[PATCH] 8217561 : X86: Add floating-point Math.min/max intrinsics

[Bhateja, Jatin]

Hi Blaser,

Please see my response embedder.

Best Regards,
Jatin

> -----Original Message-----
> From: B. Blaser [mailto:bsrbnd at gmail.com]
> Sent: Monday, February 4, 2019 8:01 PM
> To: Bhateja, Jatin <jatin.bhateja at intel.com>
> Cc: Viswanathan, Sandhya <sandhya.viswanathan at intel.com>; hotspot-
> compiler-dev at openjdk.java.net; Vladimir Kozlov
> <vladimir.kozlov at oracle.com>; Deshpande, Vivek R
> <vivek.r.deshpande at intel.com>
> Subject: Re: [PATCH] 8217561 : X86: Add floating-point Math.min/max
> intrinsics
> 
> Hi Jatin,
> 
> On Mon, 4 Feb 2019 at 13:53, Bhateja, Jatin <jatin.bhateja at intel.com>
> wrote:
> >
> > Hi Blaser,
> >
> > Please see response embedded in following mail.
> >
> > Best Regards,
> > Jatin
> >
> > > -----Original Message-----
> > > From: B. Blaser [mailto:bsrbnd at gmail.com]
> > > Sent: Monday, February 4, 2019 5:13 PM
> > >
> > > Yes, of course, but I meant:
> > >
> > > http://cr.openjdk.java.net/~sviswanathan/Jatin/8217561/webrev.01/tes
> > > t/ho
> > > tspot/jtreg/compiler/intrinsics/math/TestFpMinMaxIntrinsics.java.htm
> > > l
> > >
> > > I believe '-XX:CompileOnly=java/lang/Math' induce the compilation of
> > > 'Math.max()' but not its intrinsification which occurs when the call
> > > is inlined,
> > > see:
> > >
> > > http://hg.openjdk.java.net/jdk/jdk/rev/f15af1e2c683#l9.29
> > >
> >
> > I can see that if a method is a candidate for intrinsification (which
> > is decided during initialization as we create explicit vmSymbols for them)
> then during initial graph creation itself a specialized node is created for the
> call site (refer to processing of invoke* bytecodes done in Parse::do_call()).
> Thus intrinsification in this case will implicitly do the inlining.
> >
> > > http://hg.openjdk.java.net/jdk/jdk/file/d997c227e968/src/hotspot/sha
> > > re/op
> > > to/library_call.cpp#l6611
> > >
> > > But this would be good if someone knowledgeable in this area could
> > > confirm this?
> > An experienced hand could comment more on this.
> 
> I think this is what Nils meant here:
> 
> http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2019-
> January/032528.html
> 
> >>> Allow compilation of the methods in the test:
> >>>
> >>> "-
> XX:CompileCommand=compileonly,compiler.intrinsics.math.TestFpMinMaxI
> ntrinsics*"
> >>>
> >>> And add a loop in the main method, so the test case is run multiple
> >>> times
> 
> This is also what I observed in my example; you have to enable compilation
> of the caller '-XX:CompileOnly=MinMax::test' and run it multiple times to
> trigger inlining of the intrinsic (I'm not sure that
> 100 iterations as you added in 'TestFpMinMaxIntrinsics' are enough though).

@run is being passed -XX:-TieredCompilation -Xcomp, this should enable highest compilation level (C2).  But with no loop there is a chance of the method being interpreted till the time compilation thread emits the jit code, thus a loop of 100 will make sure  that successive invocation of method uses the jit code as soon as its available. 

BTW, we have taken care of your comment regarding spurious register copy before blend and next patch update will fix it. Thanks!!

> 
> Bernard