src/cpu/x86/vm/assembler_x86.cpp

*** 1110,1121 ****
    emit_int8((unsigned char)0xBC);
    emit_int8((unsigned char)(0xC0 | encode));
  }
  
  void Assembler::bsrl(Register dst, Register src) {
!   assert(!VM_Version::supports_lzcnt(), "encoding is treated as LZCNT");
    int encode = prefix_and_encode(dst->encoding(), src->encoding());
    emit_int8(0x0F);
    emit_int8((unsigned char)0xBD);
    emit_int8((unsigned char)(0xC0 | encode));
  }
  
--- 1110,1125 ----
    emit_int8((unsigned char)0xBC);
    emit_int8((unsigned char)(0xC0 | encode));
  }
  
  void Assembler::bsrl(Register dst, Register src) {
! #ifdef ASSERT
!   address prefix = pc();
! #endif
    int encode = prefix_and_encode(dst->encoding(), src->encoding());
+   // x86 oddity: bsr with a rep prefix (f3) is lzcnt when CPU supports it
+   assert(!VM_Version::supports_lzcnt() || pc() == prefix || *prefix != REP, "encoding is treated as LZCNT with REP prefix");
    emit_int8(0x0F);
    emit_int8((unsigned char)0xBD);
    emit_int8((unsigned char)(0xC0 | encode));
  }
  
*** 4975,4986 ****
    emit_int8((unsigned char)0xBC);
    emit_int8((unsigned char)(0xC0 | encode));
  }
  
  void Assembler::bsrq(Register dst, Register src) {
!   assert(!VM_Version::supports_lzcnt(), "encoding is treated as LZCNT");
    int encode = prefixq_and_encode(dst->encoding(), src->encoding());
    emit_int8(0x0F);
    emit_int8((unsigned char)0xBD);
    emit_int8((unsigned char)(0xC0 | encode));
  }
  
--- 4979,4994 ----
    emit_int8((unsigned char)0xBC);
    emit_int8((unsigned char)(0xC0 | encode));
  }
  
  void Assembler::bsrq(Register dst, Register src) {
! #ifdef ASSERT
!   address prefix = pc();
! #endif
    int encode = prefixq_and_encode(dst->encoding(), src->encoding());
+   // x86 oddity: bsr with a rep prefix (f3) is lzcnt when CPU supports it
+   assert(!VM_Version::supports_lzcnt() || pc() == prefix || *prefix != REP, "encoding is treated as LZCNT with REP prefix");
    emit_int8(0x0F);
    emit_int8((unsigned char)0xBD);
    emit_int8((unsigned char)(0xC0 | encode));
  }