Build stack frames for stubs only when needed.

src/compiler/arm64/code-generator-arm64.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/code-generator.h"
 
 #include "src/arm64/macro-assembler-arm64.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 869 matching lines @@
 
 // TODO(dcarney): increase stack slots in frame once before first use.
 static int AlignedStackSlots(int stack_slots) {
   if (stack_slots & 1) stack_slots++;
   return stack_slots;
 }
 
 
 void CodeGenerator::AssemblePrologue() {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
+  int stack_slots = frame()->GetSpillSlotCount();
   if (descriptor->kind() == CallDescriptor::kCallAddress) {
     __ SetStackPointer(csp);
     __ Push(lr, fp);
     __ Mov(fp, csp);
     // TODO(dcarney): correct callee saved registers.
     __ PushCalleeSavedRegisters();
     frame()->SetRegisterSaveAreaSize(20 * kPointerSize);
   } else if (descriptor->IsJSFunctionCall()) {
     CompilationInfo* info = this->info();
     __ SetStackPointer(jssp);
     __ Prologue(info->IsCodePreAgingActive());
     frame()->SetRegisterSaveAreaSize(
         StandardFrameConstants::kFixedFrameSizeFromFp);
-  } else {
+  } else if (stack_slots > 0) {
     __ SetStackPointer(jssp);
     __ StubPrologue();
     frame()->SetRegisterSaveAreaSize(
         StandardFrameConstants::kFixedFrameSizeFromFp);
   }
-  int stack_slots = frame()->GetSpillSlotCount();
 
   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) {
     Register sp = __ StackPointer();
     if (!sp.Is(csp)) {
       __ Sub(sp, sp, stack_slots * kPointerSize);
     }
     __ Sub(csp, csp, AlignedStackSlots(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) {
         __ Add(csp, csp, AlignedStackSlots(stack_slots) * kPointerSize);
       }
       // Restore registers.
       // TODO(dcarney): correct callee saved registers.
       __ PopCalleeSavedRegisters();
     }
     __ Mov(csp, fp);
     __ Pop(fp, lr);
     __ Ret();
-  } else {
+  } else if (descriptor->IsJSFunctionCall() || stack_slots > 0) {
     __ Mov(jssp, fp);
     __ Pop(fp, lr);
     int pop_count = descriptor->IsJSFunctionCall()
                         ? static_cast<int>(descriptor->JSParameterCount())
                         : 0;
     __ Drop(pop_count);
     __ Ret();
+  } else {
+    __ Ret();
   }
 }
 
 
 void CodeGenerator::AssembleMove(InstructionOperand* source,
                                  InstructionOperand* destination) {
   Arm64OperandConverter g(this, NULL);
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister()) {
@@ skipping 163 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8