[compiler] Mark each variable stored on entry to catch block.

We do not generate explicit control flow and phis for exceptional
edges. Instead CatchBlockEntry has a Parameter instruction for
each local variable. These Parameter-s represent that state
of local variables on entry into the catch block. This means
that we should mark all variables assigned on entry to the
catch block.

Previous version of the code was incorrectly marking only
direct parameters as stored.

Fixes dart-lang/sdk#36953

Bug: 36953
Change-Id: I2e8040d75ba23d2483e451300f44bbdcef458655
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103802
Reviewed-by: Daco Harkes <[email protected]>
Commit-Queue: Vyacheslav Egorov <[email protected]>

Author: mraleph

runtime/tests/vm/dart/regress36953_test.dart

@@ -0,0 +1,30 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Regression test for dartbug.com/36953: check that phi is inserted correctly
+// when try block has no normal exit.
+
+// VMOptions=--optimization_counter_threshold=10 --deterministic
+
+import "package:expect/expect.dart";
+
+void testBody() {
+  var v;
+  do {
+    try {} catch (e, st) {
+      continue;
+    }
+
+    try {
+      v = 10;
+      throw "";
+    } catch (e, st) {}
+  } while (v++ < 10);
+  Expect.equals(11, v);
+}
+
+void main() {
+  testBody();
+  testBody();
+}

runtime/vm/compiler/backend/flow_graph.cc

@@ -756,10 +756,12 @@ void VariableLivenessAnalysis::ComputeInitialSets() {
     // to the kill set.
     const bool is_function_entry = block->IsFunctionEntry();
     const bool is_osr_entry = block->IsOsrEntry();
-    if (is_function_entry || is_osr_entry || block->IsCatchBlockEntry()) {
+    const bool is_catch_block_entry = block->IsCatchBlockEntry();
+    if (is_function_entry || is_osr_entry || is_catch_block_entry) {
       const intptr_t parameter_count =
-          is_osr_entry ? flow_graph_->variable_count()
-                       : flow_graph_->num_direct_parameters();
+          (is_osr_entry || is_catch_block_entry)
+              ? flow_graph_->variable_count()
+              : flow_graph_->num_direct_parameters();
       for (intptr_t i = 0; i < parameter_count; ++i) {
         live_in->Remove(i);
         kill->Add(i);