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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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37
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,
&ast::pat_id_map ids) {
fn assoc(str key, &tup(str, ValueRef)[] list) -> ValueRef {
&ast::pat_id_map ids) -> bool {
fn assoc(str key, &tup(str, ValueRef)[] list) -> option::t[ValueRef] {
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 success = true;
for each (@tup(ast::ident, ast::node_id) item in ids.items()) {
auto llbbs = ~[];
auto vals = ~[];
for (exit_node ex in map) {
if (ex.to as uint == our_block) {
llbbs += ~[ex.from];
vals += ~[assoc(item._0, ex.bound)];
alt (assoc(item._0, ex.bound)) {
some(?val) {
llbbs += ~[ex.from];
vals += ~[val];
}
none {}
}
}
}
auto phi = bcx.build.Phi(val_ty(vals.(0)), vals, llbbs);
bcx.fcx.lllocals.insert(item._1, phi);
if (ivec::len(vals) > 0u) {
auto phi = bcx.build.Phi(val_ty(vals.(0)), vals, llbbs);
bcx.fcx.lllocals.insert(item._1, phi);
} else { success = false; }
}
ret success;
}
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 = ~[];
for (ast::arm a in arms) {
auto body_cx = bodies.(i);
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);
arm_results += ~[block_res];
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);
arm_results += ~[block_res];
} else { // Unreachable
arm_results += ~[rslt(body_cx, C_nil())];
}
i += 1u;
}
ret rslt(trans::join_branches(cx, arm_results), C_nil());