Use a loop in generated code to allocate stack slots for function with many l...

src/arm/virtual-frame-arm.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 125 matching lines @@
   __ mov(sp, fp);
   __ ldm(ia_w, sp, fp.bit() | lr.bit());
 }
 
 
 void VirtualFrame::AllocateStackSlots() {
   int count = local_count();
   if (count > 0) {
     Comment cmnt(masm(), "[ Allocate space for locals");
     Adjust(count);
-      // Initialize stack slots with 'undefined' value.
+    // Initialize stack slots with 'undefined' value.
     __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
-  }
-  __ LoadRoot(r2, Heap::kStackLimitRootIndex);
-  for (int i = 0; i < count; i++) {
-    __ push(ip);
+    __ LoadRoot(r2, Heap::kStackLimitRootIndex);
+    if (count < kLocalVarBound) {
+      // For less locals the unrolled loop is more compact.
+      for (int i = 0; i < count; i++) {
+        __ push(ip);
+      }
+    } else {
+      // For more locals a loop in generated code is more compact.
+      Label alloc_locals_loop;
+      __ mov(r1, Operand(count));
+      __ bind(&alloc_locals_loop);
+      __ push(ip);
+      __ sub(r1, r1, Operand(1), SetCC);
+      __ b(ne, &alloc_locals_loop);
+    }
+  } else {
+    __ LoadRoot(r2, Heap::kStackLimitRootIndex);
   }
   // Check the stack for overflow or a break request.
   // Put the lr setup instruction in the delay slot.  The kInstrSize is added
   // to the implicit 8 byte offset that always applies to operations with pc
   // and gives a return address 12 bytes down.
   masm()->add(lr, pc, Operand(Assembler::kInstrSize));
   masm()->cmp(sp, Operand(r2));
   StackCheckStub stub;
   // Call the stub if lower.
   masm()->mov(pc,
@@ skipping 228 matching lines @@
 void VirtualFrame::EmitPushMultiple(int count, int src_regs) {
   ASSERT(stack_pointer_ == element_count() - 1);
   Adjust(count);
   __ stm(db_w, sp, src_regs);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal