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-rw-r--r--src/cmd/gc/select.c116
1 files changed, 41 insertions, 75 deletions
diff --git a/src/cmd/gc/select.c b/src/cmd/gc/select.c
index cd3de8c7b..58a120674 100644
--- a/src/cmd/gc/select.c
+++ b/src/cmd/gc/select.c
@@ -69,6 +69,7 @@ typecheckselect(Node *sel)
n->op = OSELRECV2;
n->left = n->list->n;
n->ntest = n->list->next->n;
+ n->list = nil;
n->right = n->rlist->n;
n->rlist = nil;
break;
@@ -94,7 +95,7 @@ void
walkselect(Node *sel)
{
int lno, i;
- Node *n, *r, *a, *tmp, *var, *cas, *dflt, *ch;
+ Node *n, *r, *a, *var, *cas, *dflt, *ch;
NodeList *l, *init;
if(sel->list == nil && sel->xoffset != 0)
@@ -110,6 +111,8 @@ walkselect(Node *sel)
}
// optimization: one-case select: single op.
+ // TODO(rsc): Reenable optimization once order.c can handle it.
+ // golang.org/issue/7672.
if(i == 1) {
cas = sel->list->n;
setlineno(cas);
@@ -123,32 +126,34 @@ walkselect(Node *sel)
fatal("select %O", n->op);
case OSEND:
- ch = cheapexpr(n->left, &l);
- n->left = ch;
+ // ok already
+ ch = n->left;
break;
case OSELRECV:
- r = n->right;
- ch = cheapexpr(r->left, &l);
- r->left = ch;
-
+ ch = n->right->left;
+ Selrecv1:
if(n->left == N)
- n = r;
- else {
- n = nod(OAS, n->left, r);
- typecheck(&n, Etop);
- }
+ n = n->right;
+ else
+ n->op = OAS;
break;
case OSELRECV2:
- r = n->right;
- ch = cheapexpr(r->left, &l);
- r->left = ch;
-
- a = nod(OAS2, N, N);
- a->list = n->list;
- a->rlist = list1(n->right);
- n = a;
+ ch = n->right->left;
+ if(n->ntest == N)
+ goto Selrecv1;
+ if(n->left == N) {
+ typecheck(&nblank, Erv | Easgn);
+ n->left = nblank;
+ }
+ n->op = OAS2;
+ n->list = list(list1(n->left), n->ntest);
+ n->rlist = list1(n->right);
+ n->right = N;
+ n->left = N;
+ n->ntest = N;
+ n->typecheck = 0;
typecheck(&n, Etop);
break;
}
@@ -166,7 +171,7 @@ walkselect(Node *sel)
goto out;
}
- // introduce temporary variables for OSELRECV where needed.
+ // convert case value arguments to addresses.
// this rewrite is used by both the general code and the next optimization.
for(l=sel->list; l; l=l->next) {
cas = l->n;
@@ -175,58 +180,24 @@ walkselect(Node *sel)
if(n == N)
continue;
switch(n->op) {
+ case OSEND:
+ n->right = nod(OADDR, n->right, N);
+ typecheck(&n->right, Erv);
+ break;
case OSELRECV:
case OSELRECV2:
- ch = n->right->left;
-
- // If we can use the address of the target without
- // violating addressability or order of operations, do so.
- // Otherwise introduce a temporary.
- // Also introduce a temporary for := variables that escape,
- // so that we can delay the heap allocation until the case
- // is selected.
+ if(n->op == OSELRECV2 && n->ntest == N)
+ n->op = OSELRECV;
if(n->op == OSELRECV2) {
- if(n->ntest == N || isblank(n->ntest))
- n->ntest = nodnil();
- else if(n->ntest->op == ONAME &&
- (!n->colas || (n->ntest->class&PHEAP) == 0) &&
- convertop(types[TBOOL], n->ntest->type, nil) == OCONVNOP) {
- n->ntest = nod(OADDR, n->ntest, N);
- n->ntest->etype = 1; // pointer does not escape
- typecheck(&n->ntest, Erv);
- } else {
- tmp = temp(types[TBOOL]);
- a = nod(OADDR, tmp, N);
- a->etype = 1; // pointer does not escape
- typecheck(&a, Erv);
- r = nod(OAS, n->ntest, tmp);
- typecheck(&r, Etop);
- cas->nbody = concat(list1(r), cas->nbody);
- n->ntest = a;
- }
+ n->ntest = nod(OADDR, n->ntest, N);
+ typecheck(&n->ntest, Erv);
}
-
- if(n->left == N || isblank(n->left))
+ if(n->left == N)
n->left = nodnil();
- else if(n->left->op == ONAME &&
- (!n->colas || (n->left->class&PHEAP) == 0) &&
- convertop(ch->type->type, n->left->type, nil) == OCONVNOP) {
+ else {
n->left = nod(OADDR, n->left, N);
- n->left->etype = 1; // pointer does not escape
typecheck(&n->left, Erv);
- } else {
- tmp = temp(ch->type->type);
- a = nod(OADDR, tmp, N);
- a->etype = 1; // pointer does not escape
- typecheck(&a, Erv);
- r = nod(OAS, n->left, tmp);
- typecheck(&r, Etop);
- cas->nbody = concat(list1(r), cas->nbody);
- n->left = a;
- }
-
- cas->nbody = concat(n->ninit, cas->nbody);
- n->ninit = nil;
+ }
break;
}
}
@@ -250,8 +221,8 @@ walkselect(Node *sel)
fatal("select %O", n->op);
case OSEND:
- // if c != nil && selectnbsend(c, v) { body } else { default body }
- ch = cheapexpr(n->left, &r->ninit);
+ // if selectnbsend(c, v) { body } else { default body }
+ ch = n->left;
r->ntest = mkcall1(chanfn("selectnbsend", 2, ch->type),
types[TBOOL], &r->ninit, typename(ch->type), ch, n->right);
break;
@@ -260,7 +231,7 @@ walkselect(Node *sel)
// if c != nil && selectnbrecv(&v, c) { body } else { default body }
r = nod(OIF, N, N);
r->ninit = cas->ninit;
- ch = cheapexpr(n->right->left, &r->ninit);
+ ch = n->right->left;
r->ntest = mkcall1(chanfn("selectnbrecv", 2, ch->type),
types[TBOOL], &r->ninit, typename(ch->type), n->left, ch);
break;
@@ -269,7 +240,7 @@ walkselect(Node *sel)
// if c != nil && selectnbrecv2(&v, c) { body } else { default body }
r = nod(OIF, N, N);
r->ninit = cas->ninit;
- ch = cheapexpr(n->right->left, &r->ninit);
+ ch = n->right->left;
r->ntest = mkcall1(chanfn("selectnbrecv2", 2, ch->type),
types[TBOOL], &r->ninit, typename(ch->type), n->left, n->ntest, ch);
break;
@@ -313,11 +284,6 @@ walkselect(Node *sel)
case OSEND:
// selectsend(sel *byte, hchan *chan any, elem *any) (selected bool);
- n->left = localexpr(safeexpr(n->left, &r->ninit), n->left->type, &r->ninit);
- n->right = localexpr(n->right, n->left->type->type, &r->ninit);
- n->right = nod(OADDR, n->right, N);
- n->right->etype = 1; // pointer does not escape
- typecheck(&n->right, Erv);
r->ntest = mkcall1(chanfn("selectsend", 2, n->left->type), types[TBOOL],
&r->ninit, var, n->left, n->right);
break;
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-17 08:44:04 +0000