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#include "src/v8.h" 6 7#if V8_TARGET_ARCH_IA32 8 9#include "src/codegen.h" 10#include "src/debug.h" 11 12 13namespace v8 { 14namespace internal { 15 16bool BreakLocationIterator::IsDebugBreakAtReturn() { 17 return Debug::IsDebugBreakAtReturn(rinfo()); 18} 19 20 21// Patch the JS frame exit code with a debug break call. See 22// CodeGenerator::VisitReturnStatement and VirtualFrame::Exit in codegen-ia32.cc 23// for the precise return instructions sequence. 24void BreakLocationIterator::SetDebugBreakAtReturn() { 25 DCHECK(Assembler::kJSReturnSequenceLength >= 26 Assembler::kCallInstructionLength); 27 rinfo()->PatchCodeWithCall( 28 debug_info_->GetIsolate()->builtins()->Return_DebugBreak()->entry(), 29 Assembler::kJSReturnSequenceLength - Assembler::kCallInstructionLength); 30} 31 32 33// Restore the JS frame exit code. 34void BreakLocationIterator::ClearDebugBreakAtReturn() { 35 rinfo()->PatchCode(original_rinfo()->pc(), 36 Assembler::kJSReturnSequenceLength); 37} 38 39 40// A debug break in the frame exit code is identified by the JS frame exit code 41// having been patched with a call instruction. 42bool Debug::IsDebugBreakAtReturn(RelocInfo* rinfo) { 43 DCHECK(RelocInfo::IsJSReturn(rinfo->rmode())); 44 return rinfo->IsPatchedReturnSequence(); 45} 46 47 48bool BreakLocationIterator::IsDebugBreakAtSlot() { 49 DCHECK(IsDebugBreakSlot()); 50 // Check whether the debug break slot instructions have been patched. 51 return rinfo()->IsPatchedDebugBreakSlotSequence(); 52} 53 54 55void BreakLocationIterator::SetDebugBreakAtSlot() { 56 DCHECK(IsDebugBreakSlot()); 57 Isolate* isolate = debug_info_->GetIsolate(); 58 rinfo()->PatchCodeWithCall( 59 isolate->builtins()->Slot_DebugBreak()->entry(), 60 Assembler::kDebugBreakSlotLength - Assembler::kCallInstructionLength); 61} 62 63 64void BreakLocationIterator::ClearDebugBreakAtSlot() { 65 DCHECK(IsDebugBreakSlot()); 66 rinfo()->PatchCode(original_rinfo()->pc(), Assembler::kDebugBreakSlotLength); 67} 68 69 70#define __ ACCESS_MASM(masm) 71 72static void Generate_DebugBreakCallHelper(MacroAssembler* masm, 73 RegList object_regs, 74 RegList non_object_regs, 75 bool convert_call_to_jmp) { 76 // Enter an internal frame. 77 { 78 FrameScope scope(masm, StackFrame::INTERNAL); 79 80 // Load padding words on stack. 81 for (int i = 0; i < LiveEdit::kFramePaddingInitialSize; i++) { 82 __ push(Immediate(Smi::FromInt(LiveEdit::kFramePaddingValue))); 83 } 84 __ push(Immediate(Smi::FromInt(LiveEdit::kFramePaddingInitialSize))); 85 86 // Store the registers containing live values on the expression stack to 87 // make sure that these are correctly updated during GC. Non object values 88 // are stored as a smi causing it to be untouched by GC. 89 DCHECK((object_regs & ~kJSCallerSaved) == 0); 90 DCHECK((non_object_regs & ~kJSCallerSaved) == 0); 91 DCHECK((object_regs & non_object_regs) == 0); 92 for (int i = 0; i < kNumJSCallerSaved; i++) { 93 int r = JSCallerSavedCode(i); 94 Register reg = { r }; 95 if ((object_regs & (1 << r)) != 0) { 96 __ push(reg); 97 } 98 if ((non_object_regs & (1 << r)) != 0) { 99 if (FLAG_debug_code) { 100 __ test(reg, Immediate(0xc0000000)); 101 __ Assert(zero, kUnableToEncodeValueAsSmi); 102 } 103 __ SmiTag(reg); 104 __ push(reg); 105 } 106 } 107 108#ifdef DEBUG 109 __ RecordComment("// Calling from debug break to runtime - come in - over"); 110#endif 111 __ Move(eax, Immediate(0)); // No arguments. 112 __ mov(ebx, Immediate(ExternalReference::debug_break(masm->isolate()))); 113 114 CEntryStub ceb(masm->isolate(), 1); 115 __ CallStub(&ceb); 116 117 // Automatically find register that could be used after register restore. 118 // We need one register for padding skip instructions. 119 Register unused_reg = { -1 }; 120 121 // Restore the register values containing object pointers from the 122 // expression stack. 123 for (int i = kNumJSCallerSaved; --i >= 0;) { 124 int r = JSCallerSavedCode(i); 125 Register reg = { r }; 126 if (FLAG_debug_code) { 127 __ Move(reg, Immediate(kDebugZapValue)); 128 } 129 bool taken = reg.code() == esi.code(); 130 if ((object_regs & (1 << r)) != 0) { 131 __ pop(reg); 132 taken = true; 133 } 134 if ((non_object_regs & (1 << r)) != 0) { 135 __ pop(reg); 136 __ SmiUntag(reg); 137 taken = true; 138 } 139 if (!taken) { 140 unused_reg = reg; 141 } 142 } 143 144 DCHECK(unused_reg.code() != -1); 145 146 // Read current padding counter and skip corresponding number of words. 147 __ pop(unused_reg); 148 // We divide stored value by 2 (untagging) and multiply it by word's size. 149 STATIC_ASSERT(kSmiTagSize == 1 && kSmiShiftSize == 0); 150 __ lea(esp, Operand(esp, unused_reg, times_half_pointer_size, 0)); 151 152 // Get rid of the internal frame. 153 } 154 155 // If this call did not replace a call but patched other code then there will 156 // be an unwanted return address left on the stack. Here we get rid of that. 157 if (convert_call_to_jmp) { 158 __ add(esp, Immediate(kPointerSize)); 159 } 160 161 // Now that the break point has been handled, resume normal execution by 162 // jumping to the target address intended by the caller and that was 163 // overwritten by the address of DebugBreakXXX. 164 ExternalReference after_break_target = 165 ExternalReference::debug_after_break_target_address(masm->isolate()); 166 __ jmp(Operand::StaticVariable(after_break_target)); 167} 168 169 170void DebugCodegen::GenerateCallICStubDebugBreak(MacroAssembler* masm) { 171 // Register state for CallICStub 172 // ----------- S t a t e ------------- 173 // -- edx : type feedback slot (smi) 174 // -- edi : function 175 // ----------------------------------- 176 Generate_DebugBreakCallHelper(masm, edx.bit() | edi.bit(), 177 0, false); 178} 179 180 181void DebugCodegen::GenerateLoadICDebugBreak(MacroAssembler* masm) { 182 // Register state for IC load call (from ic-ia32.cc). 183 Register receiver = LoadDescriptor::ReceiverRegister(); 184 Register name = LoadDescriptor::NameRegister(); 185 Generate_DebugBreakCallHelper(masm, receiver.bit() | name.bit(), 0, false); 186} 187 188 189void DebugCodegen::GenerateStoreICDebugBreak(MacroAssembler* masm) { 190 // Register state for IC store call (from ic-ia32.cc). 191 Register receiver = StoreDescriptor::ReceiverRegister(); 192 Register name = StoreDescriptor::NameRegister(); 193 Register value = StoreDescriptor::ValueRegister(); 194 Generate_DebugBreakCallHelper( 195 masm, receiver.bit() | name.bit() | value.bit(), 0, false); 196} 197 198 199void DebugCodegen::GenerateKeyedLoadICDebugBreak(MacroAssembler* masm) { 200 // Register state for keyed IC load call (from ic-ia32.cc). 201 GenerateLoadICDebugBreak(masm); 202} 203 204 205void DebugCodegen::GenerateKeyedStoreICDebugBreak(MacroAssembler* masm) { 206 // Register state for keyed IC store call (from ic-ia32.cc). 207 Register receiver = StoreDescriptor::ReceiverRegister(); 208 Register name = StoreDescriptor::NameRegister(); 209 Register value = StoreDescriptor::ValueRegister(); 210 Generate_DebugBreakCallHelper( 211 masm, receiver.bit() | name.bit() | value.bit(), 0, false); 212} 213 214 215void DebugCodegen::GenerateCompareNilICDebugBreak(MacroAssembler* masm) { 216 // Register state for CompareNil IC 217 // ----------- S t a t e ------------- 218 // -- eax : value 219 // ----------------------------------- 220 Generate_DebugBreakCallHelper(masm, eax.bit(), 0, false); 221} 222 223 224void DebugCodegen::GenerateReturnDebugBreak(MacroAssembler* masm) { 225 // Register state just before return from JS function (from codegen-ia32.cc). 226 // ----------- S t a t e ------------- 227 // -- eax: return value 228 // ----------------------------------- 229 Generate_DebugBreakCallHelper(masm, eax.bit(), 0, true); 230} 231 232 233void DebugCodegen::GenerateCallFunctionStubDebugBreak(MacroAssembler* masm) { 234 // Register state for CallFunctionStub (from code-stubs-ia32.cc). 235 // ----------- S t a t e ------------- 236 // -- edi: function 237 // ----------------------------------- 238 Generate_DebugBreakCallHelper(masm, edi.bit(), 0, false); 239} 240 241 242void DebugCodegen::GenerateCallConstructStubDebugBreak(MacroAssembler* masm) { 243 // Register state for CallConstructStub (from code-stubs-ia32.cc). 244 // eax is the actual number of arguments not encoded as a smi see comment 245 // above IC call. 246 // ----------- S t a t e ------------- 247 // -- eax: number of arguments (not smi) 248 // -- edi: constructor function 249 // ----------------------------------- 250 // The number of arguments in eax is not smi encoded. 251 Generate_DebugBreakCallHelper(masm, edi.bit(), eax.bit(), false); 252} 253 254 255void DebugCodegen::GenerateCallConstructStubRecordDebugBreak( 256 MacroAssembler* masm) { 257 // Register state for CallConstructStub (from code-stubs-ia32.cc). 258 // eax is the actual number of arguments not encoded as a smi see comment 259 // above IC call. 260 // ----------- S t a t e ------------- 261 // -- eax: number of arguments (not smi) 262 // -- ebx: feedback array 263 // -- edx: feedback slot (smi) 264 // -- edi: constructor function 265 // ----------------------------------- 266 // The number of arguments in eax is not smi encoded. 267 Generate_DebugBreakCallHelper(masm, ebx.bit() | edx.bit() | edi.bit(), 268 eax.bit(), false); 269} 270 271 272void DebugCodegen::GenerateSlot(MacroAssembler* masm) { 273 // Generate enough nop's to make space for a call instruction. 274 Label check_codesize; 275 __ bind(&check_codesize); 276 __ RecordDebugBreakSlot(); 277 __ Nop(Assembler::kDebugBreakSlotLength); 278 DCHECK_EQ(Assembler::kDebugBreakSlotLength, 279 masm->SizeOfCodeGeneratedSince(&check_codesize)); 280} 281 282 283void DebugCodegen::GenerateSlotDebugBreak(MacroAssembler* masm) { 284 // In the places where a debug break slot is inserted no registers can contain 285 // object pointers. 286 Generate_DebugBreakCallHelper(masm, 0, 0, true); 287} 288 289 290void DebugCodegen::GeneratePlainReturnLiveEdit(MacroAssembler* masm) { 291 masm->ret(0); 292} 293 294 295void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) { 296 ExternalReference restarter_frame_function_slot = 297 ExternalReference::debug_restarter_frame_function_pointer_address( 298 masm->isolate()); 299 __ mov(Operand::StaticVariable(restarter_frame_function_slot), Immediate(0)); 300 301 // We do not know our frame height, but set esp based on ebp. 302 __ lea(esp, Operand(ebp, -1 * kPointerSize)); 303 304 __ pop(edi); // Function. 305 __ pop(ebp); 306 307 // Load context from the function. 308 __ mov(esi, FieldOperand(edi, JSFunction::kContextOffset)); 309 310 // Get function code. 311 __ mov(edx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset)); 312 __ mov(edx, FieldOperand(edx, SharedFunctionInfo::kCodeOffset)); 313 __ lea(edx, FieldOperand(edx, Code::kHeaderSize)); 314 315 // Re-run JSFunction, edi is function, esi is context. 316 __ jmp(edx); 317} 318 319 320const bool LiveEdit::kFrameDropperSupported = true; 321 322#undef __ 323 324} } // namespace v8::internal 325 326#endif // V8_TARGET_ARCH_IA32 327