ARM: Merge redundant entries in literal pool.

src/arm/assembler-arm.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 499 matching lines @@
 const Instr kLdrStrInstrTypeMask = 0xffff0000;
 const Instr kLdrStrInstrArgumentMask = 0x0000ffff;
 const Instr kLdrStrOffsetMask = 0x00000fff;
 
 
 Assembler::Assembler(Isolate* isolate, void* buffer, int buffer_size)
     : AssemblerBase(isolate, buffer, buffer_size),
       recorded_ast_id_(TypeFeedbackId::None()),
       positions_recorder_(this) {
   reloc_info_writer.Reposition(buffer_ + buffer_size_, pc_);
-  num_pending_reloc_info_ = 0;
+  num_pending_32_bit_reloc_info_ = 0;
   num_pending_64_bit_reloc_info_ = 0;
   next_buffer_check_ = 0;
   const_pool_blocked_nesting_ = 0;
   no_const_pool_before_ = 0;
-  first_const_pool_use_ = -1;
+  first_const_pool_32_use_ = -1;
+  first_const_pool_64_use_ = -1;
   last_bound_pos_ = 0;
   ClearRecordedAstId();
 }
 
 
 Assembler::~Assembler() {
   ASSERT(const_pool_blocked_nesting_ == 0);
 }
 
 
 void Assembler::GetCode(CodeDesc* desc) {
   // Emit constant pool if necessary.
   CheckConstPool(true, false);
-  ASSERT(num_pending_reloc_info_ == 0);
+  ASSERT(num_pending_32_bit_reloc_info_ == 0);
   ASSERT(num_pending_64_bit_reloc_info_ == 0);
 
   // Set up code descriptor.
   desc->buffer = buffer_;
   desc->buffer_size = buffer_size_;
   desc->instr_size = pc_offset();
   desc->reloc_size = (buffer_ + buffer_size_) - reloc_info_writer.pos();
 }
 
 
@@ skipping 2592 matching lines @@
   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);
 
   // None of our relocation types are pc relative pointing outside the code
   // buffer nor pc absolute pointing inside the code buffer, so there is no need
   // to relocate any emitted relocation entries.
 
   // Relocate pending relocation entries.
-  for (int i = 0; i < num_pending_reloc_info_; i++) {
-    RelocInfo& rinfo = pending_reloc_info_[i];
+  for (int i = 0; i < num_pending_32_bit_reloc_info_; i++) {
+    RelocInfo& rinfo = pending_32_bit_reloc_info_[i];
     ASSERT(rinfo.rmode() != RelocInfo::COMMENT &&
            rinfo.rmode() != RelocInfo::POSITION);
     if (rinfo.rmode() != RelocInfo::JS_RETURN) {
       rinfo.set_pc(rinfo.pc() + pc_delta);
     }
   }
+  for (int i = 0; i < num_pending_64_bit_reloc_info_; i++) {
+    RelocInfo& rinfo = pending_64_bit_reloc_info_[i];
+    ASSERT(rinfo.rmode() == RelocInfo::NONE64);
+    rinfo.set_pc(rinfo.pc() + pc_delta);
+  }
 }
 
 
 void Assembler::db(uint8_t data) {
   // No relocation info should be pending while using db. db is used
   // to write pure data with no pointers and the constant pool should
   // be emitted before using db.
-  ASSERT(num_pending_reloc_info_ == 0);
+  ASSERT(num_pending_32_bit_reloc_info_ == 0);
   ASSERT(num_pending_64_bit_reloc_info_ == 0);
   CheckBuffer();
   *reinterpret_cast<uint8_t*>(pc_) = data;
   pc_ += sizeof(uint8_t);
 }
 
 
 void Assembler::dd(uint32_t data) {
   // No relocation info should be pending while using dd. dd is used
   // to write pure data with no pointers and the constant pool should
   // be emitted before using dd.
-  ASSERT(num_pending_reloc_info_ == 0);
+  ASSERT(num_pending_32_bit_reloc_info_ == 0);
   ASSERT(num_pending_64_bit_reloc_info_ == 0);
   CheckBuffer();
   *reinterpret_cast<uint32_t*>(pc_) = data;
   pc_ += sizeof(uint32_t);
 }
 
 
 void Assembler::emit_code_stub_address(Code* stub) {
   CheckBuffer();
   *reinterpret_cast<uint32_t*>(pc_) =
@@ skipping 49 matching lines @@
 
 
 void Assembler::RecordRelocInfo(double data) {
   // We do not try to reuse pool constants.
   RelocInfo rinfo(pc_, data);
   RecordRelocInfoConstantPoolEntryHelper(rinfo);
 }
 
 
 void Assembler::RecordRelocInfoConstantPoolEntryHelper(const RelocInfo& rinfo) {
-  ASSERT(num_pending_reloc_info_ < kMaxNumPendingRelocInfo);
-  if (num_pending_reloc_info_ == 0) {
-    first_const_pool_use_ = pc_offset();
+  if (rinfo.rmode() == RelocInfo::NONE64) {
+    ASSERT(num_pending_64_bit_reloc_info_ < kMaxNumPending64RelocInfo);
+    if (num_pending_64_bit_reloc_info_ == 0) {
+      first_const_pool_64_use_ = pc_offset();
+    }
+    pending_64_bit_reloc_info_[num_pending_64_bit_reloc_info_++] = rinfo;
+  } else {
+    ASSERT(num_pending_32_bit_reloc_info_ < kMaxNumPending32RelocInfo);
+    if (num_pending_32_bit_reloc_info_ == 0) {
+      first_const_pool_32_use_ = pc_offset();
+    }
+    pending_32_bit_reloc_info_[num_pending_32_bit_reloc_info_++] = rinfo;
   }
-  pending_reloc_info_[num_pending_reloc_info_++] = rinfo;
-  if (rinfo.rmode() == RelocInfo::NONE64) {
-    ++num_pending_64_bit_reloc_info_;
-  }
-  ASSERT(num_pending_64_bit_reloc_info_ <= num_pending_reloc_info_);
   // Make sure the constant pool is not emitted in place of the next
   // instruction for which we just recorded relocation info.
   BlockConstPoolFor(1);
 }
 
 
 void Assembler::BlockConstPoolFor(int instructions) {
   int pc_limit = pc_offset() + instructions * kInstrSize;
   if (no_const_pool_before_ < pc_limit) {
-    // If there are some pending entries, the constant pool cannot be blocked
-    // further than constant pool instruction's reach.
-    ASSERT((num_pending_reloc_info_ == 0) ||
-           (pc_limit - first_const_pool_use_ < kMaxDistToIntPool));
-    // TODO(jfb) Also check 64-bit entries are in range (requires splitting
-    //           them up from 32-bit entries).
+    // Max pool start (if we need a jump and an alignment).
+#ifdef DEBUG
+    int start = pc_limit + kInstrSize + 2 * kPointerSize;
+    ASSERT((num_pending_32_bit_reloc_info_ == 0) ||
+           (start - first_const_pool_32_use_ +
+            num_pending_64_bit_reloc_info_ * kDoubleSize < kMaxDistToIntPool));
+    ASSERT((num_pending_64_bit_reloc_info_ == 0) ||
+           (start - first_const_pool_64_use_ < kMaxDistToFPPool));
+#endif
     no_const_pool_before_ = pc_limit;
   }
 
   if (next_buffer_check_ < no_const_pool_before_) {
     next_buffer_check_ = no_const_pool_before_;
   }
 }
 
 
 void Assembler::CheckConstPool(bool force_emit, bool require_jump) {
   // Some short sequence of instruction mustn't be broken up by constant pool
   // emission, such sequences are protected by calls to BlockConstPoolFor and
   // BlockConstPoolScope.
   if (is_const_pool_blocked()) {
     // Something is wrong if emission is forced and blocked at the same time.
     ASSERT(!force_emit);
     return;
   }
 
   // There is nothing to do if there are no pending constant pool entries.
-  if (num_pending_reloc_info_ == 0)  {
-    ASSERT(num_pending_64_bit_reloc_info_ == 0);
+  if ((num_pending_32_bit_reloc_info_ == 0) &&
+      (num_pending_64_bit_reloc_info_ == 0)) {
     // Calculate the offset of the next check.
     next_buffer_check_ = pc_offset() + kCheckPoolInterval;
     return;
   }
 
   // Check that the code buffer is large enough before emitting the constant
   // pool (include the jump over the pool and the constant pool marker and
   // the gap to the relocation information).
-  // Note 64-bit values are wider, and the first one needs to be 64-bit aligned.
   int jump_instr = require_jump ? kInstrSize : 0;
   int size_up_to_marker = jump_instr + kInstrSize;
-  int size_after_marker = num_pending_reloc_info_ * kPointerSize;
+  int size_after_marker = num_pending_32_bit_reloc_info_ * kPointerSize;
   bool has_fp_values = (num_pending_64_bit_reloc_info_ > 0);
-  // 64-bit values must be 64-bit aligned.
-  // We'll start emitting at PC: branch+marker, then 32-bit values, then
-  // 64-bit values which might need to be aligned.
-  bool require_64_bit_align = has_fp_values &&
-      (((uintptr_t)pc_ + size_up_to_marker + size_after_marker) & 0x3);
-  if (require_64_bit_align) {
-    size_after_marker += kInstrSize;
+  bool require_64_bit_align = false;
+  if (has_fp_values) {
+    require_64_bit_align = (((uintptr_t)pc_ + size_up_to_marker) & 0x3);

[Benedikt Meurer, 2013/11/15 08:47:01]

Checking for 64 bit alignment should use & 0x7.

[Rodolph Perfetta, 2013/11/15 11:04:26]

Done.

+    if (require_64_bit_align) {
+      size_after_marker += kInstrSize;
+    }
+    size_after_marker += num_pending_64_bit_reloc_info_ * kDoubleSize;
   }
-  // num_pending_reloc_info_ also contains 64-bit entries, the above code
-  // therefore already counted half of the size for 64-bit entries. Add the
-  // remaining size.
-  STATIC_ASSERT(kPointerSize == kDoubleSize / 2);
-  size_after_marker += num_pending_64_bit_reloc_info_ * (kDoubleSize / 2);
 
   int size = size_up_to_marker + size_after_marker;
 
   // We emit a constant pool when:
   //  * requested to do so by parameter force_emit (e.g. after each function).
   //  * the distance from the first instruction accessing the constant pool to
   //    any of the constant pool entries will exceed its limit the next
   //    time the pool is checked. This is overly restrictive, but we don't emit
   //    constant pool entries in-order so it's conservatively correct.
   //  * the instruction doesn't require a jump after itself to jump over the
   //    constant pool, and we're getting close to running out of range.
   if (!force_emit) {
-    ASSERT((first_const_pool_use_ >= 0) && (num_pending_reloc_info_ > 0));
-    int dist = pc_offset() + size - first_const_pool_use_;
+    ASSERT((first_const_pool_32_use_ >= 0) || (first_const_pool_64_use_ >= 0));
+    bool need_emit = false;
     if (has_fp_values) {
-      if ((dist < kMaxDistToFPPool - kCheckPoolInterval) &&
-          (require_jump || (dist < kMaxDistToFPPool / 2))) {
-        return;
-      }
-    } else {
-      if ((dist < kMaxDistToIntPool - kCheckPoolInterval) &&
-          (require_jump || (dist < kMaxDistToIntPool / 2))) {
-        return;
+      int dist64 = pc_offset() +
+                   size -
+                   num_pending_32_bit_reloc_info_ * kPointerSize -
+                   first_const_pool_64_use_;
+      if ((dist64 >= kMaxDistToFPPool - kCheckPoolInterval) ||
+          (!require_jump && (dist64 >= kMaxDistToFPPool / 2))) {
+        need_emit = true;
       }
     }
+    int dist32 =
+      pc_offset() + size - first_const_pool_32_use_;
+    if ((dist32 >= kMaxDistToIntPool - kCheckPoolInterval) ||
+        (!require_jump && (dist32 >= kMaxDistToIntPool / 2))) {
+      need_emit = true;
+    }
+    if (!need_emit) return;
   }
 
   int needed_space = size + kGap;
   while (buffer_space() <= needed_space) GrowBuffer();
 
   {
     // Block recursive calls to CheckConstPool.
     BlockConstPoolScope block_const_pool(this);
     RecordComment("[ Constant Pool");
     RecordConstPool(size);
 
     // Emit jump over constant pool if necessary.
     Label after_pool;
     if (require_jump) {
       b(&after_pool);
     }
 
     // Put down constant pool marker "Undefined instruction".
     // The data size helps disassembly know what to print.
     emit(kConstantPoolMarker |
          EncodeConstantPoolLength(size_after_marker / kPointerSize));
 
     if (require_64_bit_align) {
       emit(kConstantPoolMarker);
     }
 
     // Emit 64-bit constant pool entries first: their range is smaller than
     // 32-bit entries.
-    for (int i = 0; i < num_pending_reloc_info_; i++) {
-      RelocInfo& rinfo = pending_reloc_info_[i];
-
-      if (rinfo.rmode() != RelocInfo::NONE64) {
-        // 32-bit values emitted later.
-        continue;
-      }
+    for (int i = 0; i < num_pending_64_bit_reloc_info_; i++) {
+      RelocInfo& rinfo = pending_64_bit_reloc_info_[i];
 
       ASSERT(!((uintptr_t)pc_ & 0x3));  // Check 64-bit alignment.
 
       Instr instr = instr_at(rinfo.pc());
       // Instruction to patch must be 'vldr rd, [pc, #offset]' with offset == 0.
       ASSERT((IsVldrDPcImmediateOffset(instr) &&
               GetVldrDRegisterImmediateOffset(instr) == 0));
 
       int delta = pc_ - rinfo.pc() - kPcLoadDelta;
       ASSERT(is_uint10(delta));
 
+      bool found = false;
+      uint64_t value = rinfo.raw_data64();
+      for (int j = 0; j < i; j++) {
+        RelocInfo& rinfo2 = pending_64_bit_reloc_info_[j];
+        if (value == rinfo2.raw_data64()) {
+          found = true;
+          ASSERT(rinfo2.rmode() == RelocInfo::NONE64);
+          Instr instr2 = instr_at(rinfo2.pc());
+          ASSERT(IsVldrDPcImmediateOffset(instr2));
+          delta = GetVldrDRegisterImmediateOffset(instr2);
+          delta += rinfo2.pc() - rinfo.pc();
+          break;
+        }
+      }
+
       instr_at_put(rinfo.pc(), SetVldrDRegisterImmediateOffset(instr, delta));
 
-      const double double_data = rinfo.data64();
-      uint64_t uint_data = 0;
-      OS::MemCopy(&uint_data, &double_data, sizeof(double_data));
-      emit(uint_data & 0xFFFFFFFF);
-      emit(uint_data >> 32);
+      if (!found) {
+        const double double_data = rinfo.data64();
+        uint64_t uint_data = 0;
+        memcpy(&uint_data, &double_data, sizeof(double_data));

[Benedikt Meurer, 2013/11/15 08:47:01]

How about using BitCast here?

[Rodolph Perfetta, 2013/11/15 11:04:26]

We don't even need Bitcast, raw_data64 already does it. Updated.

On 2013/11/15 08:47:01, Benedikt Meurer wrote:

+        emit(uint_data & 0xFFFFFFFF);
+        emit(uint_data >> 32);
+      }
     }
 
     // Emit 32-bit constant pool entries.
-    for (int i = 0; i < num_pending_reloc_info_; i++) {
-      RelocInfo& rinfo = pending_reloc_info_[i];
+    for (int i = 0; i < num_pending_32_bit_reloc_info_; i++) {
+      RelocInfo& rinfo = pending_32_bit_reloc_info_[i];
       ASSERT(rinfo.rmode() != RelocInfo::COMMENT &&
              rinfo.rmode() != RelocInfo::POSITION &&
              rinfo.rmode() != RelocInfo::STATEMENT_POSITION &&
-             rinfo.rmode() != RelocInfo::CONST_POOL);
-
-      if (rinfo.rmode() == RelocInfo::NONE64) {
-        // 64-bit values emitted earlier.
-        continue;
-      }
+             rinfo.rmode() != RelocInfo::CONST_POOL &&
+             rinfo.rmode() != RelocInfo::NONE64);
 
       Instr instr = instr_at(rinfo.pc());
 
       // 64-bit loads shouldn't get here.
       ASSERT(!IsVldrDPcImmediateOffset(instr));
 
-      int delta = pc_ - rinfo.pc() - kPcLoadDelta;
-      // 0 is the smallest delta:
-      //   ldr rd, [pc, #0]
-      //   constant pool marker
-      //   data
-
       if (IsLdrPcImmediateOffset(instr) &&
           GetLdrRegisterImmediateOffset(instr) == 0) {
+        int delta = pc_ - rinfo.pc() - kPcLoadDelta;
         ASSERT(is_uint12(delta));
+        // 0 is the smallest delta:
+        //   ldr rd, [pc, #0]
+        //   constant pool marker
+        //   data
+
+        bool found = false;
+        if (!Serializer::enabled() && (rinfo.rmode() >= RelocInfo::CELL)) {
+          for (int j = 0; j < i; j++) {
+            RelocInfo& rinfo2 = pending_32_bit_reloc_info_[j];
+
+            if ((rinfo2.data() == rinfo.data()) &&
+                (rinfo2.rmode() == rinfo.rmode())) {
+              Instr instr2 = instr_at(rinfo2.pc());
+              if (IsLdrPcImmediateOffset(instr2)) {
+                delta = GetLdrRegisterImmediateOffset(instr2);
+                delta += rinfo2.pc() - rinfo.pc();
+                found = true;
+                break;
+              }
+            }
+          }
+        }
+
         instr_at_put(rinfo.pc(), SetLdrRegisterImmediateOffset(instr, delta));
-        emit(rinfo.data());
+
+        if (!found) {
+          emit(rinfo.data());
+        }
       } else {
         ASSERT(IsMovW(instr));
-        emit(rinfo.data());
       }
     }
 
-    num_pending_reloc_info_ = 0;
+    num_pending_32_bit_reloc_info_ = 0;
     num_pending_64_bit_reloc_info_ = 0;
-    first_const_pool_use_ = -1;
+    first_const_pool_32_use_ = -1;
+    first_const_pool_64_use_ = -1;
 
     RecordComment("]");
 
     if (after_pool.is_linked()) {
       bind(&after_pool);
     }
   }
 
   // Since a constant pool was just emitted, move the check offset forward by
   // the standard interval.
   next_buffer_check_ = pc_offset() + kCheckPoolInterval;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM