diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/6g/gen.c | 6 | ||||
| -rw-r--r-- | src/cmd/gc/walk.c | 41 |
2 files changed, 42 insertions, 5 deletions
diff --git a/src/cmd/6g/gen.c b/src/cmd/6g/gen.c index dbdafd612..9751402ad 100644 --- a/src/cmd/6g/gen.c +++ b/src/cmd/6g/gen.c @@ -68,8 +68,10 @@ if(newproc == N) { gclean(); checklabels(); -// if(curfn->type->outtuple != 0) -// gins(AGOK, N, N); + if(curfn->type->outtuple != 0) { + nodconst(&nod1, types[TUINT8], 6); // 6 is opcode trap + gins(AINT, &nod1, N); + } pc->as = ARET; // overwrite AEND pc->lineno = lineno; diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c index 8612f6d13..abb7ce0bd 100644 --- a/src/cmd/gc/walk.c +++ b/src/cmd/gc/walk.c @@ -10,6 +10,38 @@ static Type* sw3(Node*, Type*); static Node* curfn; static Node* addtop; +// can this code branch reach the end +// without an undcontitional RETURN +// this is hard, so it is conservative +int +walkret(Node *n) +{ + +loop: + if(n != N) + switch(n->op) { + case OLIST: + if(n->right == N) { + n = n->left; + goto loop; + } + n = n->right; + goto loop; + + // at this point, we have the last + // statement of the function + + case OGOTO: + case OPANIC: + case ORETURN: + return 0; + } + + // all other statements + // will flow to the end + return 1; +} + void walk(Node *fn) { @@ -18,12 +50,15 @@ walk(Node *fn) curfn = fn; if(debug['W']) { snprint(s, sizeof(s), "\nbefore %S", curfn->nname->sym); - dump(s, fn->nbody); + dump(s, curfn->nbody); } - walkstate(fn->nbody); + if(curfn->type->outtuple) + if(walkret(curfn->nbody)) + warn("function ends without a return statement"); + walkstate(curfn->nbody); if(debug['W']) { snprint(s, sizeof(s), "after %S", curfn->nname->sym); - dump(s, fn->nbody); + dump(s, curfn->nbody); } } |