1// Copyright 2012 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
6
7#include "src/v8.h"
8
9#if V8_TARGET_ARCH_MIPS
10
11#include "src/codegen.h"
12#include "src/debug.h"
13
14namespace v8 {
15namespace internal {
16
17bool BreakLocationIterator::IsDebugBreakAtReturn() {
18  return Debug::IsDebugBreakAtReturn(rinfo());
19}
20
21
22void BreakLocationIterator::SetDebugBreakAtReturn() {
23  // Mips return sequence:
24  // mov sp, fp
25  // lw fp, sp(0)
26  // lw ra, sp(4)
27  // addiu sp, sp, 8
28  // addiu sp, sp, N
29  // jr ra
30  // nop (in branch delay slot)
31
32  // Make sure this constant matches the number if instrucntions we emit.
33  DCHECK(Assembler::kJSReturnSequenceInstructions == 7);
34  CodePatcher patcher(rinfo()->pc(), Assembler::kJSReturnSequenceInstructions);
35  // li and Call pseudo-instructions emit two instructions each.
36  patcher.masm()->li(v8::internal::t9, Operand(reinterpret_cast<int32_t>(
37      debug_info_->GetIsolate()->builtins()->Return_DebugBreak()->entry())));
38  patcher.masm()->Call(v8::internal::t9);
39  patcher.masm()->nop();
40  patcher.masm()->nop();
41  patcher.masm()->nop();
42
43  // TODO(mips): Open issue about using breakpoint instruction instead of nops.
44  // patcher.masm()->bkpt(0);
45}
46
47
48// Restore the JS frame exit code.
49void BreakLocationIterator::ClearDebugBreakAtReturn() {
50  rinfo()->PatchCode(original_rinfo()->pc(),
51                     Assembler::kJSReturnSequenceInstructions);
52}
53
54
55// A debug break in the exit code is identified by the JS frame exit code
56// having been patched with li/call psuedo-instrunction (liu/ori/jalr).
57bool Debug::IsDebugBreakAtReturn(RelocInfo* rinfo) {
58  DCHECK(RelocInfo::IsJSReturn(rinfo->rmode()));
59  return rinfo->IsPatchedReturnSequence();
60}
61
62
63bool BreakLocationIterator::IsDebugBreakAtSlot() {
64  DCHECK(IsDebugBreakSlot());
65  // Check whether the debug break slot instructions have been patched.
66  return rinfo()->IsPatchedDebugBreakSlotSequence();
67}
68
69
70void BreakLocationIterator::SetDebugBreakAtSlot() {
71  DCHECK(IsDebugBreakSlot());
72  // Patch the code changing the debug break slot code from:
73  //   nop(DEBUG_BREAK_NOP) - nop(1) is sll(zero_reg, zero_reg, 1)
74  //   nop(DEBUG_BREAK_NOP)
75  //   nop(DEBUG_BREAK_NOP)
76  //   nop(DEBUG_BREAK_NOP)
77  // to a call to the debug break slot code.
78  //   li t9, address   (lui t9 / ori t9 instruction pair)
79  //   call t9          (jalr t9 / nop instruction pair)
80  CodePatcher patcher(rinfo()->pc(), Assembler::kDebugBreakSlotInstructions);
81  patcher.masm()->li(v8::internal::t9, Operand(reinterpret_cast<int32_t>(
82      debug_info_->GetIsolate()->builtins()->Slot_DebugBreak()->entry())));
83  patcher.masm()->Call(v8::internal::t9);
84}
85
86
87void BreakLocationIterator::ClearDebugBreakAtSlot() {
88  DCHECK(IsDebugBreakSlot());
89  rinfo()->PatchCode(original_rinfo()->pc(),
90                     Assembler::kDebugBreakSlotInstructions);
91}
92
93
94#define __ ACCESS_MASM(masm)
95
96
97
98static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
99                                          RegList object_regs,
100                                          RegList non_object_regs) {
101  {
102    FrameScope scope(masm, StackFrame::INTERNAL);
103
104    // Load padding words on stack.
105    __ li(at, Operand(Smi::FromInt(LiveEdit::kFramePaddingValue)));
106    __ Subu(sp, sp,
107            Operand(kPointerSize * LiveEdit::kFramePaddingInitialSize));
108    for (int i = LiveEdit::kFramePaddingInitialSize - 1; i >= 0; i--) {
109      __ sw(at, MemOperand(sp, kPointerSize * i));
110    }
111    __ li(at, Operand(Smi::FromInt(LiveEdit::kFramePaddingInitialSize)));
112    __ push(at);
113
114    // Store the registers containing live values on the expression stack to
115    // make sure that these are correctly updated during GC. Non object values
116    // are stored as a smi causing it to be untouched by GC.
117    DCHECK((object_regs & ~kJSCallerSaved) == 0);
118    DCHECK((non_object_regs & ~kJSCallerSaved) == 0);
119    DCHECK((object_regs & non_object_regs) == 0);
120    if ((object_regs | non_object_regs) != 0) {
121      for (int i = 0; i < kNumJSCallerSaved; i++) {
122        int r = JSCallerSavedCode(i);
123        Register reg = { r };
124        if ((non_object_regs & (1 << r)) != 0) {
125          if (FLAG_debug_code) {
126            __ And(at, reg, 0xc0000000);
127            __ Assert(eq, kUnableToEncodeValueAsSmi, at, Operand(zero_reg));
128          }
129          __ sll(reg, reg, kSmiTagSize);
130        }
131      }
132      __ MultiPush(object_regs | non_object_regs);
133    }
134
135#ifdef DEBUG
136    __ RecordComment("// Calling from debug break to runtime - come in - over");
137#endif
138    __ PrepareCEntryArgs(0);  // No arguments.
139    __ PrepareCEntryFunction(ExternalReference::debug_break(masm->isolate()));
140
141    CEntryStub ceb(masm->isolate(), 1);
142    __ CallStub(&ceb);
143
144    // Restore the register values from the expression stack.
145    if ((object_regs | non_object_regs) != 0) {
146      __ MultiPop(object_regs | non_object_regs);
147      for (int i = 0; i < kNumJSCallerSaved; i++) {
148        int r = JSCallerSavedCode(i);
149        Register reg = { r };
150        if ((non_object_regs & (1 << r)) != 0) {
151          __ srl(reg, reg, kSmiTagSize);
152        }
153        if (FLAG_debug_code &&
154            (((object_regs |non_object_regs) & (1 << r)) == 0)) {
155          __ li(reg, kDebugZapValue);
156        }
157      }
158    }
159
160    // Don't bother removing padding bytes pushed on the stack
161    // as the frame is going to be restored right away.
162
163    // Leave the internal frame.
164  }
165
166  // Now that the break point has been handled, resume normal execution by
167  // jumping to the target address intended by the caller and that was
168  // overwritten by the address of DebugBreakXXX.
169  ExternalReference after_break_target =
170      ExternalReference::debug_after_break_target_address(masm->isolate());
171  __ li(t9, Operand(after_break_target));
172  __ lw(t9, MemOperand(t9));
173  __ Jump(t9);
174}
175
176
177void DebugCodegen::GenerateCallICStubDebugBreak(MacroAssembler* masm) {
178  // Register state for CallICStub
179  // ----------- S t a t e -------------
180  //  -- a1 : function
181  //  -- a3 : slot in feedback array (smi)
182  // -----------------------------------
183  Generate_DebugBreakCallHelper(masm, a1.bit() | a3.bit(), 0);
184}
185
186
187void DebugCodegen::GenerateLoadICDebugBreak(MacroAssembler* masm) {
188  Register receiver = LoadDescriptor::ReceiverRegister();
189  Register name = LoadDescriptor::NameRegister();
190  Generate_DebugBreakCallHelper(masm, receiver.bit() | name.bit(), 0);
191}
192
193
194void DebugCodegen::GenerateStoreICDebugBreak(MacroAssembler* masm) {
195  // Calling convention for IC store (from ic-mips.cc).
196  Register receiver = StoreDescriptor::ReceiverRegister();
197  Register name = StoreDescriptor::NameRegister();
198  Register value = StoreDescriptor::ValueRegister();
199  Generate_DebugBreakCallHelper(
200      masm, receiver.bit() | name.bit() | value.bit(), 0);
201}
202
203
204void DebugCodegen::GenerateKeyedLoadICDebugBreak(MacroAssembler* masm) {
205  // Calling convention for keyed IC load (from ic-mips.cc).
206  GenerateLoadICDebugBreak(masm);
207}
208
209
210void DebugCodegen::GenerateKeyedStoreICDebugBreak(MacroAssembler* masm) {
211  // Calling convention for IC keyed store call (from ic-mips.cc).
212  Register receiver = StoreDescriptor::ReceiverRegister();
213  Register name = StoreDescriptor::NameRegister();
214  Register value = StoreDescriptor::ValueRegister();
215  Generate_DebugBreakCallHelper(
216      masm, receiver.bit() | name.bit() | value.bit(), 0);
217}
218
219
220void DebugCodegen::GenerateCompareNilICDebugBreak(MacroAssembler* masm) {
221  // Register state for CompareNil IC
222  // ----------- S t a t e -------------
223  //  -- a0    : value
224  // -----------------------------------
225  Generate_DebugBreakCallHelper(masm, a0.bit(), 0);
226}
227
228
229void DebugCodegen::GenerateReturnDebugBreak(MacroAssembler* masm) {
230  // In places other than IC call sites it is expected that v0 is TOS which
231  // is an object - this is not generally the case so this should be used with
232  // care.
233  Generate_DebugBreakCallHelper(masm, v0.bit(), 0);
234}
235
236
237void DebugCodegen::GenerateCallFunctionStubDebugBreak(MacroAssembler* masm) {
238  // Register state for CallFunctionStub (from code-stubs-mips.cc).
239  // ----------- S t a t e -------------
240  //  -- a1 : function
241  // -----------------------------------
242  Generate_DebugBreakCallHelper(masm, a1.bit(), 0);
243}
244
245
246void DebugCodegen::GenerateCallConstructStubDebugBreak(MacroAssembler* masm) {
247  // Calling convention for CallConstructStub (from code-stubs-mips.cc).
248  // ----------- S t a t e -------------
249  //  -- a0     : number of arguments (not smi)
250  //  -- a1     : constructor function
251  // -----------------------------------
252  Generate_DebugBreakCallHelper(masm, a1.bit() , a0.bit());
253}
254
255
256void DebugCodegen::GenerateCallConstructStubRecordDebugBreak(
257    MacroAssembler* masm) {
258  // Calling convention for CallConstructStub (from code-stubs-mips.cc).
259  // ----------- S t a t e -------------
260  //  -- a0     : number of arguments (not smi)
261  //  -- a1     : constructor function
262  //  -- a2     : feedback array
263  //  -- a3     : feedback slot (smi)
264  // -----------------------------------
265  Generate_DebugBreakCallHelper(masm, a1.bit() | a2.bit() | a3.bit(), a0.bit());
266}
267
268
269void DebugCodegen::GenerateSlot(MacroAssembler* masm) {
270  // Generate enough nop's to make space for a call instruction. Avoid emitting
271  // the trampoline pool in the debug break slot code.
272  Assembler::BlockTrampolinePoolScope block_trampoline_pool(masm);
273  Label check_codesize;
274  __ bind(&check_codesize);
275  __ RecordDebugBreakSlot();
276  for (int i = 0; i < Assembler::kDebugBreakSlotInstructions; i++) {
277    __ nop(MacroAssembler::DEBUG_BREAK_NOP);
278  }
279  DCHECK_EQ(Assembler::kDebugBreakSlotInstructions,
280            masm->InstructionsGeneratedSince(&check_codesize));
281}
282
283
284void DebugCodegen::GenerateSlotDebugBreak(MacroAssembler* masm) {
285  // In the places where a debug break slot is inserted no registers can contain
286  // object pointers.
287  Generate_DebugBreakCallHelper(masm, 0, 0);
288}
289
290
291void DebugCodegen::GeneratePlainReturnLiveEdit(MacroAssembler* masm) {
292  __ Ret();
293}
294
295
296void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
297  ExternalReference restarter_frame_function_slot =
298      ExternalReference::debug_restarter_frame_function_pointer_address(
299          masm->isolate());
300  __ li(at, Operand(restarter_frame_function_slot));
301  __ sw(zero_reg, MemOperand(at, 0));
302
303  // We do not know our frame height, but set sp based on fp.
304  __ Subu(sp, fp, Operand(kPointerSize));
305
306  __ Pop(ra, fp, a1);  // Return address, Frame, Function.
307
308  // Load context from the function.
309  __ lw(cp, FieldMemOperand(a1, JSFunction::kContextOffset));
310
311  // Get function code.
312  __ lw(at, FieldMemOperand(a1, JSFunction::kSharedFunctionInfoOffset));
313  __ lw(at, FieldMemOperand(at, SharedFunctionInfo::kCodeOffset));
314  __ Addu(t9, at, Operand(Code::kHeaderSize - kHeapObjectTag));
315
316  // Re-run JSFunction, a1 is function, cp is context.
317  __ Jump(t9);
318}
319
320
321const bool LiveEdit::kFrameDropperSupported = true;
322
323#undef __
324
325} }  // namespace v8::internal
326
327#endif  // V8_TARGET_ARCH_MIPS
328