cmd/gc: fix compiler crash during race instrumentation

The compiler is crashing on the following code:

type TypeID int
func (t *TypeID) encodeType(x int) (tt TypeID, err error) {
        switch x {
        case 0:
                return t.encodeType(x * x)
        }
        return 0, nil
}
The pass marks "return struct" {tt TypeID, err error} as used,
and this causes internal check failure.
I've added the test to:
https://golang.org/cl/6525052/diff/7020/src/pkg/runtime/race/regression_test.go

R=golang-dev, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6611049

diff --git a/src/cmd/gc/racewalk.c b/src/cmd/gc/racewalk.c
index 6f8597a16128ef29380d46ad393573379c0366de..9a01abb0977a210b509ab24651ccc865a433d411 100644 (file)
--- a/src/cmd/gc/racewalk.c
+++ b/src/cmd/gc/racewalk.c
@@ -17,12 +17,12 @@
 #include "go.h"
 #include "opnames.h"
 
-//TODO: do not instrument initialization as writes:
+// TODO(dvyukov): do not instrument initialization as writes:
 // a := make([]int, 10)
 
 static void racewalklist(NodeList *l, NodeList **init);
 static void racewalknode(Node **np, NodeList **init, int wr, int skip);
-static void callinstr(Node *n, NodeList **init, int wr, int skip);
+static int callinstr(Node *n, NodeList **init, int wr, int skip);
 static Node* uintptraddr(Node *n);
 static Node* basenod(Node *n);
 
@@ -42,6 +42,9 @@ racewalk(Node *fn)
                }
        }
 
+       // 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 = list(fn->enter, nd);
        nd = mkcall("racefuncexit", T, nil);
@@ -200,7 +203,7 @@ racewalknode(Node **np, NodeList **init, int wr, int skip)
                racewalknode(&n->left, init, 0, 0);
                if(istype(n->left->type, TMAP)) {
                        // crashes on len(m[0]) or len(f())
-                       USED(&n1);
+                       USED(n1);
                        /*
                        n1 = nod(OADDR, n->left, N);
                        n1 = conv(n1, types[TUNSAFEPTR]);
@@ -350,41 +353,44 @@ ret:
        *np = n;
 }
 
-static void
+static int
 callinstr(Node *n, NodeList **init, int wr, int skip)
 {
        Node *f, *b;
        Type *t, *t1;
-       int class;
+       int class, res;
 
        //print("callinstr for %N [ %s ] etype=%d class=%d\n",
        //        n, opnames[n->op], n->type ? n->type->etype : -1, n->class);
 
        if(skip || n->type == T || n->type->etype >= TIDEAL)
-               return;
+               return 0;
        t = n->type;
        if(n->op == ONAME) {
                if(n->sym != S) {
                        if(n->sym->name != nil) {
                                if(strncmp(n->sym->name, "_", sizeof("_")-1) == 0)
-                                       return;
+                                       return 0;
                                if(strncmp(n->sym->name, "autotmp_", sizeof("autotmp_")-1) == 0)
-                                       return;
+                                       return 0;
                                if(strncmp(n->sym->name, "statictmp_", sizeof("statictmp_")-1) == 0)
-                                       return;
+                                       return 0;
                        }
                }
        }
-       if (t->etype == TSTRUCT) {
+       if(t->etype == TSTRUCT) {
+               res = 0;
                for(t1=t->type; t1; t1=t1->down) {
                        if(t1->sym && strncmp(t1->sym->name, "_", sizeof("_")-1)) {
                                n = treecopy(n);
                                f = nod(OXDOT, n, newname(t1->sym));
-                               typecheck(&f, Erv);
-                               callinstr(f, init, wr, 0);
+                               if(callinstr(f, init, wr, 0)) {
+                                       typecheck(&f, Erv);
+                                       res = 1;
+                               }
                        }
                }
-               return;
+               return res;
        }
 
        b = basenod(n);
@@ -399,7 +405,9 @@ callinstr(Node *n, NodeList **init, int wr, int skip)
                f = mkcall(wr ? "racewrite" : "raceread", T, nil, uintptraddr(n));
                //typecheck(&f, Etop);
                *init = list(*init, f);
+               return 1;
        }
+       return 0;
 }
 
 static Node*