Fix all "unscheduled update()" warnings in our code (#7991)

* Fix all "unscheduled update()" warnings in our code

And also fix the Mullapudi scheduler to explicitly touch all update stages. This allows us to mark this warning as an error if we so choose.

* fixes

* fixes

* Update recursive_box_filters.cpp

apps/hist/hist_generator.cpp

@@ -181,6 +181,7 @@ class Hist : public Halide::Generator<Hist> {
                     .compute_at(hist_rows.in(), y)
                     .vectorize(x, vec);
 
+                hist_rows.update(0).unscheduled();
                 hist_rows.in()
                     .compute_root()
                     .vectorize(x, vec)
@@ -199,7 +200,7 @@ class Hist : public Halide::Generator<Hist> {
                     .parallel(x)
                     .reorder(ry, x);
 
-                cdf.compute_root();
+                cdf.compute_root().update().unscheduled();
                 output.reorder(c, x, y)
                     .bound(c, 0, 3)
                     .unroll(c)

apps/iir_blur/iir_blur_generator.cpp

@@ -51,6 +51,8 @@ Func blur_cols_transpose(Func input, Expr height, Expr alpha, bool skip_schedule
             blur.compute_at(transpose, yo);
 
             // Vectorize computations within the strips.
+            blur.update(0)
+                .unscheduled();
             blur.update(1)
                 .reorder(x, ry)
                 .vectorize(x);

src/autoschedulers/anderson2021/cost_model_generator.cpp

@@ -661,7 +661,7 @@ class CostModel : public Generator<CostModel<training>> {
             };
 
             // Pipeline features processing
-            conv1_stage1.compute_root().vectorize(c);
+            conv1_stage1.compute_root().vectorize(c).update().vectorize(c);
             squashed_head1_filter.compute_root().vectorize(c);
 
             // Schedule features processing. The number of schedule

src/autoschedulers/mullapudi2016/AutoSchedule.cpp

@@ -837,20 +837,27 @@ struct AutoSchedule {
                 }
             }
 
-            for (const auto &m : f.second) {
-                const int stage = m.first;
-                const vector<string> &schedules = m.second;
-                internal_assert(!schedules.empty());
+            const int num_stages = func.updates().size() + 1;
+            for (int stage = 0; stage < num_stages; stage++) {
                 schedule_ss << "    " << fname;
                 if (stage > 0) {
-                    schedule_ss << ".update(" << std::to_string(stage - 1) << ")";
+                    schedule_ss << ".update(" << (stage - 1) << ")";
                 }
-                for (const std::string &s : schedules) {
-                    schedule_ss << "\n        ." << s;
+                auto it = f.second.find(stage);
+                if (it != f.second.end()) {
+                    const vector<string> &schedules = it->second;
+                    internal_assert(!schedules.empty());
+                    for (const std::string &s : schedules) {
+                        internal_assert(!s.empty());
+                        schedule_ss << "\n        ." << s;
+                    }
+                } else {
+                    if (stage > 0) {
+                        schedule_ss << ".unscheduled()";
+                    }
                 }
                 schedule_ss << ";\n";
             }
-
             schedule_ss << "}\n";
         }
 
@@ -3386,6 +3393,16 @@ string generate_schedules(const vector<Function> &outputs, const Target &target,
     debug(2) << "Generating CPU schedule...\n";
     part.generate_cpu_schedule(target, sched);
 
+    // Ensure that all update stages are "touched" so we get no warnings/errors
+    for (const auto &f : sched.func_schedules) {
+        const Function &func = get_element(sched.env, f.first);
+        const int num_update_stages = func.updates().size();
+        for (int stage = 0; stage < num_update_stages; stage++) {
+            Definition def = get_stage_definition(func, stage + 1);
+            def.schedule().touched() = true;
+        }
+    }
+
     std::ostringstream oss;
     oss << sched;
     string sched_string = oss.str();

test/correctness/recursive_box_filters.cpp

@@ -26,6 +26,10 @@ int main(int argc, char **argv) {
     // have to pass 'true' to the atomic call to tell it to skip the check.
     h.update(2).atomic(true).vectorize(r, 16);
 
+    // These stages don't need scheduling
+    h.update(0).unscheduled();
+    h.update(1).unscheduled();
+
     Buffer<int> r0(size);
     Buffer<int> r1(size);
     h.realize({r0, r1});

test/error/tuple_output_bounds_check.cpp

@@ -17,6 +17,7 @@ int main(int argc, char **argv) {
 
     Var xo, xi;
     h.split(x, xo, xi, 16, TailStrategy::RoundUp);
+    h.update(0).unscheduled();
 
     Buffer<int> r0(size);
     Buffer<int> r1(size);