Streamline the code for patching optimized code for lazy deopt.

Rewrite the lazy deopt patching code on IA32 to use addresses throughout,
rather than offsets and a base address.

Also, rename a couple of ambiguous Code fields from _start to _offset.

Review URL: http://codereview.chromium.org/6334083

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6611 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/deoptimizer-arm.cc

@@ -97,7 +97,7 @@ void Deoptimizer::DeoptimizeFunction(JSFunction* function) {
 #ifdef DEBUG
   // Destroy the code which is not supposed to be run again.
   int instructions =
-      (code->safepoint_table_start() - last_pc_offset) / Assembler::kInstrSize;
+      (code->safepoint_table_offset() - last_pc_offset) / Assembler::kInstrSize;
   CodePatcher destroyer(code->instruction_start() + last_pc_offset,
                         instructions);
   for (int x = 0; x < instructions; x++) {

src/arm/lithium-codegen-arm.cc

@@ -223,7 +223,7 @@ bool LCodeGen::GenerateCode() {
 void LCodeGen::FinishCode(Handle<Code> code) {
   ASSERT(is_done());
   code->set_stack_slots(StackSlotCount());
-  code->set_safepoint_table_start(safepoints_.GetCodeOffset());
+  code->set_safepoint_table_offset(safepoints_.GetCodeOffset());
   PopulateDeoptimizationData(code);
 }
 

src/deoptimizer.cc

@@ -817,7 +817,7 @@ void Deoptimizer::PatchStackCheckCode(Code* unoptimized_code,
   // call to an unconditional call to the replacement code.
   ASSERT(unoptimized_code->kind() == Code::FUNCTION);
   Address stack_check_cursor = unoptimized_code->instruction_start() +
-      unoptimized_code->stack_check_table_start();
+      unoptimized_code->stack_check_table_offset();
   uint32_t table_length = Memory::uint32_at(stack_check_cursor);
   stack_check_cursor += kIntSize;
   for (uint32_t i = 0; i < table_length; ++i) {
@@ -836,7 +836,7 @@ void Deoptimizer::RevertStackCheckCode(Code* unoptimized_code,
   // stack check calls.
   ASSERT(unoptimized_code->kind() == Code::FUNCTION);
   Address stack_check_cursor = unoptimized_code->instruction_start() +
-      unoptimized_code->stack_check_table_start();
+      unoptimized_code->stack_check_table_offset();
   uint32_t table_length = Memory::uint32_at(stack_check_cursor);
   stack_check_cursor += kIntSize;
   for (uint32_t i = 0; i < table_length; ++i) {

src/disassembler.cc

@@ -313,12 +313,12 @@ int Disassembler::Decode(FILE* f, byte* begin, byte* end) {
 // Called by Code::CodePrint.
 void Disassembler::Decode(FILE* f, Code* code) {
   int decode_size = (code->kind() == Code::OPTIMIZED_FUNCTION)
-      ? static_cast<int>(code->safepoint_table_start())
+      ? static_cast<int>(code->safepoint_table_offset())
       : code->instruction_size();
   // If there might be a stack check table, stop before reaching it.
   if (code->kind() == Code::FUNCTION) {
     decode_size =
-        Min(decode_size, static_cast<int>(code->stack_check_table_start()));
+        Min(decode_size, static_cast<int>(code->stack_check_table_offset()));
   }
 
   byte* begin = code->instruction_start();

src/full-codegen.cc

@@ -304,7 +304,7 @@ bool FullCodeGenerator::MakeCode(CompilationInfo* info) {
   cgen.PopulateDeoptimizationData(code);
   code->set_has_deoptimization_support(info->HasDeoptimizationSupport());
   code->set_allow_osr_at_loop_nesting_level(0);
-  code->set_stack_check_table_start(table_offset);
+  code->set_stack_check_table_offset(table_offset);
   CodeGenerator::PrintCode(code, info);
   info->SetCode(code);  // may be an empty handle.
 #ifdef ENABLE_GDB_JIT_INTERFACE

src/ia32/deoptimizer-ia32.cc

@@ -45,6 +45,16 @@ int Deoptimizer::patch_size() {
 }
 
 
+static void ZapCodeRange(Address start, Address end) {
+#ifdef DEBUG
+  ASSERT(start <= end);
+  int size = end - start;
+  CodePatcher destroyer(start, size);
+  while (size-- > 0) destroyer.masm()->int3();
+#endif
+}
+
+
 void Deoptimizer::DeoptimizeFunction(JSFunction* function) {
   AssertNoAllocation no_allocation;
 
@@ -52,90 +62,61 @@ void Deoptimizer::DeoptimizeFunction(JSFunction* function) {
 
   // Get the optimized code.
   Code* code = function->code();
-
-  // For each return after a safepoint insert a absolute call to the
-  // corresponding deoptimization entry.
-  unsigned last_pc_offset = 0;
-  SafepointTable table(function->code());
+  Address code_start_address = code->instruction_start();
 
   // We will overwrite the code's relocation info in-place. Relocation info
-  // is written backward. The relocation info is the payload of a byte array.
-  // Later on we will align this at the start of the byte array and create
-  // a trash byte array of the remaining space.
+  // is written backward. The relocation info is the payload of a byte
+  // array.  Later on we will slide this to the start of the byte array and
+  // create a filler object in the remaining space.
   ByteArray* reloc_info = code->relocation_info();
-  Address end_address = reloc_info->address() + reloc_info->Size();
-  RelocInfoWriter reloc_info_writer(end_address, code->instruction_start());
+  Address reloc_end_address = reloc_info->address() + reloc_info->Size();
+  RelocInfoWriter reloc_info_writer(reloc_end_address, code_start_address);
+
+  // For each return after a safepoint insert a call to the corresponding
+  // deoptimization entry.  Since the call is a relative encoding, write new
+  // reloc info.  We do not need any of the existing reloc info because the
+  // existing code will not be used again (we zap it in debug builds).
+  SafepointTable table(code);
+  Address prev_address = code_start_address;
+  for (unsigned i = 0; i < table.length(); ++i) {
+    Address curr_address = code_start_address + table.GetPcOffset(i);
+    ZapCodeRange(prev_address, curr_address);
 
-  for (unsigned i = 0; i < table.length(); i++) {
-    unsigned pc_offset = table.GetPcOffset(i);
     SafepointEntry safepoint_entry = table.GetEntry(i);
     int deoptimization_index = safepoint_entry.deoptimization_index();
-    int gap_code_size = safepoint_entry.gap_code_size();
-#ifdef DEBUG
-    // Destroy the code which is not supposed to run again.
-    unsigned instructions = pc_offset - last_pc_offset;
-    CodePatcher destroyer(code->instruction_start() + last_pc_offset,
-                          instructions);
-    for (unsigned i = 0; i < instructions; i++) {
-      destroyer.masm()->int3();
-    }
-#endif
-    last_pc_offset = pc_offset;
     if (deoptimization_index != Safepoint::kNoDeoptimizationIndex) {
-      last_pc_offset += gap_code_size;
-      Address call_pc = code->instruction_start() + last_pc_offset;
-      CodePatcher patcher(call_pc, patch_size());
-      Address entry = GetDeoptimizationEntry(deoptimization_index, LAZY);
-      patcher.masm()->call(entry, RelocInfo::NONE);
-      last_pc_offset += patch_size();
-      RelocInfo rinfo(call_pc + 1, RelocInfo::RUNTIME_ENTRY,
-                      reinterpret_cast<intptr_t>(entry));
+      // The gap code is needed to get to the state expected at the bailout.
+      curr_address += safepoint_entry.gap_code_size();
+
+      CodePatcher patcher(curr_address, patch_size());
+      Address deopt_entry = GetDeoptimizationEntry(deoptimization_index, LAZY);
+      patcher.masm()->call(deopt_entry, RelocInfo::NONE);
+
+      // We use RUNTIME_ENTRY for deoptimization bailouts.
+      RelocInfo rinfo(curr_address + 1,  // 1 after the call opcode.
+                      RelocInfo::RUNTIME_ENTRY,
+                      reinterpret_cast<intptr_t>(deopt_entry));
       reloc_info_writer.Write(&rinfo);
+
+      curr_address += patch_size();
     }
+    prev_address = curr_address;
   }
-#ifdef DEBUG
-  // Destroy the code which is not supposed to run again.
-  unsigned instructions = code->safepoint_table_start() - last_pc_offset;
-  CodePatcher destroyer(code->instruction_start() + last_pc_offset,
-                        instructions);
-  for (unsigned i = 0; i < instructions; i++) {
-    destroyer.masm()->int3();
-  }
-#endif
+  ZapCodeRange(prev_address,
+               code_start_address + code->safepoint_table_offset());
 
   // Move the relocation info to the beginning of the byte array.
-  int reloc_size = end_address - reloc_info_writer.pos();
-  memmove(code->relocation_start(), reloc_info_writer.pos(), reloc_size);
+  int new_reloc_size = reloc_end_address - reloc_info_writer.pos();
+  memmove(code->relocation_start(), reloc_info_writer.pos(), new_reloc_size);
 
   // The relocation info is in place, update the size.
-  reloc_info->set_length(reloc_size);
+  reloc_info->set_length(new_reloc_size);
 
   // Handle the junk part after the new relocation info. We will create
   // a non-live object in the extra space at the end of the former reloc info.
-  Address junk = reloc_info->address() + reloc_info->Size();
-  ASSERT(junk <= end_address);
-
-  if (end_address - junk <= ByteArray::kHeaderSize) {
-    // We get in here if there is not enough space for a ByteArray.
-
-    // Both addresses are kPointerSize alligned.
-    CHECK_EQ((end_address - junk) % 4, 0);
-    Map* filler_map = Heap::one_pointer_filler_map();
-    while (junk < end_address) {
-      HeapObject::FromAddress(junk)->set_map(filler_map);
-      junk += kPointerSize;
-    }
-  } else {
-    int size = end_address - junk;
-    // Since the reloc_end address and junk are both alligned, we shouild,
-    // never have junk which is not a multipla of kPointerSize.
-    CHECK_EQ(size % kPointerSize, 0);
-    CHECK_GT(size, 0);
-    HeapObject* junk_object = HeapObject::FromAddress(junk);
-    junk_object->set_map(Heap::byte_array_map());
-    int length = ByteArray::LengthFor(end_address - junk);
-    ByteArray::cast(junk_object)->set_length(length);
-  }
+  Address junk_address = reloc_info->address() + reloc_info->Size();
+  ASSERT(junk_address <= reloc_end_address);
+  Heap::CreateFillerObjectAt(junk_address, reloc_end_address - junk_address);
 
   // Add the deoptimizing code to the list.
   DeoptimizingCodeListNode* node = new DeoptimizingCodeListNode(code);

src/ia32/lithium-codegen-ia32.cc

@@ -77,7 +77,7 @@ bool LCodeGen::GenerateCode() {
 void LCodeGen::FinishCode(Handle<Code> code) {
   ASSERT(is_done());
   code->set_stack_slots(StackSlotCount());
-  code->set_safepoint_table_start(safepoints_.GetCodeOffset());
+  code->set_safepoint_table_offset(safepoints_.GetCodeOffset());
   PopulateDeoptimizationData(code);
 }
 

src/objects-inl.h

@@ -2510,29 +2510,29 @@ void Code::set_stack_slots(unsigned slots) {
 }
 
 
-unsigned Code::safepoint_table_start() {
+unsigned Code::safepoint_table_offset() {
   ASSERT(kind() == OPTIMIZED_FUNCTION);
-  return READ_UINT32_FIELD(this, kSafepointTableStartOffset);
+  return READ_UINT32_FIELD(this, kSafepointTableOffsetOffset);
 }
 
 
-void Code::set_safepoint_table_start(unsigned offset) {
+void Code::set_safepoint_table_offset(unsigned offset) {
   ASSERT(kind() == OPTIMIZED_FUNCTION);
   ASSERT(IsAligned(offset, static_cast<unsigned>(kIntSize)));
-  WRITE_UINT32_FIELD(this, kSafepointTableStartOffset, offset);
+  WRITE_UINT32_FIELD(this, kSafepointTableOffsetOffset, offset);
 }
 
 
-unsigned Code::stack_check_table_start() {
+unsigned Code::stack_check_table_offset() {
   ASSERT(kind() == FUNCTION);
-  return READ_UINT32_FIELD(this, kStackCheckTableStartOffset);
+  return READ_UINT32_FIELD(this, kStackCheckTableOffsetOffset);
 }
 
 
-void Code::set_stack_check_table_start(unsigned offset) {
+void Code::set_stack_check_table_offset(unsigned offset) {
   ASSERT(kind() == FUNCTION);
   ASSERT(IsAligned(offset, static_cast<unsigned>(kIntSize)));
-  WRITE_UINT32_FIELD(this, kStackCheckTableStartOffset, offset);
+  WRITE_UINT32_FIELD(this, kStackCheckTableOffsetOffset, offset);
 }
 
 

src/objects.cc

@@ -6001,7 +6001,7 @@ SafepointEntry Code::GetSafepointEntry(Address pc) {
 void Code::SetNoStackCheckTable() {
   // Indicate the absence of a stack-check table by a table start after the
   // end of the instructions.  Table start must be aligned, so round up.
-  set_stack_check_table_start(RoundUp(instruction_size(), kIntSize));
+  set_stack_check_table_offset(RoundUp(instruction_size(), kIntSize));
 }
 
 
@@ -6278,7 +6278,7 @@ void Code::Disassemble(const char* name, FILE* out) {
     }
     PrintF(out, "\n");
   } else if (kind() == FUNCTION) {
-    unsigned offset = stack_check_table_start();
+    unsigned offset = stack_check_table_offset();
     // If there is no stack check table, the "table start" will at or after
     // (due to alignment) the end of the instruction stream.
     if (static_cast<int>(offset) < instruction_size()) {

src/objects.h

@@ -3275,13 +3275,13 @@ class Code: public HeapObject {
 
   // [safepoint_table_start]: For kind OPTIMIZED_CODE, the offset in
   // the instruction stream where the safepoint table starts.
-  inline unsigned safepoint_table_start();
-  inline void set_safepoint_table_start(unsigned offset);
+  inline unsigned safepoint_table_offset();
+  inline void set_safepoint_table_offset(unsigned offset);
 
   // [stack_check_table_start]: For kind FUNCTION, the offset in the
   // instruction stream where the stack check table starts.
-  inline unsigned stack_check_table_start();
-  inline void set_stack_check_table_start(unsigned offset);
+  inline unsigned stack_check_table_offset();
+  inline void set_stack_check_table_offset(unsigned offset);
 
   // [check type]: For kind CALL_IC, tells how to check if the
   // receiver is valid for the given call.
@@ -3445,8 +3445,8 @@ class Code: public HeapObject {
   static const int kAllowOSRAtLoopNestingLevelOffset =
       kHasDeoptimizationSupportOffset + 1;
 
-  static const int kSafepointTableStartOffset = kStackSlotsOffset + kIntSize;
-  static const int kStackCheckTableStartOffset = kStackSlotsOffset + kIntSize;
+  static const int kSafepointTableOffsetOffset = kStackSlotsOffset + kIntSize;
+  static const int kStackCheckTableOffsetOffset = kStackSlotsOffset + kIntSize;
 
   // Flags layout.
   static const int kFlagsICStateShift        = 0;

src/runtime.cc

@@ -6970,7 +6970,7 @@ static MaybeObject* Runtime_CompileForOnStackReplacement(Arguments args) {
     // the AST id matching the PC.
     Address start = unoptimized->instruction_start();
     unsigned target_pc_offset = static_cast<unsigned>(frame->pc() - start);
-    Address table_cursor = start + unoptimized->stack_check_table_start();
+    Address table_cursor = start + unoptimized->stack_check_table_offset();
     uint32_t table_length = Memory::uint32_at(table_cursor);
     table_cursor += kIntSize;
     for (unsigned i = 0; i < table_length; ++i) {

src/safepoint-table.cc

@@ -58,7 +58,7 @@ bool SafepointEntry::HasRegisterAt(int reg_index) const {
 SafepointTable::SafepointTable(Code* code) {
   ASSERT(code->kind() == Code::OPTIMIZED_FUNCTION);
   code_ = code;
-  Address header = code->instruction_start() + code->safepoint_table_start();
+  Address header = code->instruction_start() + code->safepoint_table_offset();
   length_ = Memory::uint32_at(header + kLengthOffset);
   entry_size_ = Memory::uint32_at(header + kEntrySizeOffset);
   pc_and_deoptimization_indexes_ = header + kHeaderSize;

src/x64/deoptimizer-x64.cc

@@ -88,8 +88,8 @@ void Deoptimizer::DeoptimizeFunction(JSFunction* function) {
   }
 #ifdef DEBUG
   // Destroy the code which is not supposed to run again.
-  CHECK(code->safepoint_table_start() >= last_pc_offset);
-  unsigned instructions = code->safepoint_table_start() - last_pc_offset;
+  CHECK(code->safepoint_table_offset() >= last_pc_offset);
+  unsigned instructions = code->safepoint_table_offset() - last_pc_offset;
   CodePatcher destroyer(code->instruction_start() + last_pc_offset,
                         instructions);
   for (unsigned i = 0; i < instructions; i++) {

src/x64/lithium-codegen-x64.cc

@@ -53,7 +53,7 @@ bool LCodeGen::GenerateCode() {
 void LCodeGen::FinishCode(Handle<Code> code) {
   ASSERT(is_done());
   code->set_stack_slots(StackSlotCount());
-  code->set_safepoint_table_start(safepoints_.GetCodeOffset());
+  code->set_safepoint_table_offset(safepoints_.GetCodeOffset());
   PopulateDeoptimizationData(code);
 }