[turbofan] Fewer gap moves for tail calls

src/compiler/code-generator.cc

 // Copyright 2013 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/code-generator.h"
 
 #include "src/address-map.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/pipeline.h"
@@ skipping 657 matching lines @@
 
 void CodeGenerator::MarkLazyDeoptSite() {
   last_lazy_deopt_pc_ = masm()->pc_offset();
 }
 
 
 int CodeGenerator::TailCallFrameStackSlotDelta(int stack_param_delta) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   int spill_slots = frame()->GetSpillSlotCount();
   bool has_frame = descriptor->IsJSFunctionCall() || spill_slots > 0;
-  // Leave the PC and saved frame pointer on the stack.
+  // Leave the PC on the stack on platforms that have that as part of their ABI
+  int pc_slots = V8_TARGET_ARCH_STORES_RETURN_ADDRESS_ON_STACK ? 1 : 0;
   int sp_slot_delta =
-      has_frame
-          ? (frame()->GetTotalFrameSlotCount() -
-             (StandardFrameConstants::kFixedFrameSizeFromFp / kPointerSize))
-          : 0;
+      has_frame ? (frame()->GetTotalFrameSlotCount() - pc_slots) : 0;
   // Discard only slots that won't be used by new parameters.
   sp_slot_delta += stack_param_delta;
   return sp_slot_delta;
 }
 
 
 OutOfLineCode::OutOfLineCode(CodeGenerator* gen)
     : frame_(gen->frame()), masm_(gen->masm()), next_(gen->ools_) {
   gen->ools_ = this;
 }
 
 
 OutOfLineCode::~OutOfLineCode() {}
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8