MIPS: Remove unused J(Label *).

Remove unused macro-asm instruction and associated address patching.

On mips64, remove unused JumpLabelToJumpRegister(). On mips, rename
it appropriately (it's still used there for JR->J optimizations).

BUG=

Review URL: https://codereview.chromium.org/1059433003

Cr-Commit-Position: refs/heads/master@{#27593}

src/mips/assembler-mips-inl.h

@@ -123,7 +123,7 @@ void RelocInfo::apply(intptr_t delta, ICacheFlushMode icache_flush_mode) {
     uint32_t scope2 = reinterpret_cast<uint32_t>(pc_) & ~kImm28Mask;
 
     if (scope1 != scope2) {
-      Assembler::JumpLabelToJumpRegister(pc_);
+      Assembler::JumpToJumpRegister(pc_);
     }
   }
   if (IsInternalReference(rmode_) || IsInternalReferenceEncoded(rmode_)) {

src/mips/assembler-mips.cc

@@ -663,7 +663,7 @@ int Assembler::target_at(int pos, bool is_internal) {
      }
   }
   // Check we have a branch or jump instruction.
-  DCHECK(IsBranch(instr) || IsJ(instr) || IsLui(instr));
+  DCHECK(IsBranch(instr) || IsLui(instr));
   // Do NOT change this to <<2. We rely on arithmetic shifts here, assuming
   // the compiler uses arithmectic shifts for signed integers.
   if (IsBranch(instr)) {
@@ -692,17 +692,8 @@ int Assembler::target_at(int pos, bool is_internal) {
       return pos - delta;
     }
   } else {
-    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 {
-      uint32_t instr_address = reinterpret_cast<int32_t>(buffer_ + pos);
-      instr_address &= kImm28Mask;
-      int delta = static_cast<int>(instr_address - imm28);
-      DCHECK(pos > delta);
-      return pos - delta;
-    }
+    UNREACHABLE();
+    return 0;
   }
 }
 
@@ -724,7 +715,7 @@ void Assembler::target_at_put(int32_t pos, int32_t target_pos,
     return;
   }
 
-  DCHECK(IsBranch(instr) || IsJ(instr) || IsLui(instr));
+  DCHECK(IsBranch(instr) || IsLui(instr));
   if (IsBranch(instr)) {
     int32_t imm18 = target_pos - (pos + kBranchPCOffset);
     DCHECK((imm18 & 3) == 0);
@@ -749,15 +740,7 @@ void Assembler::target_at_put(int32_t pos, int32_t target_pos,
     instr_at_put(pos + 1 * Assembler::kInstrSize,
                  instr_ori | (imm & kImm16Mask));
   } else {
-    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));
+    UNREACHABLE();
   }
 }
 
@@ -2418,21 +2401,6 @@ int Assembler::RelocateInternalReference(RelocInfo::Mode rmode, byte* pc,
       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;
@@ -2759,7 +2727,7 @@ void Assembler::set_target_address_at(Address pc,
 }
 
 
-void Assembler::JumpLabelToJumpRegister(Address pc) {
+void Assembler::JumpToJumpRegister(Address pc) {
   // Address pc points to lui/ori instructions.
   // Jump to label may follow at pc + 2 * kInstrSize.
   uint32_t* p = reinterpret_cast<uint32_t*>(pc);

src/mips/assembler-mips.h

@@ -531,7 +531,7 @@ class Assembler : public AssemblerBase {
   // Return the code target address of the patch debug break slot
   inline static Address break_address_from_return_address(Address pc);
 
-  static void JumpLabelToJumpRegister(Address pc);
+  static void JumpToJumpRegister(Address pc);
 
   static void QuietNaN(HeapObject* nan);
 

src/mips/macro-assembler-mips.cc

@@ -3092,24 +3092,6 @@ void MacroAssembler::Ret(Condition cond,
 }
 
 
-void MacroAssembler::J(Label* L, BranchDelaySlot bdslot) {
-  BlockTrampolinePoolScope block_trampoline_pool(this);
-
-  uint32_t imm28;
-  imm28 = jump_address(L);
-  imm28 &= kImm28Mask;
-  { 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);
-    j(imm28);
-  }
-  // Emit a nop in the branch delay slot if required.
-  if (bdslot == PROTECT)
-    nop();
-}
-
-
 void MacroAssembler::Jr(Label* L, BranchDelaySlot bdslot) {
   BlockTrampolinePoolScope block_trampoline_pool(this);
 

src/mips/macro-assembler-mips.h

@@ -1633,7 +1633,6 @@ const Operand& rt = Operand(zero_reg), BranchDelaySlot bd = PROTECT
   void BranchAndLinkShort(Label* L, Condition cond, Register rs,
                           const Operand& rt,
                           BranchDelaySlot bdslot = PROTECT);
-  void J(Label* L, BranchDelaySlot bdslot);
   void Jr(Label* L, BranchDelaySlot bdslot);
   void Jalr(Label* L, BranchDelaySlot bdslot);
 

src/mips64/assembler-mips64.cc

@@ -637,7 +637,7 @@ int Assembler::target_at(int pos, bool is_internal) {
      }
   }
   // Check we have a branch or jump instruction.
-  DCHECK(IsBranch(instr) || IsJ(instr) || IsLui(instr));
+  DCHECK(IsBranch(instr) || IsLui(instr));
   // Do NOT change this to <<2. We rely on arithmetic shifts here, assuming
   // the compiler uses arithmetic shifts for signed integers.
   if (IsBranch(instr)) {
@@ -673,17 +673,8 @@ int Assembler::target_at(int pos, bool is_internal) {
       return pos - delta;
     }
   } else {
-    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 {
-      uint64_t instr_address = reinterpret_cast<int64_t>(buffer_ + pos);
-      instr_address &= kImm28Mask;
-      int delta = static_cast<int>(instr_address - imm28);
-      DCHECK(pos > delta);
-      return pos - delta;
-    }
+    UNREACHABLE();
+    return 0;
   }
 }
 
@@ -703,7 +694,7 @@ void Assembler::target_at_put(int pos, int target_pos, bool is_internal) {
     return;
   }
 
-  DCHECK(IsBranch(instr) || IsJ(instr) || IsLui(instr));
+  DCHECK(IsBranch(instr) || IsLui(instr));
   if (IsBranch(instr)) {
     int32_t imm18 = target_pos - (pos + kBranchPCOffset);
     DCHECK((imm18 & 3) == 0);
@@ -734,15 +725,7 @@ void Assembler::target_at_put(int pos, int target_pos, bool is_internal) {
     instr_at_put(pos + 3 * Assembler::kInstrSize,
                  instr_ori2 | (imm & kImm16Mask));
   } else {
-    uint64_t imm28 = reinterpret_cast<uint64_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));
+    UNREACHABLE();
   }
 }
 
@@ -2596,7 +2579,6 @@ int Assembler::RelocateInternalReference(RelocInfo::Mode rmode, byte* pc,
   }
   Instr instr = instr_at(pc);
   DCHECK(RelocInfo::IsInternalReferenceEncoded(rmode));
-  DCHECK(IsJ(instr) || IsLui(instr));
   if (IsLui(instr)) {
     Instr instr_lui = instr_at(pc + 0 * Assembler::kInstrSize);
     Instr instr_ori = instr_at(pc + 1 * Assembler::kInstrSize);
@@ -2628,21 +2610,8 @@ int Assembler::RelocateInternalReference(RelocInfo::Mode rmode, byte* pc,
                  instr_ori2 | (imm & kImm16Mask));
     return 4;  // Number of instructions patched.
   } else {
-    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.
+    UNREACHABLE();
+    return 0;  // Number of instructions patched.
   }
 }
 
@@ -2916,40 +2885,6 @@ void Assembler::set_target_address_at(Address pc,
 }
 
 
-void Assembler::JumpLabelToJumpRegister(Address pc) {
-  // Address pc points to lui/ori instructions.
-  // Jump to label may follow at pc + 2 * kInstrSize.
-  uint32_t* p = reinterpret_cast<uint32_t*>(pc);
-#ifdef DEBUG
-  Instr instr1 = instr_at(pc);
-#endif
-  Instr instr2 = instr_at(pc + 1 * kInstrSize);
-  Instr instr3 = instr_at(pc + 6 * kInstrSize);
-  bool patched = false;
-
-  if (IsJal(instr3)) {
-    DCHECK(GetOpcodeField(instr1) == LUI);
-    DCHECK(GetOpcodeField(instr2) == ORI);
-
-    uint32_t rs_field = GetRt(instr2) << kRsShift;
-    uint32_t rd_field = ra.code() << kRdShift;  // Return-address (ra) reg.
-    *(p+6) = SPECIAL | rs_field | rd_field | JALR;
-    patched = true;
-  } else if (IsJ(instr3)) {
-    DCHECK(GetOpcodeField(instr1) == LUI);
-    DCHECK(GetOpcodeField(instr2) == ORI);
-
-    uint32_t rs_field = GetRt(instr2) << kRsShift;
-    *(p+6) = SPECIAL | rs_field | JR;
-    patched = true;
-  }
-
-  if (patched) {
-      CpuFeatures::FlushICache(pc+6, sizeof(int32_t));
-  }
-}
-
-
 Handle<ConstantPoolArray> Assembler::NewConstantPool(Isolate* isolate) {
   // No out-of-line constant pool support.
   DCHECK(!FLAG_enable_ool_constant_pool);

src/mips64/assembler-mips64.h

@@ -524,8 +524,6 @@ class Assembler : public AssemblerBase {
   // Return the code target address of the patch debug break slot
   inline static Address break_address_from_return_address(Address pc);
 
-  static void JumpLabelToJumpRegister(Address pc);
-
   static void QuietNaN(HeapObject* nan);
 
   // This sets the branch destination (which gets loaded at the call address).

src/mips64/macro-assembler-mips64.cc

@@ -3107,24 +3107,6 @@ void MacroAssembler::Ret(Condition cond,
 }
 
 
-void MacroAssembler::J(Label* L, BranchDelaySlot bdslot) {
-  BlockTrampolinePoolScope block_trampoline_pool(this);
-
-  uint64_t imm28;
-  imm28 = jump_address(L);
-  imm28 &= kImm28Mask;
-  { 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);
-    j(imm28);
-  }
-  // Emit a nop in the branch delay slot if required.
-  if (bdslot == PROTECT)
-    nop();
-}
-
-
 void MacroAssembler::Jr(Label* L, BranchDelaySlot bdslot) {
   BlockTrampolinePoolScope block_trampoline_pool(this);
 

src/mips64/macro-assembler-mips64.h

@@ -1702,7 +1702,6 @@ const Operand& rt = Operand(zero_reg), BranchDelaySlot bd = PROTECT
   void BranchAndLinkShort(Label* L, Condition cond, Register rs,
                           const Operand& rt,
                           BranchDelaySlot bdslot = PROTECT);
-  void J(Label* L, BranchDelaySlot bdslot);
   void Jr(Label* L, BranchDelaySlot bdslot);
   void Jalr(Label* L, BranchDelaySlot bdslot);