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cmd/goyacc: reduce array sizes using smaller base types
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These arrays can be quite large, reducing the size of them
save lot of space reducing cache usage and file size.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>
Change-Id: I446088627bc135cb47f6bee919e147b24d1ad848
Reviewed-on: https://go-review.googlesource.com/c/tools/+/374434
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
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@freddy77 @ianlancetaylor
freddy77 authored and ianlancetaylor committed Feb 16, 2022
1 parent c677677 commit 59f1f2c
Showing 1 changed file with 92 additions and 54 deletions.
146 changes: 92 additions & 54 deletions cmd/goyacc/yacc.go
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@ import (
"fmt"
"go/format"
"io/ioutil"
"math"
"os"
"strconv"
"strings"
Expand Down Expand Up @@ -2157,7 +2158,7 @@ func output() {
if !lflag {
fmt.Fprintf(ftable, "\n//line yacctab:1")
}
fmt.Fprintf(ftable, "\nvar %sExca = [...]int{\n", prefix)
var actions []int

if len(errors) > 0 {
stateTable = make([]Row, nstate)
Expand Down Expand Up @@ -2230,10 +2231,11 @@ func output() {
}
}
}
wract(i)
actions = addActions(actions, i)
}

fmt.Fprintf(ftable, "}\n")
arrayOutColumns("Exca", actions, 2, false)
fmt.Fprintf(ftable, "\n")
ftable.WriteRune('\n')
fmt.Fprintf(ftable, "const %sPrivate = %v\n", prefix, PRIVATE)
}
Expand Down Expand Up @@ -2278,7 +2280,7 @@ func precftn(r, t, s int) {
// output state i
// temp1 has the actions, lastred the default
//
func wract(i int) {
func addActions(act []int, i int) []int {
var p, p1 int

// find the best choice for lastred
Expand Down Expand Up @@ -2351,18 +2353,19 @@ func wract(i int) {
continue
}
if flag == 0 {
fmt.Fprintf(ftable, "\t-1, %v,\n", i)
act = append(act, -1, i)
}
flag++
fmt.Fprintf(ftable, "\t%v, %v,\n", p, p1)
act = append(act, p, p1)
zzexcp++
}
}
if flag != 0 {
defact[i] = -2
fmt.Fprintf(ftable, "\t-2, %v,\n", lastred)
act = append(act, -2, lastred)
}
optst[i] = os
return act
}

//
Expand Down Expand Up @@ -2855,7 +2858,7 @@ func others() {
}
}
arout("Chk", temp1, nstate)
arout("Def", defact, nstate)
arrayOutColumns("Def", defact[:nstate], 10, false)

// put out token translation tables
// table 1 has 0-256
Expand Down Expand Up @@ -2903,8 +2906,7 @@ func others() {

// table 3 has everything else
ftable.WriteRune('\n')
fmt.Fprintf(ftable, "var %sTok3 = [...]int{\n\t", prefix)
c = 0
var v []int
for i = 1; i <= ntokens; i++ {
j = tokset[i].value
if j >= 0 && j < 256 {
Expand All @@ -2914,19 +2916,11 @@ func others() {
continue
}

if c%5 != 0 {
ftable.WriteRune(' ')
}
fmt.Fprintf(ftable, "%d, %d,", j, i)
c++
if c%5 == 0 {
fmt.Fprint(ftable, "\n\t")
}
v = append(v, j, i)
}
if c%5 != 0 {
ftable.WriteRune(' ')
}
fmt.Fprintf(ftable, "%d,\n}\n", 0)
v = append(v, 0)
arout("Tok3", v, len(v))
fmt.Fprintf(ftable, "\n")

// Custom error messages.
fmt.Fprintf(ftable, "\n")
Expand Down Expand Up @@ -3013,21 +3007,65 @@ Loop:
}
}

func arout(s string, v []int, n int) {
func minMax(v []int) (min, max int) {
if len(v) == 0 {
return
}
min = v[0]
max = v[0]
for _, i := range v {
if i < min {
min = i
}
if i > max {
max = i
}
}
return
}

// return the smaller integral base type to store the values in v
func minType(v []int, allowUnsigned bool) (typ string) {
typ = "int"
typeLen := 8
min, max := minMax(v)
checkType := func(name string, size, minType, maxType int) {
if min >= minType && max <= maxType && typeLen > size {
typ = name
typeLen = size
}
}
checkType("int32", 4, math.MinInt32, math.MaxInt32)
checkType("int16", 2, math.MinInt16, math.MaxInt16)
checkType("int8", 1, math.MinInt8, math.MaxInt8)
if allowUnsigned {
// Do not check for uint32, not worth and won't compile on 32 bit systems
checkType("uint16", 2, 0, math.MaxUint16)
checkType("uint8", 1, 0, math.MaxUint8)
}
return
}

func arrayOutColumns(s string, v []int, columns int, allowUnsigned bool) {
s = prefix + s
ftable.WriteRune('\n')
fmt.Fprintf(ftable, "var %v = [...]int{", s)
for i := 0; i < n; i++ {
if i%10 == 0 {
minType := minType(v, allowUnsigned)
fmt.Fprintf(ftable, "var %v = [...]%s{", s, minType)
for i, val := range v {
if i%columns == 0 {
fmt.Fprintf(ftable, "\n\t")
} else {
ftable.WriteRune(' ')
}
fmt.Fprintf(ftable, "%d,", v[i])
fmt.Fprintf(ftable, "%d,", val)
}
fmt.Fprintf(ftable, "\n}\n")
}

func arout(s string, v []int, n int) {
arrayOutColumns(s, v[:n], 10, true)
}

//
// output the summary on y.output
//
Expand Down Expand Up @@ -3332,9 +3370,9 @@ func $$ErrorMessage(state, lookAhead int) string {
expected := make([]int, 0, 4)
// Look for shiftable tokens.
base := $$Pact[state]
base := int($$Pact[state])
for tok := TOKSTART; tok-1 < len($$Toknames); tok++ {
if n := base + tok; n >= 0 && n < $$Last && $$Chk[$$Act[n]] == tok {
if n := base + tok; n >= 0 && n < $$Last && int($$Chk[int($$Act[n])]) == tok {
if len(expected) == cap(expected) {
return res
}
Expand All @@ -3344,13 +3382,13 @@ func $$ErrorMessage(state, lookAhead int) string {
if $$Def[state] == -2 {
i := 0
for $$Exca[i] != -1 || $$Exca[i+1] != state {
for $$Exca[i] != -1 || int($$Exca[i+1]) != state {
i += 2
}
// Look for tokens that we accept or reduce.
for i += 2; $$Exca[i] >= 0; i += 2 {
tok := $$Exca[i]
tok := int($$Exca[i])
if tok < TOKSTART || $$Exca[i+1] == 0 {
continue
}
Expand Down Expand Up @@ -3381,30 +3419,30 @@ func $$lex1(lex $$Lexer, lval *$$SymType) (char, token int) {
token = 0
char = lex.Lex(lval)
if char <= 0 {
token = $$Tok1[0]
token = int($$Tok1[0])
goto out
}
if char < len($$Tok1) {
token = $$Tok1[char]
token = int($$Tok1[char])
goto out
}
if char >= $$Private {
if char < $$Private+len($$Tok2) {
token = $$Tok2[char-$$Private]
token = int($$Tok2[char-$$Private])
goto out
}
}
for i := 0; i < len($$Tok3); i += 2 {
token = $$Tok3[i+0]
token = int($$Tok3[i+0])
if token == char {
token = $$Tok3[i+1]
token = int($$Tok3[i+1])
goto out
}
}
out:
if token == 0 {
token = $$Tok2[1] /* unknown char */
token = int($$Tok2[1]) /* unknown char */
}
if $$Debug >= 3 {
__yyfmt__.Printf("lex %s(%d)\n", $$Tokname(token), uint(char))
Expand Down Expand Up @@ -3459,7 +3497,7 @@ $$stack:
$$S[$$p].yys = $$state
$$newstate:
$$n = $$Pact[$$state]
$$n = int($$Pact[$$state])
if $$n <= $$Flag {
goto $$default /* simple state */
}
Expand All @@ -3470,8 +3508,8 @@ $$newstate:
if $$n < 0 || $$n >= $$Last {
goto $$default
}
$$n = $$Act[$$n]
if $$Chk[$$n] == $$token { /* valid shift */
$$n = int($$Act[$$n])
if int($$Chk[$$n]) == $$token { /* valid shift */
$$rcvr.char = -1
$$token = -1
$$VAL = $$rcvr.lval
Expand All @@ -3484,7 +3522,7 @@ $$newstate:
$$default:
/* default state action */
$$n = $$Def[$$state]
$$n = int($$Def[$$state])
if $$n == -2 {
if $$rcvr.char < 0 {
$$rcvr.char, $$token = $$lex1($$lex, &$$rcvr.lval)
Expand All @@ -3493,18 +3531,18 @@ $$default:
/* look through exception table */
xi := 0
for {
if $$Exca[xi+0] == -1 && $$Exca[xi+1] == $$state {
if $$Exca[xi+0] == -1 && int($$Exca[xi+1]) == $$state {
break
}
xi += 2
}
for xi += 2; ; xi += 2 {
$$n = $$Exca[xi+0]
$$n = int($$Exca[xi+0])
if $$n < 0 || $$n == $$token {
break
}
}
$$n = $$Exca[xi+1]
$$n = int($$Exca[xi+1])
if $$n < 0 {
goto ret0
}
Expand All @@ -3526,10 +3564,10 @@ $$default:
/* find a state where "error" is a legal shift action */
for $$p >= 0 {
$$n = $$Pact[$$S[$$p].yys] + $$ErrCode
$$n = int($$Pact[$$S[$$p].yys]) + $$ErrCode
if $$n >= 0 && $$n < $$Last {
$$state = $$Act[$$n] /* simulate a shift of "error" */
if $$Chk[$$state] == $$ErrCode {
$$state = int($$Act[$$n]) /* simulate a shift of "error" */
if int($$Chk[$$state]) == $$ErrCode {
goto $$stack
}
}
Expand Down Expand Up @@ -3565,7 +3603,7 @@ $$default:
$$pt := $$p
_ = $$pt // guard against "declared and not used"
$$p -= $$R2[$$n]
$$p -= int($$R2[$$n])
// $$p is now the index of $0. Perform the default action. Iff the
// reduced production is ε, $1 is possibly out of range.
if $$p+1 >= len($$S) {
Expand All @@ -3576,16 +3614,16 @@ $$default:
$$VAL = $$S[$$p+1]
/* consult goto table to find next state */
$$n = $$R1[$$n]
$$g := $$Pgo[$$n]
$$n = int($$R1[$$n])
$$g := int($$Pgo[$$n])
$$j := $$g + $$S[$$p].yys + 1
if $$j >= $$Last {
$$state = $$Act[$$g]
$$state = int($$Act[$$g])
} else {
$$state = $$Act[$$j]
if $$Chk[$$state] != -$$n {
$$state = $$Act[$$g]
$$state = int($$Act[$$j])
if int($$Chk[$$state]) != -$$n {
$$state = int($$Act[$$g])
}
}
// dummy call; replaced with literal code
Expand Down

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