[turbofan] Add single --turbo flag.

This flag is intended as a staging flag for TurboFan. It serves as a
single flag that always enables a most recent configuration of TurboFan
for test suites and benchmarks, without needing to update test drivers.

R=titzer@chromium.org,machenbach@chromium.org

Review URL: https://codereview.chromium.org/1094573002

Cr-Commit-Position: refs/heads/master@{#27896}

src/flag-definitions.h

@@ -380,7 +380,9 @@ DEFINE_BOOL(omit_map_checks_for_leaf_maps, true,
             "deoptimize the optimized code if the layout of the maps changes.")
 
 // Flags for TurboFan.
-DEFINE_STRING(turbo_filter, "~", "optimization filter for TurboFan compiler")
+DEFINE_BOOL(turbo, false, "enable TurboFan compiler")
+DEFINE_IMPLICATION(turbo, turbo_deoptimization)
+DEFINE_STRING(turbo_filter, "~~", "optimization filter for TurboFan compiler")
 DEFINE_BOOL(trace_turbo, false, "trace generated TurboFan IR")
 DEFINE_BOOL(trace_turbo_graph, false, "trace generated TurboFan graphs")
 DEFINE_IMPLICATION(trace_turbo_graph, trace_turbo)

src/v8.cc

@@ -77,6 +77,11 @@ void V8::InitializeOncePerProcessImpl() {
     FLAG_max_semi_space_size = 1;
   }
 
+  if (FLAG_turbo && strcmp(FLAG_turbo_filter, "~~") == 0) {
+    const char* filter_flag = "--turbo-filter=*";
+    FlagList::SetFlagsFromString(filter_flag, StrLength(filter_flag));
+  }
+
   base::OS::Initialize(FLAG_random_seed, FLAG_hard_abort, FLAG_gc_fake_mmap);
 
   Isolate::InitializeOncePerProcess();

test/benchmarks/testcfg.py

@@ -186,7 +186,7 @@ class BenchmarksTestSuite(testsuite.TestSuite):
     # Both --nocrankshaft and --stressopt are very slow. Add TF but without
     # always opt to match the way the benchmarks are run for performance
     # testing.
-    return [[], ["--turbo-filter=*"]]
+    return [[], ["--turbo"]]
 
 
 def GetSuite(name, root):

tools/testrunner/local/testsuite.py

@@ -38,7 +38,7 @@ from ..objects import testcase
 VARIANT_FLAGS = {
     "default": [],
     "stress": ["--stress-opt", "--always-opt"],
-    "turbofan": ["--turbo-deoptimization", "--turbo-filter=*", "--always-opt"],
+    "turbofan": ["--turbo", "--always-opt"],
     "nocrankshaft": ["--nocrankshaft"]}
 
 FAST_VARIANT_FLAGS = [