Initial SIMDBC interpreter.

runtime/vm/stack_frame_dbc.h

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef VM_STACK_FRAME_DBC_H_
+#define VM_STACK_FRAME_DBC_H_
+
+namespace dart {
+
+/* DBC Frame Layout
+
+IMPORTANT: On DBC stack is growing upwards which is different from all other
+architectures. This enables effecient addressing for locals via unsigned index.
+
+               |                    | <- TOS
+Callee frame   | ...                |
+               | saved FP           |    (FP of current frame)
+               | saved PC           |    (PC of current frame)
+               | code object        |
+               | function object    |
+               +--------------------+
+Current frame  | ...               T| <- SP of current frame
+               | ...               T|
+               | first local       T| <- FP of current frame
+               | caller's FP       *|
+               | caller's PC       *|
+               | code object       T|    (current frame's code object)
+               | function object   T|    (current frame's function object)
+               +--------------------+
+Caller frame   | last parameter     | <- SP of caller frame
+               |  ...               |
+
+               T against a slot indicates it needs to be traversed during GC.
+               * against a slot indicates that is can be traversed during GC

[zra, 2016/04/08 22:37:35]

that *it* can be

[Vyacheslav Egorov (Google), 2016/04/11 10:49:11]

Done.

+                 because it will look like a smi to the visitor.
+*/
+
+static const int kDartFrameFixedSize = 4;  // Function, Code, PC, FP
+static const int kSavedPcSlotFromSp = 3;
+
+static const int kFirstObjectSlotFromFp = -4;  // Used by GC to traverse stack.
+
+static const int kSavedCallerFpSlotFromFp = -1;
+static const int kSavedCallerPpSlotFromFp = kSavedCallerFpSlotFromFp;
+static const int kSavedCallerPcSlotFromFp = -2;
+static const int kCallerSpSlotFromFp = -kDartFrameFixedSize-1;
+static const int kPcMarkerSlotFromFp = -3;
+static const int kFunctionSlotFromFp = -4;
+
+// Note: These constants don't match actual DBC behavior. This is done because
+// setting kFirstLocalSlotFromFp to 0 breaks assumptions spread across the code.
+// Instead for the purposes of local variable allocation we pretend that DBC
+// behaves as other architectures (stack growing downwards) and later fix
+// this indices during code generate in the backend.

[zra, 2016/04/08 22:37:35]

these ... generation

[Vyacheslav Egorov (Google), 2016/04/11 10:49:11]

Done.

+static const int kParamEndSlotFromFp = 4;  // One slot past last parameter.
+static const int kFirstLocalSlotFromFp = -1;
+
+
+DART_FORCE_INLINE static uword LocalVarAddress(uword fp, intptr_t index) {
+  ASSERT(index != 0);
+  if (index > 0) {
+     return fp - index * kWordSize;
+  } else {
+     return fp - (index + 1) * kWordSize;
+  }
+}
+
+DART_FORCE_INLINE static uword ParamAddress(uword fp, intptr_t reverse_index) {
+  return fp - (kDartFrameFixedSize + reverse_index) * kWordSize;
+}
+
+DART_FORCE_INLINE static bool IsCalleeFrameOf(uword fp, uword other_fp) {
+  return other_fp > fp;
+}
+
+static const int kExitLinkSlotFromEntryFp = 0;
+
+}  // namespace dart
+
+#endif  // VM_STACK_FRAME_DBC_H_