More general CHA-based inlining and devirtualization for precompiled code.

runtime/vm/flow_graph_inliner.cc

Index: runtime/vm/flow_graph_inliner.cc
diff --git a/runtime/vm/flow_graph_inliner.cc b/runtime/vm/flow_graph_inliner.cc
index 7aa1adb0d0e8b9348798baa1629930dcf3386c03..9de829e638089f6c400b33154a597eb083ecbe4d 100644
--- a/runtime/vm/flow_graph_inliner.cc
+++ b/runtime/vm/flow_graph_inliner.cc
@@ -626,6 +626,16 @@ class CallSiteInliner : public ValueObject {
       return false;
     }
 
+    // Function has not beed compiled yet.  With lazy compilation a function
+    // that has not been executed won't have any type feedback. In
+    // precompilation mode we don't rely on type feedback.

[srdjan, 2015/10/21 17:37:46]

This can be a problem for Siva's change where we store type feedback in
snapshots and first compilation is optimized. How about checking the invocation
counter instead of HasCode?

[rmacnak, 2015/10/21 18:00:30]

Can this check if the function has an ic data array instead? --collect-code can
drop code but leave the ic data array.

[Florian Schneider, 2015/10/22 13:59:25]

I would opt for checking the ic data array, but I did want to 
change inlining heuristics for regular compilation in this change.

Note that this is exactly the same test that we already have with lazy
compilation. I just moved it from Function::CanBeInlined to here so that I can
skip this condition with precompilation.

[srdjan, 2015/10/22 15:31:26]

OK, to replicate current behavior. CC-ing Siva to know what to fix to enable
inlining in snapshots with instant optimization

+    if (!Compiler::always_optimize() && !function.HasCode()) {
+      TRACE_INLINING(THR_Print("     Bailout: not compiled yet\n"));
+      PRINT_INLINING_TREE("Not compiled",
+          &call_data->caller, &function, call_data->call);
+      return false;
+    }
+
     // Abort if this function has deoptimized too much.
     if (function.deoptimization_counter() >=
         FLAG_deoptimization_counter_threshold) {