[turbofan] Fewer gap moves for tail calls

src/compiler/instruction-selector.cc

 // Copyright 2014 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.
 
 #include "src/compiler/instruction-selector.h"
 
 #include <limits>
 
 #include "src/base/adapters.h"
 #include "src/compiler/instruction-selector-impl.h"
@@ skipping 489 matching lines @@
       }
       DCHECK(!buffer->pushed_nodes[stack_index]);
       buffer->pushed_nodes[stack_index] = *iter;
       pushed_count++;
     } else {
       buffer->instruction_args.push_back(op);
     }
   }
   DCHECK_EQ(input_count, buffer->instruction_args.size() + pushed_count -
                              buffer->frame_state_value_count());
-  if (call_tail && stack_param_delta != 0) {
-    // For tail calls that change the size of their parameter list, move the
-    // saved caller return address, parent frame pointer and parent constant
-    // pool pointer to just above the parameters.
-
-    // Return address
+  if (V8_TARGET_ARCH_STORES_RETURN_ADDRESS_ON_STACK && call_tail &&
+      stack_param_delta != 0) {
+    // For tail calls that change the size of their parameter list and keep
+    // their return address on the stack, move the return address to just above
+    // the parameters.
     LinkageLocation saved_return_location =
         LinkageLocation::ForSavedCallerReturnAddress();
     InstructionOperand return_address =
         g.UsePointerLocation(LinkageLocation::ConvertToTailCallerLocation(
                                  saved_return_location, stack_param_delta),
                              saved_return_location);
     buffer->instruction_args.push_back(return_address);
-
-    // Parent frame pointer
-    LinkageLocation saved_frame_location =
-        LinkageLocation::ForSavedCallerFramePtr();
-    InstructionOperand saved_frame =
-        g.UsePointerLocation(LinkageLocation::ConvertToTailCallerLocation(
-                                 saved_frame_location, stack_param_delta),
-                             saved_frame_location);
-    buffer->instruction_args.push_back(saved_frame);
-
-    if (V8_EMBEDDED_CONSTANT_POOL) {
-      // Constant pool pointer
-      LinkageLocation saved_cp_location =
-          LinkageLocation::ForSavedCallerConstantPool();
-      InstructionOperand saved_cp =
-          g.UsePointerLocation(LinkageLocation::ConvertToTailCallerLocation(
-                                   saved_cp_location, stack_param_delta),
-                               saved_cp_location);
-      buffer->instruction_args.push_back(saved_cp);
-    }
   }
 }
 
 
 void InstructionSelector::VisitBlock(BasicBlock* block) {
   DCHECK(!current_block_);
   current_block_ = block;
   int current_block_end = static_cast<int>(instructions_.size());
 
   // Generate code for the block control "top down", but schedule the code
@@ skipping 924 matching lines @@
   return new (instruction_zone()) FrameStateDescriptor(
       instruction_zone(), state_info.type(), state_info.bailout_id(),
       state_info.state_combine(), parameters, locals, stack,
       state_info.shared_info(), outer_state);
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8