Be less aggressive in sharing contexts between scopes so that sibling contexts

runtime/vm/parser_test.cc

 // Copyright (c) 2011, 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.
 
 
 #include "vm/ast_printer.h"
 #include "vm/class_finalizer.h"
 #include "vm/debugger.h"
 #include "vm/longjump.h"
 #include "vm/object.h"
@@ skipping 259 matching lines @@
       "   name=:current_context_var\n"
 
       // Closure call saves current context.
       "_FunctionImpl.call\n"
       " 0 StackVar      scope=1   begin=0   end=4   name=this\n"
       " 1 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
 
       // function main uses one ctx var at (1); saves caller ctx.
       "main\n"
-      " 0 ContextLevel  level=1   scope=1   begin=2   end=37\n"
-      " 1 CurrentCtx    scope=0   begin=0   end=0"
+      " 0 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
+      " 1 ContextLevel  level=1   scope=2   begin=4   end=37\n"
       " 2 ContextVar    level=1   begin=10  end=37  name=value\n"
       " 3 StackVar      scope=2   begin=12  end=37  name=f\n",
       CaptureVarsAtLine(lib, "main", 4));
 }
 
 
 TEST_CASE(Parser_AllocateVariables_NestedCapturedVar) {
   const char* kScriptChars =
       "int a() {\n"
       "  int b() {\n"
@@ skipping 18 matching lines @@
       // Closure call saves current context.
       "_FunctionImpl.call\n"
       " 0 StackVar      scope=1   begin=0   end=4   name=this\n"
       " 1 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
 
       // Middle function saves the entry context.  Notice that this
       // happens here and not in the outermost function.  We always
       // save the entry context at the last possible moment.
       "a.b\n"
-      " 0 ContextLevel  level=1   scope=1   begin=8   end=38\n"
-      " 1 CurrentCtx    scope=0   begin=0   end=0"
+      " 0 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
+      " 1 ContextLevel  level=1   scope=2   begin=10  end=38\n"
       " 2 ContextVar    level=1   begin=16  end=38  name=value\n"
       " 3 StackVar      scope=2   begin=18  end=38  name=c\n"
 
       // Closure call saves current context.
       "_FunctionImpl.call\n"
       " 0 StackVar      scope=1   begin=0   end=4   name=this\n"
       " 1 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
 
       // Outermost function neglects to save the entry context.  We
@@ skipping 36 matching lines @@
       // Closure call saves current context.
       "_FunctionImpl.call\n"
       " 0 StackVar      scope=1   begin=0   end=4   name=this\n"
       " 1 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
 
       // aa shares value2. Notice that we save the entry ctx instead
       // of chaining from b.  This keeps us from holding onto closures
       // that we would never access.
       "a.b.aa\n"
-      " 0 ContextLevel  level=1   scope=1   begin=20  end=50\n"
-      " 1 CurrentCtx    scope=0   begin=0   end=0"
+      " 0 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
+      " 1 ContextLevel  level=1   scope=2   begin=22  end=50\n"
       " 2 ContextVar    level=1   begin=28  end=50  name=value2\n"
       " 3 StackVar      scope=2   begin=30  end=50  name=bb\n"
 
       // Closure call saves current context.
       "_FunctionImpl.call\n"
       " 0 StackVar      scope=1   begin=0   end=4   name=this\n"
       " 1 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
 
       // b captures value1 from a.
       "a.b\n"
       " 0 ContextVar    level=0   begin=14  end=60  name=value1\n"
       " 1 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
       " 2 StackVar      scope=2   begin=18  end=60  name=aa\n"
 
       // Closure call saves current context.
       "_FunctionImpl.call\n"
       " 0 StackVar      scope=1   begin=0   end=4   name=this\n"
       " 1 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
 
       // a shares value1, saves entry ctx.
       "a\n"
-      " 0 ContextLevel  level=1   scope=1   begin=2   end=68\n"
-      " 1 CurrentCtx    scope=0   begin=0   end=0"
+      " 0 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
+      " 1 ContextLevel  level=1   scope=2   begin=4   end=68\n"
       " 2 ContextVar    level=1   begin=10  end=68  name=value1\n"
       " 3 StackVar      scope=2   begin=12  end=68  name=b\n",
       CaptureVarsAtLine(lib, "a", 7));
 }
 
 
 TEST_CASE(Parser_AllocateVariables_Issue7681) {
   // This is a distilled version of the program from Issue 7681.
   //
   // When we create the closure at line 11, we need to make sure to
@@ skipping 130 matching lines @@
       " 3 ContextLevel  level=1   scope=3   begin=18  end=46\n"
       " 4 ContextVar    level=1   begin=22  end=46  name=i\n"
       " 5 StackVar      scope=4   begin=32  end=46  name=d\n"
 
       "_FunctionImpl.call\n"
       " 0 StackVar      scope=1   begin=0   end=4   name=this\n"
       " 1 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
 
       "a\n"
-      " 0 ContextLevel  level=1   scope=1   begin=1   end=76\n"
-      " 1 CurrentCtx    scope=0   begin=0   end=0"
+      " 0 CurrentCtx    scope=0   begin=0   end=0"
       "   name=:current_context_var\n"
+      " 1 ContextLevel  level=1   scope=2   begin=3   end=76\n"
       " 2 ContextVar    level=1   begin=9   end=76  name=x\n"
       " 3 StackVar      scope=2   begin=11  end=76  name=b\n",
       CaptureVarsAtLine(lib, "a", 10));
 }
 
 }  // namespace dart