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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 RUNTIME_VM_STACK_FRAME_DBC_H_
#define RUNTIME_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 efficient 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 kLastFixedObjectSlotFromFp = -3;
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;
static const int kLastParamSlotFromEntrySp = 0; // Should not be used on DBC.
DART_FORCE_INLINE static intptr_t LocalVarIndex(intptr_t fp_offset,
intptr_t var_index) {
if (var_index > 0) {
return fp_offset - var_index;
} else {
return fp_offset - (var_index + 1);
}
}
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 // RUNTIME_VM_STACK_FRAME_DBC_H_