Adds an API for setting the stack limit per-thread.

src/arm/simulator-arm.h

Index: src/arm/simulator-arm.h
diff --git a/src/arm/simulator-arm.h b/src/arm/simulator-arm.h
index 3917d6a5af1bc4c82b68be3e2b07c56cc60741b1..e877bdb8acecf90c0b8b1c7d0576a61055c05846 100644
--- a/src/arm/simulator-arm.h
+++ b/src/arm/simulator-arm.h
@@ -42,12 +42,11 @@
 #define CALL_GENERATED_CODE(entry, p0, p1, p2, p3, p4) \
   (entry(p0, p1, p2, p3, p4))
 
-// Calculated the stack limit beyond which we will throw stack overflow errors.
-// This macro must be called from a C++ method. It relies on being able to take
-// the address of "this" to get a value on the current execution stack and then
-// calculates the stack limit based on that value.
-#define GENERATED_CODE_STACK_LIMIT(limit) \
-  (reinterpret_cast<uintptr_t>(this) - limit)
+// The stack limit beyond which we will throw stack overflow errors in
+// generated code. Because generated code on arm uses the C stack, we
+// just use the C stack limit.
+#define GENERATED_CODE_STACK_LIMIT(c_limit) \
+  (c_limit)
 
 
 // Call the generated regexp code directly. The entry function pointer should
@@ -66,7 +65,7 @@
 
 // The simulator has its own stack. Thus it has a different stack limit from
 // the C-based native code.
-#define GENERATED_CODE_STACK_LIMIT(limit) \
+#define GENERATED_CODE_STACK_LIMIT(c_limit) \
   (assembler::arm::Simulator::current()->StackLimit())