Index: runtime/vm/stack_frame_dbc.h |
diff --git a/runtime/vm/stack_frame_dbc.h b/runtime/vm/stack_frame_dbc.h |
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+// 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 it can be traversed during GC |
+ 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 |
+// these indices during code generation in the backend. |
+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; |
+ |
+// Value for stack limit that is used to cause an interrupt. |
+// Note that on DBC stack is growing upwards so interrupt limit is 0 unlike |
+// on all other architectures. |
+static const uword kInterruptStackLimit = 0; |
+ |
+} // namespace dart |
+ |
+#endif // VM_STACK_FRAME_DBC_H_ |