When Crankshaft aborts compilation, use TurboFan next time

src/compiler.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_H_
 #define V8_COMPILER_H_
 
 #include "src/allocation.h"
 #include "src/ast/ast.h"
 #include "src/bailout-reason.h"
@@ skipping 369 matching lines @@
 
   Code::Kind output_code_kind() const {
     return Code::ExtractKindFromFlags(code_flags_);
   }
 
  protected:
   ParseInfo* parse_info_;
 
   void DisableFutureOptimization() {
     if (GetFlag(kDisableFutureOptimization) && has_shared_info()) {
-      shared_info()->DisableOptimization(bailout_reason());
+      // If Crankshaft tried to optimize this function, bailed out, and
+      // doesn't want to try again, then use TurboFan next time.
+      if (!shared_info()->dont_crankshaft()) {
+        shared_info()->set_dont_crankshaft(true);

[Michael Starzinger, 2016/03/01 14:34:56]

Just for posterity: This will also disable Crankshaft for transient reasons that
might "disappear" over time (e.g. kFunctionBeingDebugged). It will also disable
Crankshaft and favor TurboFan for reasons not specific to Crankshaft (e.g.
kOptimizedTooManyTimes). This will need to be cleaned up once we try to get
compiler.cc in shape for shipping Ignition.

[adamk, 2016/03/01 19:15:44]

The second one of these examples, kOptimizedTooManyTimes, worries me a bit: does
that have the potential to make code where we spend all our time compiling
perform even worse?

+        if (FLAG_trace_opt) {
+          PrintF("[disabled Crankshaft for ");
+          shared_info()->ShortPrint();
+          PrintF(", reason: %s]\n", GetBailoutReason(bailout_reason()));
+        }
+      } else {
+        shared_info()->DisableOptimization(bailout_reason());
+      }
     }
   }
 
  private:
   // Compilation mode.
   // BASE is generated by the full codegen, optionally prepared for bailouts.
   // OPTIMIZE is optimized code generated by the Hydrogen-based backend.
   enum Mode {
     BASE,
     OPTIMIZE,
@@ skipping 276 matching lines @@
   size_t info_zone_start_allocation_size_;
   base::ElapsedTimer timer_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilationPhase);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_H_