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cmd/compile: load some live values into registers before loop
If we're about to enter a loop, load values which are live and will soon be used in the loop into registers. name old time/op new time/op delta BinaryTree17-8 2.80s ± 4% 2.62s ± 2% -6.43% (p=0.008 n=5+5) Fannkuch11-8 2.45s ± 2% 2.14s ± 1% -12.43% (p=0.008 n=5+5) FmtFprintfEmpty-8 49.0ns ± 1% 48.4ns ± 1% -1.35% (p=0.032 n=5+5) FmtFprintfString-8 160ns ± 1% 153ns ± 0% -4.63% (p=0.008 n=5+5) FmtFprintfInt-8 152ns ± 0% 150ns ± 0% -1.57% (p=0.000 n=5+4) FmtFprintfIntInt-8 252ns ± 2% 244ns ± 1% -3.02% (p=0.008 n=5+5) FmtFprintfPrefixedInt-8 223ns ± 0% 223ns ± 0% ~ (all samples are equal) FmtFprintfFloat-8 293ns ± 2% 291ns ± 2% ~ (p=0.389 n=5+5) FmtManyArgs-8 956ns ± 0% 936ns ± 0% -2.05% (p=0.008 n=5+5) GobDecode-8 7.18ms ± 0% 7.11ms ± 0% -1.02% (p=0.008 n=5+5) GobEncode-8 6.12ms ± 3% 6.07ms ± 1% ~ (p=0.690 n=5+5) Gzip-8 284ms ± 1% 284ms ± 0% ~ (p=1.000 n=5+5) Gunzip-8 40.8ms ± 1% 40.6ms ± 1% ~ (p=0.310 n=5+5) HTTPClientServer-8 69.8µs ± 1% 72.2µs ± 4% ~ (p=0.056 n=5+5) JSONEncode-8 16.1ms ± 2% 16.2ms ± 1% ~ (p=0.151 n=5+5) JSONDecode-8 54.9ms ± 0% 57.0ms ± 1% +3.79% (p=0.008 n=5+5) Mandelbrot200-8 4.35ms ± 0% 4.39ms ± 0% +0.85% (p=0.008 n=5+5) GoParse-8 3.56ms ± 1% 3.42ms ± 1% -4.03% (p=0.008 n=5+5) RegexpMatchEasy0_32-8 75.6ns ± 1% 75.0ns ± 0% -0.83% (p=0.016 n=5+4) RegexpMatchEasy0_1K-8 250ns ± 0% 252ns ± 1% +0.80% (p=0.016 n=4+5) RegexpMatchEasy1_32-8 75.0ns ± 0% 75.4ns ± 2% ~ (p=0.206 n=5+5) RegexpMatchEasy1_1K-8 401ns ± 0% 398ns ± 1% ~ (p=0.056 n=5+5) RegexpMatchMedium_32-8 119ns ± 0% 118ns ± 0% -0.84% (p=0.008 n=5+5) RegexpMatchMedium_1K-8 36.6µs ± 0% 36.9µs ± 0% +0.91% (p=0.008 n=5+5) RegexpMatchHard_32-8 1.95µs ± 1% 1.92µs ± 0% -1.23% (p=0.032 n=5+5) RegexpMatchHard_1K-8 58.3µs ± 1% 58.1µs ± 1% ~ (p=0.548 n=5+5) Revcomp-8 425ms ± 1% 389ms ± 1% -8.39% (p=0.008 n=5+5) Template-8 65.5ms ± 1% 63.6ms ± 1% -2.86% (p=0.008 n=5+5) TimeParse-8 363ns ± 0% 354ns ± 1% -2.59% (p=0.008 n=5+5) TimeFormat-8 363ns ± 0% 364ns ± 1% ~ (p=0.159 n=5+5) Fixes #14511 Change-Id: I1b79d2545271fa90d5b04712cc25573bdc94f2ce Reviewed-on: https://go-review.googlesource.com/20151 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Keith Randall
parent
5be961a352
commit
c03ed491fe
@ -5081,8 +5081,10 @@ func moveByType(t ssa.Type) int {
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return x86.AMOVL
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case 8:
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return x86.AMOVQ
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case 16:
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return x86.AMOVUPS // int128s are in SSE registers
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default:
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panic("bad int register width")
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panic(fmt.Sprintf("bad int register width %d:%s", t.Size(), t))
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}
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}
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panic("bad register type")
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@ -102,6 +102,14 @@ import (
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const regDebug = false // TODO: compiler flag
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const logSpills = false
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// distance is a measure of how far into the future values are used.
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// distance is measured in units of instructions.
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const (
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likelyDistance = 1
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normalDistance = 10
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unlikelyDistance = 100
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)
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// regalloc performs register allocation on f. It sets f.RegAlloc
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// to the resulting allocation.
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func regalloc(f *Func) {
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@ -550,7 +558,7 @@ func (s *regAllocState) setState(regs []endReg) {
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// compatRegs returns the set of registers which can store a type t.
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func (s *regAllocState) compatRegs(t Type) regMask {
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var m regMask
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if t.IsFloat() {
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if t.IsFloat() || t == TypeInt128 {
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m = 0xffff << 16 // X0-X15
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} else {
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m = 0xffef << 0 // AX-R15, except SP
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@ -576,8 +584,12 @@ func (s *regAllocState) regalloc(f *Func) {
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// Initialize liveSet and uses fields for this block.
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// Walk backwards through the block doing liveness analysis.
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liveSet.clear()
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d := int32(len(b.Values))
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if b.Kind == BlockCall {
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d += unlikelyDistance
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}
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for _, e := range s.live[b.ID] {
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s.addUse(e.ID, int32(len(b.Values))+e.dist) // pseudo-uses from beyond end of block
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s.addUse(e.ID, d+e.dist) // pseudo-uses from beyond end of block
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liveSet.add(e.ID)
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}
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if v := b.Control; v != nil && s.values[v.ID].needReg {
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@ -944,11 +956,11 @@ func (s *regAllocState) regalloc(f *Func) {
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}
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}
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// Load control value into reg.
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if v := b.Control; v != nil && s.values[v.ID].needReg {
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if regDebug {
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fmt.Printf(" processing control %s\n", v.LongString())
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}
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// Load control value into reg.
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// TODO: regspec for block control values, instead of using
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// register set from the control op's output.
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s.allocValToReg(v, opcodeTable[v.Op].reg.outputs[0], false, b.Line)
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@ -963,6 +975,53 @@ func (s *regAllocState) regalloc(f *Func) {
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s.freeUseRecords = u
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}
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// If we are approaching a merge point and we are the primary
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// predecessor of it, find live values that we use soon after
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// the merge point and promote them to registers now.
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if len(b.Succs) == 1 && len(b.Succs[0].Preds) > 1 && b.Succs[0].Preds[s.primary[b.Succs[0].ID]] == b {
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// For this to be worthwhile, the loop must have no calls in it.
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// Use a very simple loop detector. TODO: incorporate David's loop stuff
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// once it is in.
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top := b.Succs[0]
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for _, p := range top.Preds {
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if p == b {
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continue
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}
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for {
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if p.Kind == BlockCall {
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goto badloop
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}
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if p == top {
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break
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}
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if len(p.Preds) != 1 {
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goto badloop
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}
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p = p.Preds[0]
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}
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}
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// TODO: sort by distance, pick the closest ones?
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for _, live := range s.live[b.ID] {
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if live.dist >= unlikelyDistance {
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// Don't preload anything live after the loop.
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continue
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}
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vid := live.ID
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vi := &s.values[vid]
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if vi.regs != 0 {
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continue
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}
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v := s.orig[vid]
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m := s.compatRegs(v.Type) &^ s.used
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if m != 0 {
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s.allocValToReg(v, m, false, b.Line)
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}
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}
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}
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badloop:
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;
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// Save end-of-block register state.
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// First count how many, this cuts allocations in half.
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k := 0
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@ -1539,8 +1598,14 @@ func (s *regAllocState) computeLive() {
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// Add len(b.Values) to adjust from end-of-block distance
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// to beginning-of-block distance.
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live.clear()
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d := int32(len(b.Values))
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if b.Kind == BlockCall {
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// Because we keep no values in registers across a call,
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// make every use past a call very far away.
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d += unlikelyDistance
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}
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for _, e := range s.live[b.ID] {
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live.set(e.ID, e.dist+int32(len(b.Values)))
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live.set(e.ID, e.dist+d)
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}
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// Mark control value as live
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@ -1570,20 +1635,17 @@ func (s *regAllocState) computeLive() {
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// invariant: live contains the values live at the start of b (excluding phi inputs)
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for i, p := range b.Preds {
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// Compute additional distance for the edge.
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const normalEdge = 10
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const likelyEdge = 1
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const unlikelyEdge = 100
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// Note: delta must be at least 1 to distinguish the control
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// value use from the first user in a successor block.
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delta := int32(normalEdge)
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delta := int32(normalDistance)
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if len(p.Succs) == 2 {
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if p.Succs[0] == b && p.Likely == BranchLikely ||
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p.Succs[1] == b && p.Likely == BranchUnlikely {
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delta = likelyEdge
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delta = likelyDistance
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}
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if p.Succs[0] == b && p.Likely == BranchUnlikely ||
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p.Succs[1] == b && p.Likely == BranchLikely {
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delta = unlikelyEdge
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delta = unlikelyDistance
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}
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}
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@ -46,13 +46,14 @@ type Type interface {
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// Special compiler-only types.
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type CompilerType struct {
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Name string
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size int64
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Memory bool
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Flags bool
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Void bool
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Int128 bool
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}
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func (t *CompilerType) Size() int64 { return 0 } // Size in bytes
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func (t *CompilerType) Size() int64 { return t.size } // Size in bytes
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func (t *CompilerType) Alignment() int64 { return 0 }
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func (t *CompilerType) IsBoolean() bool { return false }
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func (t *CompilerType) IsInteger() bool { return false }
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@ -127,5 +128,5 @@ var (
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TypeMem = &CompilerType{Name: "mem", Memory: true}
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TypeFlags = &CompilerType{Name: "flags", Flags: true}
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TypeVoid = &CompilerType{Name: "void", Void: true}
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TypeInt128 = &CompilerType{Name: "int128", Int128: true}
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TypeInt128 = &CompilerType{Name: "int128", size: 16, Int128: true}
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)
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