diff options
Diffstat (limited to 'src/cmd/8g/cgen.c')
| -rw-r--r-- | src/cmd/8g/cgen.c | 53 |
1 files changed, 32 insertions, 21 deletions
diff --git a/src/cmd/8g/cgen.c b/src/cmd/8g/cgen.c index f93be57e5..d54db7e62 100644 --- a/src/cmd/8g/cgen.c +++ b/src/cmd/8g/cgen.c @@ -739,6 +739,19 @@ agen(Node *n, Node *res) case ODOT: agen(nl, res); + // explicit check for nil if struct is large enough + // that we might derive too big a pointer. If the left node + // was ODOT we have already done the nil check. + if(nl->op != ODOT) + if(nl->type->width >= unmappedzero) { + regalloc(&n1, types[tptr], res); + gmove(res, &n1); + n1.op = OINDREG; + n1.type = types[TUINT8]; + n1.xoffset = 0; + gins(ATESTB, nodintconst(0), &n1); + regfree(&n1); + } if(n->xoffset != 0) { nodconst(&n1, types[tptr], n->xoffset); gins(optoas(OADD, types[tptr]), &n1, res); @@ -750,18 +763,18 @@ agen(Node *n, Node *res) if(!isptr[t->etype]) fatal("agen: not ptr %N", n); cgen(nl, res); + // explicit check for nil if struct is large enough + // that we might derive too big a pointer. + if(nl->type->type->width >= unmappedzero) { + regalloc(&n1, types[tptr], res); + gmove(res, &n1); + n1.op = OINDREG; + n1.type = types[TUINT8]; + n1.xoffset = 0; + gins(ATESTB, nodintconst(0), &n1); + regfree(&n1); + } if(n->xoffset != 0) { - // explicit check for nil if struct is large enough - // that we might derive too big a pointer. - if(nl->type->type->width >= unmappedzero) { - regalloc(&n1, types[tptr], res); - gmove(res, &n1); - n1.op = OINDREG; - n1.type = types[TUINT8]; - n1.xoffset = 0; - gins(ATESTB, nodintconst(0), &n1); - regfree(&n1); - } nodconst(&n1, types[tptr], n->xoffset); gins(optoas(OADD, types[tptr]), &n1, res); } @@ -825,16 +838,14 @@ igen(Node *n, Node *a, Node *res) regalloc(a, types[tptr], res); cgen(n->left, a); } - if(n->xoffset != 0) { - // explicit check for nil if struct is large enough - // that we might derive too big a pointer. - if(n->left->type->type->width >= unmappedzero) { - n1 = *a; - n1.op = OINDREG; - n1.type = types[TUINT8]; - n1.xoffset = 0; - gins(ATESTB, nodintconst(0), &n1); - } + // explicit check for nil if struct is large enough + // that we might derive too big a pointer. + if(n->left->type->type->width >= unmappedzero) { + n1 = *a; + n1.op = OINDREG; + n1.type = types[TUINT8]; + n1.xoffset = 0; + gins(ATESTB, nodintconst(0), &n1); } a->op = OINDREG; a->xoffset += n->xoffset; |