[turbofan] Remove deprecated --turbo-from-bytecode flag.

This flag is on by default for now. Whenever heuristics in the compiler
pipeline decide to use Ignition+TurboFan, then {BytecodeGraphBuilder} is
active. Removing the flag reduces maintenance overhead.

R=mvstanton@chromium.org

Review-Url: https://codereview.chromium.org/2437103002
Cr-Commit-Position: refs/heads/master@{#40639}

src/ast/ast-numbering.cc

@@ -592,12 +592,7 @@ bool AstNumberingVisitor::Renumber(FunctionLiteral* node) {
   }
 
   if (IsGeneratorFunction(node->kind()) || IsAsyncFunction(node->kind())) {
-    // Generators can be optimized if --turbo-from-bytecode is set.
-    if (FLAG_turbo_from_bytecode) {
-      DisableCrankshaft(kGenerator);
-    } else {
-      DisableOptimization(kGenerator);
-    }
+    DisableCrankshaft(kGenerator);
   }
 
   if (IsClassConstructor(node->kind())) {

src/compiler.cc

@@ -619,9 +619,6 @@ MaybeHandle<Code> GetOptimizedCode(Handle<JSFunction> function,
   // Shared function no longer needs to be tiered up
   shared->set_marked_for_tier_up(false);
 
-  // Flag combination --ignition-osr --no-turbo-from-bytecode is unsupported.
-  if (ignition_osr && !FLAG_turbo_from_bytecode) return MaybeHandle<Code>();
-
   Handle<Code> cached_code;
   // TODO(4764): When compiling for OSR from bytecode, BailoutId might derive
   // from bytecode offset and overlap with actual BailoutId. No lookup!
@@ -675,7 +672,7 @@ MaybeHandle<Code> GetOptimizedCode(Handle<JSFunction> function,
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.OptimizeCode");
 
   // TurboFan can optimize directly from existing bytecode.
-  if (FLAG_turbo_from_bytecode && use_turbofan && ShouldUseIgnition(info)) {
+  if (use_turbofan && ShouldUseIgnition(info)) {
     if (info->is_osr() && !ignition_osr) return MaybeHandle<Code>();
     if (!Compiler::EnsureBytecode(info)) {
       if (isolate->has_pending_exception()) isolate->clear_pending_exception();
@@ -788,10 +785,9 @@ class InterpreterActivationsFinder : public ThreadVisitor,
     JavaScriptFrameIterator it(isolate, top);
     for (; !it.done(); it.Advance()) {
       JavaScriptFrame* frame = it.frame();
-      if (FLAG_turbo_from_bytecode && FLAG_ignition_osr &&
-          frame->is_optimized() && frame->function()->shared() == shared_) {
-        // If we are able to optimize functions directly from bytecode, then
-        // there might be optimized OSR code active on the stack that is not
+      if (FLAG_ignition_osr && frame->is_optimized() &&
+          frame->function()->shared() == shared_) {
+        // There might be optimized OSR code active on the stack that is not
         // reachable through a function. We count this as an activation.
         has_activations_ = true;
       }
@@ -838,12 +834,9 @@ bool HasInterpreterActivations(
     Isolate* isolate, InterpreterActivationsFinder* activations_finder) {
   activations_finder->VisitThread(isolate, isolate->thread_local_top());
   isolate->thread_manager()->IterateArchivedThreads(activations_finder);
-  if (FLAG_turbo_from_bytecode) {
-    // If we are able to optimize functions directly from bytecode, then there
-    // might be optimized functions that rely on bytecode being around. We need
-    // to prevent switching the given function to baseline code in those cases.
-    Deoptimizer::VisitAllOptimizedFunctions(isolate, activations_finder);
-  }
+  // There might be optimized functions that rely on bytecode being around. We
+  // need to prevent switching the given function to baseline code.
+  Deoptimizer::VisitAllOptimizedFunctions(isolate, activations_finder);
   return activations_finder->has_activations();
 }
 
@@ -1372,7 +1365,7 @@ bool Compiler::EnsureDeoptimizationSupport(CompilationInfo* info) {
 Compiler::CompilationTier Compiler::NextCompilationTier(JSFunction* function) {
   Handle<SharedFunctionInfo> shared(function->shared(), function->GetIsolate());
   if (shared->code()->is_interpreter_trampoline_builtin()) {
-    if (FLAG_turbo_from_bytecode && UseTurboFan(shared)) {
+    if (UseTurboFan(shared)) {
       return OPTIMIZED;
     } else {
       return BASELINE;

src/flag-definitions.h

@@ -427,7 +427,6 @@ DEFINE_BOOL(omit_map_checks_for_leaf_maps, true,
 DEFINE_BOOL(turbo, false, "enable TurboFan compiler")
 DEFINE_IMPLICATION(turbo, turbo_asm_deoptimization)
 DEFINE_IMPLICATION(turbo, turbo_loop_peeling)
-DEFINE_BOOL(turbo_from_bytecode, true, "enable building graphs from bytecode")
 DEFINE_BOOL(turbo_sp_frame_access, false,
             "use stack pointer-relative access to frame wherever possible")
 DEFINE_BOOL(turbo_preprocess_ranges, true,

test/mjsunit/array-literal-transitions.js

@@ -25,8 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --allow-natives-syntax --expose-gc
-// Flags: --ignition-osr --turbo-from-bytecode
+// Flags: --allow-natives-syntax --expose-gc --ignition-osr
 
 // IC and Crankshaft support for smi-only elements in dynamic array literals.
 function get(foo) { return foo; }  // Used to generate dynamic values.

test/mjsunit/ignition/osr-from-bytecode.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --ignition --ignition-osr --turbo-from-bytecode
+// Flags: --allow-natives-syntax --ignition --ignition-osr
 
 function f() {
   for (var i = 0; i < 10; i++) {

test/mjsunit/regress/regress-2618.js

@@ -25,7 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --use-osr --allow-natives-syntax --ignition-osr --turbo-from-bytecode
+// Flags: --use-osr --allow-natives-syntax --ignition-osr
 
 function f() {
   do {

test/mjsunit/regress/regress-5252.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --ignition --ignition-osr --turbo-from-bytecode
+// Flags: --allow-natives-syntax --ignition --ignition-osr
 
 (function TestNonLoopyLoop() {
   function f() {

test/mjsunit/regress/regress-5262.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --ignition --ignition-osr --turbo-from-bytecode --allow-natives-syntax
+// Flags: --ignition --ignition-osr --allow-natives-syntax
 
 function g() { return 23 }
 function h() { return 42 }

test/mjsunit/regress/regress-632289.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --ignition --turbo-from-bytecode --always-opt --allow-natives-syntax
+// Flags: --ignition --always-opt --allow-natives-syntax
 
 try {
 } catch(e) {; }

test/mjsunit/regress/regress-crbug-632800.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --ignition --ignition-osr --turbo-from-bytecode
+// Flags: --ignition --ignition-osr
 
 function osr() {
   for (var i = 0; i < 50000; ++i) Math.random();

test/mjsunit/regress/regress-crbug-635923.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --ignition --turbo-from-bytecode --turbo-filter=f
+// Flags: --allow-natives-syntax --ignition --turbo-filter=f
 
 function f(x) { return x + 23 }
 function g(x) { return f(x) + 42 }