diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/passes/TypeRefining.cpp | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/src/passes/TypeRefining.cpp b/src/passes/TypeRefining.cpp index 87366e148..7fd039411 100644 --- a/src/passes/TypeRefining.cpp +++ b/src/passes/TypeRefining.cpp @@ -250,7 +250,29 @@ struct TypeRefining : public Pass { } void visitStructGet(StructGet* curr) { - if (curr->ref->type == Type::unreachable || curr->ref->type.isNull()) { + if (curr->ref->type == Type::unreachable) { + return; + } + + if (curr->ref->type.isNull()) { + // This get will trap. In theory we could leave this for later + // optimizations to do, but we must actually handle it here, because + // of the situation where this get's type is refined, and the input + // type is the result of a refining: + // + // (struct.get $A ;; should be refined to something + // (struct.get $B ;; just refined to nullref + // + // If the input has become a nullref then we can't just return out of + // this function, as we'd be leaving a struct.get of $A with the + // wrong type. But we can't find the right type since in Binaryen IR + // we use the ref's type to see what is being read, and that just + // turned into nullref. To avoid that corner case, just turn this code + // into unreachable code now, and the later refinalize will turn all + // the parents unreachable, avoiding any type-checking problems. + Builder builder(*getModule()); + replaceCurrent(builder.makeSequence(builder.makeDrop(curr->ref), + builder.makeUnreachable())); return; } |