Change the handling of stack check on backward branches

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 04712dc3e4e90a2f1cbf62badfc721a4f6cde7fa..f5800f22468dd0c559e9bf5c248c9fd5e1bc0158 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -1589,45 +1589,17 @@ void LCodeGen::DoBranch(LBranch* instr) {
 }
 
 
-void LCodeGen::EmitGoto(int block, LDeferredCode* deferred_stack_check) {
+void LCodeGen::EmitGoto(int block) {
   block = chunk_->LookupDestination(block);
   int next_block = GetNextEmittedBlock(current_block_);
   if (block != next_block) {
-    // Perform stack overflow check if this goto needs it before jumping.
-    if (deferred_stack_check != NULL) {
-      __ LoadRoot(ip, Heap::kStackLimitRootIndex);
-      __ cmp(sp, Operand(ip));
-      __ b(hs, chunk_->GetAssemblyLabel(block));
-      __ jmp(deferred_stack_check->entry());
-      deferred_stack_check->SetExit(chunk_->GetAssemblyLabel(block));
-    } else {
-      __ jmp(chunk_->GetAssemblyLabel(block));
-    }
+    __ jmp(chunk_->GetAssemblyLabel(block));
   }
 }
 
 
-void LCodeGen::DoDeferredStackCheck(LGoto* instr) {
-  PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
-  CallRuntimeFromDeferred(Runtime::kStackGuard, 0, instr);
-}
-
-
 void LCodeGen::DoGoto(LGoto* instr) {
-  class DeferredStackCheck: public LDeferredCode {
-   public:
-    DeferredStackCheck(LCodeGen* codegen, LGoto* instr)
-        : LDeferredCode(codegen), instr_(instr) { }
-    virtual void Generate() { codegen()->DoDeferredStackCheck(instr_); }
-   private:
-    LGoto* instr_;
-  };
-
-  DeferredStackCheck* deferred = NULL;
-  if (instr->include_stack_check()) {
-    deferred = new DeferredStackCheck(this, instr);
-  }
-  EmitGoto(instr->block_id(), deferred);
+  EmitGoto(instr->block_id());
 }
 
 
@@ -4597,15 +4569,42 @@ void LCodeGen::DoIn(LIn* instr) {
 }
 
 
+void LCodeGen::DoDeferredStackCheck(LStackCheck* instr) {
+  PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
+  CallRuntimeFromDeferred(Runtime::kStackGuard, 0, instr);
+}
+
+
 void LCodeGen::DoStackCheck(LStackCheck* instr) {
-  // Perform stack overflow check.
-  Label ok;
-  __ LoadRoot(ip, Heap::kStackLimitRootIndex);
-  __ cmp(sp, Operand(ip));
-  __ b(hs, &ok);
-  StackCheckStub stub;
-  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
-  __ bind(&ok);
+  class DeferredStackCheck: public LDeferredCode {
+   public:
+    DeferredStackCheck(LCodeGen* codegen, LStackCheck* instr)
+        : LDeferredCode(codegen), instr_(instr) { }
+    virtual void Generate() { codegen()->DoDeferredStackCheck(instr_); }
+   private:
+    LStackCheck* instr_;
+  };
+
+  if (instr->hydrogen()->is_function_entry()) {
+    // Perform stack overflow check.
+    Label done;
+    __ LoadRoot(ip, Heap::kStackLimitRootIndex);
+    __ cmp(sp, Operand(ip));
+    __ b(hs, &done);
+    StackCheckStub stub;
+    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+    __ bind(&done);
+  } else {
+    ASSERT(instr->hydrogen()->is_backwards_branch());
+    // Perform stack overflow check if this goto needs it before jumping.
+    DeferredStackCheck* deferred_stack_check =
+        new DeferredStackCheck(this, instr);
+    __ LoadRoot(ip, Heap::kStackLimitRootIndex);
+    __ cmp(sp, Operand(ip));
+    __ b(lo, deferred_stack_check->entry());
+    __ bind(instr->done_label());
+    deferred_stack_check->SetExit(instr->done_label());
+  }
 }