src/cpu/aarch64/vm/stubGenerator_aarch64.cpp

rev 10076 : 8149080: AArch64: Recoginize disjoint array copy in stub code
Summary: Detect array copy not overlapping by checking (dest-src) above_same (copy_size)
Reviewed-by: duke

*** 789,798 ****
--- 789,804 ----
  
      assert_different_registers(rscratch1, t0, t1, t2, t3, t4, t5, t6, t7);
      assert_different_registers(s, d, count, rscratch1);
  
      Label again, large, small;
+     const char *stub_name;
+     if (direction == copy_forwards)
+       stub_name = "foward_copy_longs";
+     else
+       stub_name = "backward_copy_longs";
+     StubCodeMark mark(this, "StubRoutines", stub_name);
      __ align(6);
      __ bind(start);
      __ cmp(count, 8);
      __ br(Assembler::LO, small);
      if (direction == copy_forwards) {
*** 1149,1160 ****
      if (entry != NULL) {
        *entry = __ pc();
        // caller can pass a 64-bit byte count here (from Unsafe.copyMemory)
        BLOCK_COMMENT("Entry:");
      }
!     __ cmp(d, s);
!     __ br(Assembler::LS, nooverlap_target);
  
      if (is_oop) {
        __ push(RegSet::of(d, count), sp);
        // no registers are destroyed by this call
        gen_write_ref_array_pre_barrier(d, count, dest_uninitialized);
--- 1155,1169 ----
      if (entry != NULL) {
        *entry = __ pc();
        // caller can pass a 64-bit byte count here (from Unsafe.copyMemory)
        BLOCK_COMMENT("Entry:");
      }
! 
!     // no overlap when (d-s) above_equal (count*size)
!     __ sub(rscratch1, d, s);
!     __ cmp(rscratch1, count, Assembler::LSL, exact_log2(size));
!     __ br(Assembler::HS, nooverlap_target);
  
      if (is_oop) {
        __ push(RegSet::of(d, count), sp);
        // no registers are destroyed by this call
        gen_write_ref_array_pre_barrier(d, count, dest_uninitialized);