Merge pull request #3776 from halide/srj-gv

IRGraphVisitor should increment refcount of visited items

src/CodeGen_C.cpp

@@ -275,10 +275,6 @@ class TypeInfoGatherer : public IRGraphVisitor {
  include_type(op->type);
  if (op->is_intrinsic(Call::lerp)) {
  // lower_lerp() can synthesize wider vector types.
- // It's not safe to feed temporary Exprs into IRGraphVisitor
- // (it tracks the seen values by IRNode*, which could get recycled
- // if we are unlucky), so just add widened versions of any
- // types present -- it's safe to add types we might not use.
  for (auto &a : op->args) {
  include_lerp_types(a.type());
  }

src/IRVisitor.h

@@ -92,7 +92,7 @@ class IRGraphVisitor : public IRVisitor {
 
 private:
  /** The nodes visited so far */
- std::set<const IRNode *> visited;
+ std::set<IRHandle> visited;
 
 protected:
  /** These methods should call 'include' on the children to only