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runtime: use better hash for non-empty interface

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The implementation 'return 0' results in too many collisions.

LGTM=khr
R=golang-codereviews, adonovan, khr
CC=golang-codereviews, iant, khr, r
https://golang.org/cl/125720044
This commit is contained in:
Russ Cox 2014-08-06 16:22:52 -04:00
parent 2185dbcd85
commit f098a29630
3 changed files with 29 additions and 54 deletions
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17
src/pkg/runtime/alg.go
View file

@ -111,7 +111,22 @@ func nohash(a unsafe.Pointer, s uintptr, h uintptr) uintptr {
func interhash(a *interface {
f()
}, s uintptr, h uintptr) uintptr {
return 0
tab := (*iface)(unsafe.Pointer(a)).tab
if tab == nil {
return h
}
t := tab._type
fn := goalg(t.alg).hash
if **(**uintptr)(unsafe.Pointer(&fn)) == nohashcode {
// calling nohash will panic too,
// but we can print a better error.
panic(errorString("hash of unhashable type " + *t._string))
}
if uintptr(t.size) <= ptrSize {
return c1 * fn(unsafe.Pointer(&(*eface)(unsafe.Pointer(a)).data), uintptr(t.size), h^c0)
} else {
return c1 * fn((*eface)(unsafe.Pointer(a)).data, uintptr(t.size), h^c0)
}
}
func nilinterhash(a *interface{}, s uintptr, h uintptr) uintptr {

38
src/pkg/runtime/iface.goc
View file

@ -475,44 +475,6 @@ func assertE2E2(inter *InterfaceType, e Eface) (ret Eface, ok bool) {
ok = e.type != nil;
}
static uintptr
ifacehash1(void *data, Type *t, uintptr h)
{
Alg *alg;
uintptr size;
Eface err;
if(t == nil)
return 0;
alg = t->alg;
size = t->size;
if(alg->hash->fn == (void(*)())runtime·nohash) {
// calling nohash will panic too,
// but we can print a better error.
runtime·newErrorString(runtime·catstring(runtime·gostringnocopy((byte*)"hash of unhashable type "), *t->string), &err);
runtime·panic(err);
}
if(size <= sizeof(data))
return ((uintptr(*)(void**,uintptr,uintptr))alg->hash)(&data, size, h);
else
return ((uintptr(*)(void*,uintptr,uintptr))alg->hash)(data, size, h);
}
uintptr
runtime·ifacehash(Iface a, uintptr h)
{
if(a.tab == nil)
return h;
return ifacehash1(a.data, a.tab->type, h);
}
uintptr
runtime·efacehash(Eface a, uintptr h)
{
return ifacehash1(a.data, a.type, h);
}
static bool
ifaceeq1(void *data1, void *data2, Type *t)
{

28
src/pkg/runtime/runtime.h
View file

@ -651,19 +651,19 @@ enum {
};
void runtime·hashinit(void);
uintptr runtime·memhash(void*, uintptr, uintptr);
uintptr runtime·nohash(void*, uintptr, uintptr);
uintptr runtime·strhash(void*, uintptr, uintptr);
uintptr runtime·interhash(void*, uintptr, uintptr);
uintptr runtime·nilinterhash(void*, uintptr, uintptr);
uintptr runtime·f32hash(void*, uintptr, uintptr);
uintptr runtime·f64hash(void*, uintptr, uintptr);
uintptr runtime·c64hash(void*, uintptr, uintptr);
uintptr runtime·c128hash(void*, uintptr, uintptr);
uintptr runtime·aeshash(void*, uintptr, uintptr);
uintptr runtime·aeshash32(void*, uintptr, uintptr);
uintptr runtime·aeshash64(void*, uintptr, uintptr);
uintptr runtime·aeshashstr(void*, uintptr, uintptr);
void runtime·memhash(void*, uintptr, uintptr, uintptr);
void runtime·nohash(void*, uintptr, uintptr, uintptr);
void runtime·strhash(void*, uintptr, uintptr, uintptr);
void runtime·interhash(void*, uintptr, uintptr, uintptr);
void runtime·nilinterhash(void*, uintptr, uintptr, uintptr);
void runtime·f32hash(void*, uintptr, uintptr, uintptr);
void runtime·f64hash(void*, uintptr, uintptr, uintptr);
void runtime·c64hash(void*, uintptr, uintptr, uintptr);
void runtime·c128hash(void*, uintptr, uintptr, uintptr);
void runtime·aeshash(void*, uintptr, uintptr, uintptr);
void runtime·aeshash32(void*, uintptr, uintptr, uintptr);
void runtime·aeshash64(void*, uintptr, uintptr, uintptr);
void runtime·aeshashstr(void*, uintptr, uintptr, uintptr);
void runtime·memequal(bool*, uintptr, void*, void*);
void runtime·noequal(bool*, uintptr, void*, void*);
@ -876,8 +876,6 @@ void runtime·mallocinit(void);
void runtime·chaninit(void);
bool runtime·ifaceeq_c(Iface, Iface);
bool runtime·efaceeq_c(Eface, Eface);
uintptr runtime·ifacehash(Iface, uintptr);
uintptr runtime·efacehash(Eface, uintptr);
void* runtime·malloc(uintptr size);
void runtime·runpanic(Panic*);
uintptr runtime·getcallersp(void*);