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cmd/compile: add opt branchelim to rewrite some CondSelect into math
This allows something like:
if y { x++ }
To be compiled to:
MOVBLZX BX, CX
ADDQ CX, AX
Instead of:
LEAQ 1(AX), CX
MOVBLZX BL, DX
TESTQ DX, DX
CMOVQNE CX, AX
While ./make.bash uniqued per LOC, there is 100 additions and 75 substractions.
See benchmark here: https://go.dev/play/p/DJf5COjwhd_s
Either it's a performance no-op or it is faster:
goos: linux
goarch: amd64
cpu: AMD Ryzen 5 3600 6-Core Processor
│ /tmp/old.logs │ /tmp/new.logs │
│ sec/op │ sec/op vs base │
CmovInlineConditionAddLatency-12 0.5443n ± 5% 0.5339n ± 3% -1.90% (p=0.004 n=10)
CmovInlineConditionAddThroughputBy6-12 1.492n ± 1% 1.494n ± 1% ~ (p=0.955 n=10)
CmovInlineConditionSubLatency-12 0.5419n ± 3% 0.5282n ± 3% -2.52% (p=0.019 n=10)
CmovInlineConditionSubThroughputBy6-12 1.587n ± 1% 1.584n ± 2% ~ (p=0.492 n=10)
CmovOutlineConditionAddLatency-12 0.5223n ± 1% 0.2639n ± 4% -49.47% (p=0.000 n=10)
CmovOutlineConditionAddThroughputBy6-12 1.159n ± 1% 1.097n ± 2% -5.35% (p=0.000 n=10)
CmovOutlineConditionSubLatency-12 0.5271n ± 3% 0.2654n ± 2% -49.66% (p=0.000 n=10)
CmovOutlineConditionSubThroughputBy6-12 1.053n ± 1% 1.050n ± 1% ~ (p=1.000 n=10)
geomean
There are other benefits not tested by this benchmark:
- the math form is usually a couple bytes shorter (ICACHE)
- the math form is usually 0~2 uops shorter (UCACHE)
- the math form has usually less register pressure*
- the math form can sometimes be optimized further
*regalloc rarely find how it can use less registers
As far as pass ordering goes there are many possible options,
I've decided to reorder branchelim before late opt since:
- unlike running exclusively the CondSelect rules after branchelim,
some extra optimizations might trigger on the adds or subs.
- I don't want to maintain a second generic.rules file of only the stuff,
that can trigger after branchelim.
- rerunning all of opt a third time increase compilation time for little gains.
By elimination moving branchelim seems fine.
Change-Id: I869adf57e4d109948ee157cfc47144445146bafd
Reviewed-on: https://go-review.googlesource.com/c/go/+/685676
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
This commit is contained in:
Jorropo
parent
f32cf8e4b0
commit
fcd28070fe
4 changed files with 292 additions and 4 deletions
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@ -56,6 +56,8 @@ func rewriteValuegeneric(v *Value) bool {
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return rewriteValuegeneric_OpCom64(v)
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case OpCom8:
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return rewriteValuegeneric_OpCom8(v)
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case OpCondSelect:
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return rewriteValuegeneric_OpCondSelect(v)
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case OpConstInterface:
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return rewriteValuegeneric_OpConstInterface(v)
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case OpConstSlice:
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@ -5694,6 +5696,254 @@ func rewriteValuegeneric_OpCom8(v *Value) bool {
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}
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return false
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}
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func rewriteValuegeneric_OpCondSelect(v *Value) bool {
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v_2 := v.Args[2]
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v_1 := v.Args[1]
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v_0 := v.Args[0]
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b := v.Block
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config := b.Func.Config
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// match: (CondSelect x _ (ConstBool [true ]))
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// result: x
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for {
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x := v_0
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if v_2.Op != OpConstBool || auxIntToBool(v_2.AuxInt) != true {
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break
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}
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v.copyOf(x)
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return true
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}
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// match: (CondSelect _ y (ConstBool [false]))
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// result: y
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for {
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y := v_1
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if v_2.Op != OpConstBool || auxIntToBool(v_2.AuxInt) != false {
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break
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}
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v.copyOf(y)
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return true
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}
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// match: (CondSelect (Add8 <t> x (Const8 [1])) x bool)
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// cond: config.arch != "arm64"
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// result: (Add8 x (CvtBoolToUint8 <t> bool))
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for {
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if v_0.Op != OpAdd8 {
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break
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}
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t := v_0.Type
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_ = v_0.Args[1]
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v_0_0 := v_0.Args[0]
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v_0_1 := v_0.Args[1]
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for _i0 := 0; _i0 <= 1; _i0, v_0_0, v_0_1 = _i0+1, v_0_1, v_0_0 {
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x := v_0_0
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if v_0_1.Op != OpConst8 || auxIntToInt8(v_0_1.AuxInt) != 1 || x != v_1 {
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continue
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}
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bool := v_2
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if !(config.arch != "arm64") {
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continue
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}
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v.reset(OpAdd8)
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v0 := b.NewValue0(v.Pos, OpCvtBoolToUint8, t)
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v0.AddArg(bool)
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v.AddArg2(x, v0)
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return true
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}
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break
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}
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// match: (CondSelect (Add64 <t> x (Const64 [1])) x bool)
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// cond: config.arch != "arm64"
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// result: (Add64 x (ZeroExt8to64 <t> (CvtBoolToUint8 <types.Types[types.TUINT8]> bool)))
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for {
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if v_0.Op != OpAdd64 {
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break
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}
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t := v_0.Type
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_ = v_0.Args[1]
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v_0_0 := v_0.Args[0]
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v_0_1 := v_0.Args[1]
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for _i0 := 0; _i0 <= 1; _i0, v_0_0, v_0_1 = _i0+1, v_0_1, v_0_0 {
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x := v_0_0
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if v_0_1.Op != OpConst64 || auxIntToInt64(v_0_1.AuxInt) != 1 || x != v_1 {
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continue
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}
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bool := v_2
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if !(config.arch != "arm64") {
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continue
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}
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v.reset(OpAdd64)
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v0 := b.NewValue0(v.Pos, OpZeroExt8to64, t)
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v1 := b.NewValue0(v.Pos, OpCvtBoolToUint8, types.Types[types.TUINT8])
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v1.AddArg(bool)
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v0.AddArg(v1)
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v.AddArg2(x, v0)
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return true
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}
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break
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}
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// match: (CondSelect (Add32 <t> x (Const32 [1])) x bool)
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// cond: config.arch != "arm64"
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// result: (Add32 x (ZeroExt8to32 <t> (CvtBoolToUint8 <types.Types[types.TUINT8]> bool)))
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for {
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if v_0.Op != OpAdd32 {
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break
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}
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t := v_0.Type
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_ = v_0.Args[1]
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v_0_0 := v_0.Args[0]
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v_0_1 := v_0.Args[1]
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for _i0 := 0; _i0 <= 1; _i0, v_0_0, v_0_1 = _i0+1, v_0_1, v_0_0 {
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x := v_0_0
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if v_0_1.Op != OpConst32 || auxIntToInt32(v_0_1.AuxInt) != 1 || x != v_1 {
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continue
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}
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bool := v_2
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if !(config.arch != "arm64") {
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continue
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}
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v.reset(OpAdd32)
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v0 := b.NewValue0(v.Pos, OpZeroExt8to32, t)
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v1 := b.NewValue0(v.Pos, OpCvtBoolToUint8, types.Types[types.TUINT8])
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v1.AddArg(bool)
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v0.AddArg(v1)
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v.AddArg2(x, v0)
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return true
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}
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break
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}
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// match: (CondSelect (Add16 <t> x (Const16 [1])) x bool)
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// cond: config.arch != "arm64"
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// result: (Add16 x (ZeroExt8to16 <t> (CvtBoolToUint8 <types.Types[types.TUINT8]> bool)))
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for {
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if v_0.Op != OpAdd16 {
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break
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}
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t := v_0.Type
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_ = v_0.Args[1]
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v_0_0 := v_0.Args[0]
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v_0_1 := v_0.Args[1]
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for _i0 := 0; _i0 <= 1; _i0, v_0_0, v_0_1 = _i0+1, v_0_1, v_0_0 {
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x := v_0_0
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if v_0_1.Op != OpConst16 || auxIntToInt16(v_0_1.AuxInt) != 1 || x != v_1 {
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continue
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}
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bool := v_2
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if !(config.arch != "arm64") {
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continue
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}
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v.reset(OpAdd16)
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v0 := b.NewValue0(v.Pos, OpZeroExt8to16, t)
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v1 := b.NewValue0(v.Pos, OpCvtBoolToUint8, types.Types[types.TUINT8])
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v1.AddArg(bool)
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v0.AddArg(v1)
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v.AddArg2(x, v0)
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return true
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}
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break
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}
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// match: (CondSelect (Add8 <t> x (Const8 [-1])) x bool)
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// result: (Sub8 x (CvtBoolToUint8 <t> bool))
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for {
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if v_0.Op != OpAdd8 {
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break
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}
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t := v_0.Type
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_ = v_0.Args[1]
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v_0_0 := v_0.Args[0]
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v_0_1 := v_0.Args[1]
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for _i0 := 0; _i0 <= 1; _i0, v_0_0, v_0_1 = _i0+1, v_0_1, v_0_0 {
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x := v_0_0
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if v_0_1.Op != OpConst8 || auxIntToInt8(v_0_1.AuxInt) != -1 || x != v_1 {
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continue
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}
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bool := v_2
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v.reset(OpSub8)
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v0 := b.NewValue0(v.Pos, OpCvtBoolToUint8, t)
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v0.AddArg(bool)
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v.AddArg2(x, v0)
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return true
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}
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break
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}
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// match: (CondSelect (Add64 <t> x (Const64 [-1])) x bool)
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// result: (Sub64 x (ZeroExt8to64 <t> (CvtBoolToUint8 <types.Types[types.TUINT8]> bool)))
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for {
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if v_0.Op != OpAdd64 {
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break
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}
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t := v_0.Type
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_ = v_0.Args[1]
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v_0_0 := v_0.Args[0]
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v_0_1 := v_0.Args[1]
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for _i0 := 0; _i0 <= 1; _i0, v_0_0, v_0_1 = _i0+1, v_0_1, v_0_0 {
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x := v_0_0
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if v_0_1.Op != OpConst64 || auxIntToInt64(v_0_1.AuxInt) != -1 || x != v_1 {
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continue
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}
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bool := v_2
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v.reset(OpSub64)
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v0 := b.NewValue0(v.Pos, OpZeroExt8to64, t)
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v1 := b.NewValue0(v.Pos, OpCvtBoolToUint8, types.Types[types.TUINT8])
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v1.AddArg(bool)
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v0.AddArg(v1)
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v.AddArg2(x, v0)
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return true
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}
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break
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}
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// match: (CondSelect (Add32 <t> x (Const32 [-1])) x bool)
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// result: (Sub32 x (ZeroExt8to32 <t> (CvtBoolToUint8 <types.Types[types.TUINT8]> bool)))
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for {
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if v_0.Op != OpAdd32 {
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break
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}
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t := v_0.Type
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_ = v_0.Args[1]
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v_0_0 := v_0.Args[0]
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v_0_1 := v_0.Args[1]
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for _i0 := 0; _i0 <= 1; _i0, v_0_0, v_0_1 = _i0+1, v_0_1, v_0_0 {
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x := v_0_0
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if v_0_1.Op != OpConst32 || auxIntToInt32(v_0_1.AuxInt) != -1 || x != v_1 {
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continue
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}
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bool := v_2
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v.reset(OpSub32)
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v0 := b.NewValue0(v.Pos, OpZeroExt8to32, t)
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v1 := b.NewValue0(v.Pos, OpCvtBoolToUint8, types.Types[types.TUINT8])
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v1.AddArg(bool)
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v0.AddArg(v1)
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v.AddArg2(x, v0)
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return true
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}
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break
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}
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// match: (CondSelect (Add16 <t> x (Const16 [-1])) x bool)
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// result: (Sub16 x (ZeroExt8to16 <t> (CvtBoolToUint8 <types.Types[types.TUINT8]> bool)))
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for {
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if v_0.Op != OpAdd16 {
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break
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}
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t := v_0.Type
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_ = v_0.Args[1]
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v_0_0 := v_0.Args[0]
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v_0_1 := v_0.Args[1]
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for _i0 := 0; _i0 <= 1; _i0, v_0_0, v_0_1 = _i0+1, v_0_1, v_0_0 {
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x := v_0_0
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if v_0_1.Op != OpConst16 || auxIntToInt16(v_0_1.AuxInt) != -1 || x != v_1 {
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continue
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}
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bool := v_2
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v.reset(OpSub16)
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v0 := b.NewValue0(v.Pos, OpZeroExt8to16, t)
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v1 := b.NewValue0(v.Pos, OpCvtBoolToUint8, types.Types[types.TUINT8])
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v1.AddArg(bool)
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v0.AddArg(v1)
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v.AddArg2(x, v0)
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return true
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}
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break
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}
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return false
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}
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func rewriteValuegeneric_OpConstInterface(v *Value) bool {
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b := v.Block
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typ := &b.Func.Config.Types
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