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cmd/internal/obj: continue to optimize ARM's constant pool
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Both Keith's https://go-review.googlesource.com/c/41612/ and
and Ben's https://go-review.googlesource.com/c/41679/ optimized ARM's
constant pool. But neither was complete.

First, BIC was forgotten.
1. "BIC $0xff00ff00, Reg" can be optimized to
   "BIC $0xff000000, Reg
    BIC $0x0000ff00, Reg"
2. "BIC $0xffff00ff, Reg" can be optimized to
   "AND $0x0000ff00, Reg"
3. "AND $0xffff00ff, Reg" can be optimized to
   "BIC $0x0000ff00, Reg"

Second, break a non-ARMImmRot to the subtraction of two ARMImmRots was
left as TODO.
1. "ADD $0x00fffff0, Reg" can be optimized to
   "ADD $0x01000000, Reg
    SUB $0x00000010, Reg"
2. "SUB $0x00fffff0, Reg" can be optimized to
   "SUB $0x01000000, Reg
    ADD $0x00000010, Reg"

This patch fixes them and issue #19844.

The go1 benchmark shows improvements.

name                     old time/op    new time/op    delta
BinaryTree17-4              41.4s ± 1%     41.7s ± 1%  +0.54%  (p=0.000 n=50+49)
Fannkuch11-4                24.7s ± 1%     25.1s ± 0%  +1.70%  (p=0.000 n=50+49)
FmtFprintfEmpty-4           853ns ± 1%     852ns ± 1%    ~     (p=0.833 n=50+50)
FmtFprintfString-4         1.33µs ± 1%    1.33µs ± 1%    ~     (p=0.163 n=50+50)
FmtFprintfInt-4            1.40µs ± 1%    1.40µs ± 0%    ~     (p=0.293 n=50+35)
FmtFprintfIntInt-4         2.09µs ± 1%    2.08µs ± 1%  -0.39%  (p=0.000 n=50+49)
FmtFprintfPrefixedInt-4    2.43µs ± 1%    2.43µs ± 1%    ~     (p=0.552 n=50+50)
FmtFprintfFloat-4          4.57µs ± 1%    4.42µs ± 1%  -3.18%  (p=0.000 n=50+50)
FmtManyArgs-4              8.62µs ± 1%    8.52µs ± 0%  -1.08%  (p=0.000 n=50+50)
GobDecode-4                 101ms ± 1%     101ms ± 2%  +0.45%  (p=0.001 n=49+49)
GobEncode-4                90.7ms ± 1%    91.1ms ± 2%  +0.51%  (p=0.001 n=50+50)
Gzip-4                      4.23s ± 1%     4.21s ± 1%  -0.62%  (p=0.000 n=50+50)
Gunzip-4                    623ms ± 1%     619ms ± 0%  -0.63%  (p=0.000 n=50+42)
HTTPClientServer-4          721µs ± 5%     683µs ± 3%  -5.25%  (p=0.000 n=50+47)
JSONEncode-4                251ms ± 1%     253ms ± 1%  +0.54%  (p=0.000 n=49+50)
JSONDecode-4                941ms ± 1%     944ms ± 1%  +0.30%  (p=0.001 n=49+50)
Mandelbrot200-4            49.3ms ± 1%    49.3ms ± 0%    ~     (p=0.918 n=50+48)
GoParse-4                  47.1ms ± 1%    47.2ms ± 1%  +0.18%  (p=0.025 n=50+50)
RegexpMatchEasy0_32-4      1.23µs ± 1%    1.24µs ± 1%  +0.30%  (p=0.000 n=49+50)
RegexpMatchEasy0_1K-4      7.74µs ± 7%    7.76µs ± 5%    ~     (p=0.888 n=50+50)
RegexpMatchEasy1_32-4      1.32µs ± 1%    1.32µs ± 1%  +0.23%  (p=0.003 n=50+50)
RegexpMatchEasy1_1K-4      10.6µs ± 2%    10.5µs ± 3%  -1.29%  (p=0.000 n=49+50)
RegexpMatchMedium_32-4     2.19µs ± 1%    2.10µs ± 1%  -3.79%  (p=0.000 n=49+49)
RegexpMatchMedium_1K-4      544µs ± 0%     545µs ± 0%    ~     (p=0.123 n=41+50)
RegexpMatchHard_32-4       28.8µs ± 0%    28.8µs ± 1%    ~     (p=0.580 n=46+50)
RegexpMatchHard_1K-4        863µs ± 1%     865µs ± 1%  +0.31%  (p=0.027 n=47+50)
Revcomp-4                  82.2ms ± 2%    82.3ms ± 2%    ~     (p=0.894 n=48+49)
Template-4                  1.06s ± 1%     1.04s ± 1%  -1.18%  (p=0.000 n=50+49)
TimeParse-4                7.25µs ± 1%    7.35µs ± 0%  +1.48%  (p=0.000 n=50+50)
TimeFormat-4               13.3µs ± 1%    13.2µs ± 1%  -0.13%  (p=0.007 n=50+50)
[Geo mean]                  736µs          733µs       -0.37%

name                     old speed      new speed      delta
GobDecode-4              7.60MB/s ± 1%  7.56MB/s ± 2%  -0.46%  (p=0.001 n=49+49)
GobEncode-4              8.47MB/s ± 1%  8.42MB/s ± 2%  -0.50%  (p=0.001 n=50+50)
Gzip-4                   4.58MB/s ± 1%  4.61MB/s ± 1%  +0.59%  (p=0.000 n=50+50)
Gunzip-4                 31.2MB/s ± 1%  31.4MB/s ± 0%  +0.63%  (p=0.000 n=50+42)
JSONEncode-4             7.73MB/s ± 1%  7.69MB/s ± 1%  -0.53%  (p=0.000 n=49+50)
JSONDecode-4             2.06MB/s ± 1%  2.06MB/s ± 1%    ~     (p=0.052 n=44+50)
GoParse-4                1.23MB/s ± 0%  1.23MB/s ± 2%    ~     (p=0.526 n=26+50)
RegexpMatchEasy0_32-4    25.9MB/s ± 1%  25.9MB/s ± 1%  -0.30%  (p=0.000 n=49+50)
RegexpMatchEasy0_1K-4     132MB/s ± 7%   132MB/s ± 6%    ~     (p=0.885 n=50+50)
RegexpMatchEasy1_32-4    24.2MB/s ± 1%  24.1MB/s ± 1%  -0.22%  (p=0.003 n=50+50)
RegexpMatchEasy1_1K-4    96.4MB/s ± 2%  97.8MB/s ± 3%  +1.36%  (p=0.000 n=50+50)
RegexpMatchMedium_32-4    460kB/s ± 0%   476kB/s ± 1%  +3.43%  (p=0.000 n=49+50)
RegexpMatchMedium_1K-4   1.88MB/s ± 0%  1.88MB/s ± 0%    ~     (all equal)
RegexpMatchHard_32-4     1.11MB/s ± 0%  1.11MB/s ± 1%  +0.34%  (p=0.000 n=45+50)
RegexpMatchHard_1K-4     1.19MB/s ± 1%  1.18MB/s ± 1%  -0.34%  (p=0.033 n=50+50)
Revcomp-4                30.9MB/s ± 2%  30.9MB/s ± 2%    ~     (p=0.894 n=48+49)
Template-4               1.84MB/s ± 1%  1.86MB/s ± 2%  +1.19%  (p=0.000 n=48+50)
[Geo mean]               6.63MB/s       6.65MB/s       +0.26%


Fixes #19844.

Change-Id: I5ad16cc0b29267bb4579aca3dcc10a0b8ade1aa4
Reviewed-on: https://go-review.googlesource.com/42430
Run-TryBot: Cherry Zhang <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Cherry Zhang <[email protected]>
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@benshi001 @cherrymui
benshi001 authored and cherrymui committed May 11, 2017
1 parent 19b05ac commit 6897030
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Showing 6 changed files with 225 additions and 58 deletions.
2 changes: 2 additions & 0 deletions src/cmd/compile/internal/ssa/gen/ARM.rules
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Original file line number Diff line number Diff line change
Expand Up @@ -798,6 +798,8 @@
// generic constant folding
(ADDconst [c] x) && !isARMImmRot(uint32(c)) && isARMImmRot(uint32(-c)) -> (SUBconst [int64(int32(-c))] x)
(SUBconst [c] x) && !isARMImmRot(uint32(c)) && isARMImmRot(uint32(-c)) -> (ADDconst [int64(int32(-c))] x)
(ANDconst [c] x) && !isARMImmRot(uint32(c)) && isARMImmRot(^uint32(c)) -> (BICconst [int64(^uint32(c))] x)
(BICconst [c] x) && !isARMImmRot(uint32(c)) && isARMImmRot(^uint32(c)) -> (ANDconst [int64(^uint32(c))] x)
(ADDconst [c] (MOVWconst [d])) -> (MOVWconst [int64(int32(c+d))])
(ADDconst [c] (ADDconst [d] x)) -> (ADDconst [int64(int32(c+d))] x)
(ADDconst [c] (SUBconst [d] x)) -> (ADDconst [int64(int32(c-d))] x)
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28 changes: 28 additions & 0 deletions src/cmd/compile/internal/ssa/rewriteARM.go
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9 changes: 5 additions & 4 deletions src/cmd/internal/obj/arm/a.out.go
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Original file line number Diff line number Diff line change
Expand Up @@ -121,10 +121,11 @@ const (
C_PSR
C_FCR

C_RCON /* 0xff rotated */
C_NCON /* ~RCON */
C_RCON2 /* OR of two disjoint C_RCON constants */
C_SCON /* 0xffff */
C_RCON /* 0xff rotated */
C_NCON /* ~RCON */
C_RCON2A /* OR of two disjoint C_RCON constants */
C_RCON2S /* subtraction of two disjoint C_RCON constants */
C_SCON /* 0xffff */
C_LCON
C_LCONADDR
C_ZFCON
Expand Down
3 changes: 2 additions & 1 deletion src/cmd/internal/obj/arm/anames5.go
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,8 @@ var cnames5 = []string{
"FCR",
"RCON",
"NCON",
"RCON2",
"RCON2A",
"RCON2S",
"SCON",
"LCON",
"LCONADDR",
Expand Down
107 changes: 88 additions & 19 deletions src/cmd/internal/obj/arm/asm5.go
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Original file line number Diff line number Diff line change
Expand Up @@ -88,20 +88,26 @@ var optab = []Optab{
{AADD, C_REG, C_NONE, C_REG, 1, 4, 0, 0, 0},
{AAND, C_REG, C_REG, C_REG, 1, 4, 0, 0, 0},
{AAND, C_REG, C_NONE, C_REG, 1, 4, 0, 0, 0},
{AORR, C_REG, C_REG, C_REG, 1, 4, 0, 0, 0},
{AORR, C_REG, C_NONE, C_REG, 1, 4, 0, 0, 0},
{AMOVW, C_REG, C_NONE, C_REG, 1, 4, 0, 0, 0},
{AMVN, C_REG, C_NONE, C_REG, 1, 4, 0, 0, 0},
{ACMP, C_REG, C_REG, C_NONE, 1, 4, 0, 0, 0},
{AADD, C_RCON, C_REG, C_REG, 2, 4, 0, 0, 0},
{AADD, C_RCON, C_NONE, C_REG, 2, 4, 0, 0, 0},
{AAND, C_RCON, C_REG, C_REG, 2, 4, 0, 0, 0},
{AAND, C_RCON, C_NONE, C_REG, 2, 4, 0, 0, 0},
{AORR, C_RCON, C_REG, C_REG, 2, 4, 0, 0, 0},
{AORR, C_RCON, C_NONE, C_REG, 2, 4, 0, 0, 0},
{AMOVW, C_RCON, C_NONE, C_REG, 2, 4, 0, 0, 0},
{AMVN, C_RCON, C_NONE, C_REG, 2, 4, 0, 0, 0},
{ACMP, C_RCON, C_REG, C_NONE, 2, 4, 0, 0, 0},
{AADD, C_SHIFT, C_REG, C_REG, 3, 4, 0, 0, 0},
{AADD, C_SHIFT, C_NONE, C_REG, 3, 4, 0, 0, 0},
{AAND, C_SHIFT, C_REG, C_REG, 3, 4, 0, 0, 0},
{AAND, C_SHIFT, C_NONE, C_REG, 3, 4, 0, 0, 0},
{AORR, C_SHIFT, C_REG, C_REG, 3, 4, 0, 0, 0},
{AORR, C_SHIFT, C_NONE, C_REG, 3, 4, 0, 0, 0},
{AMVN, C_SHIFT, C_NONE, C_REG, 3, 4, 0, 0, 0},
{ACMP, C_SHIFT, C_REG, C_NONE, 3, 4, 0, 0, 0},
{AMOVW, C_RACON, C_NONE, C_REG, 4, 4, REGSP, 0, 0},
Expand Down Expand Up @@ -136,20 +142,27 @@ var optab = []Optab{
{AADD, C_NCON, C_NONE, C_REG, 13, 8, 0, 0, 0},
{AAND, C_NCON, C_REG, C_REG, 13, 8, 0, 0, 0},
{AAND, C_NCON, C_NONE, C_REG, 13, 8, 0, 0, 0},
{AORR, C_NCON, C_REG, C_REG, 13, 8, 0, 0, 0},
{AORR, C_NCON, C_NONE, C_REG, 13, 8, 0, 0, 0},
{AMVN, C_NCON, C_NONE, C_REG, 13, 8, 0, 0, 0},
{ACMP, C_NCON, C_REG, C_NONE, 13, 8, 0, 0, 0},
{AADD, C_SCON, C_REG, C_REG, 13, 8, 0, 0, 0},
{AADD, C_SCON, C_NONE, C_REG, 13, 8, 0, 0, 0},
{AAND, C_SCON, C_REG, C_REG, 13, 8, 0, 0, 0},
{AAND, C_SCON, C_NONE, C_REG, 13, 8, 0, 0, 0},
{AORR, C_SCON, C_REG, C_REG, 13, 8, 0, 0, 0},
{AORR, C_SCON, C_NONE, C_REG, 13, 8, 0, 0, 0},
{AMVN, C_SCON, C_NONE, C_REG, 13, 8, 0, 0, 0},
{ACMP, C_SCON, C_REG, C_NONE, 13, 8, 0, 0, 0},
{AADD, C_RCON2, C_REG, C_REG, 106, 8, 0, 0, 0},
// TODO: RCON2: how to do AND and BIC?
{AADD, C_RCON2A, C_REG, C_REG, 106, 8, 0, 0, 0},
{AORR, C_RCON2A, C_REG, C_REG, 106, 8, 0, 0, 0},
{AADD, C_RCON2S, C_REG, C_REG, 107, 8, 0, 0, 0},
{AADD, C_LCON, C_REG, C_REG, 13, 8, 0, LFROM, 0},
{AADD, C_LCON, C_NONE, C_REG, 13, 8, 0, LFROM, 0},
{AAND, C_LCON, C_REG, C_REG, 13, 8, 0, LFROM, 0},
{AAND, C_LCON, C_NONE, C_REG, 13, 8, 0, LFROM, 0},
{AORR, C_LCON, C_REG, C_REG, 13, 8, 0, LFROM, 0},
{AORR, C_LCON, C_NONE, C_REG, 13, 8, 0, LFROM, 0},
{AMVN, C_LCON, C_NONE, C_REG, 13, 8, 0, LFROM, 0},
{ACMP, C_LCON, C_REG, C_NONE, 13, 8, 0, LFROM, 0},
{AMOVB, C_REG, C_NONE, C_REG, 1, 4, 0, 0, 0},
Expand Down Expand Up @@ -970,10 +983,10 @@ func immrot(v uint32) int32 {
return 0
}

// immrot2 returns bits encoding the immediate constant fields of two instructions,
// immrot2a returns bits encoding the immediate constant fields of two instructions,
// such that the encoded constants x, y satisfy x|y==v, x&y==0.
// Returns 0,0 if no such decomposition of v exists.
func immrot2(v uint32) (uint32, uint32) {
func immrot2a(v uint32) (uint32, uint32) {
for i := uint(1); i < 32; i++ {
m := uint32(1<<i - 1)
if x, y := immrot(v&m), immrot(v&^m); x != 0 && y != 0 {
Expand All @@ -985,6 +998,32 @@ func immrot2(v uint32) (uint32, uint32) {
return 0, 0
}

// immrot2s returns bits encoding the immediate constant fields of two instructions,
// such that the encoded constants y, x satisfy y-x==v, y&x==0.
// Returns 0,0 if no such decomposition of v exists.
func immrot2s(v uint32) (uint32, uint32) {
if immrot(v) == 0 {
return v, 0
}
// suppose v in the form of {leading 00, upper effective bits, lower 8 effective bits, trailing 00}
// omit trailing 00
var i uint32
for i = 2; i < 32; i += 2 {
if v&(1<<i-1) != 0 {
break
}
}
// i must be <= 24, then adjust i just above lower 8 effective bits of v
i += 6
// let x = {the complement of lower 8 effective bits, trailing 00}, y = x + v
x := 1<<i - v&(1<<i-1)
y := v + x
if y, x = uint32(immrot(y)), uint32(immrot(x)); y != 0 && x != 0 {
return y, x
}
return 0, 0
}

func immaddr(v int32) int32 {
if v >= 0 && v <= 0xfff {
return v&0xfff | 1<<24 | 1<<23 /* pre indexing */ /* pre indexing, up */
Expand Down Expand Up @@ -1159,8 +1198,11 @@ func (c *ctxt5) aclass(a *obj.Addr) int {
if uint32(c.instoffset) <= 0xffff && objabi.GOARM == 7 {
return C_SCON
}
if x, y := immrot2(uint32(c.instoffset)); x != 0 && y != 0 {
return C_RCON2
if x, y := immrot2a(uint32(c.instoffset)); x != 0 && y != 0 {
return C_RCON2A
}
if y, x := immrot2s(uint32(c.instoffset)); x != 0 && y != 0 {
return C_RCON2S
}
return C_LCON

Expand Down Expand Up @@ -1226,13 +1268,12 @@ func (c *ctxt5) oplook(p *obj.Prog) *Optab {
a2 = C_REG
}

// If Scond != 0, we must use the constant pool instead of
// splitting the instruction in two. The most common reason is
// .S (flag updating) instructions. There may be others.
if a1 == C_RCON2 && p.Scond != 0 {
// If current instruction has a .S suffix (flags update),
// we must use the constant pool instead of splitting it.
if (a1 == C_RCON2A || a1 == C_RCON2S) && p.Scond&C_SBIT != 0 {
a1 = C_LCON
}
if a3 == C_RCON2 && p.Scond != 0 {
if (a3 == C_RCON2A || a3 == C_RCON2S) && p.Scond&C_SBIT != 0 {
a3 = C_LCON
}

Expand Down Expand Up @@ -1266,7 +1307,7 @@ func cmp(a int, b int) bool {
}
switch a {
case C_LCON:
if b == C_RCON || b == C_NCON || b == C_SCON || b == C_RCON2 {
if b == C_RCON || b == C_NCON || b == C_SCON || b == C_RCON2A || b == C_RCON2S {
return true
}

Expand Down Expand Up @@ -1406,16 +1447,14 @@ func buildop(ctxt *obj.Link) {
log.Fatalf("bad code")

case AADD:
opset(AEOR, r0)
opset(ASUB, r0)
opset(ARSB, r0)
opset(AADC, r0)
opset(ASBC, r0)
opset(ARSC, r0)
opset(AORR, r0)

case AAND:
opset(AAND, r0)
case AORR:
opset(AEOR, r0)
opset(ABIC, r0)

case ACMP:
Expand Down Expand Up @@ -1541,6 +1580,7 @@ func buildop(ctxt *obj.Link) {
ALDREXD,
ASTREXD,
APLD,
AAND,
obj.AUNDEF,
obj.AFUNCDATA,
obj.APCDATA,
Expand Down Expand Up @@ -1609,11 +1649,11 @@ func (c *ctxt5) asmout(p *obj.Prog, o *Optab, out []uint32) {
c.aclass(&p.From)
r := int(p.Reg)
rt := int(p.To.Reg)
x, y := immrot2(uint32(c.instoffset))
x, y := immrot2a(uint32(c.instoffset))
var as2 obj.As
switch p.As {
case AADD, ASUB, AORR, AEOR:
as2 = p.As // ADD, SUB, ORR, EOR
case AADD, ASUB, AORR, AEOR, ABIC:
as2 = p.As // ADD, SUB, ORR, EOR, BIC
case ARSB:
as2 = AADD // RSB -> RSB/ADD pair
case AADC:
Expand All @@ -1632,6 +1672,35 @@ func (c *ctxt5) asmout(p *obj.Prog, o *Optab, out []uint32) {
o1 |= x
o2 |= y

case 107: /* op $I,R,R where I can be decomposed into 2 immediates */
c.aclass(&p.From)
r := int(p.Reg)
rt := int(p.To.Reg)
y, x := immrot2s(uint32(c.instoffset))
var as2 obj.As
switch p.As {
case AADD:
as2 = ASUB // ADD -> ADD/SUB pair
case ASUB:
as2 = AADD // SUB -> SUB/ADD pair
case ARSB:
as2 = ASUB // RSB -> RSB/SUB pair
case AADC:
as2 = ASUB // ADC -> ADC/SUB pair
case ASBC:
as2 = AADD // SBC -> SBC/ADD pair
case ARSC:
as2 = ASUB // RSC -> RSC/SUB pair
default:
c.ctxt.Diag("unknown second op for %v", p)
}
o1 = c.oprrr(p, p.As, int(p.Scond))
o2 = c.oprrr(p, as2, int(p.Scond))
o1 |= (uint32(r)&15)<<16 | (uint32(rt)&15)<<12
o2 |= (uint32(rt)&15)<<16 | (uint32(rt)&15)<<12
o1 |= y
o2 |= x

case 3: /* add R<<[IR],[R],R */
o1 = c.mov(p)

Expand Down
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