| // Copyright (c) 2018, 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_KBC_H_ |
| #define RUNTIME_VM_STACK_FRAME_KBC_H_ |
| |
| namespace dart { |
| |
| /* Kernel Bytecode Frame Layout |
| |
| IMPORTANT: KBC 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 kKBCDartFrameFixedSize = 4; // Function, Code, PC, FP |
| static const int kKBCSavedPcSlotFromSp = 3; |
| |
| static const int kKBCFirstObjectSlotFromFp = -4; // Used by GC. |
| static const int kKBCLastFixedObjectSlotFromFp = -3; |
| |
| static const int kKBCSavedCallerFpSlotFromFp = -1; |
| static const int kKBCSavedCallerPpSlotFromFp = kKBCSavedCallerFpSlotFromFp; |
| static const int kKBCSavedCallerPcSlotFromFp = -2; |
| static const int kKBCCallerSpSlotFromFp = -kKBCDartFrameFixedSize - 1; |
| static const int kKBCPcMarkerSlotFromFp = -3; |
| static const int kKBCFunctionSlotFromFp = -4; |
| |
| // Note: These constants don't match actual KBC behavior. This is done because |
| // setting kKBCFirstLocalSlotFromFp to 0 breaks assumptions spread across the |
| // code. |
| // Instead for the purposes of local variable allocation we pretend that KBC |
| // behaves as other architectures (stack growing downwards) and later fix |
| // these indices during code generation in the backend. |
| static const int kKBCParamEndSlotFromFp = 4; // One slot past last parameter. |
| static const int kKBCFirstLocalSlotFromFp = -1; |
| static const int kKBCExitLinkSlotFromEntryFp = 0; |
| |
| // Value for stack limit that is used to cause an interrupt. |
| // Note that on KBC stack is growing upwards so interrupt limit is 0 unlike |
| // on all other architectures. |
| static const uword kKBCInterruptStackLimit = 0; |
| |
| } // namespace dart |
| |
| #endif // RUNTIME_VM_STACK_FRAME_KBC_H_ |