Revert r8309 "ARM: Clean up literal pool generation." because of crashes.

src/arm/assembler-arm.cc

Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index ec28da400255ddac296032c684ab17e8b87b25ff..8bd1b9ba05c6522a61170478bc3399da72cd820d 100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -324,11 +324,11 @@ Assembler::Assembler(Isolate* arg_isolate, void* buffer, int buffer_size)
   ASSERT(buffer_ != NULL);
   pc_ = buffer_;
   reloc_info_writer.Reposition(buffer_ + buffer_size, pc_);
-  num_pending_reloc_info_ = 0;
+  num_prinfo_ = 0;
   next_buffer_check_ = 0;
   const_pool_blocked_nesting_ = 0;
   no_const_pool_before_ = 0;
-  first_const_pool_use_ = -1;
+  last_const_pool_end_ = 0;
   last_bound_pos_ = 0;
   ClearRecordedAstId();
 }
@@ -350,7 +350,7 @@ Assembler::~Assembler() {
 void Assembler::GetCode(CodeDesc* desc) {
   // Emit constant pool if necessary.
   CheckConstPool(true, false);
-  ASSERT(num_pending_reloc_info_ == 0);
+  ASSERT(num_prinfo_ == 0);
 
   // Set up code descriptor.
   desc->buffer = buffer_;
@@ -877,7 +877,7 @@ void Assembler::addrmod1(Instr instr,
   emit(instr | rn.code()*B16 | rd.code()*B12);
   if (rn.is(pc) || x.rm_.is(pc)) {
     // Block constant pool emission for one instruction after reading pc.
-    BlockConstPoolFor(1);
+    BlockConstPoolBefore(pc_offset() + kInstrSize);
   }
 }
 
@@ -1001,7 +1001,7 @@ int Assembler::branch_offset(Label* L, bool jump_elimination_allowed) {
 
   // Block the emission of the constant pool, since the branch instruction must
   // be emitted at the pc offset recorded by the label.
-  BlockConstPoolFor(1);
+  BlockConstPoolBefore(pc_offset() + kInstrSize);
   return target_pos - (pc_offset() + kPcLoadDelta);
 }
 
@@ -1497,17 +1497,15 @@ void Assembler::stm(BlockAddrMode am,
 void Assembler::stop(const char* msg, Condition cond, int32_t code) {
 #ifndef __arm__
   ASSERT(code >= kDefaultStopCode);
-  {
-    // The Simulator will handle the stop instruction and get the message
-    // address. It expects to find the address just after the svc instruction.
-    BlockConstPoolScope block_const_pool(this);
-    if (code >= 0) {
-      svc(kStopCode + code, cond);
-    } else {
-      svc(kStopCode + kMaxStopCode, cond);
-    }
-    emit(reinterpret_cast<Instr>(msg));
+  // The Simulator will handle the stop instruction and get the message address.
+  // It expects to find the address just after the svc instruction.
+  BlockConstPoolFor(2);
+  if (code >= 0) {
+    svc(kStopCode + code, cond);
+  } else {
+    svc(kStopCode + kMaxStopCode, cond);
   }
+  emit(reinterpret_cast<Instr>(msg));
 #else  // def __arm__
 #ifdef CAN_USE_ARMV5_INSTRUCTIONS
   if (cond != al) {
@@ -2412,6 +2410,11 @@ bool Assembler::ImmediateFitsAddrMode1Instruction(int32_t imm32) {
 }
 
 
+void Assembler::BlockConstPoolFor(int instructions) {
+  BlockConstPoolBefore(pc_offset() + instructions * kInstrSize);
+}
+
+
 // Debugging.
 void Assembler::RecordJSReturn() {
   positions_recorder()->WriteRecordedPositions();
@@ -2475,8 +2478,8 @@ void Assembler::GrowBuffer() {
   // 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_prinfo_; i++) {
+    RelocInfo& rinfo = prinfo_[i];
     ASSERT(rinfo.rmode() != RelocInfo::COMMENT &&
            rinfo.rmode() != RelocInfo::POSITION);
     if (rinfo.rmode() != RelocInfo::JS_RETURN) {
@@ -2490,7 +2493,7 @@ 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_prinfo_ == 0);
   CheckBuffer();
   *reinterpret_cast<uint8_t*>(pc_) = data;
   pc_ += sizeof(uint8_t);
@@ -2501,7 +2504,7 @@ 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_prinfo_ == 0);
   CheckBuffer();
   *reinterpret_cast<uint32_t*>(pc_) = data;
   pc_ += sizeof(uint32_t);
@@ -2519,14 +2522,11 @@ void Assembler::RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data) {
            || RelocInfo::IsPosition(rmode));
     // These modes do not need an entry in the constant pool.
   } else {
-    ASSERT(num_pending_reloc_info_ < kMaxNumPendingRelocInfo);
-    if (num_pending_reloc_info_ == 0) {
-      first_const_pool_use_ = pc_offset();
-    }
-    pending_reloc_info_[num_pending_reloc_info_++] = rinfo;
+    ASSERT(num_prinfo_ < kMaxNumPRInfo);
+    prinfo_[num_prinfo_++] = rinfo;
     // Make sure the constant pool is not emitted in place of the next
     // instruction for which we just recorded relocation info.
-    BlockConstPoolFor(1);
+    BlockConstPoolBefore(pc_offset() + kInstrSize);
   }
   if (rinfo.rmode() != RelocInfo::NONE) {
     // Don't record external references unless the heap will be serialized.
@@ -2552,112 +2552,111 @@ void Assembler::RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data) {
 }
 
 
-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 first_const_pool_use_ + kMaxDistToPool
-    ASSERT((num_pending_reloc_info_ == 0) ||
-           (pc_limit < (first_const_pool_use_ + kMaxDistToPool)));
-    no_const_pool_before_ = pc_limit;
+void Assembler::CheckConstPool(bool force_emit, bool require_jump) {
+  // Calculate the offset of the next check. It will be overwritten
+  // when a const pool is generated or when const pools are being
+  // blocked for a specific range.
+  next_buffer_check_ = pc_offset() + kCheckConstInterval;
+
+  // There is nothing to do if there are no pending relocation info entries.
+  if (num_prinfo_ == 0) return;
+
+  // We emit a constant pool at regular intervals of about kDistBetweenPools
+  // or when requested by parameter force_emit (e.g. after each function).
+  // We prefer not to emit a jump unless the max distance is reached or if we
+  // are running low on slots, which can happen if a lot of constants are being
+  // emitted (e.g. --debug-code and many static references).
+  int dist = pc_offset() - last_const_pool_end_;
+  if (!force_emit && dist < kMaxDistBetweenPools &&
+      (require_jump || dist < kDistBetweenPools) &&
+      // TODO(1236125): Cleanup the "magic" number below. We know that
+      // the code generation will test every kCheckConstIntervalInst.
+      // Thus we are safe as long as we generate less than 7 constant
+      // entries per instruction.
+      (num_prinfo_ < (kMaxNumPRInfo - (7 * kCheckConstIntervalInst)))) {
+    return;
   }
 
-  if (next_buffer_check_ < no_const_pool_before_) {
-    next_buffer_check_ = no_const_pool_before_;
-  }
-}
+  // If we did not return by now, we need to emit the constant pool soon.
 
+  // However, some small sequences of instructions must not be broken up by the
+  // insertion of a constant pool; such sequences are protected by setting
+  // either const_pool_blocked_nesting_ or no_const_pool_before_, which are
+  // both checked here. Also, recursive calls to CheckConstPool are blocked by
+  // no_const_pool_before_.
+  if (const_pool_blocked_nesting_ > 0 || pc_offset() < no_const_pool_before_) {
+    // Emission is currently blocked; make sure we try again as soon as
+    // possible.
+    if (const_pool_blocked_nesting_ > 0) {
+      next_buffer_check_ = pc_offset() + kInstrSize;
+    } else {
+      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)  {
-    // Calculate the offset of the next check.
-    next_buffer_check_ = pc_offset() + kCheckPoolInterval;
-    return;
-  }
-
-  // We emit a constant pool when:
-  //  * requested to do so by parameter force_emit (e.g. after each function).
-  //  * the distance to the first instruction accessing the constant pool is
-  //    kAvgDistToPool or more.
-  //  * no jump is required and the distance to the first instruction accessing
-  //    the constant pool is at least kMaxDistToPool / 2.
-  ASSERT(first_const_pool_use_ >= 0);
-  int dist = pc_offset() - first_const_pool_use_;
-  if (!force_emit && dist < kAvgDistToPool &&
-      (require_jump || (dist < (kMaxDistToPool / 2)))) {
-    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).
   int jump_instr = require_jump ? kInstrSize : 0;
-  int needed_space = jump_instr + kInstrSize +
-                     num_pending_reloc_info_ * kInstrSize + kGap;
-  while (buffer_space() <= needed_space) GrowBuffer();
-
-  {
-    // Block recursive calls to CheckConstPool.
-    BlockConstPoolScope block_const_pool(this);
-
-    // Emit jump over constant pool if necessary.
-    Label after_pool;
-    if (require_jump) {
-      b(&after_pool);
-    }
 
-    RecordComment("[ Constant Pool");
-
-    // Put down constant pool marker "Undefined instruction" as specified by
-    // A5.6 (ARMv7) Instruction set encoding.
-    emit(kConstantPoolMarker | num_pending_reloc_info_);
-
-    // Emit constant pool entries.
-    for (int i = 0; i < num_pending_reloc_info_; i++) {
-      RelocInfo& rinfo = pending_reloc_info_[i];
-      ASSERT(rinfo.rmode() != RelocInfo::COMMENT &&
-             rinfo.rmode() != RelocInfo::POSITION &&
-             rinfo.rmode() != RelocInfo::STATEMENT_POSITION);
-
-      Instr instr = instr_at(rinfo.pc());
-      // Instruction to patch must be 'ldr rd, [pc, #offset]' with offset == 0.
-      ASSERT(IsLdrPcImmediateOffset(instr) &&
-             GetLdrRegisterImmediateOffset(instr) == 0);
-
-      int delta = pc_ - rinfo.pc() - kPcLoadDelta;
-      // 0 is the smallest delta:
-      //   ldr rd, [pc, #0]
-      //   constant pool marker
-      //   data
-      ASSERT(is_uint12(delta));
-
-      instr_at_put(rinfo.pc(), SetLdrRegisterImmediateOffset(instr, delta));
-      emit(rinfo.data());
+  // Check that the code buffer is large enough before emitting the constant
+  // pool and relocation information (include the jump over the pool and the
+  // constant pool marker).
+  int max_needed_space =
+      jump_instr + kInstrSize + num_prinfo_*(kInstrSize + kMaxRelocSize);
+  while (buffer_space() <= (max_needed_space + kGap)) GrowBuffer();
+
+  // Block recursive calls to CheckConstPool.
+  BlockConstPoolBefore(pc_offset() + jump_instr + kInstrSize +
+                       num_prinfo_*kInstrSize);
+  // Don't bother to check for the emit calls below.
+  next_buffer_check_ = no_const_pool_before_;
+
+  // Emit jump over constant pool if necessary.
+  Label after_pool;
+  if (require_jump) b(&after_pool);
+
+  RecordComment("[ Constant Pool");
+
+  // Put down constant pool marker "Undefined instruction" as specified by
+  // A5.6 (ARMv7) Instruction set encoding.
+  emit(kConstantPoolMarker | num_prinfo_);
+
+  // Emit constant pool entries.
+  for (int i = 0; i < num_prinfo_; i++) {
+    RelocInfo& rinfo = prinfo_[i];
+    ASSERT(rinfo.rmode() != RelocInfo::COMMENT &&
+           rinfo.rmode() != RelocInfo::POSITION &&
+           rinfo.rmode() != RelocInfo::STATEMENT_POSITION);
+    Instr instr = instr_at(rinfo.pc());
+
+    // Instruction to patch must be a ldr/str [pc, #offset].
+    // P and U set, B and W clear, Rn == pc, offset12 still 0.
+    ASSERT((instr & (7*B25 | P | U | B | W | 15*B16 | kOff12Mask)) ==
+           (2*B25 | P | U | pc.code()*B16));
+    int delta = pc_ - rinfo.pc() - 8;
+    ASSERT(delta >= -4);  // instr could be ldr pc, [pc, #-4] followed by targ32
+    if (delta < 0) {
+      instr &= ~U;
+      delta = -delta;
     }
+    ASSERT(is_uint12(delta));
+    instr_at_put(rinfo.pc(), instr + delta);
+    emit(rinfo.data());
+  }
+  num_prinfo_ = 0;
+  last_const_pool_end_ = pc_offset();
 
-    num_pending_reloc_info_ = 0;
-    first_const_pool_use_ = -1;
-
-    RecordComment("]");
+  RecordComment("]");
 
-    if (after_pool.is_linked()) {
-      bind(&after_pool);
-    }
+  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;
+  next_buffer_check_ = pc_offset() + kCheckConstInterval;
 }