cmd/gc: racewalk: fix a bunch of minor issues

1. Prepend racefuncenter() to fn->enter -- fn->enter can contain new() calls,
and we want them to be in the scope of the function.
2. Dump fn->enter and fn->exit.
3. Add TODO that OTYPESW expression can contain interesting memory accesses.
4. Ignore only _ names instead of all names starting with _.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6822048

diff --git a/src/cmd/gc/racewalk.c b/src/cmd/gc/racewalk.c
index 034a5a5a343015f6d75b4fc0a32b770e123d50dd..a09b7adf4395f87118fffc787b46110738724d75 100644 (file)
--- a/src/cmd/gc/racewalk.c
+++ b/src/cmd/gc/racewalk.c
@@ -43,6 +43,13 @@ racewalk(Node *fn)
                }
        }
 
+<<<<<<< local
+       // TODO(dvyukov): ideally this should be:
+       // racefuncenter(getreturnaddress())
+       // because it's much more costly to obtain from runtime library.
+       nd = mkcall("racefuncenter", T, nil);
+       fn->enter = concat(list1(nd), fn->enter);
+=======
        // nodpc is the PC of the caller as extracted by
        // getcallerpc. We use -widthptr(FP) for x86.
        // BUG: this will not work on arm.
@@ -52,13 +59,18 @@ racewalk(Node *fn)
        nodpc->xoffset = -widthptr;
        nd = mkcall("racefuncenter", T, nil, nodpc);
        fn->enter = list(fn->enter, nd);
+>>>>>>> other
        nd = mkcall("racefuncexit", T, nil);
-       fn->exit = list(fn->exit, nd); // works fine if (!fn->exit)
+       fn->exit = list(fn->exit, nd);
        racewalklist(curfn->nbody, nil);
 
        if(debug['W']) {
                snprint(s, sizeof(s), "after racewalk %S", curfn->nname->sym);
                dumplist(s, curfn->nbody);
+               snprint(s, sizeof(s), "after walk %S", curfn->nname->sym);
+               dumplist(s, curfn->nbody);
+               snprint(s, sizeof(s), "enter %S", curfn->nname->sym);
+               dumplist(s, curfn->enter);
        }
 }
 
@@ -163,7 +175,7 @@ racewalknode(Node **np, NodeList **init, int wr, int skip)
 
        case OSWITCH:
                if(n->ntest->op == OTYPESW)
-                       // don't bother, we have static typization
+                       // TODO(dvyukov): the expression can contain calls or reads.
                        return;
                racewalknode(&n->ntest, &n->ninit, 0, 0);
                racewalklist(n->nbody, nil);
@@ -369,7 +381,7 @@ callinstr(Node *n, NodeList **init, int wr, int skip)
        if(n->op == ONAME) {
                if(n->sym != S) {
                        if(n->sym->name != nil) {
-                               if(strncmp(n->sym->name, "_", sizeof("_")-1) == 0)
+                               if(strcmp(n->sym->name, "_") == 0)
                                        return 0;
                                if(strncmp(n->sym->name, "autotmp_", sizeof("autotmp_")-1) == 0)
                                        return 0;
@@ -381,7 +393,7 @@ callinstr(Node *n, NodeList **init, int wr, int skip)
        if(t->etype == TSTRUCT) {
                res = 0;
                for(t1=t->type; t1; t1=t1->down) {
-                       if(t1->sym && strncmp(t1->sym->name, "_", sizeof("_")-1)) {
+                       if(t1->sym && strcmp(t1->sym->name, "_")) {
                                n = treecopy(n);
                                f = nod(OXDOT, n, newname(t1->sym));
                                if(callinstr(f, init, wr, 0)) {