src/cpu/x86/vm/stubGenerator_x86_32.cpp

rev 4534 : 8010927: Kitchensink crashed with SIGSEGV, Problematic frame: v ~StubRoutines::checkcast_arraycopy
Summary: Changed gen_write_ref_array_post_barrier() code on x64 to pass start address and number of copied oop elements. In generate_checkcast_copy() skip post barrier code if no elements are copied.
Reviewed-by: roland

*** 1532,1555 ****
  
      // It was a real error; we must depend on the caller to finish the job.
      // Register "count" = -1 * number of *remaining* oops, length_arg = *total* oops.
      // Emit GC store barriers for the oops we have copied (length_arg + count),
      // and report their number to the caller.
      __ addl(count, length_arg);         // transfers = (length - remaining)
      __ movl2ptr(rax, count);            // save the value
!     __ notptr(rax);                     // report (-1^K) to caller
!     __ movptr(to, to_arg);              // reload
!     assert_different_registers(to, count, rax);
!     gen_write_ref_array_post_barrier(to, count);
!     __ jmpb(L_done);
  
      // Come here on success only.
      __ BIND(L_do_card_marks);
      __ movl2ptr(count, length_arg);
      __ movptr(to, to_arg);                // reload
      gen_write_ref_array_post_barrier(to, count);
-     __ xorptr(rax, rax);                  // return 0 on success
  
      // Common exit point (success or failure).
      __ BIND(L_done);
      __ pop(rbx);
      __ pop(rdi);
--- 1532,1557 ----
  
      // It was a real error; we must depend on the caller to finish the job.
      // Register "count" = -1 * number of *remaining* oops, length_arg = *total* oops.
      // Emit GC store barriers for the oops we have copied (length_arg + count),
      // and report their number to the caller.
+     assert_different_registers(to, count, rax);
+     Label L_post_barrier;
      __ addl(count, length_arg);         // transfers = (length - remaining)
      __ movl2ptr(rax, count);            // save the value
!     __ notptr(rax);                     // report (-1^K) to caller (does not affect flags)
!     __ jccb(Assembler::notZero, L_post_barrier);
!     __ jmp(L_done); // K == 0, nothing was copied, skip post barrier
  
      // Come here on success only.
      __ BIND(L_do_card_marks);
+     __ xorptr(rax, rax);                // return 0 on success
      __ movl2ptr(count, length_arg);
+ 
+     __ BIND(L_post_barrier);
      __ movptr(to, to_arg);              // reload
      gen_write_ref_array_post_barrier(to, count);
  
      // Common exit point (success or failure).
      __ BIND(L_done);
      __ pop(rbx);
      __ pop(rdi);