On 02/24/2015 02:47 PM, Paul Sandoz wrote:
> On Feb 24, 2015, at 2:48 PM, Andrew Haley <a...@redhat.com> wrote:
>>> With that in mind is there any need to intrinsify the new methods
>>> at all given those new Java methods can defer to the older ones
>>> based on a constant check? Also should that anyway be done for the
>>> interpreter?
>>>
>>> public void putIntUnaligned(Object o, long offset, int x) { if
>>> (IS_UNALIGNED || (offset & 3) == 0) { putInt(o, offset, x); } else if
>>> (byteOrder == BIG_ENDIAN) { putIntB(o, offset, x); } else { putIntL(o,
>>> offset, x); } }
>>
>> Yes. It certainly could be done like this but I think C1 doesn't do
>> the optimization to remove the IS_UNALIGNED test, so we'd still want
>> the C1 builtins.
>
> Hmm.... if i run the following code on my Mac:
>
>
> public int x(int i) {
> if (X || (i & 3) == 0) {
> return i + i;
> }
> else {
> return Integer.sum(i, i);
> }
> }
> With the options:
>
> -XX:TieredStopAtLevel=1 -XX:+UnlockDiagnosticVMOptions -XX:+PrintAssembly
>
> Then Y.x is compiled to:
>
> 0x000000011155ea80: mov %eax,-0x14000(%rsp)
> 0x000000011155ea87: push %rbp
> 0x000000011155ea88: sub $0x30,%rsp ;*getstatic X
> ; - Y::x@0 (line 43)
>
> 0x000000011155ea8c: mov %rdx,%rax
> 0x000000011155ea8f: add %edx,%eax
> 0x000000011155ea91: add $0x30,%rsp
> 0x000000011155ea95: pop %rbp
> 0x000000011155ea96: test %eax,-0x62ca9c(%rip) # 0x0000000110f32000
> ; {poll_return}
> 0x000000011155ea9c: retq
Oh, right, better than I thought. I should know by now to check
before posting. But even so, we don't know that the method will
be inlined.
>>> If we expose the endianness query via a new method in unsafe we
>>> should reuse that in java.nio.Bits and get rid of the associated
>>> static code block.
>>
>> Sure, I already did that.
>>
>
> Locally i guess? (just in case i missed something in the current webrev).
Ah. I used the query but I forgot to get rid of the static code
block:
http://cr.openjdk.java.net/~aph/unaligned.jdk.1/src/java.base/share/classes/java/nio/Bits.java.cdiff.html
Andrew.
