ -1746,9 +1746,10 @@ type edgeState struct {
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destinations []dstRecord
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extra []dstRecord
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usedRegs regMask // registers currently holding something
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uniqueRegs regMask // registers holding the only copy of a value
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finalRegs regMask // registers holding final target
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usedRegs regMask // registers currently holding something
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uniqueRegs regMask // registers holding the only copy of a value
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finalRegs regMask // registers holding final target
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rematerializeableRegs regMask // registers that hold rematerializeable values
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}
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type contentRecord struct {
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@ -1782,6 +1783,7 @@ func (e *edgeState) setup(idx int, srcReg []endReg, dstReg []startReg, stacklive
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e.usedRegs = 0
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e.uniqueRegs = 0
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e.finalRegs = 0
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e.rematerializeableRegs = 0
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// Live registers can be sources.
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for _, x := range srcReg {
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@ -2041,6 +2043,9 @@ func (e *edgeState) set(loc Location, vid ID, c *Value, final bool, pos src.XPos
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e.uniqueRegs &^= regMask(1) << uint(t.num)
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}
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}
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if e.s.values[vid].rematerializeable {
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e.rematerializeableRegs |= regMask(1) << uint(r.num)
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}
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}
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if e.s.f.pass.debug > regDebug {
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fmt.Printf("%s\n", c.LongString())
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@ -2082,6 +2087,7 @@ func (e *edgeState) erase(loc Location) {
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if cr.final {
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e.finalRegs &^= regMask(1) << uint(r.num)
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}
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e.rematerializeableRegs &^= regMask(1) << uint(r.num)
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}
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if len(a) == 1 {
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if r, ok := e.s.f.getHome(a[0].ID).(*Register); ok {
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@ -2105,7 +2111,7 @@ func (e *edgeState) findRegFor(typ *types.Type) Location {
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// 1) an unused register
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// 2) a non-unique register not holding a final value
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// 3) a non-unique register
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// 4) TODO: a register holding a rematerializeable value
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// 4) a register holding a rematerializeable value
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x := m &^ e.usedRegs
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if x != 0 {
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return &e.s.registers[pickReg(x)]
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@ -2118,6 +2124,10 @@ func (e *edgeState) findRegFor(typ *types.Type) Location {
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if x != 0 {
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return &e.s.registers[pickReg(x)]
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}
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x = m & e.rematerializeableRegs
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if x != 0 {
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return &e.s.registers[pickReg(x)]
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}
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// No register is available.
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// Pick a register to spill.
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@ -2145,7 +2155,7 @@ func (e *edgeState) findRegFor(typ *types.Type) Location {
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}
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}
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fmt.Printf("m:%d unique:%d final:%d\n", m, e.uniqueRegs, e.finalRegs)
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fmt.Printf("m:%d unique:%d final:%d rematerializable:%d\n", m, e.uniqueRegs, e.finalRegs, e.rematerializeableRegs)
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for _, vid := range e.cachedVals {
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a := e.cache[vid]
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for _, c := range a {
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