Fix failure to pop loop var info

src/Simplify_Stmts.cpp

@@ -217,7 +217,12 @@ Stmt Simplify::visit(const For *op) {
                                          (in_vector_loop ||
                                           op->for_type == ForType::Vectorized));
 
-    bool bounds_tracked = false;
+    Expr extent_positive = mutate(0 < new_extent, nullptr);
+    if (is_const_zero(extent_positive)) {
+        // This loop never runs
+        return Evaluate::make(0);
+    }
+
     ExprInfo loop_var_info;
     // Deduce bounds for the loop var that are true for any code than runs
     // inside the loop body. Code in the inner loop only runs if the extent is
@@ -226,24 +231,19 @@ Stmt Simplify::visit(const For *op) {
     loop_var_info.bounds =
         ConstantInterval::make_union(min_info.bounds,
                                      min_info.bounds + max(extent_info.bounds, 1) - 1);
-
-    if (loop_var_info.bounds.max_defined ||
-        loop_var_info.bounds.min_defined) {
-        bounds_tracked = true;
-        bounds_and_alignment_info.push(op->name, loop_var_info);
-    }
-
-    Expr extent_positive = mutate(0 < new_extent, nullptr);
-    if (is_const_zero(extent_positive)) {
-        return Evaluate::make(0);
-    }
-
     Stmt new_body;
     {
+        ScopedBinding<ExprInfo> bind_if((loop_var_info.bounds.max_defined ||
+                                         loop_var_info.bounds.min_defined),
+                                        bounds_and_alignment_info,
+                                        op->name,
+                                        loop_var_info);
+
         // If we're in the loop, the extent must be greater than 0.
         ScopedFact fact = scoped_truth(extent_positive);
         new_body = mutate(op->body);
     }
+
     if (in_unreachable) {
         // We found that the body of this loop is unreachable when recursively
         // mutating it, so we can remove the loop. Additionally, if we know the
@@ -254,10 +254,6 @@ Stmt Simplify::visit(const For *op) {
         return Evaluate::make(0);
     }
 
-    if (bounds_tracked) {
-        bounds_and_alignment_info.pop(op->name);
-    }
-
     if (const Acquire *acquire = new_body.as<Acquire>()) {
         if (is_no_op(acquire->body)) {
             // Rewrite iterated no-op acquires as a single acquire.