Indeed, that's quite nice and not what I saw in java 7 so good to see that this case is EA'd out. Does anyone know if there was EA work done in java 9 or is this simply inlining policy change that makes EA work (as John alluded to)?
sent from my phone On Feb 18, 2015 6:13 AM, "Andrew Haley" <a...@redhat.com> wrote: > On 02/18/2015 09:15 AM, Andrew Haley wrote: > > On 18/02/15 09:14, Florian Weimer wrote: > >> Wow, looks nice. What OpenJDK build did you use? I want to see if this > >> happens on x86_64, too. > > > > I'm working on JDK9. You don't have this code yet. I'll do an x86 > > build. > > 0x00007f2948acbf8c: mov 0xc(%rdx),%r10d ;*synchronization entry > ; - > java.nio.HeapByteBuffer::<init>@-1 (line 84) > ; - > java.nio.ByteBuffer::wrap@7 (line 373) > ; - > java.nio.ByteBuffer::wrap@4 (line 396) > ; - > bytebuffertests.ByteBufferTests3::getLong@1 (line 23) > ; implicit exception: > dispatches to 0x00007f2948acbff5 > ;; B2: # B5 B3 <- B1 Freq: 0.999999 > > ;; MEMBAR-release ! (empty encoding) > > 0x00007f2948acbf90: test %ecx,%ecx > 0x00007f2948acbf92: jl 0x00007f2948acbfb5 ;*iflt > ; - > java.nio.Buffer::checkIndex@1 (line 545) > ; - > java.nio.HeapByteBuffer::getLong@18 (line 465) > ; - > bytebuffertests.ByteBufferTests3::getLong@5 (line 23) > > ;; B3: # B6 B4 <- B2 Freq: 0.999999 > > 0x00007f2948acbf94: mov %r10d,%ebp > 0x00007f2948acbf97: sub %ecx,%ebp ;*isub > ; - > java.nio.Buffer::checkIndex@10 (line 545) > ; - > java.nio.HeapByteBuffer::getLong@18 (line 465) > ; - > bytebuffertests.ByteBufferTests3::getLong@5 (line 23) > > 0x00007f2948acbf99: cmp $0x8,%ebp > 0x00007f2948acbf9c: jl 0x00007f2948acbfd5 ;*if_icmple > ; - > java.nio.Buffer::checkIndex@11 (line 545) > ; - > java.nio.HeapByteBuffer::getLong@18 (line 465) > ; - > bytebuffertests.ByteBufferTests3::getLong@5 (line 23) > > ;; B4: # N95 <- B3 Freq: 0.999998 > > 0x00007f2948acbf9e: movslq %ecx,%r10 > 0x00007f2948acbfa1: mov 0x10(%rdx,%r10,1),%rax > 0x00007f2948acbfa6: bswap %rax ;*invokestatic reverseBytes > ; - java.nio.Bits::swap@1 > (line 61) > ; - > java.nio.HeapByteBuffer::getLong@41 (line 466) > ; - > bytebuffertests.ByteBufferTests3::getLong@5 (line 23) > > So, just the same except that there is no explicit fence instruction > to remove. It's a shame for AArch64 because that fence really kills > performance but it's bad for x86 too. Even on machines that don't > emit fence instructions the fence still acts as a compiler barrier. > > Andrew. >
