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https://github.com/dart-lang/sdk
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89ce54fe0e
We've been getting away with skipping this slot because - ObjectPools are allocated into old space and never move, and - the ObjectPools are also reachable from the PC marker in the caller's frame. However, ObjectPools will become movable during compacting GCs. Bug: https://github.com/dart-lang/sdk/issues/30978 Change-Id: Ied3a1588365fe5362ad7f1d2d446a7a59df6ced6 Reviewed-on: https://dart-review.googlesource.com/10680 Reviewed-by: Siva Annamalai <asiva@google.com> Commit-Queue: Ryan Macnak <rmacnak@google.com>
87 lines
3.4 KiB
C++
87 lines
3.4 KiB
C++
// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#ifndef RUNTIME_VM_STACK_FRAME_DBC_H_
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#define RUNTIME_VM_STACK_FRAME_DBC_H_
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namespace dart {
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/* DBC Frame Layout
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IMPORTANT: On DBC stack is growing upwards which is different from all other
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architectures. This enables efficient addressing for locals via unsigned index.
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| | <- TOS
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Callee frame | ... |
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| saved FP | (FP of current frame)
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| saved PC | (PC of current frame)
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| code object |
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| function object |
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+--------------------+
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Current frame | ... T| <- SP of current frame
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| ... T|
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| first local T| <- FP of current frame
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| caller's FP *|
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| caller's PC *|
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| code object T| (current frame's code object)
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| function object T| (current frame's function object)
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+--------------------+
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Caller frame | last parameter | <- SP of caller frame
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| ... |
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T against a slot indicates it needs to be traversed during GC.
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* against a slot indicates that it can be traversed during GC
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because it will look like a smi to the visitor.
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*/
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static const int kDartFrameFixedSize = 4; // Function, Code, PC, FP
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static const int kSavedPcSlotFromSp = 3;
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static const int kFirstObjectSlotFromFp = -4; // Used by GC to traverse stack.
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static const int kLastFixedObjectSlotFromFp = -3;
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static const int kSavedCallerFpSlotFromFp = -1;
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static const int kSavedCallerPpSlotFromFp = kSavedCallerFpSlotFromFp;
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static const int kSavedCallerPcSlotFromFp = -2;
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static const int kCallerSpSlotFromFp = -kDartFrameFixedSize - 1;
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static const int kPcMarkerSlotFromFp = -3;
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static const int kFunctionSlotFromFp = -4;
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// Note: These constants don't match actual DBC behavior. This is done because
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// setting kFirstLocalSlotFromFp to 0 breaks assumptions spread across the code.
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// Instead for the purposes of local variable allocation we pretend that DBC
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// behaves as other architectures (stack growing downwards) and later fix
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// these indices during code generation in the backend.
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static const int kParamEndSlotFromFp = 4; // One slot past last parameter.
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static const int kFirstLocalSlotFromFp = -1;
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DART_FORCE_INLINE static intptr_t LocalVarIndex(intptr_t fp_offset,
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intptr_t var_index) {
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ASSERT(var_index != 0);
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if (var_index > 0) {
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return fp_offset - var_index;
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} else {
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return fp_offset - (var_index + 1);
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}
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}
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DART_FORCE_INLINE static uword ParamAddress(uword fp, intptr_t reverse_index) {
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return fp - (kDartFrameFixedSize + reverse_index) * kWordSize;
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}
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DART_FORCE_INLINE static bool IsCalleeFrameOf(uword fp, uword other_fp) {
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return other_fp > fp;
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}
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static const int kExitLinkSlotFromEntryFp = 0;
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// Value for stack limit that is used to cause an interrupt.
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// Note that on DBC stack is growing upwards so interrupt limit is 0 unlike
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// on all other architectures.
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static const uword kInterruptStackLimit = 0;
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} // namespace dart
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#endif // RUNTIME_VM_STACK_FRAME_DBC_H_
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