gc: bug242

R=ken2
CC=golang-dev
https://golang.org/cl/198053

diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index d634d0d3a9a2f5f01aeea484a8331ce4749e0eab..16cf87f0c22a9682613e9eb60bd0cd0e60a8d86e 100644 (file)
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -875,8 +875,7 @@ int isselect(Node*);
 Node*  staticname(Type*);
 int    iscomposite(Type*);
 Node*  callnew(Type*);
-Node*  saferef(Node*, NodeList**);
-Node*  safeval(Node*, NodeList**);
+Node*  safeexpr(Node*, NodeList**);
 int    is64(Type*);
 int    noconv(Type*, Type*);
 NodeList*      list1(Node*);
@@ -1073,6 +1072,7 @@ void      typecheckrange(Node*);
 Node*  typecheckconv(Node*, Node*, Type*, int, char*);
 int    checkconv(Type*, Type*, int, int*, int*, char*);
 Node*  typecheck(Node**, int);
+int    islvalue(Node*);
 
 /*
  *     const.c

diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 40d8b6f9dbac8401d02930a087a27cf36fefd2f4..3e58415a896f393c50ecad8b3f0772f67da39bf5 100644 (file)
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -2410,10 +2410,11 @@ staticname(Type *t)
 }
 
 /*
- * return side effect-free, assignable n, appending side effects to init.
+ * return side effect-free appending side effects to init.
+ * result is assignable if n is.
  */
 Node*
-saferef(Node *n, NodeList **init)
+safeexpr(Node *n, NodeList **init)
 {
        Node *l;
        Node *r;
@@ -2421,9 +2422,11 @@ saferef(Node *n, NodeList **init)
 
        switch(n->op) {
        case ONAME:
+       case OLITERAL:
                return n;
+
        case ODOT:
-               l = saferef(n->left, init);
+               l = safeexpr(n->left, init);
                if(l == n->left)
                        return n;
                r = nod(OXXX, N, N);
@@ -2433,41 +2436,34 @@ saferef(Node *n, NodeList **init)
                walkexpr(&r, init);
                return r;
 
-       case OINDEX:
        case ODOTPTR:
        case OIND:
-               l = nod(OXXX, N, N);
-               tempname(l, ptrto(n->type));
-               a = nod(OAS, l, nod(OADDR, n, N));
-               typecheck(&a, Etop);
+               l = safeexpr(n->left, init);
+               if(l == n->left)
+                       return n;
+               a = nod(OXXX, N, N);
+               *a = *n;
+               a->left = l;
                walkexpr(&a, init);
-               *init = list(*init, a);
-               r = nod(OIND, l, N);
-               typecheck(&r, Erv);
-               walkexpr(&r, init);
-               return r;
-       }
-       fatal("saferef %N", n);
-       return N;
-}
-
-/*
- * return side effect-free n, appending side effects to init.
- */
-Node*
-safeval(Node *n, NodeList **init)
-{
-       Node *l;
-       Node *a;
+               return a;
 
-       // is this a local variable or a dot of a local variable?
-       for(l=n; l->op == ODOT; l=l->left)
-               if(l->left->type != T && isptr[l->left->type->etype])
-                       goto copy;
-       if(l->op == ONAME && (l->class == PAUTO || l->class == PPARAM))
-               return n;
+       case OINDEX:
+       case OINDEXMAP:
+               l = safeexpr(n->left, init);
+               r = safeexpr(n->right, init);
+               if(l == n->left && r == n->right)
+                       return n;
+               a = nod(OXXX, N, N);
+               *a = *n;
+               a->left = l;
+               a->right = r;
+               walkexpr(&a, init);
+               return a;
+       }
 
-copy:
+       // make a copy; must not be used as an lvalue
+       if(islvalue(n))
+               fatal("missing lvalue case in safeexpr: %N", n);
        l = nod(OXXX, N, N);
        tempname(l, n->type);
        a = nod(OAS, l, n);

diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 7b0ce038298deeff5e121e08f5fb43ec2b22f103..9c06ff6a154859eda48f37f3dba0103b6d344b54 100644 (file)
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -31,7 +31,6 @@ static void   typecheckfunc(Node*);
 static void    checklvalue(Node*, char*);
 static void    checkassign(Node*);
 static void    checkassignlist(NodeList*);
-static int     islvalue(Node*);
 static void    toslice(Node**);
 
 void
@@ -1940,7 +1939,7 @@ addrescapes(Node *n)
 /*
  * lvalue etc
  */
-static int
+int
 islvalue(Node *n)
 {
        switch(n->op) {

diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index cac2d50ea11e1d4d6b410acfa9569c6fe2592a73..f560d5be27a60f3b1f086ad7bfcf563142c78482 100644 (file)
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -457,6 +457,15 @@ walkexprlist(NodeList *l, NodeList **init)
                walkexpr(&l->n, init);
 }
 
+void
+walkexprlistsafe(NodeList *l, NodeList **init)
+{
+       for(; l; l=l->next) {
+               l->n = safeexpr(l->n, init);
+               walkexpr(&l->n, init);
+       }
+}
+
 void
 walkexpr(Node **np, NodeList **init)
 {
@@ -610,6 +619,7 @@ walkexpr(Node **np, NodeList **init)
                *init = concat(*init, n->ninit);
                n->ninit = nil;
                walkexpr(&n->left, init);
+               n->left = safeexpr(n->left, init);
                if(oaslit(n, init))
                        goto ret;
                walkexpr(&n->right, init);
@@ -626,8 +636,8 @@ walkexpr(Node **np, NodeList **init)
        as2:
                *init = concat(*init, n->ninit);
                n->ninit = nil;
-               walkexprlist(n->list, init);
-               walkexprlist(n->rlist, init);
+               walkexprlistsafe(n->list, init);
+               walkexprlistsafe(n->rlist, init);
                ll = ascompatee(OAS, n->list, n->rlist, init);
                ll = reorder3(ll);
                n = liststmt(ll);
@@ -639,7 +649,7 @@ walkexpr(Node **np, NodeList **init)
                *init = concat(*init, n->ninit);
                n->ninit = nil;
                r = n->rlist->n;
-               walkexprlist(n->list, init);
+               walkexprlistsafe(n->list, init);
                walkexpr(&r, init);
                ll = ascompatet(n->op, n->list, &r->type, 0, init);
                n = liststmt(concat(list1(r), ll));
@@ -650,7 +660,7 @@ walkexpr(Node **np, NodeList **init)
                *init = concat(*init, n->ninit);
                n->ninit = nil;
                r = n->rlist->n;
-               walkexprlist(n->list, init);
+               walkexprlistsafe(n->list, init);
                walkexpr(&r->left, init);
                fn = chanfn("chanrecv2", 2, r->left->type);
                r = mkcall1(fn, getoutargx(fn->type), init, r->left);
@@ -663,7 +673,7 @@ walkexpr(Node **np, NodeList **init)
                *init = concat(*init, n->ninit);
                n->ninit = nil;
                r = n->rlist->n;
-               walkexprlist(n->list, init);
+               walkexprlistsafe(n->list, init);
                walkexpr(&r->left, init);
                fn = mapfn("mapaccess2", r->left->type);
                r = mkcall1(fn, getoutargx(fn->type), init, r->left, r->right);
@@ -676,7 +686,7 @@ walkexpr(Node **np, NodeList **init)
                // a,b = m[i];
                *init = concat(*init, n->ninit);
                n->ninit = nil;
-               walkexprlist(n->list, init);
+               walkexprlistsafe(n->list, init);
                l = n->list->n;
                t = l->left->type;
                n = mkcall1(mapfn("mapassign2", t), T, init, l->left, l->right, n->rlist->n, n->rlist->next->n);
@@ -687,7 +697,7 @@ walkexpr(Node **np, NodeList **init)
                *init = concat(*init, n->ninit);
                n->ninit = nil;
                r = n->rlist->n;
-               walkexprlist(n->list, init);
+               walkexprlistsafe(n->list, init);
                walkdottype(r, init);
                et = ifaceas1(r->type, r->left->type, 1);
                switch(et) {
@@ -744,6 +754,7 @@ walkexpr(Node **np, NodeList **init)
                goto ret;
 
        case OASOP:
+               n->left = safeexpr(n->left, init);
                walkexpr(&n->left, init);
                l = n->left;
                if(l->op == OINDEXMAP)
@@ -761,7 +772,7 @@ walkexpr(Node **np, NodeList **init)
                 */
                et = n->left->type->etype;
                if(widthptr == 4 && (et == TUINT64 || et == TINT64)) {
-                       l = saferef(n->left, init);
+                       l = safeexpr(n->left, init);
                        r = nod(OAS, l, nod(n->etype, l, n->right));
                        typecheck(&r, Etop);
                        walkexpr(&r, init);
@@ -1183,6 +1194,13 @@ ascompatee(int op, NodeList *nl, NodeList *nr, NodeList **init)
         * a expression list. called in
         *      expr-list = expr-list
         */
+
+       // ensure order of evaluation for function calls
+       for(ll=nl; ll; ll=ll->next)
+               ll->n = safeexpr(ll->n, init);
+       for(lr=nr; lr; lr=lr->next)
+               lr->n = safeexpr(lr->n, init);
+
        nn = nil;
        for(ll=nl, lr=nr; ll && lr; ll=ll->next, lr=lr->next)
                nn = list(nn, ascompatee1(op, ll->n, lr->n, init));
@@ -1766,8 +1784,8 @@ mapop(Node *n, NodeList **init)
                // into tmpi := index; map[tmpi] = map[tmpi] op right
 
                // make it ok to double-evaluate map[tmpi]
-               n->left->left = safeval(n->left->left, init);
-               n->left->right = safeval(n->left->right, init);
+               n->left->left = safeexpr(n->left->left, init);
+               n->left->right = safeexpr(n->left->right, init);
 
                a = nod(OXXX, N, N);
                *a = *n->left;          // copy of map[tmpi]

diff --git a/test/bugs/bug242.go b/test/fixedbugs/bug242.go
similarity index 100%
rename from test/bugs/bug242.go
rename to test/fixedbugs/bug242.go

diff --git a/test/golden.out b/test/golden.out
index 72719ab33e5f6e2d56e866a8388761297210c9ee..63d179cba5423c817f7f100798739dd4888b1b54 100644 (file)
--- a/test/golden.out
+++ b/test/golden.out
@@ -151,11 +151,6 @@ panic PC=xxx
 
 == bugs/
 
-=========== bugs/bug242.go
-bad map check 13 false false
-panic PC=xxx
-BUG: tuple evaluation order
-
 =========== bugs/bug246.go
 bugs/bug246.go:17: cannot convert 0 to type unsafe.Pointer
 bugs/bug246.go:17: cannot convert 0 (type uintptr) to type *int in conversion