[turbofan] Remove obsolete {SupportsTailCalls} flag.

R=jarin@chromium.org

Change-Id: I2b2d5095e7c5c06c509a0e1b1b1121e78a80735a
Reviewed-on: https://chromium-review.googlesource.com/796031Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49708}

src/compiler/code-assembler.cc

@@ -1006,7 +1006,7 @@ TNode<Object> CodeAssembler::TailCallRuntimeImpl(Runtime::FunctionId function,
   int argc = static_cast<int>(sizeof...(args));
   CallDescriptor* desc = Linkage::GetRuntimeCallDescriptor(
       zone(), function, argc, Operator::kNoProperties,
-      CallDescriptor::kSupportsTailCalls);
+      CallDescriptor::kNoFlags);
   int return_count = static_cast<int>(desc->ReturnCount());
 
   Node* centry =
@@ -1076,7 +1076,7 @@ Node* CodeAssembler::TailCallStubImpl(const CallInterfaceDescriptor& descriptor,
   size_t result_size = 1;
   CallDescriptor* desc = Linkage::GetStubCallDescriptor(
       isolate(), zone(), descriptor, descriptor.GetStackParameterCount(),
-      CallDescriptor::kSupportsTailCalls, Operator::kNoProperties,
+      CallDescriptor::kNoFlags, Operator::kNoProperties,
       MachineType::AnyTagged(), result_size);
 
   Node* nodes[] = {target, args..., context};
@@ -1102,7 +1102,7 @@ Node* CodeAssembler::TailCallStubThenBytecodeDispatch(
   DCHECK_LE(descriptor.GetStackParameterCount(), stack_parameter_count);
   CallDescriptor* desc = Linkage::GetStubCallDescriptor(
       isolate(), zone(), descriptor, stack_parameter_count,
-      CallDescriptor::kSupportsTailCalls, Operator::kNoProperties,
+      CallDescriptor::kNoFlags, Operator::kNoProperties,
       MachineType::AnyTagged(), 0);
 
   Node* nodes[] = {target, args..., context};

src/compiler/instruction-selector.cc

@@ -690,6 +690,7 @@ struct CallBuffer {
 // InstructionSelector::VisitCall platform independent instead.
 void InstructionSelector::InitializeCallBuffer(Node* call, CallBuffer* buffer,
                                                CallBufferFlags flags,
+                                               bool is_tail_call,
                                                int stack_param_delta) {
   OperandGenerator g(this);
   DCHECK_LE(call->op()->ValueOutputCount(),
@@ -787,7 +788,7 @@ void InstructionSelector::InitializeCallBuffer(Node* call, CallBuffer* buffer,
     // If it was a syntactic tail call we need to drop the current frame and
     // all the frames on top of it that are either an arguments adaptor frame
     // or a tail caller frame.
-    if (buffer->descriptor->SupportsTailCalls()) {
+    if (is_tail_call) {
       frame_state = NodeProperties::GetFrameStateInput(frame_state);
       buffer->frame_state_descriptor =
           buffer->frame_state_descriptor->outer_state();
@@ -2565,7 +2566,7 @@ void InstructionSelector::VisitCall(Node* node, BasicBlock* handler) {
   // Improve constant pool and the heuristics in the register allocator
   // for where to emit constants.
   CallBufferFlags call_buffer_flags(kCallCodeImmediate | kCallAddressImmediate);
-  InitializeCallBuffer(node, &buffer, call_buffer_flags);
+  InitializeCallBuffer(node, &buffer, call_buffer_flags, false);
 
   EmitPrepareArguments(&(buffer.pushed_nodes), descriptor, node);
 
@@ -2630,7 +2631,6 @@ void InstructionSelector::VisitCallWithCallerSavedRegisters(
 void InstructionSelector::VisitTailCall(Node* node) {
   OperandGenerator g(this);
   CallDescriptor const* descriptor = CallDescriptorOf(node->op());
-  DCHECK_NE(0, descriptor->flags() & CallDescriptor::kSupportsTailCalls);
 
   CallDescriptor* caller = linkage()->GetIncomingDescriptor();
   DCHECK(caller->CanTailCall(node));
@@ -2643,7 +2643,7 @@ void InstructionSelector::VisitTailCall(Node* node) {
   if (IsTailCallAddressImmediate()) {
     flags |= kCallAddressImmediate;
   }
-  InitializeCallBuffer(node, &buffer, flags, stack_param_delta);
+  InitializeCallBuffer(node, &buffer, flags, true, stack_param_delta);
 
   // Select the appropriate opcode based on the call type.
   InstructionCode opcode;

src/compiler/instruction-selector.h

@@ -285,7 +285,8 @@ class V8_EXPORT_PRIVATE InstructionSelector final {
   // {call_code_immediate} to generate immediate operands to calls of code.
   // {call_address_immediate} to generate immediate operands to address calls.
   void InitializeCallBuffer(Node* call, CallBuffer* buffer,
-                            CallBufferFlags flags, int stack_slot_delta = 0);
+                            CallBufferFlags flags, bool is_tail_call,
+                            int stack_slot_delta = 0);
   bool IsTailCallAddressImmediate();
   int GetTempsCountForTailCallFromJSFunction();
 

src/compiler/js-typed-lowering.cc

@@ -1455,7 +1455,6 @@ void ReduceBuiltin(Isolate* isolate, JSGraph* jsgraph, Node* node,
   const bool is_construct = (node->opcode() == IrOpcode::kJSConstruct);
 
   DCHECK(Builtins::HasCppImplementation(builtin_index));
-  DCHECK_EQ(0, flags & CallDescriptor::kSupportsTailCalls);
 
   Node* target = NodeProperties::GetValueInput(node, 0);
   Node* new_target = is_construct

src/compiler/linkage.cc

@@ -49,7 +49,7 @@ std::ostream& operator<<(std::ostream& os, const CallDescriptor& d) {
   // TODO(svenpanne) Output properties etc. and be less cryptic.
   return os << d.kind() << ":" << d.debug_name() << ":r" << d.ReturnCount()
             << "s" << d.StackParameterCount() << "i" << d.InputCount() << "f"
-            << d.FrameStateCount() << "t" << d.SupportsTailCalls();
+            << d.FrameStateCount();
 }
 
 MachineSignature* CallDescriptor::GetMachineSignature(Zone* zone) const {
@@ -462,8 +462,7 @@ CallDescriptor* Linkage::GetBytecodeDispatchCallDescriptor(
       Operator::kNoProperties,       // properties
       kNoCalleeSaved,                // callee-saved registers
       kNoCalleeSaved,                // callee-saved fp
-      CallDescriptor::kCanUseRoots |           // flags
-          CallDescriptor::kSupportsTailCalls,  // flags
+      CallDescriptor::kCanUseRoots,  // flags
       descriptor.DebugName(isolate));
 }
 

src/compiler/linkage.h

@@ -176,19 +176,18 @@ class V8_EXPORT_PRIVATE CallDescriptor final
     kNoFlags = 0u,
     kNeedsFrameState = 1u << 0,
     kHasExceptionHandler = 1u << 1,
-    kSupportsTailCalls = 1u << 2,
-    kCanUseRoots = 1u << 3,
+    kCanUseRoots = 1u << 2,
     // (arm64 only) native stack should be used for arguments.
-    kUseNativeStack = 1u << 4,
+    kUseNativeStack = 1u << 3,
     // (arm64 only) call instruction has to restore JSSP or CSP.
-    kRestoreJSSP = 1u << 5,
-    kRestoreCSP = 1u << 6,
+    kRestoreJSSP = 1u << 4,
+    kRestoreCSP = 1u << 5,
     // Causes the code generator to initialize the root register.
-    kInitializeRootRegister = 1u << 7,
+    kInitializeRootRegister = 1u << 6,
     // Does not ever try to allocate space on our heap.
-    kNoAllocate = 1u << 8,
+    kNoAllocate = 1u << 7,
     // Push argument count as part of function prologue.
-    kPushArgumentCount = 1u << 9
+    kPushArgumentCount = 1u << 8
   };
   typedef base::Flags<Flag> Flags;
 
@@ -249,7 +248,6 @@ class V8_EXPORT_PRIVATE CallDescriptor final
   Flags flags() const { return flags_; }
 
   bool NeedsFrameState() const { return flags() & kNeedsFrameState; }
-  bool SupportsTailCalls() const { return flags() & kSupportsTailCalls; }
   bool UseNativeStack() const { return flags() & kUseNativeStack; }
   bool PushArgumentCount() const { return flags() & kPushArgumentCount; }
   bool InitializeRootRegister() const {

src/compiler/wasm-compiler.cc

@@ -3076,7 +3076,7 @@ void WasmGraphBuilder::BuildWasmToWasmWrapper(WasmCodeWrapper wasm_code,
   args[pos++] = *control_;
 
   // Tail-call the wasm code.
-  CallDescriptor* desc = GetWasmCallDescriptor(jsgraph()->zone(), sig_, true);
+  CallDescriptor* desc = GetWasmCallDescriptor(jsgraph()->zone(), sig_);
   Node* tail_call =
       graph()->NewNode(jsgraph()->common()->TailCall(desc), count, args);
   MergeControlToEnd(jsgraph(), tail_call);

src/compiler/wasm-compiler.h

@@ -572,7 +572,7 @@ class WasmGraphBuilder {
 constexpr int kWasmContextParameterIndex = 0;
 
 V8_EXPORT_PRIVATE CallDescriptor* GetWasmCallDescriptor(
-    Zone* zone, wasm::FunctionSig* sig, bool supports_tails_calls = false);
+    Zone* zone, wasm::FunctionSig* signature);
 V8_EXPORT_PRIVATE CallDescriptor* GetI32WasmCallDescriptor(
     Zone* zone, CallDescriptor* descriptor);
 V8_EXPORT_PRIVATE CallDescriptor* GetI32WasmCallDescriptorForSimd(

src/compiler/wasm-linkage.cc

@@ -221,8 +221,7 @@ static constexpr Allocator parameter_registers(kGPParamRegisters,
 }  // namespace
 
 // General code uses the above configuration data.
-CallDescriptor* GetWasmCallDescriptor(Zone* zone, wasm::FunctionSig* fsig,
-                                      bool supports_tail_calls) {
+CallDescriptor* GetWasmCallDescriptor(Zone* zone, wasm::FunctionSig* fsig) {
   // The '+ 1' here is to accomodate the wasm_context as first parameter.
   LocationSignature::Builder locations(zone, fsig->return_count(),
                                        fsig->parameter_count() + 1);
@@ -257,7 +256,6 @@ CallDescriptor* GetWasmCallDescriptor(Zone* zone, wasm::FunctionSig* fsig,
   LinkageLocation target_loc = LinkageLocation::ForAnyRegister(target_type);
 
   CallDescriptor::Flags flags = CallDescriptor::kUseNativeStack;
-  if (supports_tail_calls) flags |= CallDescriptor::kSupportsTailCalls;
   CallDescriptor::Kind kind = FLAG_wasm_jit_to_native
                                   ? CallDescriptor::kCallWasmFunction
                                   : CallDescriptor::kCallCodeObject;