[ia32] Assembler support for internal references.

BUG=v8:3872
LOG=n
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/900223006

Cr-Commit-Position: refs/heads/master@{#26478}

src/ia32/assembler-ia32.cc

@@ -1340,6 +1340,13 @@ void Assembler::ret(int imm16) {
 }
 
 
+void Assembler::ud2() {
+  EnsureSpace ensure_space(this);
+  EMIT(0x0F);
+  EMIT(0x0B);
+}
+
+
 // Labels refer to positions in the (to be) generated code.
 // There are bound, linked, and unused labels.
 //
@@ -1378,7 +1385,10 @@ void Assembler::bind_to(Label* L, int pos) {
   while (L->is_linked()) {
     Displacement disp = disp_at(L);
     int fixup_pos = L->pos();
-    if (disp.type() == Displacement::CODE_RELATIVE) {
+    if (disp.type() == Displacement::CODE_ABSOLUTE) {
+      long_at_put(fixup_pos, reinterpret_cast<int>(buffer_ + pos));
+      internal_reference_positions_.push_back(fixup_pos);
+    } else if (disp.type() == Displacement::CODE_RELATIVE) {
       // Relative to Code* heap object pointer.
       long_at_put(fixup_pos, pos + Code::kHeaderSize - kHeapObjectTag);
     } else {
@@ -2690,15 +2700,10 @@ void Assembler::GrowBuffer() {
   reloc_info_writer.Reposition(reloc_info_writer.pos() + rc_delta,
                                reloc_info_writer.last_pc() + pc_delta);
 
-  // Relocate runtime entries.
+  // Relocate internal references.
-  for (RelocIterator it(desc); !it.done(); it.next()) {
+  for (auto pos : internal_reference_positions_) {
-    RelocInfo::Mode rmode = it.rinfo()->rmode();
+    int32_t* p = reinterpret_cast<int32_t*>(buffer_ + pos);
-    if (rmode == RelocInfo::INTERNAL_REFERENCE) {
+    *p += pc_delta;
-      int32_t* p = reinterpret_cast<int32_t*>(it.rinfo()->pc());
-      if (*p != 0) {  // 0 means uninitialized.
-        *p += pc_delta;
-      }
-    }
   }
 
   DCHECK(!buffer_overflow());
@@ -2748,7 +2753,21 @@ void Assembler::emit_operand(Register reg, const Operand& adr) {
   if (length >= sizeof(int32_t) && !RelocInfo::IsNone(adr.rmode_)) {
     pc_ -= sizeof(int32_t);  // pc_ must be *at* disp32
     RecordRelocInfo(adr.rmode_);
-    pc_ += sizeof(int32_t);
+    if (adr.rmode_ == RelocInfo::INTERNAL_REFERENCE) {  // Fixup for labels
+      emit_label(*reinterpret_cast<Label**>(pc_));
+    } else {
+      pc_ += sizeof(int32_t);
+    }
+  }
+}
+
+
+void Assembler::emit_label(Label* label) {
+  if (label->is_bound()) {
+    internal_reference_positions_.push_back(pc_offset());
+    emit(reinterpret_cast<uint32_t>(buffer_ + label->pos()));
+  } else {
+    emit_disp(label, Displacement::CODE_ABSOLUTE);
   }
 }
 
@@ -2773,6 +2792,13 @@ void Assembler::dd(uint32_t data) {
 }
 
 
+void Assembler::dd(Label* label) {
+  EnsureSpace ensure_space(this);
+  RecordRelocInfo(RelocInfo::INTERNAL_REFERENCE);
+  emit_label(label);
+}
+
+
 void Assembler::RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data) {
   DCHECK(!RelocInfo::IsNone(rmode));
   // Don't record external references unless the heap will be serialized.

src/ia32/assembler-ia32.h

@@ -37,6 +37,8 @@
 #ifndef V8_IA32_ASSEMBLER_IA32_H_
 #define V8_IA32_ASSEMBLER_IA32_H_
 
+#include <deque>
+
 #include "src/isolate.h"
 #include "src/serialize.h"
 
@@ -357,6 +359,11 @@ class Operand BASE_EMBEDDED {
                    int32_t disp,
                    RelocInfo::Mode rmode = RelocInfo::NONE32);
 
+  static Operand JumpTable(Register index, ScaleFactor scale, Label* table) {
+    return Operand(index, scale, reinterpret_cast<int32_t>(table),
+                   RelocInfo::INTERNAL_REFERENCE);
+  }
+
   static Operand StaticVariable(const ExternalReference& ext) {
     return Operand(reinterpret_cast<int32_t>(ext.address()),
                    RelocInfo::EXTERNAL_REFERENCE);
@@ -430,11 +437,7 @@ class Operand BASE_EMBEDDED {
 
 class Displacement BASE_EMBEDDED {
  public:
-  enum Type {
+  enum Type { UNCONDITIONAL_JUMP, CODE_RELATIVE, OTHER, CODE_ABSOLUTE };
-    UNCONDITIONAL_JUMP,
-    CODE_RELATIVE,
-    OTHER
-  };
 
   int data() const { return data_; }
   Type type() const { return TypeField::decode(data_); }
@@ -804,6 +807,7 @@ class Assembler : public AssemblerBase {
   void int3();
   void nop();
   void ret(int imm16);
+  void ud2();
 
   // Label operations & relative jumps (PPUM Appendix D)
   //
@@ -1268,6 +1272,7 @@ class Assembler : public AssemblerBase {
   // inline tables, e.g., jump-tables.
   void db(uint8_t data);
   void dd(uint32_t data);
+  void dd(Label* label);
 
   // Check if there is less than kGap bytes available in the buffer.
   // If this is the case, we need to grow the buffer before emitting
@@ -1343,6 +1348,8 @@ class Assembler : public AssemblerBase {
 
   void emit_operand(Register reg, const Operand& adr);
 
+  void emit_label(Label* label);
+
   void emit_farith(int b1, int b2, int i);
 
   // Emit vex prefix
@@ -1369,6 +1376,11 @@ class Assembler : public AssemblerBase {
   friend class CodePatcher;
   friend class EnsureSpace;
 
+  // Internal reference positions, required for (potential) patching in
+  // GrowBuffer(); contains only those internal references whose labels
+  // are already bound.
+  std::deque<int> internal_reference_positions_;
+
   // code generation
   RelocInfoWriter reloc_info_writer;
 

src/ia32/disasm-ia32.cc

@@ -1035,6 +1035,8 @@ int DisassemblerIA32::RegisterFPUInstruction(int escape_opcode,
 // Returns NULL if the instruction is not handled here.
 static const char* F0Mnem(byte f0byte) {
   switch (f0byte) {
+    case 0x0B:
+      return "ud2";
     case 0x18: return "prefetch";
     case 0xA2: return "cpuid";
     case 0xBE: return "movsx_b";
@@ -1215,7 +1217,7 @@ int DisassemblerIA32::InstructionDecode(v8::internal::Vector<char> out_buffer,
                      data[7] == 0) {
             AppendToBuffer("nop");  // 8 byte nop.
             data += 8;
-          } else if (f0byte == 0xA2 || f0byte == 0x31) {
+          } else if (f0byte == 0x0B || f0byte == 0xA2 || f0byte == 0x31) {
             AppendToBuffer("%s", f0mnem);
             data += 2;
           } else if (f0byte == 0x28) {

test/cctest/test-assembler-ia32.cc

@@ -1043,4 +1043,100 @@ TEST(AssemblerX64FMA_ss) {
   F10 f = FUNCTION_CAST<F10>(code->entry());
   CHECK_EQ(0, f(9.26621069e-05f, -2.4607749f, -1.09587872f));
 }
+
+
+TEST(AssemblerIa32JumpTables1) {
+  // Test jump tables with forward jumps.
+  CcTest::InitializeVM();
+  Isolate* isolate = reinterpret_cast<Isolate*>(CcTest::isolate());
+  HandleScope scope(isolate);
+  Assembler assm(isolate, nullptr, 0);
+
+  const int kNumCases = 512;
+  int values[kNumCases];
+  isolate->random_number_generator()->NextBytes(values, sizeof(values));
+  Label labels[kNumCases];
+
+  Label done, table;
+  __ mov(eax, Operand(esp, 4));
+  __ jmp(Operand::JumpTable(eax, times_4, &table));
+  __ ud2();
+  __ bind(&table);
+  for (int i = 0; i < kNumCases; ++i) {
+    __ dd(&labels[i]);
+  }
+
+  for (int i = 0; i < kNumCases; ++i) {
+    __ bind(&labels[i]);
+    __ mov(eax, Immediate(values[i]));
+    __ jmp(&done);
+  }
+
+  __ bind(&done);
+  __ ret(0);
+
+  CodeDesc desc;
+  assm.GetCode(&desc);
+  Handle<Code> code = isolate->factory()->NewCode(
+      desc, Code::ComputeFlags(Code::STUB), Handle<Code>());
+#ifdef OBJECT_PRINT
+  OFStream os(stdout);
+  code->Print(os);
+#endif
+  F1 f = FUNCTION_CAST<F1>(code->entry());
+  for (int i = 0; i < kNumCases; ++i) {
+    int res = f(i);
+    ::printf("f(%d) = %d\n", i, res);
+    CHECK_EQ(values[i], res);
+  }
+}
+
+
+TEST(AssemblerIa32JumpTables2) {
+  // Test jump tables with backward jumps.
+  CcTest::InitializeVM();
+  Isolate* isolate = reinterpret_cast<Isolate*>(CcTest::isolate());
+  HandleScope scope(isolate);
+  Assembler assm(isolate, nullptr, 0);
+
+  const int kNumCases = 512;
+  int values[kNumCases];
+  isolate->random_number_generator()->NextBytes(values, sizeof(values));
+  Label labels[kNumCases];
+
+  Label done, table;
+  __ mov(eax, Operand(esp, 4));
+  __ jmp(Operand::JumpTable(eax, times_4, &table));
+  __ ud2();
+
+  for (int i = 0; i < kNumCases; ++i) {
+    __ bind(&labels[i]);
+    __ mov(eax, Immediate(values[i]));
+    __ jmp(&done);
+  }
+
+  __ bind(&table);
+  for (int i = 0; i < kNumCases; ++i) {
+    __ dd(&labels[i]);
+  }
+
+  __ bind(&done);
+  __ ret(0);
+
+  CodeDesc desc;
+  assm.GetCode(&desc);
+  Handle<Code> code = isolate->factory()->NewCode(
+      desc, Code::ComputeFlags(Code::STUB), Handle<Code>());
+#ifdef OBJECT_PRINT
+  OFStream os(stdout);
+  code->Print(os);
+#endif
+  F1 f = FUNCTION_CAST<F1>(code->entry());
+  for (int i = 0; i < kNumCases; ++i) {
+    int res = f(i);
+    ::printf("f(%d) = %d\n", i, res);
+    CHECK_EQ(values[i], res);
+  }
+}
+
 #undef __