c1_MacroAssembler_aarch32.cpp

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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// This file is a derivative work resulting from (and including) modifications
// made by Azul Systems, Inc.  The dates of such changes are 2013-2016.
// Copyright 2013-2016 Azul Systems, Inc.  All Rights Reserved.
//
// Please contact Azul Systems, 385 Moffett Park Drive, Suite 115, Sunnyvale,
// CA 94089 USA or visit www.azul.com if you need additional information or
// have any questions.

#include "precompiled.hpp"
#include "c1/c1_MacroAssembler.hpp"
#include "c1/c1_Runtime1.hpp"
#include "classfile/systemDictionary.hpp"
#include "gc_interface/collectedHeap.hpp"
#include "interpreter/interpreter.hpp"
#include "oops/arrayOop.hpp"
#include "oops/markOop.hpp"
#include "runtime/basicLock.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/os.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/stubRoutines.hpp"

void C1_MacroAssembler::float_cmp(bool is_float, int unordered_result,
                                  FloatRegister f0, FloatRegister f1,
                                  Register result)
{
  Label done;
  if (is_float) {
    vcmp_f32(f0, f1);
  } else {
    vcmp_f64(f0, f1);
  }

  get_fpsr();

  mov(result, 0);
  if (unordered_result < 0) {
    // we want -1 for unordered or less than, 0 for equal and 1 for
    // greater than.
    mov(result, 1, NE); // Not equal or unordered
    neg(result, result, LT);  // Less than or unordered
  } else {
    // we want -1 for less than, 0 for equal and 1 for unordered or
    // greater than.
    mov(result, 1, NE); // Not equal or unordered
    neg(result, result, LO);  // Less than
  }
}

int C1_MacroAssembler::lock_object(Register hdr, Register obj, Register disp_hdr, Register scratch, Label& slow_case) {
  const int aligned_mask = BytesPerWord -1;
  const int hdr_offset = oopDesc::mark_offset_in_bytes();
  assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
  Label done, fail;
  int null_check_offset = -1;

  verify_oop(obj);

  // save object being locked into the BasicObjectLock
  str(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));

  if (UseBiasedLocking) {
    assert(scratch != noreg, "should have scratch register at this point");
    null_check_offset = biased_locking_enter(disp_hdr, obj, hdr, scratch, false, done, &slow_case);
  } else {
    null_check_offset = offset();
  }

  // Load object header
  ldr(hdr, Address(obj, hdr_offset));
  // and mark it as unlocked
  orr(hdr, hdr, markOopDesc::unlocked_value);
  // save unlocked object header into the displaced header location on the stack
  str(hdr, Address(disp_hdr, 0));
  // test if object header is still the same (i.e. unlocked), and if so, store the
  // displaced header address in the object header - if it is not the same, get the
  // object header instead
  lea(rscratch2, Address(obj, hdr_offset));
  cmpxchgptr(hdr, disp_hdr, rscratch2, rscratch1, done, /*fallthough*/NULL);
  // if the object header was the same, we're done
  // if the object header was not the same, it is now in the hdr register
  // => test if it is a stack pointer into the same stack (recursive locking), i.e.:
  //
  // 1) (hdr & aligned_mask) == 0
  // 2) sp <= hdr
  // 3) hdr <= sp + page_size
  //
  // these 3 tests can be done by evaluating the following expression:
  //
  // (hdr - sp) & (aligned_mask - page_size)
  //
  // assuming both the stack pointer and page_size have their least
  // significant 2 bits cleared and page_size is a power of 2
  mov(rscratch1, sp);
  sub(hdr, hdr, rscratch1);
  mov(rscratch2, aligned_mask - os::vm_page_size());
  ands(hdr, hdr, rscratch2);
  // for recursive locking, the result is zero => save it in the displaced header
  // location (NULL in the displaced hdr location indicates recursive locking)
  str(hdr, Address(disp_hdr, 0));
  // otherwise we don't care about the result and handle locking via runtime call
  cbnz(hdr, slow_case);
  // done
  bind(done);
  if (PrintBiasedLockingStatistics) {
    lea(rscratch2, ExternalAddress((address)BiasedLocking::fast_path_entry_count_addr()));
    addmw(Address(rscratch2, 0), 1, rscratch1);
  }
  return null_check_offset;
}


void C1_MacroAssembler::unlock_object(Register hdr, Register obj, Register disp_hdr, Label& slow_case) {
  const int aligned_mask = BytesPerWord -1;
  const int hdr_offset = oopDesc::mark_offset_in_bytes();
  assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
  Label done;

  if (UseBiasedLocking) {
    // load object
    ldr(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));
    biased_locking_exit(obj, hdr, done);
  }

  // load displaced header
  ldr(hdr, Address(disp_hdr, 0));
  // if the loaded hdr is NULL we had recursive locking
  // if we had recursive locking, we are done
  cbz(hdr, done);
  if (!UseBiasedLocking) {
    // load object
    ldr(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));
  }
  verify_oop(obj);
  // test if object header is pointing to the displaced header, and if so, restore
  // the displaced header in the object - if the object header is not pointing to
  // the displaced header, get the object header instead
  // if the object header was not pointing to the displaced header,
  // we do unlocking via runtime call
  if (hdr_offset) {
    lea(rscratch1, Address(obj, hdr_offset));
    cmpxchgptr(disp_hdr, hdr, rscratch1, rscratch2, done, &slow_case);
  } else {
    cmpxchgptr(disp_hdr, hdr, obj, rscratch2, done, &slow_case);
  }
  // done
  bind(done);
}


// Defines obj, preserves var_size_in_bytes
void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
  if (UseTLAB) {
    tlab_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
  } else {
    eden_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, slow_case);
    incr_allocated_bytes(noreg, var_size_in_bytes, con_size_in_bytes, t1);
  }
}

void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
  assert_different_registers(obj, klass, len);
  if (UseBiasedLocking && !len->is_valid()) {
    assert_different_registers(obj, klass, len, t1, t2);
    ldr(t1, Address(klass, Klass::prototype_header_offset()));
  } else {
    // This assumes that all prototype bits fit in an int32_t
    mov(t1, (int32_t)(intptr_t)markOopDesc::prototype());
  }
  str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
  str(klass, Address(obj, oopDesc::klass_offset_in_bytes()));

  if (len->is_valid()) {
    str(len, Address(obj, arrayOopDesc::length_offset_in_bytes()));
  }
}

// Zero words; len is in bytes
// Destroys all registers except addr
// len must be a nonzero multiple of wordSize
void C1_MacroAssembler::zero_memory(Register addr, Register len, Register t1) {
  assert_different_registers(addr, len, t1, rscratch1, rscratch2);

#ifdef ASSERT
  { Label L;
    tst(len, BytesPerWord - 1);
    b(L, Assembler::EQ);
    stop("len is not a multiple of BytesPerWord");
    bind(L);
  }
#endif

#ifndef PRODUCT
  block_comment("zero memory");
#endif

  Label loop;
  Label entry;

//  Algorithm:
//
//    scratch1 = cnt & 7;
//    cnt -= scratch1;
//    p += scratch1;
//    switch (scratch1) {
//      do {
//        cnt -= 8;
//          p[-8] = 0;
//        case 7:
//          p[-7] = 0;
//        case 6:
//          p[-6] = 0;
//          // ...
//        case 1:
//          p[-1] = 0;
//        case 0:
//          p += 8;
//      } while (cnt);
//    }

  const int unroll = 8; // Number of str instructions we'll unroll

  lsr(len, len, LogBytesPerWord);
  andr(rscratch1, len, unroll - 1);  // tmp1 = cnt % unroll
  sub(len, len, rscratch1);      // cnt -= unroll
  // t1 always points to the end of the region we're about to zero
  add(t1, addr, rscratch1, lsl(LogBytesPerWord));
  adr(rscratch2, entry);
  sub(rscratch2, rscratch2, rscratch1, lsl(2));
  mov(rscratch1, 0);
  b(rscratch2);
  bind(loop);
  sub(len, len, unroll);
  for (int i = -unroll; i < 0; i++)
    str(rscratch1, Address(t1, i * wordSize));
  bind(entry);
  add(t1, t1, unroll * wordSize);
  cbnz(len, loop);
}

// preserves obj, destroys len_in_bytes
void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1) {
  Label done;
  assert(obj != len_in_bytes && obj != t1 && t1 != len_in_bytes, "registers must be different");
  assert((hdr_size_in_bytes & (BytesPerWord - 1)) == 0, "header size is not a multiple of BytesPerWord");
  Register index = len_in_bytes;
  // index is positive and ptr sized
  subs(index, index, hdr_size_in_bytes);
  b(done, Assembler::EQ);
  // note: for the remaining code to work, index must be a multiple of BytesPerWord
#ifdef ASSERT
  { Label L;
    tst(index, BytesPerWord - 1);
    b(L, Assembler::EQ);
    stop("index is not a multiple of BytesPerWord");
    bind(L);
  }
#endif

  // Preserve obj
  if (hdr_size_in_bytes)
    add(obj, obj, hdr_size_in_bytes);
  zero_memory(obj, index, t1);
  if (hdr_size_in_bytes)
    sub(obj, obj, hdr_size_in_bytes);

  // done
  bind(done);
}


void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
  assert_different_registers(obj, t1, t2); // XXX really?
  assert(header_size >= 0 && object_size >= header_size, "illegal sizes");

  try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);

  initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2);
}

// This method clobbers t1, t2, and rscratch1 registers.
void C1_MacroAssembler::initialize_object(Register obj, Register klass,
                                          Register var_size_in_bytes,
                                          int con_size_in_bytes,
                                          Register t1, Register t2) {
  assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
         "con_size_in_bytes is not multiple of alignment");

  const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;

  initialize_header(obj, klass, noreg, t1, t2);

  // Null out rest of allocated space
  const Register index = t2;
  const int threshold = 8 * BytesPerWord;
  if (var_size_in_bytes != noreg) {
    mov(index, var_size_in_bytes);
    initialize_body(obj, index, hdr_size_in_bytes, t1);
  } else if (con_size_in_bytes <= threshold) {
    // Emit required number of str instructions (unroll loop completely)
    mov(t1, 0);
    for (int i = hdr_size_in_bytes; i < con_size_in_bytes; i += BytesPerWord) {
      str(t1, Address(obj, i));
    }
  } else if (con_size_in_bytes > hdr_size_in_bytes) {
    // Use loop to null out fields
    int words = (con_size_in_bytes - hdr_size_in_bytes) / BytesPerWord;
    mov(t1, 0);

    const int unroll = 4; // Number of str instructions we'll unroll
    mov(index, words / unroll);
    int remainder = words % unroll;
    lea(rscratch1, Address(obj, hdr_size_in_bytes + remainder * BytesPerWord));

    Label entry_point, loop;
    b(entry_point);
    bind(loop);
    sub(index, index, 1);
    for (int i = -unroll; i < 0; i++) {
      if (-i == remainder) {
        bind(entry_point);
      }
      str(t1, Address(rscratch1, i * BytesPerWord));
    }
    if (remainder == 0) {
      bind(entry_point);
    }
    add(rscratch1, rscratch1, unroll * BytesPerWord);
    cbnz(index, loop);
  }

  membar(StoreStore);

  if (CURRENT_ENV->dtrace_alloc_probes()) {
    assert(obj == r0, "must be");
    far_call(RuntimeAddress(Runtime1::entry_for(
             Runtime1::dtrace_object_alloc_id)));
  }

  verify_oop(obj);
}

void C1_MacroAssembler::allocate_array(Register obj, Register len, Register t1, Register t2, int header_size, int f, Register klass, Label& slow_case) {
  assert_different_registers(obj, len, t1, t2, klass);

  // determine alignment mask
  assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");

  // check for negative or excessive length
  mov(rscratch1, (int32_t)max_array_allocation_length);
  cmp(len, rscratch1);
  b(slow_case, Assembler::HS);

  const Register arr_size = t2; // okay to be the same
  // align object end
  mov(arr_size, (int32_t)header_size * BytesPerWord + MinObjAlignmentInBytesMask);
  add(arr_size, arr_size, len, Assembler::lsl(f));
  mov(t1, ~MinObjAlignmentInBytesMask);
  andr(arr_size, arr_size, t1);

  try_allocate(obj, arr_size, 0, t1, t2, slow_case);

  initialize_header(obj, klass, len, t1, t2);

  // clear rest of allocated space
  const Register len_zero = len;
  initialize_body(obj, arr_size, header_size * BytesPerWord, len_zero);

  membar(StoreStore);

  if (CURRENT_ENV->dtrace_alloc_probes()) {
    assert(obj == r0, "must be");
    far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
  }

  verify_oop(obj);
}


void C1_MacroAssembler::inline_cache_check(Register receiver, Register iCache) {
  verify_oop(receiver);
  // explicit NULL check not needed since load from [klass_offset] causes a trap
  // check against inline cache
  assert(!MacroAssembler::needs_explicit_null_check(oopDesc::klass_offset_in_bytes()), "must add explicit null check");

  cmp_klass(receiver, iCache, rscratch1);
}

void C1_MacroAssembler::build_frame(int frame_size_in_bytes,
                                    int bang_size_in_bytes) {
  assert(bang_size_in_bytes >= frame_size_in_bytes,
         "stack bang size incorrect");

  // If we have to make this method not-entrant, we'll overwrite its first
  // instruction with a jump. For this action to be legal we must ensure that
  // this first instruction is a B, BL, NOP, BKPT, or SVC. Make it a NOP
  nop();

  // Make sure there is enough stack space for this method's activation
  generate_stack_overflow_check(bang_size_in_bytes);

  // Push lr, rfp, and optionally update rfp. rfp points to the first stack
  // word used by the new frame.
  stmdb(sp, RegSet::of(rfp, lr).bits());
  if (PreserveFramePointer) {
    add(rfp, sp, BytesPerWord);
  }

  // Create frame. frame_size_in_bytes always comes from
  // LIR_Assembler::initial_frame_size_in_bytes() method, and it already
  // takes into account two stack words spent on saving lr and rfp.
  decrement(sp, frame_size_in_bytes);
}

void C1_MacroAssembler::remove_frame(int frame_size_in_bytes) {
  // Remove frame. frame_size_in_bytes always comes from
  // LIR_Assembler::initial_frame_size_in_bytes() method, and it already
  // takes into account two stack words spent on saving lr and rfp.
  increment(sp, frame_size_in_bytes);

  // Pop rfp and lr
  ldmia(sp, RegSet::of(rfp, lr).bits());
}

void C1_MacroAssembler::verified_entry() {
}

void C1_MacroAssembler::patchable_load(Register reg, address addr) {
  nop();
  membar(Assembler::LoadLoad);
  far_load(reg, addr);
}

#ifndef PRODUCT

void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
  if (!VerifyOops) return;
  verify_oop_addr(Address(sp, stack_offset), "oop");
}

void C1_MacroAssembler::verify_not_null_oop(Register r) {
  if (!VerifyOops) return;
  Label not_null;
  cbnz(r, not_null);
  stop("non-null oop required");
  bind(not_null);
  verify_oop(r);
}

void C1_MacroAssembler::invalidate_registers(bool inv_r0, bool inv_r2, bool inv_r3) {
#ifdef ASSERT
  static int nn;
  if (inv_r0) mov(r0, 0xDEAD);
  if (inv_r2) mov(r2, nn++);
  if (inv_r3) mov(r3, 0xDEAD);
#endif
}
#endif // ifndef PRODUCT