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

src/ia32/simulator-ia32.h

Index: src/ia32/simulator-ia32.h
diff --git a/src/ia32/simulator-ia32.h b/src/ia32/simulator-ia32.h
index 3bed2681f8d785213991f148ceecc944130df413..8d225282864517dc2739966016a36d9703bdad3e 100644
--- a/src/ia32/simulator-ia32.h
+++ b/src/ia32/simulator-ia32.h
@@ -34,15 +34,11 @@
 #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.
-// NOTE: The check for overflow is not safe as there is no guarantee that the
-// running thread has its stack in all memory up to address 0x00000000.
-#define GENERATED_CODE_STACK_LIMIT(limit) \
-  (reinterpret_cast<uintptr_t>(this) >= limit ? \
-      reinterpret_cast<uintptr_t>(this) - limit : 0)
+// The stack limit beyond which we will throw stack overflow errors in
+// generated code. Because generated code on ia32 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
 // expect seven int/pointer sized arguments and return an int.