1 files changed, 63 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/b3/air/AirStackSlotKind.h b/Source/JavaScriptCore/b3/air/AirStackSlotKind.h
new file mode 100644
index 000000000..9ef205772
--- /dev/null
+++ b/Source/JavaScriptCore/b3/air/AirStackSlotKind.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2015-2016 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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 with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#pragma once
+
+#if ENABLE(B3_JIT)
+
+namespace JSC { namespace B3 { namespace Air {
+
+enum class StackSlotKind : uint8_t {
+    // A locked stack slot is an area of stack requested by the client. It cannot be killed. The
+    // client can get its FP offset and write to it from stack walking code, so we must assume
+    // that reads and writes to a locked stack slot can be clobbered the same way as reads and
+    // writes to any memory location.
+    Locked,
+
+    // A spill slot. These have fundamentally different behavior than a typical memory location.
+    // They are lowered to from temporaries. This means for example that a 32-bit ZDef store to a
+    // 8 byte stack slot will zero the top 4 bytes, even though a 32-bit ZDef store to any other
+    // kind of memory location would do no such thing. UseAddr on a spill slot is not allowed, so
+    // they never escape.
+    Spill
+
+    // FIXME: We should add a third mode, which means that the stack slot will be read asynchronously
+    // as with Locked, but never written to asynchronously. Then, Air could optimize spilling and
+    // filling by tracking whether the value had been stored to a read-only locked slot. If it had,
+    // then we can refill from that slot.
+    // https://bugs.webkit.org/show_bug.cgi?id=150587
+};
+
+} } } // namespace JSC::B3::Air
+
+namespace WTF {
+
+class PrintStream;
+
+void printInternal(PrintStream&, JSC::B3::Air::StackSlotKind);
+
+} // namespace WTF
+
+#endif // ENABLE(B3_JIT)