Oilpan: Query stack frame register instead of manual bookkeeping

Source/platform/heap/StackFrameDepth.cpp

Index: Source/platform/heap/StackFrameDepth.cpp
diff --git a/Source/platform/heap/StackFrameDepth.cpp b/Source/platform/heap/StackFrameDepth.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..8b495ed8c633a5ae241ce0e0b8a2e62290c3a830
--- /dev/null
+++ b/Source/platform/heap/StackFrameDepth.cpp
@@ -0,0 +1,30 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "platform/heap/StackFrameDepth.h"
+
+namespace blink {
+
+static const char* s_avoidOptimization = nullptr;
+
+// NEVER_INLINE ensures that |dummy| array on configureLimit() is not optimized away,
+// and the stack frame base register is adjusted |kSafeStackFrameSize|.
+NEVER_INLINE static uintptr_t currentStackFrameBaseOnCallee(const char* dummy)
+{
+    s_avoidOptimization = dummy;
+    return StackFrameDepth::currentStackFrame();
+}
+
+void StackFrameDepth::configureLimit()
+{
+    // Allocate a large object in stack and query stack frame pointer after it.
+    char dummy[kSafeStackFrameSize];
+    m_stackFrameLimit = currentStackFrameBaseOnCallee(dummy);
+
+    // Assert that the stack frame can be used.
+    dummy[sizeof(dummy) - 1] = 0;
+}
+
+} // namespace blink