review request: add intrinsics to use AES instructions

Vladimir Kozlov vladimir.kozlov at
Thu Jul 19 16:06:55 PDT 2012

I will ask my colleagues to look on this changes.


Deneau, Tom wrote:
> The 32-bit stubs have been added, the new webrev is at
> The stubGenerator files were basically the only changes.
> While adding the 32-bit stubs, I noticed that the 64-bit stubs
> could be cleaned up quite a bit, I used symbolic names rather
> than raw names for registers, etc.
> -- Tom
> -----Original Message-----
> From: Vladimir Kozlov [mailto:vladimir.kozlov at] 
> Sent: Monday, July 16, 2012 6:14 PM
> To: Deneau, Tom
> Cc: hotspot-compiler-dev at
> Subject: Re: review request: add intrinsics to use AES instructions
> Deneau, Tom wrote:
>> Vladimir --
>> OK I see now that the stubroutines_x86_xxx are bitness-dependent.
>> And are you saying that you would prefer that the intrinsics actually
>> be supported on 32-bit, not just that it builds and runs without support on 32-bit?
> Yes, please, add the support on 32-bit (when AES is present). The stubs code 
> should be the same except incoming arguments.
> Vladimir
>> -- Tom
>> -----Original Message-----
>> From: Vladimir Kozlov [mailto:vladimir.kozlov at] 
>> Sent: Monday, July 16, 2012 2:08 PM
>> To: Deneau, Tom
>> Cc: hotspot-compiler-dev at
>> Subject: Re: review request: add intrinsics to use AES instructions
>> You can't execute 32bit VM with missing 32bit changes because flags are set but 
>> stubs are missing. And, yes, 32 bit VM is still used.
>> Vladimir
>> Deneau, Tom wrote:
>>> Vladimir --
>>> Right I didn't include 32-bit changes thinking that the majority
>>> of users of AES encryption/decryption would be 64-bit servers.
>>> But there is no technical reason why 32-bit couldn't be added.
>>> Do you feel 32-bit support is important?
>>> -- Tom
>>> -----Original Message-----
>>> From: Vladimir Kozlov [mailto:vladimir.kozlov at] 
>>> Sent: Monday, July 16, 2012 12:40 PM
>>> To: Deneau, Tom
>>> Cc: hotspot-compiler-dev at
>>> Subject: Re: review request: add intrinsics to use AES instructions
>>> Thank you, Tom
>>> I created next RFE and will sponsor changes. But I don't see 32 bit changes.
>>> 7184394: add intrinsics to use AES instructions
>>> Vladimir
>>> Deneau, Tom wrote:
>>>> Please review the following webrev which adds intrinsic support to
>>>> allow some of the com/sun/crypto/provider methods to use AES
>>>> instructions when a processor supports such instructions.
>>>> I do not have a bug number for this change but a description would be
>>>> something like the following:
>>>>    Modern x86 processors have AES instructions to accelerate AES
>>>>    encryption and decryption but Hotspot does not have a way to
>>>>    generate such instructions. There is a way to hook in a native
>>>>    crypto library using PKCS11 and there are a few native libraries
>>>>    that support hardware AES instructions. However, these native
>>>>    PKCS11 libraries
>>>>       * do not scale well with multiple threads
>>>>       * are not supported on all platforms, for instance Hotspot does
>>>>         not have PKCS11 support on 64-bit Windows.
>>>>       * can be confusing to configure. 
>>>> Since this webrev adds intrinsic support for the default
>>>> com/sun/crypto/provider classes, they are supported on all platforms
>>>> and there is no additional configuration required. Measurements have
>>>> shown that they scale very well will multiple threads.
>>>> The rest of this mail describes the scope of the intrinsics and
>>>> summarizes the source file changes.
>>>> -- Tom Deneau
>>>> Scope of the Intrinsics
>>>> -----------------------
>>>> When creating a cipher the application specifies a "transformation"
>>>> consisting of "algorithm/mode/padding". For more details see
>>>>    * These intrinsics kick in only when the algorithm part is "AES". A
>>>>      single block in AES is always 16 bytes and there are intrinsics
>>>>      for encrypting or decrypting a single block. These single-block
>>>>      intrinsics can work with any mode that uses AES and with any of
>>>>      the three AES key sizes (128, 192 or 256 bit).
>>>>    * A more optimized multi-block intrinsic can kick in if the
>>>>      algorithm/mode is "AES/CBC" (Cipher Block Chaining). Again all
>>>>      three AES key sizes are supported. There is no technical reason
>>>>      why we couldn't do multi-block intrinsics for the other modes
>>>>      (eg, ECB) but I want to get some feedback from the reviewers on
>>>>      the implementation before charging off on this path.
>>>>    * The padding part is handled by java routines outside of these
>>>>      intrinsics.
>>>> Summary of Changes
>>>> ------------------
>>>> src/cpu/x86/vm/assembler_x86.cpp, hpp
>>>>    Defined the aes instructions which are used by the stub routines.
>>>> src/cpu/x86/vm/stubGenerator_x86_64.cpp,
>>>>    Actual stub code for the aes intrinsics. As described earlier there
>>>>    are both single-block and multi-block intrinsic stubs.
>>>>    Note that the stubs make use of the "expanded key" which gets
>>>>    created each time the key changes. The expanded key is used by both
>>>>    the java code and the intrinsic AES instructions.
>>>>    The java code stores the "expanded key" in big-endian 32-bit
>>>>    integers. The x86 AES instructions require the expanded key to be
>>>>    in little-endian 128-bit words. Hence the pshufb instructions to
>>>>    get the key into the little-endian format
>>>> src/cpu/x86/vm/vm_version_x86.cpp, hpp
>>>>    Detect and store the aes capability bit in cpuid. A global boolean
>>>>    command line flag UseAES can be used to turn off AES even if the
>>>>    hardware supports it.
>>>> src/share/vm/classfile/vmSymbols.hpp
>>>> src/share/vm/opto/runtime.cpp, hpp
>>>>    The usual definitions of class names, method names and signatures
>>>>    for the java methods that are being intrinsified and the signatures
>>>>    for the stubs
>>>> src/share/vm/oops/methodOop.cpp
>>>>    Up until now, every intrinsic was replacing a routine that was
>>>>    loaded by the "default" (NULL) class  loader.
>>>>    com/sun/crypto/provider is not loaded by the default class
>>>>    loader so we had to add a check here.
>>>> src/share/vm/opto/escape.cpp
>>>>    escape analysis knows about certain stubs, but if it sees a leaf
>>>>    stub it also checks against a predefined list. So the new intrinsic
>>>>    names were added to the list.
>>>> src/share/vm/opto/library_call.cpp
>>>> src/share/vm/opto/callGenerator.cpp
>>>> src/share/vm/opto/doCall.cpp
>>>>    The main logic for building up the calls to the stubs at compile
>>>>    time, assuming the platform has a stub and the global flags have
>>>>    not turned these intrinsics off.
>>>>    A new helper routine to load a field from an object was added since
>>>>    we ended up loading fields in a few places.
>>>>    For best performance, we wanted to hook into the multi-block
>>>>    encrypt and decrypt methods such as in
>>>>    This code is not AES-specific but handles CBC mode for any
>>>>    algorithm. (The algorithm part is handled by the enclosed
>>>>    "embeddedCipher" object).
>>>>    Thus at runtime we want to do the equivalent of an instanceof check
>>>>    on embeddedCipher and either call the stub (if it is AESCrypt) or
>>>>    call the original java code (if it is some other algorithm
>>>>    type). For the CipherBlockChaining.decrypt there is a further
>>>>    runtime check that the source and destination are not the same
>>>>    array which, because of the way CBC works would require cloning the
>>>>    source (cipher).
>>>>    Vladimir added some infrastructure to generate predicated
>>>>    intrinsics to solve the above problem. A particular intrinsic need
>>>>    only specify that it is predicated, and generate the particular
>>>>    guard node which if false will take the Java path. This
>>>>    infrastructure can be used for future intrinsics that have to make
>>>>    such a runtime choice. These changes from Vladimir are in
>>>>    callGenerator.cpp, doCall.cpp, and a small bit in library_call.cpp.
>>>> src/share/vm/runtime/globals.hpp
>>>>    global flags were added to
>>>>       * turn off either AES encryption or AES decryption intrinsics separately
>>>>       * turn off the multi-block CBC/AES intrinsics. 
>>>>    By default all of the above are on. These are really there for
>>>>    testing, for example one could encrypt using Java and decrypt using
>>>>    the intrinsics.
>>>>    Also, a UseAES flag to ignore the hardware capability as described above.

More information about the hotspot-compiler-dev mailing list