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Prevent memory errors when returning references to temp args.

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Issue #918
This commit is contained in:
Marijn Haverbeke 2011-09-14 16:46:54 +02:00
parent c6619f9ce0
commit 1cabe37155
1 changed files with 18 additions and 14 deletions
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28
src/comp/middle/trans.rs
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@ -3521,8 +3521,7 @@ fn trans_args(cx: @block_ctxt, llenv: ValueRef, gen: option::t<generic_info>,
args: [ValueRef],
retslot: ValueRef,
to_zero: [{v: ValueRef, t: ty::t}],
to_revoke: [{v: ValueRef, t: ty::t}],
by_ref: bool} {
to_revoke: [{v: ValueRef, t: ty::t}]} {
let args: [ty::arg] = ty::ty_fn_args(bcx_tcx(cx), fn_ty);
let llargs: [ValueRef] = [];
@ -3545,8 +3544,7 @@ fn trans_args(cx: @block_ctxt, llenv: ValueRef, gen: option::t<generic_info>,
args: [],
retslot: C_nil(),
to_zero: to_zero,
to_revoke: to_revoke,
by_ref: by_ref};
to_revoke: to_revoke};
}
let retty = ty::ty_fn_ret(tcx, fn_ty);
let llretslot_res = if by_ref {
@ -3620,8 +3618,7 @@ fn trans_args(cx: @block_ctxt, llenv: ValueRef, gen: option::t<generic_info>,
args: llargs,
retslot: llretslot,
to_zero: to_zero,
to_revoke: to_revoke,
by_ref: by_ref};
to_revoke: to_revoke};
}
fn trans_call(in_cx: @block_ctxt, f: @ast::expr,
@ -3630,10 +3627,18 @@ fn trans_call(in_cx: @block_ctxt, f: @ast::expr,
// NB: 'f' isn't necessarily a function; it might be an entire self-call
// expression because of the hack that allows us to process self-calls
// with trans_call.
let fn_expr_ty = ty::expr_ty(bcx_tcx(in_cx), f);
let fn_ty = ty::type_autoderef(bcx_tcx(in_cx), fn_expr_ty);
let by_ref = ty::ty_fn_ret_style(bcx_tcx(in_cx), fn_ty) == ast::return_ref;
// Things that return by reference must put their arguments (FIXME only
// the referenced arguments) into the outer scope, so that they are still
// alive when the return value is used.
let cx = if by_ref { in_cx } else {
let cx = new_scope_block_ctxt(in_cx, "call");
Br(in_cx, cx.llbb);
cx
};
let f_res = trans_lval_gen(cx, f);
let fn_ty = ty::expr_ty(bcx_tcx(cx), f);
let bcx = f_res.res.bcx;
let faddr = f_res.res.val;
@ -3646,10 +3651,9 @@ fn trans_call(in_cx: @block_ctxt, f: @ast::expr,
}
none. {
// It's a closure. We have to autoderef.
if f_res.is_mem { faddr = load_if_immediate(bcx, faddr, fn_ty); }
let res = autoderef(bcx, faddr, fn_ty);
if f_res.is_mem { faddr = load_if_immediate(bcx, faddr, fn_expr_ty); }
let res = autoderef(bcx, faddr, fn_expr_ty);
bcx = res.bcx;
fn_ty = res.ty;
let pair = res.val;
faddr = GEP(bcx, pair, [C_int(0), C_int(abi::fn_field_code)]);
@ -3684,7 +3688,7 @@ fn trans_call(in_cx: @block_ctxt, f: @ast::expr,
alt lliterbody {
none. {
if !ty::type_is_nil(bcx_tcx(cx), ret_ty) {
if args_res.by_ref {
if by_ref {
let retptr = Load(bcx, llretslot);
retval = load_if_immediate(bcx, retptr, ret_ty);
} else {
@ -3710,7 +3714,7 @@ fn trans_call(in_cx: @block_ctxt, f: @ast::expr,
for {v: v, t: t} in args_res.to_revoke {
bcx = revoke_clean(bcx, v, t);
}
bcx = trans_block_cleanups(bcx, cx);
if !by_ref { bcx = trans_block_cleanups(bcx, cx); }
let next_cx = new_sub_block_ctxt(in_cx, "next");
Br(bcx, next_cx.llbb);
bcx = next_cx;