1 // Copyright 2016 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "src/compiler/backend/arm64/unwinding-info-writer-arm64.h"
6 #include "src/compiler/backend/instruction.h"
7
8 namespace v8 {
9 namespace internal {
10 namespace compiler {
11
12 // TODO(v8:10026): When using CFI, we need to generate unwinding info to tell
13 // the unwinder that return addresses are signed.
14
BeginInstructionBlock(int pc_offset,const InstructionBlock * block)15 void UnwindingInfoWriter::BeginInstructionBlock(int pc_offset,
16 const InstructionBlock* block) {
17 if (!enabled()) return;
18
19 block_will_exit_ = false;
20
21 DCHECK_LT(block->rpo_number().ToInt(),
22 static_cast<int>(block_initial_states_.size()));
23 const BlockInitialState* initial_state =
24 block_initial_states_[block->rpo_number().ToInt()];
25 if (!initial_state) return;
26 if (initial_state->saved_lr_ != saved_lr_) {
27 eh_frame_writer_.AdvanceLocation(pc_offset);
28 if (initial_state->saved_lr_) {
29 eh_frame_writer_.RecordRegisterSavedToStack(lr, kSystemPointerSize);
30 eh_frame_writer_.RecordRegisterSavedToStack(fp, 0);
31 } else {
32 eh_frame_writer_.RecordRegisterFollowsInitialRule(lr);
33 }
34 saved_lr_ = initial_state->saved_lr_;
35 }
36 }
37
EndInstructionBlock(const InstructionBlock * block)38 void UnwindingInfoWriter::EndInstructionBlock(const InstructionBlock* block) {
39 if (!enabled() || block_will_exit_) return;
40
41 for (const RpoNumber& successor : block->successors()) {
42 int successor_index = successor.ToInt();
43 DCHECK_LT(successor_index, static_cast<int>(block_initial_states_.size()));
44 const BlockInitialState* existing_state =
45 block_initial_states_[successor_index];
46
47 // If we already had an entry for this BB, check that the values are the
48 // same we are trying to insert.
49 if (existing_state) {
50 DCHECK_EQ(existing_state->saved_lr_, saved_lr_);
51 } else {
52 block_initial_states_[successor_index] =
53 zone_->New<BlockInitialState>(saved_lr_);
54 }
55 }
56 }
57
MarkFrameConstructed(int at_pc)58 void UnwindingInfoWriter::MarkFrameConstructed(int at_pc) {
59 if (!enabled()) return;
60
61 // Regardless of the type of frame constructed, the relevant part of the
62 // layout is always the one in the diagram:
63 //
64 // | .... | higher addresses
65 // +----------+ ^
66 // | LR | | |
67 // +----------+ | |
68 // | saved FP | | |
69 // +----------+ <-- FP v
70 // | .... | stack growth
71 //
72 // The LR is pushed on the stack, and we can record this fact at the end of
73 // the construction, since the LR itself is not modified in the process.
74 eh_frame_writer_.AdvanceLocation(at_pc);
75 eh_frame_writer_.RecordRegisterSavedToStack(lr, kSystemPointerSize);
76 eh_frame_writer_.RecordRegisterSavedToStack(fp, 0);
77 saved_lr_ = true;
78 }
79
MarkFrameDeconstructed(int at_pc)80 void UnwindingInfoWriter::MarkFrameDeconstructed(int at_pc) {
81 if (!enabled()) return;
82
83 // The lr is restored by the last operation in LeaveFrame().
84 eh_frame_writer_.AdvanceLocation(at_pc);
85 eh_frame_writer_.RecordRegisterFollowsInitialRule(lr);
86 saved_lr_ = false;
87 }
88
MarkLinkRegisterOnTopOfStack(int pc_offset,const Register & sp)89 void UnwindingInfoWriter::MarkLinkRegisterOnTopOfStack(int pc_offset,
90 const Register& sp) {
91 if (!enabled()) return;
92
93 eh_frame_writer_.AdvanceLocation(pc_offset);
94 eh_frame_writer_.SetBaseAddressRegisterAndOffset(sp, 0);
95 eh_frame_writer_.RecordRegisterSavedToStack(lr, 0);
96 }
97
MarkPopLinkRegisterFromTopOfStack(int pc_offset)98 void UnwindingInfoWriter::MarkPopLinkRegisterFromTopOfStack(int pc_offset) {
99 if (!enabled()) return;
100
101 eh_frame_writer_.AdvanceLocation(pc_offset);
102 eh_frame_writer_.SetBaseAddressRegisterAndOffset(fp, 0);
103 eh_frame_writer_.RecordRegisterFollowsInitialRule(lr);
104 }
105
106 } // namespace compiler
107 } // namespace internal
108 } // namespace v8
109