Revert of MIPS: Fix 'Assembler support for internal references.'

src/mips/assembler-mips.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 179 matching lines @@
     ra
   };
   return kRegisters[num];
 }
 
 
 // -----------------------------------------------------------------------------
 // Implementation of RelocInfo.
 
 const int RelocInfo::kApplyMask = RelocInfo::kCodeTargetMask |
-                                  1 << RelocInfo::INTERNAL_REFERENCE |
-                                  1 << RelocInfo::INTERNAL_REFERENCE_ENCODED;
+                                  1 << RelocInfo::INTERNAL_REFERENCE;
 
 
 bool RelocInfo::IsCodedSpecially() {
   // The deserializer needs to know whether a pointer is specially coded.  Being
   // specially coded on MIPS means that it is a lui/ori instruction, and that is
   // always the case inside code objects.
   return true;
 }
 
 
@@ skipping 444 matching lines @@
   DCHECK(IsAddImmediate(instr));
   return ((instr & ~kImm16Mask) | (offset & kImm16Mask));
 }
 
 
 bool Assembler::IsAndImmediate(Instr instr) {
   return GetOpcodeField(instr) == ANDI;
 }
 
 
-int Assembler::target_at(int32_t pos, bool is_internal) {
+int Assembler::target_at(int32_t pos) {
   Instr instr = instr_at(pos);
-  if (is_internal) {
-    if (instr == 0) {
-      return kEndOfChain;
-    } else {
-      int32_t instr_address = reinterpret_cast<int32_t>(buffer_ + pos);
-      int32_t delta = instr_address - instr;
-      DCHECK(pos > delta);
-      return pos - delta;
-    }
-  }
   if ((instr & ~kImm16Mask) == 0) {
     // Emitted label constant, not part of a branch.
     if (instr == 0) {
        return kEndOfChain;
      } else {
        int32_t imm18 =((instr & static_cast<int32_t>(kImm16Mask)) << 16) >> 14;
        return (imm18 + pos);
      }
   }
   // Do NOT change this to <<2. We rely on arithmetic shifts here, assuming
@@ skipping 28 matching lines @@
     if (imm28 == kEndOfJumpChain) {
       // EndOfChain sentinel is returned directly, not relative to pc or pos.
       return kEndOfChain;
     } else {
       uint32_t instr_address = reinterpret_cast<int32_t>(buffer_ + pos);
       instr_address &= kImm28Mask;
       int32_t delta = instr_address - imm28;
       DCHECK(pos > delta);
       return pos - delta;
     }
-  } else {
-    UNREACHABLE();
-    return 0;
+  } else {  // IsLabel(instr)
+    int32_t imm28 = (instr & static_cast<int32_t>(kImm26Mask)) << 2;
+    if (imm28 == kEndOfJumpChain) {
+      // EndOfChain sentinel is returned directly, not relative to pc or pos.
+      return kEndOfChain;
+    } else {
+      return pos + imm28;
+    }
   }
 }
 
 
-void Assembler::target_at_put(int32_t pos, int32_t target_pos,
-                              bool is_internal) {
+void Assembler::target_at_put(int32_t pos, int32_t target_pos) {
   Instr instr = instr_at(pos);
-
-  if (is_internal) {
-    uint32_t imm = reinterpret_cast<uint32_t>(buffer_) + target_pos;
-    instr_at_put(pos, imm);
-    return;
-  }
   if ((instr & ~kImm16Mask) == 0) {
     DCHECK(target_pos == kEndOfChain || target_pos >= 0);
     // Emitted label constant, not part of a branch.
     // Make label relative to Code* of generated Code object.
     instr_at_put(pos, target_pos + (Code::kHeaderSize - kHeapObjectTag));
     return;
   }
 
   if (IsBranch(instr)) {
     int32_t imm18 = target_pos - (pos + kBranchPCOffset);
@@ skipping 22 matching lines @@
     uint32_t imm28 = reinterpret_cast<uint32_t>(buffer_) + target_pos;
     imm28 &= kImm28Mask;
     DCHECK((imm28 & 3) == 0);
 
     instr &= ~kImm26Mask;
     uint32_t imm26 = imm28 >> 2;
     DCHECK(is_uint26(imm26));
 
     instr_at_put(pos, instr | (imm26 & kImm26Mask));
   } else {
-    UNREACHABLE();
+    uint32_t imm = reinterpret_cast<uint32_t>(buffer_) + target_pos;
+    instr_at_put(pos, imm);
   }
 }
 
 
 void Assembler::print(Label* L) {
   if (L->is_unused()) {
     PrintF("unused label\n");
   } else if (L->is_bound()) {
     PrintF("bound label to %d\n", L->pos());
   } else if (L->is_linked()) {
     Label l = *L;
     PrintF("unbound label");
     while (l.is_linked()) {
       PrintF("@ %d ", l.pos());
       Instr instr = instr_at(l.pos());
       if ((instr & ~kImm16Mask) == 0) {
         PrintF("value\n");
       } else {
         PrintF("%d\n", instr);
       }
-      next(&l, internal_reference_positions_.find(l.pos()) !=
-                   internal_reference_positions_.end());
+      next(&l);
     }
   } else {
     PrintF("label in inconsistent state (pos = %d)\n", L->pos_);
   }
 }
 
 
 void Assembler::bind_to(Label* L, int pos) {
   DCHECK(0 <= pos && pos <= pc_offset());  // Must have valid binding position.
   int32_t trampoline_pos = kInvalidSlotPos;
-  bool is_internal = false;
   if (L->is_linked() && !trampoline_emitted_) {
     unbound_labels_count_--;
     next_buffer_check_ += kTrampolineSlotsSize;
   }
 
   while (L->is_linked()) {
     int32_t fixup_pos = L->pos();
     int32_t dist = pos - fixup_pos;
-    is_internal = internal_reference_positions_.find(fixup_pos) !=
-                  internal_reference_positions_.end();
-    next(L, is_internal);  // Call next before overwriting link with target at
-                           // fixup_pos.
+    next(L);  // Call next before overwriting link with target at fixup_pos.
     Instr instr = instr_at(fixup_pos);
-    if (is_internal) {
-      target_at_put(fixup_pos, pos, is_internal);
-    } else if (!is_internal && IsBranch(instr)) {
+    if (IsBranch(instr)) {
       if (dist > kMaxBranchOffset) {
         if (trampoline_pos == kInvalidSlotPos) {
           trampoline_pos = get_trampoline_entry(fixup_pos);
           CHECK(trampoline_pos != kInvalidSlotPos);
         }
         DCHECK((trampoline_pos - fixup_pos) <= kMaxBranchOffset);
-        target_at_put(fixup_pos, trampoline_pos, false);
+        target_at_put(fixup_pos, trampoline_pos);
         fixup_pos = trampoline_pos;
         dist = pos - fixup_pos;
       }
-      target_at_put(fixup_pos, pos, false);
+      target_at_put(fixup_pos, pos);
     } else {
-      target_at_put(fixup_pos, pos, false);
+      target_at_put(fixup_pos, pos);
     }
   }
   L->bind_to(pos);
 
   // Keep track of the last bound label so we don't eliminate any instructions
   // before a bound label.
   if (pos > last_bound_pos_)
     last_bound_pos_ = pos;
 }
 
 
 void Assembler::bind(Label* L) {
   DCHECK(!L->is_bound());  // Label can only be bound once.
   bind_to(L, pc_offset());
 }
 
 
-void Assembler::next(Label* L, bool is_internal) {
+void Assembler::next(Label* L) {
   DCHECK(L->is_linked());
-  int link = target_at(L->pos(), is_internal);
+  int link = target_at(L->pos());
   if (link == kEndOfChain) {
     L->Unuse();
   } else {
     DCHECK(link >= 0);
     L->link_to(link);
   }
 }
 
 
 bool Assembler::is_near(Label* L) {
@@ skipping 1467 matching lines @@
 
 
 void Assembler::bc1t(int16_t offset, uint16_t cc) {
   DCHECK(is_uint3(cc));
   Instr instr = COP1 | BC1 | cc << 18 | 1 << 16 | (offset & kImm16Mask);
   emit(instr);
 }
 
 
 // Debugging.
-int Assembler::RelocateInternalReference(RelocInfo::Mode rmode, byte* pc,
-                                         intptr_t pc_delta) {
+int Assembler::RelocateInternalReference(byte* pc, intptr_t pc_delta) {
   Instr instr = instr_at(pc);
+  if (IsLui(instr)) {
+    Instr instr_lui = instr_at(pc + 0 * Assembler::kInstrSize);
+    Instr instr_ori = instr_at(pc + 1 * Assembler::kInstrSize);
+    DCHECK(IsOri(instr_ori));
+    int32_t imm = (instr_lui & static_cast<int32_t>(kImm16Mask)) << kLuiShift;
+    imm |= (instr_ori & static_cast<int32_t>(kImm16Mask));
+    if (imm == kEndOfJumpChain) {
+      return 0;  // Number of instructions patched.
+    }
+    imm += pc_delta;
+    DCHECK((imm & 3) == 0);
 
-  if (RelocInfo::IsInternalReference(rmode)) {
+    instr_lui &= ~kImm16Mask;
+    instr_ori &= ~kImm16Mask;
+
+    instr_at_put(pc + 0 * Assembler::kInstrSize,
+                 instr_lui | ((imm >> kLuiShift) & kImm16Mask));
+    instr_at_put(pc + 1 * Assembler::kInstrSize,
+                 instr_ori | (imm & kImm16Mask));
+    return 2;  // Number of instructions patched.
+  } else if (IsJ(instr)) {
+    uint32_t imm28 = (instr & static_cast<int32_t>(kImm26Mask)) << 2;
+    if (static_cast<int32_t>(imm28) == kEndOfJumpChain) {
+      return 0;  // Number of instructions patched.
+    }
+    imm28 += pc_delta;
+    imm28 &= kImm28Mask;
+    DCHECK((imm28 & 3) == 0);
+
+    instr &= ~kImm26Mask;
+    uint32_t imm26 = imm28 >> 2;
+    DCHECK(is_uint26(imm26));
+
+    instr_at_put(pc, instr | (imm26 & kImm26Mask));
+    return 1;  // Number of instructions patched.
+  } else {  // IsLabel(instr)
     int32_t* p = reinterpret_cast<int32_t*>(pc);
-    if (*p == 0) {
+    uint32_t imm28 = (instr & static_cast<int32_t>(kImm26Mask)) << 2;
+    if (static_cast<int32_t>(imm28) == kEndOfJumpChain) {
       return 0;  // Number of instructions patched.
     }
     *p += pc_delta;
     return 1;  // Number of instructions patched.
-  } else {
-    DCHECK(RelocInfo::IsInternalReferenceEncoded(rmode));
-    if (IsLui(instr)) {
-      Instr instr_lui = instr_at(pc + 0 * Assembler::kInstrSize);
-      Instr instr_ori = instr_at(pc + 1 * Assembler::kInstrSize);
-      DCHECK(IsOri(instr_ori));
-      int32_t imm = (instr_lui & static_cast<int32_t>(kImm16Mask)) << kLuiShift;
-      imm |= (instr_ori & static_cast<int32_t>(kImm16Mask));
-      if (imm == kEndOfJumpChain) {
-        return 0;  // Number of instructions patched.
-      }
-      imm += pc_delta;
-      DCHECK((imm & 3) == 0);
-
-      instr_lui &= ~kImm16Mask;
-      instr_ori &= ~kImm16Mask;
-
-      instr_at_put(pc + 0 * Assembler::kInstrSize,
-                   instr_lui | ((imm >> kLuiShift) & kImm16Mask));
-      instr_at_put(pc + 1 * Assembler::kInstrSize,
-                   instr_ori | (imm & kImm16Mask));
-      return 2;  // Number of instructions patched.
-    } else if (IsJ(instr)) {
-      uint32_t imm28 = (instr & static_cast<int32_t>(kImm26Mask)) << 2;
-      if (static_cast<int32_t>(imm28) == kEndOfJumpChain) {
-        return 0;  // Number of instructions patched.
-      }
-      imm28 += pc_delta;
-      imm28 &= kImm28Mask;
-      DCHECK((imm28 & 3) == 0);
-
-      instr &= ~kImm26Mask;
-      uint32_t imm26 = imm28 >> 2;
-      DCHECK(is_uint26(imm26));
-
-      instr_at_put(pc, instr | (imm26 & kImm26Mask));
-      return 1;  // Number of instructions patched.
-    } else {
-      UNREACHABLE();
-      return 0;
-    }
   }
 }
 
 
 void Assembler::GrowBuffer() {
   if (!own_buffer_) FATAL("external code buffer is too small");
 
   // Compute new buffer size.
   CodeDesc desc;  // The new buffer.
   if (buffer_size_ < 1 * MB) {
@@ skipping 20 matching lines @@
   DeleteArray(buffer_);
   buffer_ = desc.buffer;
   buffer_size_ = desc.buffer_size;
   pc_ += pc_delta;
   reloc_info_writer.Reposition(reloc_info_writer.pos() + rc_delta,
                                reloc_info_writer.last_pc() + pc_delta);
 
   // Relocate runtime entries.
   for (RelocIterator it(desc); !it.done(); it.next()) {
     RelocInfo::Mode rmode = it.rinfo()->rmode();
-    if (rmode == RelocInfo::INTERNAL_REFERENCE_ENCODED ||
-        rmode == RelocInfo::INTERNAL_REFERENCE) {
+    if (rmode == RelocInfo::INTERNAL_REFERENCE) {
       byte* p = reinterpret_cast<byte*>(it.rinfo()->pc());
-      RelocateInternalReference(rmode, p, pc_delta);
+      RelocateInternalReference(p, pc_delta);
     }
   }
+
   DCHECK(!overflow());
 }
 
 
 void Assembler::db(uint8_t data) {
   CheckBuffer();
   *reinterpret_cast<uint8_t*>(pc_) = data;
   pc_ += sizeof(uint8_t);
 }
 
 
 void Assembler::dd(uint32_t data) {
   CheckBuffer();
   *reinterpret_cast<uint32_t*>(pc_) = data;
   pc_ += sizeof(uint32_t);
 }
 
 
 void Assembler::dd(Label* label) {
   CheckBuffer();
   RecordRelocInfo(RelocInfo::INTERNAL_REFERENCE);
   if (label->is_bound()) {
     uint32_t data = reinterpret_cast<uint32_t>(buffer_ + label->pos());
     *reinterpret_cast<uint32_t*>(pc_) = data;
     pc_ += sizeof(uint32_t);
   } else {
-    uint32_t target_pos = jump_address(label);
-    emit(target_pos);
-    internal_reference_positions_.insert(label->pos());
+    int target_pos;
+    if (label->is_linked()) {
+      // Point to previous instruction that uses the link.
+      target_pos = label->pos();
+    } else {
+      // First entry of the link chain points to itself.
+      target_pos = pc_offset();
+    }
+    label->link_to(pc_offset());
+    // Encode internal reference to unbound label. We set the least significant
+    // bit to distinguish unbound internal references in GrowBuffer() below.
+    int diff = target_pos - pc_offset();
+    DCHECK_EQ(0, diff & 3);
+    int imm26 = diff >> 2;
+    DCHECK(is_int26(imm26));
+    // Emit special LABEL instruction.
+    emit(LABEL | (imm26 & kImm26Mask));
   }
 }
 
 
 void Assembler::emit_code_stub_address(Code* stub) {
   CheckBuffer();
   *reinterpret_cast<uint32_t*>(pc_) =
       reinterpret_cast<uint32_t>(stub->instruction_start());
   pc_ += sizeof(uint32_t);
 }
@@ skipping 64 matching lines @@
       nop();
 
       int pool_start = pc_offset();
       for (int i = 0; i < unbound_labels_count_; i++) {
         uint32_t imm32;
         imm32 = jump_address(&after_pool);
         { BlockGrowBufferScope block_buf_growth(this);
           // Buffer growth (and relocation) must be blocked for internal
           // references until associated instructions are emitted and available
           // to be patched.
-          RecordRelocInfo(RelocInfo::INTERNAL_REFERENCE_ENCODED);
+          RecordRelocInfo(RelocInfo::INTERNAL_REFERENCE);
           lui(at, (imm32 & kHiMask) >> kLuiShift);
           ori(at, at, (imm32 & kImm16Mask));
         }
         jr(at);
         nop();
       }
       bind(&after_pool);
       trampoline_ = Trampoline(pool_start, unbound_labels_count_);
 
       trampoline_emitted_ = true;
@@ skipping 197 matching lines @@
 void Assembler::PopulateConstantPool(ConstantPoolArray* constant_pool) {
   // No out-of-line constant pool support.
   DCHECK(!FLAG_enable_ool_constant_pool);
   return;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS