diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/cfg/liveness-traversal.h | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/src/cfg/liveness-traversal.h b/src/cfg/liveness-traversal.h index 6deab2fd6..ee56a9925 100644 --- a/src/cfg/liveness-traversal.h +++ b/src/cfg/liveness-traversal.h @@ -118,7 +118,27 @@ struct LivenessWalker : public CFGWalker<SubType, VisitorType, Liveness> { auto* curr = (*currp)->cast<LocalGet>(); // if in unreachable code, ignore if (!self->currBasicBlock) { - *currp = Builder(*self->getModule()).replaceWithIdenticalType(curr); + Builder builder(*self->getModule()); + auto* rep = builder.replaceWithIdenticalType(curr); + if (rep->is<LocalGet>()) { + // We failed to replace the node with something simpler. This can happen + // if the local is non-nullable, for example. We still need to remove + // this node entirely, however, as it is unreachable and so we will not + // see it in the analysis we perform (for example, we may be changing + // local indexes). Replace it with something completely different, even + // if it is larger, a block with a forced type that has unreachable + // contents, + // + // (block (result X) + // (unreachable)) + // + // That pattern lets us set any type we wish. + // + // TODO: Make a helper function for this, if it is useful in other + // places. + rep = builder.makeBlock({builder.makeUnreachable()}, curr->type); + } + *currp = rep; return; } self->currBasicBlock->contents.actions.emplace_back( |