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Fix trans_alt to handle unreachable branches without blowing up

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This commit is contained in:
Marijn Haverbeke
2011-07-19 17:07:51 +02:00
parent ce3d6339e0
commit a0ab57b3f6
1 changed files with 25 additions and 12 deletions
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27
src/comp/middle/trans_alt.rs
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@@ -382,29 +382,38 @@ fn compile_submatch(@block_ctxt bcx, &match m, ValueRef[] vals, &mk_fail f,
} }
} }
// FIXME breaks on unreacheable cases // Returns false for unreachable blocks
fn make_phi_bindings(&@block_ctxt bcx, &exit_node[] map, fn make_phi_bindings(&@block_ctxt bcx, &exit_node[] map,
&ast::pat_id_map ids) { &ast::pat_id_map ids) -> bool {
fn assoc(str key, &tup(str, ValueRef)[] list) -> ValueRef { fn assoc(str key, &tup(str, ValueRef)[] list) -> option::t[ValueRef] {
for (tup(str, ValueRef) elt in list) { for (tup(str, ValueRef) elt in list) {
if (str::eq(elt._0, key)) { ret elt._1; } if (str::eq(elt._0, key)) { ret some(elt._1); }
} }
fail; ret none;
} }
auto our_block = bcx.llbb as uint; auto our_block = bcx.llbb as uint;
auto success = true;
for each (@tup(ast::ident, ast::node_id) item in ids.items()) { for each (@tup(ast::ident, ast::node_id) item in ids.items()) {
auto llbbs = ~[]; auto llbbs = ~[];
auto vals = ~[]; auto vals = ~[];
for (exit_node ex in map) { for (exit_node ex in map) {
if (ex.to as uint == our_block) { if (ex.to as uint == our_block) {
alt (assoc(item._0, ex.bound)) {
some(?val) {
llbbs += ~[ex.from]; llbbs += ~[ex.from];
vals += ~[assoc(item._0, ex.bound)]; vals += ~[val];
}
none {}
} }
} }
}
if (ivec::len(vals) > 0u) {
auto phi = bcx.build.Phi(val_ty(vals.(0)), vals, llbbs); auto phi = bcx.build.Phi(val_ty(vals.(0)), vals, llbbs);
bcx.fcx.lllocals.insert(item._1, phi); bcx.fcx.lllocals.insert(item._1, phi);
} else { success = false; }
} }
ret success;
} }
fn trans_alt(&@block_ctxt cx, &@ast::expr expr, &ast::arm[] arms, fn trans_alt(&@block_ctxt cx, &@ast::expr expr, &ast::arm[] arms,
@@ -444,9 +453,13 @@ fn trans_alt(&@block_ctxt cx, &@ast::expr expr, &ast::arm[] arms,
auto arm_results = ~[]; auto arm_results = ~[];
for (ast::arm a in arms) { for (ast::arm a in arms) {
auto body_cx = bodies.(i); auto body_cx = bodies.(i);
make_phi_bindings(body_cx, exit_map, ast::pat_id_map(a.pats.(0))); if (make_phi_bindings(body_cx, exit_map,
ast::pat_id_map(a.pats.(0)))) {
auto block_res = trans::trans_block(body_cx, a.block, output); auto block_res = trans::trans_block(body_cx, a.block, output);
arm_results += ~[block_res]; arm_results += ~[block_res];
} else { // Unreachable
arm_results += ~[rslt(body_cx, C_nil())];
}
i += 1u; i += 1u;
} }
ret rslt(trans::join_branches(cx, arm_results), C_nil()); ret rslt(trans::join_branches(cx, arm_results), C_nil());