1
0
mirror of https://github.com/golang/go synced 2024-07-05 09:50:19 +00:00
go/test/loopbce.go

254 lines
7.1 KiB
Go
Raw Normal View History

cmd/compile/internal/ssa: BCE for induction variables There are 5293 loop in the main go repository. A survey of the top most common for loops: 18 for __k__ := 0; i < len(sa.Addr); i++ { 19 for __k__ := 0; ; i++ { 19 for __k__ := 0; i < 16; i++ { 25 for __k__ := 0; i < length; i++ { 30 for __k__ := 0; i < 8; i++ { 49 for __k__ := 0; i < len(s); i++ { 67 for __k__ := 0; i < n; i++ { 376 for __k__ := range __slice__ { 685 for __k__, __v__ := range __slice__ { 2074 for __, __v__ := range __slice__ { The algorithm to find induction variables handles all cases with an upper limit. It currently doesn't find related induction variables such as c * ind or c + ind. 842 out of 22954 bound checks are removed for src/make.bash. 1957 out of 42952 bounds checks are removed for src/all.bash. Things to do in follow-up CLs: * Find the associated pointer for `for _, v := range a {}` * Drop the NilChecks on the pointer. * Replace the implicit induction variable by a loop over the pointer Generated garbage can be reduced if we share the sdom between passes. % benchstat old.txt new.txt name old time/op new time/op delta Template 337ms ± 3% 333ms ± 3% ~ (p=0.258 n=9+9) GoTypes 1.11s ± 2% 1.10s ± 2% ~ (p=0.912 n=10+10) Compiler 5.25s ± 1% 5.29s ± 2% ~ (p=0.077 n=9+9) MakeBash 33.5s ± 1% 34.1s ± 2% +1.85% (p=0.011 n=9+9) name old alloc/op new alloc/op delta Template 63.6MB ± 0% 63.9MB ± 0% +0.52% (p=0.000 n=10+9) GoTypes 218MB ± 0% 219MB ± 0% +0.59% (p=0.000 n=10+9) Compiler 978MB ± 0% 985MB ± 0% +0.69% (p=0.000 n=10+10) name old allocs/op new allocs/op delta Template 582k ± 0% 583k ± 0% +0.10% (p=0.000 n=10+10) GoTypes 1.78M ± 0% 1.78M ± 0% +0.12% (p=0.000 n=10+10) Compiler 7.68M ± 0% 7.69M ± 0% +0.05% (p=0.000 n=10+10) name old text-bytes new text-bytes delta HelloSize 581k ± 0% 581k ± 0% -0.08% (p=0.000 n=10+10) CmdGoSize 6.40M ± 0% 6.39M ± 0% -0.08% (p=0.000 n=10+10) name old data-bytes new data-bytes delta HelloSize 3.66k ± 0% 3.66k ± 0% ~ (all samples are equal) CmdGoSize 134k ± 0% 134k ± 0% ~ (all samples are equal) name old bss-bytes new bss-bytes delta HelloSize 126k ± 0% 126k ± 0% ~ (all samples are equal) CmdGoSize 149k ± 0% 149k ± 0% ~ (all samples are equal) name old exe-bytes new exe-bytes delta HelloSize 947k ± 0% 946k ± 0% -0.01% (p=0.000 n=10+10) CmdGoSize 9.92M ± 0% 9.91M ± 0% -0.06% (p=0.000 n=10+10) Change-Id: Ie74bdff46fd602db41bb457333d3a762a0c3dc4d Reviewed-on: https://go-review.googlesource.com/20517 Reviewed-by: David Chase <drchase@google.com> Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
2016-03-02 11:58:27 +00:00
// +build amd64
// errorcheck -0 -d=ssa/loopbce/debug=3
package main
func f0a(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable with minimum 0 and increment 1$"
x += a[i] // ERROR "Found redundant IsInBounds$"
}
return x
}
func f0b(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable with minimum 0 and increment 1$"
b := a[i:] // ERROR "Found redundant IsSliceInBounds$"
x += b[0]
}
return x
}
func f0c(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable with minimum 0 and increment 1$"
b := a[:i+1] // ERROR "Found redundant IsSliceInBounds \(len promoted to cap\)$"
x += b[0]
}
return x
}
func f1(a []int) int {
x := 0
for _, i := range a { // ERROR "Induction variable with minimum 0 and increment 1"
cmd/compile/internal/ssa: BCE for induction variables There are 5293 loop in the main go repository. A survey of the top most common for loops: 18 for __k__ := 0; i < len(sa.Addr); i++ { 19 for __k__ := 0; ; i++ { 19 for __k__ := 0; i < 16; i++ { 25 for __k__ := 0; i < length; i++ { 30 for __k__ := 0; i < 8; i++ { 49 for __k__ := 0; i < len(s); i++ { 67 for __k__ := 0; i < n; i++ { 376 for __k__ := range __slice__ { 685 for __k__, __v__ := range __slice__ { 2074 for __, __v__ := range __slice__ { The algorithm to find induction variables handles all cases with an upper limit. It currently doesn't find related induction variables such as c * ind or c + ind. 842 out of 22954 bound checks are removed for src/make.bash. 1957 out of 42952 bounds checks are removed for src/all.bash. Things to do in follow-up CLs: * Find the associated pointer for `for _, v := range a {}` * Drop the NilChecks on the pointer. * Replace the implicit induction variable by a loop over the pointer Generated garbage can be reduced if we share the sdom between passes. % benchstat old.txt new.txt name old time/op new time/op delta Template 337ms ± 3% 333ms ± 3% ~ (p=0.258 n=9+9) GoTypes 1.11s ± 2% 1.10s ± 2% ~ (p=0.912 n=10+10) Compiler 5.25s ± 1% 5.29s ± 2% ~ (p=0.077 n=9+9) MakeBash 33.5s ± 1% 34.1s ± 2% +1.85% (p=0.011 n=9+9) name old alloc/op new alloc/op delta Template 63.6MB ± 0% 63.9MB ± 0% +0.52% (p=0.000 n=10+9) GoTypes 218MB ± 0% 219MB ± 0% +0.59% (p=0.000 n=10+9) Compiler 978MB ± 0% 985MB ± 0% +0.69% (p=0.000 n=10+10) name old allocs/op new allocs/op delta Template 582k ± 0% 583k ± 0% +0.10% (p=0.000 n=10+10) GoTypes 1.78M ± 0% 1.78M ± 0% +0.12% (p=0.000 n=10+10) Compiler 7.68M ± 0% 7.69M ± 0% +0.05% (p=0.000 n=10+10) name old text-bytes new text-bytes delta HelloSize 581k ± 0% 581k ± 0% -0.08% (p=0.000 n=10+10) CmdGoSize 6.40M ± 0% 6.39M ± 0% -0.08% (p=0.000 n=10+10) name old data-bytes new data-bytes delta HelloSize 3.66k ± 0% 3.66k ± 0% ~ (all samples are equal) CmdGoSize 134k ± 0% 134k ± 0% ~ (all samples are equal) name old bss-bytes new bss-bytes delta HelloSize 126k ± 0% 126k ± 0% ~ (all samples are equal) CmdGoSize 149k ± 0% 149k ± 0% ~ (all samples are equal) name old exe-bytes new exe-bytes delta HelloSize 947k ± 0% 946k ± 0% -0.01% (p=0.000 n=10+10) CmdGoSize 9.92M ± 0% 9.91M ± 0% -0.06% (p=0.000 n=10+10) Change-Id: Ie74bdff46fd602db41bb457333d3a762a0c3dc4d Reviewed-on: https://go-review.googlesource.com/20517 Reviewed-by: David Chase <drchase@google.com> Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
2016-03-02 11:58:27 +00:00
x += i
}
return x
}
func f2(a []int) int {
x := 0
for i := 1; i < len(a); i++ { // ERROR "Induction variable with minimum 1 and increment 1$"
x += a[i] // ERROR "Found redundant IsInBounds$"
}
return x
}
func f4(a [10]int) int {
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable with minimum 0 and increment 2$"
x += a[i] // ERROR "Found redundant IsInBounds$"
}
return x
}
func f5(a [10]int) int {
x := 0
for i := -10; i < len(a); i += 2 { // ERROR "Induction variable with minimum -10 and increment 2$"
x += a[i]
}
return x
}
func f6(a []int) {
for i := range a { // ERROR "Induction variable with minimum 0 and increment 1$"
b := a[0:i] // ERROR "Found redundant IsSliceInBounds \(len promoted to cap\)$"
f6(b)
}
}
func g0a(a string) int {
x := 0
for i := 0; i < len(a); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
x += int(a[i]) // ERROR "Found redundant IsInBounds$"
}
return x
}
func g0b(a string) int {
x := 0
for i := 0; len(a) > i; i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
x += int(a[i]) // ERROR "Found redundant IsInBounds$"
}
return x
}
func g1() int {
a := "evenlength"
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable with minimum 0 and increment 2$"
x += int(a[i]) // ERROR "Found redundant IsInBounds$"
}
return x
}
func g2() int {
a := "evenlength"
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable with minimum 0 and increment 2$"
j := i
if a[i] == 'e' { // ERROR "Found redundant IsInBounds$"
j = j + 1
}
x += int(a[j])
}
return x
}
func g3a() {
a := "this string has length 25"
for i := 0; i < len(a); i += 5 { // ERROR "Induction variable with minimum 0 and increment 5$"
useString(a[i:]) // ERROR "Found redundant IsSliceInBounds$"
useString(a[:i+3])
}
}
func g3b(a string) {
for i := 0; i < len(a); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
useString(a[i+1:]) // ERROR "Found redundant IsSliceInBounds$"
}
}
func g3c(a string) {
for i := 0; i < len(a); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
useString(a[:i+1]) // ERROR "Found redundant IsSliceInBounds$"
}
}
func h1(a []byte) {
c := a[:128]
for i := range c { // ERROR "Induction variable with minimum 0 and increment 1$"
c[i] = byte(i) // ERROR "Found redundant IsInBounds$"
}
}
func h2(a []byte) {
for i := range a[:128] { // ERROR "Induction variable with minimum 0 and increment 1$"
a[i] = byte(i)
}
}
func k0(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable with minimum 10 and increment 1$"
a[i-11] = i
a[i-10] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 80$"
a[i-5] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 85$"
a[i] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 90$"
a[i+5] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 95$"
a[i+10] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 100$"
a[i+11] = i
}
return a
}
func k1(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable with minimum 10 and increment 1$"
useSlice(a[:i-11])
useSlice(a[:i-10]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 80$"
useSlice(a[:i-5]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 85$"
useSlice(a[:i]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 90$"
useSlice(a[:i+5]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 95$"
useSlice(a[:i+10]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 100$"
useSlice(a[:i+11]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 101$"
}
return a
}
func k2(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable with minimum 10 and increment 1$"
useSlice(a[i-11:])
useSlice(a[i-10:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 80$"
useSlice(a[i-5:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 85$"
useSlice(a[i:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 90$"
useSlice(a[i+5:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 95$"
useSlice(a[i+10:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 100$"
useSlice(a[i+11:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 101$"
}
return a
}
func k3(a [100]int) [100]int {
for i := -10; i < 90; i++ { // ERROR "Induction variable with minimum -10 and increment 1$"
a[i+10] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 100$"
}
return a
}
func k4(a [100]int) [100]int {
min := (-1) << 63
for i := min; i < min+50; i++ { // ERROR "Induction variable with minimum -9223372036854775808 and increment 1$"
a[i-min] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 50$"
}
return a
}
func k5(a [100]int) [100]int {
max := (1 << 63) - 1
for i := max - 50; i < max; i++ { // ERROR "Induction variable with minimum 9223372036854775757 and increment 1$"
cmd/compile/ssa: more aggressive constant folding Add rewrite rules that canonicalize the location of constants in expressions, and fold conststants that appear in operations that can be trivially reassociated. After this change, the compiler constant-folds expressions like "4 + x - 1" and "4 & x & 1" Benchmarks affected on darwin/amd64: name old time/op new time/op delta FmtFprintfInt-8 82.1ns ± 1% 81.7ns ± 1% -0.46% (p=0.023 n=8+9) FmtFprintfIntInt-8 122ns ± 2% 120ns ± 2% -1.48% (p=0.047 n=10+10) FmtManyArgs-8 493ns ± 0% 486ns ± 1% -1.37% (p=0.000 n=8+10) Gzip-8 230ms ± 0% 229ms ± 1% -0.46% (p=0.001 n=10+9) HTTPClientServer-8 74.5µs ± 1% 73.7µs ± 1% -1.11% (p=0.000 n=10+10) JSONDecode-8 51.7ms ± 0% 51.9ms ± 1% +0.42% (p=0.017 n=10+9) RegexpMatchEasy0_32-8 82.6ns ± 1% 81.7ns ± 0% -1.02% (p=0.000 n=9+8) RegexpMatchMedium_32-8 121ns ± 1% 120ns ± 1% -1.48% (p=0.001 n=10+10) Revcomp-8 426ms ± 1% 400ms ± 1% -6.16% (p=0.000 n=10+10) TimeFormat-8 330ns ± 1% 327ns ± 0% -0.82% (p=0.000 n=10+10) name old speed new speed delta Gzip-8 84.4MB/s ± 0% 84.8MB/s ± 1% +0.47% (p=0.001 n=10+9) JSONDecode-8 37.6MB/s ± 0% 37.4MB/s ± 1% -0.42% (p=0.016 n=10+9) RegexpMatchEasy0_32-8 387MB/s ± 1% 392MB/s ± 0% +1.06% (p=0.000 n=9+8) RegexpMatchMedium_32-8 8.21MB/s ± 1% 8.34MB/s ± 1% +1.58% (p=0.000 n=10+9) Revcomp-8 597MB/s ± 1% 636MB/s ± 1% +6.57% (p=0.000 n=10+10) Change-Id: Ie37ff91605b76a984a8400dfd1e34f50bf61c864 Reviewed-on: https://go-review.googlesource.com/37290 Reviewed-by: Keith Randall <khr@golang.org> Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-02-20 16:43:54 +00:00
a[i-max+50] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 50$"
a[i-(max-70)] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 70$"
}
return a
}
cmd/compile/internal/ssa: BCE for induction variables There are 5293 loop in the main go repository. A survey of the top most common for loops: 18 for __k__ := 0; i < len(sa.Addr); i++ { 19 for __k__ := 0; ; i++ { 19 for __k__ := 0; i < 16; i++ { 25 for __k__ := 0; i < length; i++ { 30 for __k__ := 0; i < 8; i++ { 49 for __k__ := 0; i < len(s); i++ { 67 for __k__ := 0; i < n; i++ { 376 for __k__ := range __slice__ { 685 for __k__, __v__ := range __slice__ { 2074 for __, __v__ := range __slice__ { The algorithm to find induction variables handles all cases with an upper limit. It currently doesn't find related induction variables such as c * ind or c + ind. 842 out of 22954 bound checks are removed for src/make.bash. 1957 out of 42952 bounds checks are removed for src/all.bash. Things to do in follow-up CLs: * Find the associated pointer for `for _, v := range a {}` * Drop the NilChecks on the pointer. * Replace the implicit induction variable by a loop over the pointer Generated garbage can be reduced if we share the sdom between passes. % benchstat old.txt new.txt name old time/op new time/op delta Template 337ms ± 3% 333ms ± 3% ~ (p=0.258 n=9+9) GoTypes 1.11s ± 2% 1.10s ± 2% ~ (p=0.912 n=10+10) Compiler 5.25s ± 1% 5.29s ± 2% ~ (p=0.077 n=9+9) MakeBash 33.5s ± 1% 34.1s ± 2% +1.85% (p=0.011 n=9+9) name old alloc/op new alloc/op delta Template 63.6MB ± 0% 63.9MB ± 0% +0.52% (p=0.000 n=10+9) GoTypes 218MB ± 0% 219MB ± 0% +0.59% (p=0.000 n=10+9) Compiler 978MB ± 0% 985MB ± 0% +0.69% (p=0.000 n=10+10) name old allocs/op new allocs/op delta Template 582k ± 0% 583k ± 0% +0.10% (p=0.000 n=10+10) GoTypes 1.78M ± 0% 1.78M ± 0% +0.12% (p=0.000 n=10+10) Compiler 7.68M ± 0% 7.69M ± 0% +0.05% (p=0.000 n=10+10) name old text-bytes new text-bytes delta HelloSize 581k ± 0% 581k ± 0% -0.08% (p=0.000 n=10+10) CmdGoSize 6.40M ± 0% 6.39M ± 0% -0.08% (p=0.000 n=10+10) name old data-bytes new data-bytes delta HelloSize 3.66k ± 0% 3.66k ± 0% ~ (all samples are equal) CmdGoSize 134k ± 0% 134k ± 0% ~ (all samples are equal) name old bss-bytes new bss-bytes delta HelloSize 126k ± 0% 126k ± 0% ~ (all samples are equal) CmdGoSize 149k ± 0% 149k ± 0% ~ (all samples are equal) name old exe-bytes new exe-bytes delta HelloSize 947k ± 0% 946k ± 0% -0.01% (p=0.000 n=10+10) CmdGoSize 9.92M ± 0% 9.91M ± 0% -0.06% (p=0.000 n=10+10) Change-Id: Ie74bdff46fd602db41bb457333d3a762a0c3dc4d Reviewed-on: https://go-review.googlesource.com/20517 Reviewed-by: David Chase <drchase@google.com> Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
2016-03-02 11:58:27 +00:00
func nobce1() {
// tests overflow of max-min
a := int64(9223372036854774057)
b := int64(-1547)
z := int64(1337)
if a%z == b%z {
panic("invalid test: modulos should differ")
}
for i := b; i < a; i += z {
// No induction variable is possible because i will overflow a first iteration.
useString("foobar")
}
}
func nobce2(a string) {
for i := int64(0); i < int64(len(a)); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
useString(a[i:]) // ERROR "Found redundant IsSliceInBounds$"
}
for i := int64(0); i < int64(len(a))-31337; i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
useString(a[i:]) // ERROR "Found redundant IsSliceInBounds$"
}
for i := int64(0); i < int64(len(a))+int64(-1<<63); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
// tests an overflow of StringLen-MinInt64
useString(a[i:])
}
}
func nobce3(a [100]int64) [100]int64 {
min := int64((-1) << 63)
max := int64((1 << 63) - 1)
for i := min; i < max; i++ { // ERROR "Induction variable with minimum -9223372036854775808 and increment 1$"
a[i] = i
}
return a
}
cmd/compile/internal/ssa: BCE for induction variables There are 5293 loop in the main go repository. A survey of the top most common for loops: 18 for __k__ := 0; i < len(sa.Addr); i++ { 19 for __k__ := 0; ; i++ { 19 for __k__ := 0; i < 16; i++ { 25 for __k__ := 0; i < length; i++ { 30 for __k__ := 0; i < 8; i++ { 49 for __k__ := 0; i < len(s); i++ { 67 for __k__ := 0; i < n; i++ { 376 for __k__ := range __slice__ { 685 for __k__, __v__ := range __slice__ { 2074 for __, __v__ := range __slice__ { The algorithm to find induction variables handles all cases with an upper limit. It currently doesn't find related induction variables such as c * ind or c + ind. 842 out of 22954 bound checks are removed for src/make.bash. 1957 out of 42952 bounds checks are removed for src/all.bash. Things to do in follow-up CLs: * Find the associated pointer for `for _, v := range a {}` * Drop the NilChecks on the pointer. * Replace the implicit induction variable by a loop over the pointer Generated garbage can be reduced if we share the sdom between passes. % benchstat old.txt new.txt name old time/op new time/op delta Template 337ms ± 3% 333ms ± 3% ~ (p=0.258 n=9+9) GoTypes 1.11s ± 2% 1.10s ± 2% ~ (p=0.912 n=10+10) Compiler 5.25s ± 1% 5.29s ± 2% ~ (p=0.077 n=9+9) MakeBash 33.5s ± 1% 34.1s ± 2% +1.85% (p=0.011 n=9+9) name old alloc/op new alloc/op delta Template 63.6MB ± 0% 63.9MB ± 0% +0.52% (p=0.000 n=10+9) GoTypes 218MB ± 0% 219MB ± 0% +0.59% (p=0.000 n=10+9) Compiler 978MB ± 0% 985MB ± 0% +0.69% (p=0.000 n=10+10) name old allocs/op new allocs/op delta Template 582k ± 0% 583k ± 0% +0.10% (p=0.000 n=10+10) GoTypes 1.78M ± 0% 1.78M ± 0% +0.12% (p=0.000 n=10+10) Compiler 7.68M ± 0% 7.69M ± 0% +0.05% (p=0.000 n=10+10) name old text-bytes new text-bytes delta HelloSize 581k ± 0% 581k ± 0% -0.08% (p=0.000 n=10+10) CmdGoSize 6.40M ± 0% 6.39M ± 0% -0.08% (p=0.000 n=10+10) name old data-bytes new data-bytes delta HelloSize 3.66k ± 0% 3.66k ± 0% ~ (all samples are equal) CmdGoSize 134k ± 0% 134k ± 0% ~ (all samples are equal) name old bss-bytes new bss-bytes delta HelloSize 126k ± 0% 126k ± 0% ~ (all samples are equal) CmdGoSize 149k ± 0% 149k ± 0% ~ (all samples are equal) name old exe-bytes new exe-bytes delta HelloSize 947k ± 0% 946k ± 0% -0.01% (p=0.000 n=10+10) CmdGoSize 9.92M ± 0% 9.91M ± 0% -0.06% (p=0.000 n=10+10) Change-Id: Ie74bdff46fd602db41bb457333d3a762a0c3dc4d Reviewed-on: https://go-review.googlesource.com/20517 Reviewed-by: David Chase <drchase@google.com> Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
2016-03-02 11:58:27 +00:00
//go:noinline
func useString(a string) {
}
//go:noinline
func useSlice(a []int) {
}
cmd/compile/internal/ssa: BCE for induction variables There are 5293 loop in the main go repository. A survey of the top most common for loops: 18 for __k__ := 0; i < len(sa.Addr); i++ { 19 for __k__ := 0; ; i++ { 19 for __k__ := 0; i < 16; i++ { 25 for __k__ := 0; i < length; i++ { 30 for __k__ := 0; i < 8; i++ { 49 for __k__ := 0; i < len(s); i++ { 67 for __k__ := 0; i < n; i++ { 376 for __k__ := range __slice__ { 685 for __k__, __v__ := range __slice__ { 2074 for __, __v__ := range __slice__ { The algorithm to find induction variables handles all cases with an upper limit. It currently doesn't find related induction variables such as c * ind or c + ind. 842 out of 22954 bound checks are removed for src/make.bash. 1957 out of 42952 bounds checks are removed for src/all.bash. Things to do in follow-up CLs: * Find the associated pointer for `for _, v := range a {}` * Drop the NilChecks on the pointer. * Replace the implicit induction variable by a loop over the pointer Generated garbage can be reduced if we share the sdom between passes. % benchstat old.txt new.txt name old time/op new time/op delta Template 337ms ± 3% 333ms ± 3% ~ (p=0.258 n=9+9) GoTypes 1.11s ± 2% 1.10s ± 2% ~ (p=0.912 n=10+10) Compiler 5.25s ± 1% 5.29s ± 2% ~ (p=0.077 n=9+9) MakeBash 33.5s ± 1% 34.1s ± 2% +1.85% (p=0.011 n=9+9) name old alloc/op new alloc/op delta Template 63.6MB ± 0% 63.9MB ± 0% +0.52% (p=0.000 n=10+9) GoTypes 218MB ± 0% 219MB ± 0% +0.59% (p=0.000 n=10+9) Compiler 978MB ± 0% 985MB ± 0% +0.69% (p=0.000 n=10+10) name old allocs/op new allocs/op delta Template 582k ± 0% 583k ± 0% +0.10% (p=0.000 n=10+10) GoTypes 1.78M ± 0% 1.78M ± 0% +0.12% (p=0.000 n=10+10) Compiler 7.68M ± 0% 7.69M ± 0% +0.05% (p=0.000 n=10+10) name old text-bytes new text-bytes delta HelloSize 581k ± 0% 581k ± 0% -0.08% (p=0.000 n=10+10) CmdGoSize 6.40M ± 0% 6.39M ± 0% -0.08% (p=0.000 n=10+10) name old data-bytes new data-bytes delta HelloSize 3.66k ± 0% 3.66k ± 0% ~ (all samples are equal) CmdGoSize 134k ± 0% 134k ± 0% ~ (all samples are equal) name old bss-bytes new bss-bytes delta HelloSize 126k ± 0% 126k ± 0% ~ (all samples are equal) CmdGoSize 149k ± 0% 149k ± 0% ~ (all samples are equal) name old exe-bytes new exe-bytes delta HelloSize 947k ± 0% 946k ± 0% -0.01% (p=0.000 n=10+10) CmdGoSize 9.92M ± 0% 9.91M ± 0% -0.06% (p=0.000 n=10+10) Change-Id: Ie74bdff46fd602db41bb457333d3a762a0c3dc4d Reviewed-on: https://go-review.googlesource.com/20517 Reviewed-by: David Chase <drchase@google.com> Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
2016-03-02 11:58:27 +00:00
func main() {
}