Build stack frames for stubs only when needed.

src/compiler/x64/code-generator-x64.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/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/scopes.h"
@@ skipping 1160 matching lines @@
         __ pushq(Register::from_code(i));
         register_save_area_size += kPointerSize;
       }
       frame()->SetRegisterSaveAreaSize(register_save_area_size);
     }
   } else if (descriptor->IsJSFunctionCall()) {
     CompilationInfo* info = this->info();
     __ Prologue(info->IsCodePreAgingActive());
     frame()->SetRegisterSaveAreaSize(
         StandardFrameConstants::kFixedFrameSizeFromFp);
-  } else {
+  } else if (stack_slots > 0) {
     __ StubPrologue();
     frame()->SetRegisterSaveAreaSize(
         StandardFrameConstants::kFixedFrameSizeFromFp);
   }
 
   if (info()->is_osr()) {
     // TurboFan OSR-compiled functions cannot be entered directly.
     __ Abort(kShouldNotDirectlyEnterOsrFunction);
 
     // Unoptimized code jumps directly to this entrypoint while the unoptimized
     // frame is still on the stack. Optimized code uses OSR values directly from
     // the unoptimized frame. Thus, all that needs to be done is to allocate the
     // remaining stack slots.
     if (FLAG_code_comments) __ RecordComment("-- OSR entrypoint --");
     osr_pc_offset_ = __ pc_offset();
     DCHECK(stack_slots >= frame()->GetOsrStackSlotCount());
     stack_slots -= frame()->GetOsrStackSlotCount();
   }
 
   if (stack_slots > 0) {
     __ subq(rsp, Immediate(stack_slots * kPointerSize));
   }
 }
 
 
 void CodeGenerator::AssembleReturn() {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
+  int stack_slots = frame()->GetSpillSlotCount();
   if (descriptor->kind() == CallDescriptor::kCallAddress) {
     if (frame()->GetRegisterSaveAreaSize() > 0) {
       // Remove this frame's spill slots first.
-      int stack_slots = frame()->GetSpillSlotCount();
       if (stack_slots > 0) {
         __ addq(rsp, Immediate(stack_slots * kPointerSize));
       }
       const RegList saves = descriptor->CalleeSavedRegisters();
       // Restore registers.
       if (saves != 0) {
         for (int i = 0; i < Register::kNumRegisters; i++) {
           if (!((1 << i) & saves)) continue;
           __ popq(Register::from_code(i));
         }
       }
       __ popq(rbp);  // Pop caller's frame pointer.
       __ ret(0);
     } else {
       // No saved registers.
       __ movq(rsp, rbp);  // Move stack pointer back to frame pointer.
       __ popq(rbp);       // Pop caller's frame pointer.
       __ ret(0);
     }
-  } else {
+  } else if (descriptor->IsJSFunctionCall() || stack_slots > 0) {
     __ movq(rsp, rbp);  // Move stack pointer back to frame pointer.
     __ popq(rbp);       // Pop caller's frame pointer.
     int pop_count = descriptor->IsJSFunctionCall()
                         ? static_cast<int>(descriptor->JSParameterCount())
                         : 0;
     __ ret(pop_count * kPointerSize);
+  } else {
+    __ ret(0);
   }
 }
 
 
 void CodeGenerator::AssembleMove(InstructionOperand* source,
                                  InstructionOperand* destination) {
   X64OperandConverter g(this, NULL);
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister()) {
@@ skipping 169 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8