* Make stack/preemption guard faster on ARM by putting stack...

src/arm/codegen-arm.cc

 // Copyright 2006-2009 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 1092 matching lines @@
   Condition cc = if_true ? cc_reg_ : NegateCondition(cc_reg_);
   target->Branch(cc);
   cc_reg_ = al;
 }
 
 
 void CodeGenerator::CheckStack() {
   VirtualFrame::SpilledScope spilled_scope;
   if (FLAG_check_stack) {
     Comment cmnt(masm_, "[ check stack");
+    __ LoadRoot(ip, Heap::kStackLimitRootIndex);
+    __ cmp(sp, Operand(ip));
     StackCheckStub stub;
-    frame_->CallStub(&stub, 0);
+    __ CallStub(&stub, lo);  // Call the stub if lower.
   }
 }
 
 
 void CodeGenerator::VisitStatements(ZoneList<Statement*>* statements) {
 #ifdef DEBUG
   int original_height = frame_->height();
 #endif
   VirtualFrame::SpilledScope spilled_scope;
   for (int i = 0; frame_ != NULL && i < statements->length(); i++) {
@@ skipping 4491 matching lines @@
     }
 
     default: UNREACHABLE();
   }
   // This code should be unreachable.
   __ stop("Unreachable");
 }
 
 
 void StackCheckStub::Generate(MacroAssembler* masm) {
-  Label within_limit;
-  __ mov(ip, Operand(ExternalReference::address_of_stack_guard_limit()));
-  __ ldr(ip, MemOperand(ip));
-  __ cmp(sp, Operand(ip));
-  __ b(hs, &within_limit);
   // Do tail-call to runtime routine.  Runtime routines expect at least one
   // argument, so give it a Smi.
   __ mov(r0, Operand(Smi::FromInt(0)));
   __ push(r0);
   __ TailCallRuntime(ExternalReference(Runtime::kStackGuard), 1);
-  __ bind(&within_limit);
 
   __ StubReturn(1);
 }
 
 
 void UnarySubStub::Generate(MacroAssembler* masm) {
   Label undo;
   Label slow;
   Label not_smi;
 
@@ skipping 614 matching lines @@
 int CompareStub::MinorKey() {
   // Encode the two parameters in a unique 16 bit value.
   ASSERT(static_cast<unsigned>(cc_) >> 28 < (1 << 15));
   return (static_cast<unsigned>(cc_) >> 27) | (strict_ ? 1 : 0);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal