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cmd/gc: allocate buffers for non-escaping string conversions on stack

Support the following conversions in escape analysis:
[]rune("foo")
[]byte("foo")
string([]rune{})

If the result does not escape, allocate temp buffer on stack
and pass it to runtime functions.

Change-Id: I1d075907eab8b0109ad7ad1878104b02b3d5c690
Reviewed-on: https://go-review.googlesource.com/3590
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Dmitry Vyukov 2015-01-30 09:14:13 +03:00
parent cdc2b0568f
commit 9568126f35
7 changed files with 159 additions and 36 deletions

View File

@ -36,10 +36,10 @@ char *runtimeimport =
"func @\"\".intstring (? *[4]byte, ? int64) (? string)\n"
"func @\"\".slicebytetostring (? *[32]byte, ? []byte) (? string)\n"
"func @\"\".slicebytetostringtmp (? []byte) (? string)\n"
"func @\"\".slicerunetostring (? []rune) (? string)\n"
"func @\"\".stringtoslicebyte (? string) (? []byte)\n"
"func @\"\".slicerunetostring (? *[32]byte, ? []rune) (? string)\n"
"func @\"\".stringtoslicebyte (? *[32]byte, ? string) (? []byte)\n"
"func @\"\".stringtoslicebytetmp (? string) (? []byte)\n"
"func @\"\".stringtoslicerune (? string) (? []rune)\n"
"func @\"\".stringtoslicerune (? *[32]rune, ? string) (? []rune)\n"
"func @\"\".stringiter (? string, ? int) (? int)\n"
"func @\"\".stringiter2 (? string, ? int) (@\"\".retk·1 int, @\"\".retv·2 rune)\n"
"func @\"\".slicecopy (@\"\".to·2 any, @\"\".fr·3 any, @\"\".wid·4 uintptr) (? int)\n"

View File

@ -693,12 +693,10 @@ esc(EscState *e, Node *n, Node *up)
case OMAKEMAP:
case OMAKESLICE:
case ONEW:
n->escloopdepth = e->loopdepth;
n->esc = EscNone; // until proven otherwise
e->noesc = list(e->noesc, n);
break;
case OARRAYRUNESTR:
case OARRAYBYTESTR:
case OSTRARRAYRUNE:
case OSTRARRAYBYTE:
case ORUNESTR:
n->escloopdepth = e->loopdepth;
n->esc = EscNone; // until proven otherwise
@ -824,7 +822,10 @@ escassign(EscState *e, Node *dst, Node *src)
case OMAKECHAN:
case OMAKEMAP:
case OMAKESLICE:
case OARRAYRUNESTR:
case OARRAYBYTESTR:
case OSTRARRAYRUNE:
case OSTRARRAYBYTE:
case OADDSTR:
case ONEW:
case OCLOSURE:
@ -1249,7 +1250,10 @@ escwalk(EscState *e, int level, Node *dst, Node *src)
case OMAKECHAN:
case OMAKEMAP:
case OMAKESLICE:
case OARRAYRUNESTR:
case OARRAYBYTESTR:
case OSTRARRAYRUNE:
case OSTRARRAYBYTE:
case OADDSTR:
case OMAPLIT:
case ONEW:

View File

@ -50,10 +50,10 @@ func eqstring(string, string) bool
func intstring(*[4]byte, int64) string
func slicebytetostring(*[32]byte, []byte) string
func slicebytetostringtmp([]byte) string
func slicerunetostring([]rune) string
func stringtoslicebyte(string) []byte
func slicerunetostring(*[32]byte, []rune) string
func stringtoslicebyte(*[32]byte, string) []byte
func stringtoslicebytetmp(string) []byte
func stringtoslicerune(string) []rune
func stringtoslicerune(*[32]rune, string) []rune
func stringiter(string, int) int
func stringiter2(string, int) (retk int, retv rune)
func slicecopy(to any, fr any, wid uintptr) int

View File

@ -1398,13 +1398,25 @@ walkexpr(Node **np, NodeList **init)
goto ret;
case OARRAYRUNESTR:
// slicerunetostring([]rune) string;
n = mkcall("slicerunetostring", n->type, init, n->left);
// slicerunetostring(*[32]byte, []rune) string;
a = nodnil();
if(n->esc == EscNone) {
// Create temporary buffer for string on stack.
t = aindex(nodintconst(tmpstringbufsize), types[TUINT8]);
a = nod(OADDR, temp(t), N);
}
n = mkcall("slicerunetostring", n->type, init, a, n->left);
goto ret;
case OSTRARRAYBYTE:
// stringtoslicebyte(string) []byte;
n = mkcall("stringtoslicebyte", n->type, init, conv(n->left, types[TSTRING]));
// stringtoslicebyte(*32[byte], string) []byte;
a = nodnil();
if(n->esc == EscNone) {
// Create temporary buffer for slice on stack.
t = aindex(nodintconst(tmpstringbufsize), types[TUINT8]);
a = nod(OADDR, temp(t), N);
}
n = mkcall("stringtoslicebyte", n->type, init, a, conv(n->left, types[TSTRING]));
goto ret;
case OSTRARRAYBYTETMP:
@ -1413,8 +1425,14 @@ walkexpr(Node **np, NodeList **init)
goto ret;
case OSTRARRAYRUNE:
// stringtoslicerune(string) []rune
n = mkcall("stringtoslicerune", n->type, init, n->left);
// stringtoslicerune(*[32]rune, string) []rune
a = nodnil();
if(n->esc == EscNone) {
// Create temporary buffer for slice on stack.
t = aindex(nodintconst(tmpstringbufsize), types[TINT32]);
a = nod(OADDR, temp(t), N);
}
n = mkcall("stringtoslicerune", n->type, init, a, n->left);
goto ret;
case OCMPIFACE:

View File

@ -129,8 +129,13 @@ func slicebytetostringtmp(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
func stringtoslicebyte(s string) []byte {
b := rawbyteslice(len(s))
func stringtoslicebyte(buf *tmpBuf, s string) []byte {
var b []byte
if buf != nil && len(s) <= len(buf) {
b = buf[:len(s)]
} else {
b = rawbyteslice(len(s))
}
copy(b, s)
return b
}
@ -147,7 +152,7 @@ func stringtoslicebytetmp(s string) []byte {
return *(*[]byte)(unsafe.Pointer(&ret))
}
func stringtoslicerune(s string) []rune {
func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
// two passes.
// unlike slicerunetostring, no race because strings are immutable.
n := 0
@ -157,7 +162,12 @@ func stringtoslicerune(s string) []rune {
s = s[k:]
n++
}
a := rawruneslice(n)
var a []rune
if buf != nil && n <= len(buf) {
a = buf[:n]
} else {
a = rawruneslice(n)
}
n = 0
for len(t) > 0 {
r, k := charntorune(t)
@ -168,7 +178,7 @@ func stringtoslicerune(s string) []rune {
return a
}
func slicerunetostring(a []rune) string {
func slicerunetostring(buf *tmpBuf, a []rune) string {
if raceenabled && len(a) > 0 {
racereadrangepc(unsafe.Pointer(&a[0]),
uintptr(len(a))*unsafe.Sizeof(a[0]),
@ -180,7 +190,7 @@ func slicerunetostring(a []rune) string {
for _, r := range a {
size1 += runetochar(dum[:], r)
}
s, b := rawstring(size1 + 3)
s, b := rawstringtmp(buf, size1+3)
size2 := 0
for _, r := range a {
// check for race
@ -309,11 +319,6 @@ func gobytes(p *byte, n int) []byte {
return x
}
func gostringsize(n int) string {
s, _ := rawstring(n)
return s
}
func gostring(p *byte) string {
l := findnull(p)
if l == 0 {

View File

@ -212,7 +212,7 @@ func foo21() func() int {
func foo21a() func() int {
x := 42 // ERROR "moved to heap: x"
return func() int { // ERROR "func literal escapes to heap"
x++ // ERROR "&x escapes to heap"
x++ // ERROR "&x escapes to heap"
return x
}
}
@ -1560,14 +1560,14 @@ func ptrlitNoescape() {
func ptrlitNoEscape2() {
// Literal does not escape, but element does.
i := 0 // ERROR "moved to heap: i"
i := 0 // ERROR "moved to heap: i"
x := &Lit{&i} // ERROR "&Lit literal does not escape" "&i escapes to heap"
sink = *x
}
func ptrlitEscape() {
// Both literal and element escape.
i := 0 // ERROR "moved to heap: i"
i := 0 // ERROR "moved to heap: i"
x := &Lit{&i} // ERROR "&Lit literal escapes to heap" "&i escapes to heap"
sink = x
}
@ -1619,7 +1619,7 @@ type StructWithString struct {
// to just x, and thus &i looks escaping.
func fieldFlowTracking() {
var x StructWithString
i := 0 // ERROR "moved to heap: i"
i := 0 // ERROR "moved to heap: i"
x.p = &i // ERROR "&i escapes to heap"
sink = x.s
}
@ -1703,3 +1703,51 @@ func intstring2() {
s := string(x) // ERROR "string\(x\) escapes to heap" "moved to heap: s"
sink = &s // ERROR "&s escapes to heap"
}
func stringtoslicebyte0() {
s := "foo"
x := []byte(s) // ERROR "\(\[\]byte\)\(s\) does not escape"
_ = x
}
func stringtoslicebyte1() []byte {
s := "foo"
return []byte(s) // ERROR "\(\[\]byte\)\(s\) escapes to heap"
}
func stringtoslicebyte2() {
s := "foo"
sink = []byte(s) // ERROR "\(\[\]byte\)\(s\) escapes to heap"
}
func stringtoslicerune0() {
s := "foo"
x := []rune(s) // ERROR "\(\[\]rune\)\(s\) does not escape"
_ = x
}
func stringtoslicerune1() []rune {
s := "foo"
return []rune(s) // ERROR "\(\[\]rune\)\(s\) escapes to heap"
}
func stringtoslicerune2() {
s := "foo"
sink = []rune(s) // ERROR "\(\[\]rune\)\(s\) escapes to heap"
}
func slicerunetostring0() {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape"
s := string(r) // ERROR "string\(r\) does not escape"
_ = s
}
func slicerunetostring1() string {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape"
return string(r) // ERROR "string\(r\) escapes to heap"
}
func slicerunetostring2() {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape"
sink = string(r) // ERROR "string\(r\) escapes to heap"
}

View File

@ -212,7 +212,7 @@ func foo21() func() int {
func foo21a() func() int {
x := 42 // ERROR "moved to heap: x"
return func() int { // ERROR "func literal escapes to heap"
x++ // ERROR "&x escapes to heap"
x++ // ERROR "&x escapes to heap"
return x
}
}
@ -1560,14 +1560,14 @@ func ptrlitNoescape() {
func ptrlitNoEscape2() {
// Literal does not escape, but element does.
i := 0 // ERROR "moved to heap: i"
i := 0 // ERROR "moved to heap: i"
x := &Lit{&i} // ERROR "&Lit literal does not escape" "&i escapes to heap"
sink = *x
}
func ptrlitEscape() {
// Both literal and element escape.
i := 0 // ERROR "moved to heap: i"
i := 0 // ERROR "moved to heap: i"
x := &Lit{&i} // ERROR "&Lit literal escapes to heap" "&i escapes to heap"
sink = x
}
@ -1619,7 +1619,7 @@ type StructWithString struct {
// to just x, and thus &i looks escaping.
func fieldFlowTracking() {
var x StructWithString
i := 0 // ERROR "moved to heap: i"
i := 0 // ERROR "moved to heap: i"
x.p = &i // ERROR "&i escapes to heap"
sink = x.s
}
@ -1703,3 +1703,51 @@ func intstring2() {
s := string(x) // ERROR "string\(x\) escapes to heap" "moved to heap: s"
sink = &s // ERROR "&s escapes to heap"
}
func stringtoslicebyte0() {
s := "foo"
x := []byte(s) // ERROR "\(\[\]byte\)\(s\) does not escape"
_ = x
}
func stringtoslicebyte1() []byte {
s := "foo"
return []byte(s) // ERROR "\(\[\]byte\)\(s\) escapes to heap"
}
func stringtoslicebyte2() {
s := "foo"
sink = []byte(s) // ERROR "\(\[\]byte\)\(s\) escapes to heap"
}
func stringtoslicerune0() {
s := "foo"
x := []rune(s) // ERROR "\(\[\]rune\)\(s\) does not escape"
_ = x
}
func stringtoslicerune1() []rune {
s := "foo"
return []rune(s) // ERROR "\(\[\]rune\)\(s\) escapes to heap"
}
func stringtoslicerune2() {
s := "foo"
sink = []rune(s) // ERROR "\(\[\]rune\)\(s\) escapes to heap"
}
func slicerunetostring0() {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape"
s := string(r) // ERROR "string\(r\) does not escape"
_ = s
}
func slicerunetostring1() string {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape"
return string(r) // ERROR "string\(r\) escapes to heap"
}
func slicerunetostring2() {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape"
sink = string(r) // ERROR "string\(r\) escapes to heap"
}