Use a large enough variable in CompilationCache::LookupScript to avoid overfl...

src/compilation-cache.cc

Index: src/compilation-cache.cc
===================================================================
--- src/compilation-cache.cc	(revision 1983)
+++ src/compilation-cache.cc	(working copy)
@@ -138,13 +138,17 @@
                                                   int line_offset,
                                                   int column_offset) {
   Object* result = NULL;
-  Entry generation = SCRIPT;  // First generation.
+  // Using int below so value range propagation in gcc 4.3+ won't assume
+  // |generation| can only go up to LAST_ENTRY when in fact it can go
+  // up to SCRIPT + NUMBER_OF_SCRIPT_GENERATIONS.
+  int generation = static_cast<int>(SCRIPT);  // First generation.
 
   // Probe the script generation tables. Make sure not to leak handles
   // into the caller's handle scope.
   { HandleScope scope;
     while (generation < SCRIPT + NUMBER_OF_SCRIPT_GENERATIONS) {
-      Handle<CompilationCacheTable> table = GetTable(generation);
+      Handle<CompilationCacheTable> table =
+          GetTable(static_cast<Entry>(generation));
       Handle<Object> probe(table->Lookup(*source));
       if (probe->IsJSFunction()) {
         Handle<JSFunction> boilerplate = Handle<JSFunction>::cast(probe);
@@ -156,7 +160,7 @@
         }
       }
       // Go to the next generation.
-      generation = static_cast<Entry>(generation + 1);
+      generation++;
     }
   }