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-rw-r--r--src/cmd/gc/builtin.c5
-rw-r--r--src/cmd/gc/go.h3
-rw-r--r--src/cmd/gc/lex.c2
-rw-r--r--src/cmd/gc/order.c4
-rw-r--r--src/cmd/gc/runtime.go7
-rw-r--r--src/cmd/gc/sinit.c18
-rw-r--r--src/cmd/gc/walk.c157
-rw-r--r--src/runtime/mgc0.go33
8 files changed, 216 insertions, 13 deletions
diff --git a/src/cmd/gc/builtin.c b/src/cmd/gc/builtin.c
index 60b7c2f97..ee1ac1da4 100644
--- a/src/cmd/gc/builtin.c
+++ b/src/cmd/gc/builtin.c
@@ -83,6 +83,11 @@ char *runtimeimport =
"func @\"\".chanrecv2 (@\"\".chanType·2 *byte, @\"\".hchan·3 <-chan any, @\"\".elem·4 *any) (? bool)\n"
"func @\"\".chansend1 (@\"\".chanType·1 *byte, @\"\".hchan·2 chan<- any, @\"\".elem·3 *any)\n"
"func @\"\".closechan (@\"\".hchan·1 any)\n"
+ "func @\"\".writebarrierptr (@\"\".dst·1 *any, @\"\".src·2 any)\n"
+ "func @\"\".writebarrieriface (@\"\".dst·1 *any, @\"\".src·2 any)\n"
+ "func @\"\".writebarrierstring (@\"\".dst·1 *any, @\"\".src·2 any)\n"
+ "func @\"\".writebarrierslice (@\"\".dst·1 *any, @\"\".src·2 any)\n"
+ "func @\"\".writebarrierfat (@\"\".typ·1 *byte, @\"\".dst·2 *any, @\"\".src·3 *any)\n"
"func @\"\".selectnbsend (@\"\".chanType·2 *byte, @\"\".hchan·3 chan<- any, @\"\".elem·4 *any) (? bool)\n"
"func @\"\".selectnbrecv (@\"\".chanType·2 *byte, @\"\".elem·3 *any, @\"\".hchan·4 <-chan any) (? bool)\n"
"func @\"\".selectnbrecv2 (@\"\".chanType·2 *byte, @\"\".elem·3 *any, @\"\".received·4 *bool, @\"\".hchan·5 <-chan any) (? bool)\n"
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 12c1e9853..8178f7272 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -973,6 +973,7 @@ EXTERN int funcdepth;
EXTERN int typecheckok;
EXTERN int compiling_runtime;
EXTERN int compiling_wrappers;
+EXTERN int use_writebarrier;
EXTERN int pure_go;
EXTERN char* flag_installsuffix;
EXTERN int flag_race;
@@ -1284,6 +1285,7 @@ LSym* linksym(Sym*);
* order.c
*/
void order(Node *fn);
+void orderstmtinplace(Node **stmt);
/*
* range.c
@@ -1464,6 +1466,7 @@ void walkstmt(Node **np);
void walkstmtlist(NodeList *l);
Node* conv(Node*, Type*);
int candiscard(Node*);
+int needwritebarrier(Node*, Node*);
Node* outervalue(Node*);
void usefield(Node*);
diff --git a/src/cmd/gc/lex.c b/src/cmd/gc/lex.c
index b8252a225..6d8317747 100644
--- a/src/cmd/gc/lex.c
+++ b/src/cmd/gc/lex.c
@@ -312,6 +312,8 @@ main(int argc, char *argv[])
flagcount("u", "reject unsafe code", &safemode);
flagcount("v", "increase debug verbosity", &debug['v']);
flagcount("w", "debug type checking", &debug['w']);
+ use_writebarrier = 1;
+ flagcount("wb", "enable write barrier", &use_writebarrier);
flagcount("x", "debug lexer", &debug['x']);
flagcount("y", "debug declarations in canned imports (with -d)", &debug['y']);
if(thechar == '6')
diff --git a/src/cmd/gc/order.c b/src/cmd/gc/order.c
index d11e9828c..9e64eb775 100644
--- a/src/cmd/gc/order.c
+++ b/src/cmd/gc/order.c
@@ -317,7 +317,7 @@ orderexprinplace(Node **np, Order *outer)
// Orderstmtinplace orders the side effects of the single statement *np
// and replaces it with the resulting statement list.
-static void
+void
orderstmtinplace(Node **np)
{
Node *n;
@@ -451,7 +451,7 @@ ordermapassign(Node *n, Order *order)
case OAS:
order->out = list(order->out, n);
- if(n->left->op == OINDEXMAP && !isaddrokay(n->right)) {
+ if((n->left->op == OINDEXMAP || (needwritebarrier(n->left, n->right) && n->left->type->width > widthptr)) && !isaddrokay(n->right)) {
m = n->left;
n->left = ordertemp(m->type, order, 0);
a = nod(OAS, m, n->left);
diff --git a/src/cmd/gc/runtime.go b/src/cmd/gc/runtime.go
index 128fd1a31..fa927a58a 100644
--- a/src/cmd/gc/runtime.go
+++ b/src/cmd/gc/runtime.go
@@ -107,6 +107,13 @@ func chanrecv2(chanType *byte, hchan <-chan any, elem *any) bool
func chansend1(chanType *byte, hchan chan<- any, elem *any)
func closechan(hchan any)
+// *byte is really *runtime.Type
+func writebarrierptr(dst *any, src any)
+func writebarrierstring(dst *any, src any)
+func writebarrierslice(dst *any, src any)
+func writebarrieriface(dst *any, src any)
+func writebarrierfat(typ *byte, dst *any, src *any)
+
func selectnbsend(chanType *byte, hchan chan<- any, elem *any) bool
func selectnbrecv(chanType *byte, elem *any, hchan <-chan any) bool
func selectnbrecv2(chanType *byte, elem *any, received *bool, hchan <-chan any) bool
diff --git a/src/cmd/gc/sinit.c b/src/cmd/gc/sinit.c
index 59804cd8d..508747e5a 100644
--- a/src/cmd/gc/sinit.c
+++ b/src/cmd/gc/sinit.c
@@ -633,11 +633,14 @@ structlit(int ctxt, int pass, Node *n, Node *var, NodeList **init)
a = nod(ODOT, var, newname(index->sym));
a = nod(OAS, a, value);
typecheck(&a, Etop);
- walkexpr(&a, init);
if(pass == 1) {
+ walkexpr(&a, init); // add any assignments in r to top
if(a->op != OAS)
fatal("structlit: not as");
a->dodata = 2;
+ } else {
+ orderstmtinplace(&a);
+ walkstmt(&a);
}
*init = list(*init, a);
}
@@ -693,11 +696,14 @@ arraylit(int ctxt, int pass, Node *n, Node *var, NodeList **init)
a = nod(OINDEX, var, index);
a = nod(OAS, a, value);
typecheck(&a, Etop);
- walkexpr(&a, init); // add any assignments in r to top
if(pass == 1) {
+ walkexpr(&a, init);
if(a->op != OAS)
- fatal("structlit: not as");
+ fatal("arraylit: not as");
a->dodata = 2;
+ } else {
+ orderstmtinplace(&a);
+ walkstmt(&a);
}
*init = list(*init, a);
}
@@ -807,7 +813,8 @@ slicelit(int ctxt, Node *n, Node *var, NodeList **init)
// make slice out of heap (5)
a = nod(OAS, var, nod(OSLICE, vauto, nod(OKEY, N, N)));
typecheck(&a, Etop);
- walkexpr(&a, init);
+ orderstmtinplace(&a);
+ walkstmt(&a);
*init = list(*init, a);
// put dynamics into slice (6)
@@ -839,7 +846,8 @@ slicelit(int ctxt, Node *n, Node *var, NodeList **init)
// build list of var[c] = expr
a = nod(OAS, a, value);
typecheck(&a, Etop);
- walkexpr(&a, init);
+ orderstmtinplace(&a);
+ walkstmt(&a);
*init = list(*init, a);
}
}
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 5f24db2b0..ce0f3eb95 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -8,6 +8,8 @@
#include "../ld/textflag.h"
static Node* walkprint(Node*, NodeList**, int);
+static Node* writebarrierfn(char*, Type*, Type*);
+static Node* applywritebarrier(Node*, NodeList**);
static Node* mapfn(char*, Type*);
static Node* mapfndel(char*, Type*);
static Node* ascompatee1(int, Node*, Node*, NodeList**);
@@ -633,6 +635,7 @@ walkexpr(Node **np, NodeList **init)
r = convas(nod(OAS, n->left, n->right), init);
r->dodata = n->dodata;
n = r;
+ n = applywritebarrier(n, init);
}
goto ret;
@@ -644,6 +647,8 @@ walkexpr(Node **np, NodeList **init)
walkexprlistsafe(n->rlist, init);
ll = ascompatee(OAS, n->list, n->rlist, init);
ll = reorder3(ll);
+ for(lr = ll; lr != nil; lr = lr->next)
+ lr->n = applywritebarrier(lr->n, init);
n = liststmt(ll);
goto ret;
@@ -656,6 +661,8 @@ walkexpr(Node **np, NodeList **init)
walkexpr(&r, init);
ll = ascompatet(n->op, n->list, &r->type, 0, init);
+ for(lr = ll; lr != nil; lr = lr->next)
+ lr->n = applywritebarrier(lr->n, init);
n = liststmt(concat(list1(r), ll));
goto ret;
@@ -1481,8 +1488,13 @@ ascompatee(int op, NodeList *nl, NodeList *nr, NodeList **init)
static int
fncall(Node *l, Type *rt)
{
+ Node r;
+
if(l->ullman >= UINF || l->op == OINDEXMAP)
return 1;
+ r.op = 0;
+ if(needwritebarrier(l, &r))
+ return 1;
if(eqtype(l->type, rt))
return 0;
return 1;
@@ -1533,8 +1545,10 @@ ascompatet(int op, NodeList *nl, Type **nr, int fp, NodeList **init)
a = nod(OAS, l, nodarg(r, fp));
a = convas(a, init);
ullmancalc(a);
- if(a->ullman >= UINF)
+ if(a->ullman >= UINF) {
+ dump("ascompatet ucount", a);
ucount++;
+ }
nn = list(nn, a);
r = structnext(&saver);
}
@@ -1932,6 +1946,127 @@ callnew(Type *t)
return mkcall1(fn, ptrto(t), nil, typename(t));
}
+static int
+isstack(Node *n)
+{
+ while(n->op == ODOT || n->op == OPAREN || n->op == OCONVNOP || n->op == OINDEX && isfixedarray(n->left->type))
+ n = n->left;
+
+ switch(n->op) {
+ case OINDREG:
+ // OINDREG only ends up in walk if it's indirect of SP.
+ return 1;
+
+ case ONAME:
+ switch(n->class) {
+ case PAUTO:
+ case PPARAM:
+ case PPARAMOUT:
+ return 1;
+ }
+ break;
+ }
+
+ return 0;
+}
+
+static int
+isglobal(Node *n)
+{
+ while(n->op == ODOT || n->op == OPAREN || n->op == OCONVNOP || n->op == OINDEX && isfixedarray(n->left->type))
+ n = n->left;
+
+ switch(n->op) {
+ case ONAME:
+ switch(n->class) {
+ case PEXTERN:
+ return 1;
+ }
+ break;
+ }
+
+ return 0;
+}
+
+// Do we need a write barrier for the assignment l = r?
+int
+needwritebarrier(Node *l, Node *r)
+{
+ if(!use_writebarrier)
+ return 0;
+
+ if(l == N || isblank(l))
+ return 0;
+
+ // No write barrier for write of non-pointers.
+ dowidth(l->type);
+ if(!haspointers(l->type))
+ return 0;
+
+ // No write barrier for write to stack.
+ if(isstack(l))
+ return 0;
+
+ // No write barrier for zeroing.
+ if(r == N)
+ return 0;
+
+ // No write barrier for initialization to constant.
+ if(r->op == OLITERAL)
+ return 0;
+
+ // No write barrier for storing static (read-only) data.
+ if(r->op == ONAME && strncmp(r->sym->name, "statictmp_", 10) == 0)
+ return 0;
+
+ // No write barrier for storing address of stack values,
+ // which are guaranteed only to be written to the stack.
+ if(r->op == OADDR && isstack(r->left))
+ return 0;
+
+ // No write barrier for storing address of global, which
+ // is live no matter what.
+ if(r->op == OADDR && isglobal(r->left))
+ return 0;
+
+ // Otherwise, be conservative and use write barrier.
+ return 1;
+}
+
+// TODO(rsc): Perhaps componentgen should run before this.
+static Node*
+applywritebarrier(Node *n, NodeList **init)
+{
+ Node *l, *r;
+
+ if(n->left && n->right && needwritebarrier(n->left, n->right)) {
+ l = nod(OADDR, n->left, N);
+ l->etype = 1; // addr does not escape
+ if(n->left->type->width == widthptr) {
+ n = mkcall1(writebarrierfn("writebarrierptr", n->left->type, n->right->type), T, init,
+ l, n->right);
+ } else if(n->left->type->etype == TSTRING) {
+ n = mkcall1(writebarrierfn("writebarrierstring", n->left->type, n->right->type), T, init,
+ l, n->right);
+ } else if(isslice(n->left->type)) {
+ n = mkcall1(writebarrierfn("writebarrierslice", n->left->type, n->right->type), T, init,
+ l, n->right);
+ } else if(isinter(n->left->type)) {
+ n = mkcall1(writebarrierfn("writebarrieriface", n->left->type, n->right->type), T, init,
+ l, n->right);
+ } else {
+ r = n->right;
+ while(r->op == OCONVNOP)
+ r = r->left;
+ r = nod(OADDR, r, N);
+ r->etype = 1; // addr does not escape
+ n = mkcall1(writebarrierfn("writebarrierfat", n->left->type, r->left->type), T, init,
+ typename(n->left->type), l, r);
+ }
+ }
+ return n;
+}
+
static Node*
convas(Node *n, NodeList **init)
{
@@ -1971,11 +2106,10 @@ convas(Node *n, NodeList **init)
goto out;
}
- if(eqtype(lt, rt))
- goto out;
-
- n->right = assignconv(n->right, lt, "assignment");
- walkexpr(&n->right, init);
+ if(!eqtype(lt, rt)) {
+ n->right = assignconv(n->right, lt, "assignment");
+ walkexpr(&n->right, init);
+ }
out:
ullmancalc(n);
@@ -2527,6 +2661,17 @@ mapfndel(char *name, Type *t)
}
static Node*
+writebarrierfn(char *name, Type *l, Type *r)
+{
+ Node *fn;
+
+ fn = syslook(name, 1);
+ argtype(fn, l);
+ argtype(fn, r);
+ return fn;
+}
+
+static Node*
addstr(Node *n, NodeList **init)
{
Node *r, *cat, *slice;
diff --git a/src/runtime/mgc0.go b/src/runtime/mgc0.go
index ec5edb024..5d6d91875 100644
--- a/src/runtime/mgc0.go
+++ b/src/runtime/mgc0.go
@@ -4,6 +4,8 @@
package runtime
+import "unsafe"
+
// Called from C. Returns the Go type *m.
func gc_m_ptr(ret *interface{}) {
*ret = (*m)(nil)
@@ -101,3 +103,34 @@ func bgsweep() {
goparkunlock(&gclock, "GC sweep wait")
}
}
+
+// NOTE: Really dst *unsafe.Pointer, src unsafe.Pointer,
+// but if we do that, Go inserts a write barrier on *dst = src.
+//go:nosplit
+func writebarrierptr(dst *uintptr, src uintptr) {
+ *dst = src
+}
+
+//go:nosplit
+func writebarrierstring(dst *[2]uintptr, src [2]uintptr) {
+ dst[0] = src[0]
+ dst[1] = src[1]
+}
+
+//go:nosplit
+func writebarrierslice(dst *[3]uintptr, src [3]uintptr) {
+ dst[0] = src[0]
+ dst[1] = src[1]
+ dst[2] = src[2]
+}
+
+//go:nosplit
+func writebarrieriface(dst *[2]uintptr, src [2]uintptr) {
+ dst[0] = src[0]
+ dst[1] = src[1]
+}
+
+//go:nosplit
+func writebarrierfat(typ *_type, dst, src unsafe.Pointer) {
+ memmove(dst, src, typ.size)
+}
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