[turbofan] Implement OSR for outer loops.

src/flag-definitions.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.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
@@ skipping 387 matching lines @@
 DEFINE_BOOL(trace_turbo_inlining, false, "trace TurboFan inlining")
 DEFINE_BOOL(loop_assignment_analysis, true, "perform loop assignment analysis")
 DEFINE_IMPLICATION(turbo_inlining_intrinsics, turbo_inlining)
 DEFINE_IMPLICATION(turbo_inlining, turbo_types)
 DEFINE_BOOL(turbo_profiling, false, "enable profiling in TurboFan")
 // TODO(dcarney): this is just for experimentation, remove when default.
 DEFINE_BOOL(turbo_delay_ssa_decon, false,
             "delay ssa deconstruction in TurboFan register allocator")
 // TODO(dcarney): this is just for debugging, remove eventually.
 DEFINE_BOOL(turbo_move_optimization, true, "optimize gap moves in TurboFan")
-DEFINE_BOOL(turbo_jt, true, "enable jump threading")
+DEFINE_BOOL(turbo_jt, true, "enable jump threading in TurboFan")
+DEFINE_BOOL(turbo_osr, false, "enable OSR in TurboFan")
 
 DEFINE_INT(typed_array_max_size_in_heap, 64,
            "threshold for in-heap typed array")
 
 // Profiler flags.
 DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")
 // 0x1800 fits in the immediate field of an ARM instruction.
 DEFINE_INT(interrupt_budget, 0x1800,
            "execution budget before interrupt is triggered")
 DEFINE_INT(type_info_threshold, 25,
@@ skipping 576 matching lines @@
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA