4564 

  4565 void MacroAssembler::byte_arrays_equals(Register ary1, Register ary2,

  4566                                         Register result, Register tmp1)

  4567 {

  4568   Register cnt1 = rscratch1;

  4569   Register cnt2 = rscratch2;

  4570   Register tmp2 = rscratch2;

  4571 

  4572   Label SAME, DIFFER, NEXT, TAIL07, TAIL03, TAIL01;

  4573 

  4574   int length_offset  = arrayOopDesc::length_offset_in_bytes();

  4575   int base_offset    = arrayOopDesc::base_offset_in_bytes(T_BYTE);

  4576 

  4577   BLOCK_COMMENT("byte_arrays_equals  {");

  4578 

  4579     // different until proven equal

  4580     mov(result, false);

  4581 

  4582     // same array?

  4583     cmp(ary1, ary2);

  4584     br(Assembler::EQ, SAME);

  4585 

  4586     // ne if either null

  4587     cbz(ary1, DIFFER);

  4588     cbz(ary2, DIFFER);

  4589 

  4590     // lengths ne?

  4591     ldrw(cnt1, Address(ary1, length_offset));

  4592     ldrw(cnt2, Address(ary2, length_offset));

  4593     cmp(cnt1, cnt2);

  4594     br(Assembler::NE, DIFFER);

  4595 

  4596     lea(ary1, Address(ary1, base_offset));

  4597     lea(ary2, Address(ary2, base_offset));

  4598 

  4599     subs(cnt1, cnt1, 8);

  4600     br(LT, TAIL07);

  4601 

  4602   BIND(NEXT);

  4603     ldr(tmp1, Address(post(ary1, 8)));

  4604     ldr(tmp2, Address(post(ary2, 8)));

  4605     subs(cnt1, cnt1, 8);

  4606     eor(tmp1, tmp1, tmp2);

  4607     cbnz(tmp1, DIFFER);

  4608     br(GE, NEXT);

  4609 

  4610   BIND(TAIL07);  // 0-7 bytes left, cnt1 = #bytes left - 4

  4611     tst(cnt1, 0b100);

  4612     br(EQ, TAIL03);

  4613     ldrw(tmp1, Address(post(ary1, 4)));

  4614     ldrw(tmp2, Address(post(ary2, 4)));

  4615     cmp(tmp1, tmp2);

  4616     br(NE, DIFFER);

  4617 

  4618   BIND(TAIL03);  // 0-3 bytes left, cnt1 = #bytes left - 4

  4619     tst(cnt1, 0b10);

  4620     br(EQ, TAIL01);

  4621     ldrh(tmp1, Address(post(ary1, 2)));

  4622     ldrh(tmp2, Address(post(ary2, 2)));

  4623     cmp(tmp1, tmp2);

  4624     br(NE, DIFFER);

  4625   BIND(TAIL01);  // 0-1 byte left

  4626     tst(cnt1, 0b01);

  4627     br(EQ, SAME);

  4628     ldrb(tmp1, ary1);

  4629     ldrb(tmp2, ary2);

  4630     cmp(tmp1, tmp2);

  4631     br(NE, DIFFER);

  4632 

  4633   BIND(SAME);

  4634     mov(result, true);

  4635   BIND(DIFFER); // result already set

  4636 

  4637   BLOCK_COMMENT("} byte_arrays_equals");

  4638 }

  4639