src/cpu/x86/vm/templateTable_x86_64.cpp

rev 5510 : 8027252: Crash in interpreter because get_unsigned_2_byte_index_at_bcp reads 4 bytes
Summary: Use 2-byte loads to load indexes from the byte code stream to avoid out of bounds reads.
Reviewed-by:

*** 566,576 ****
    locals_index(rbx);
    __ movptr(rax, aaddress(rbx));
  }
  
  void TemplateTable::locals_index_wide(Register reg) {
!   __ movl(reg, at_bcp(2));
    __ bswapl(reg);
    __ shrl(reg, 16);
    __ negptr(reg);
  }
  
--- 566,576 ----
    locals_index(rbx);
    __ movptr(rax, aaddress(rbx));
  }
  
  void TemplateTable::locals_index_wide(Register reg) {
!   __ load_unsigned_short(reg, at_bcp(2));
    __ bswapl(reg);
    __ shrl(reg, 16);
    __ negptr(reg);
  }
  
*** 1573,1583 ****
--- 1573,1587 ----
                               InvocationCounter::counter_offset();
    const ByteSize inv_offset = MethodCounters::invocation_counter_offset() +
                                InvocationCounter::counter_offset();
  
    // Load up edx with the branch displacement
+   if (is_wide) {
      __ movl(rdx, at_bcp(1));
+   } else {
+     __ load_signed_short(rdx, at_bcp(1));
+   }
    __ bswapl(rdx);
  
    if (!is_wide) {
      __ sarl(rdx, 16);
    }