RFR: 8271883: Math CopySign optimization for x86 [v2]

[Marcus G K Williams]

> Intrinsic for Math.copySign is disabled on x86_64.
> 
> We can improve on generated c2 instructions for float and double, and this change adds optimized intrinsics for float and double Math.copySign.
> 
> ### **Math.copySign(double)**
> _From:_
>   0x00007f7d606e5dac:   vmovq  %xmm1,%r10
>   0x00007f7d606e5db1:   vmovq  %xmm0,%r11
>   0x00007f7d606e5db6:   movabs $0x7fffffffffffffff,%r8
>   0x00007f7d606e5dc0:   and    %r8,%r11
>   0x00007f7d606e5dc3:   movabs $0x8000000000000000,%r8
>   0x00007f7d606e5dcd:   and    %r8,%r10
>   0x00007f7d606e5dd0:   or     %r11,%r10
>   0x00007f7d606e5dd3:   vmovq  %r10,%xmm0                   
> 
> _To:_
>   0x00007fc3c14c63ac:   movabs $0x7fffffffffffffff,%r10
>   0x00007fc3c14c63b6:   vmovq  %r10,%xmm2
>   0x00007fc3c14c63bb:   vpternlogq $0xe4,%xmm2,%xmm1,%xmm0
> 
> ### **Math.copySign(float)**
> _From:_
>   0x00007ff8886e60ac:   vmovd  %xmm1,%r11d
>   0x00007ff8886e60b1:   vmovd  %xmm0,%r10d
>   0x00007ff8886e60b6:   and    $0x80000000,%r11d
>   0x00007ff8886e60bd:   and    $0x7fffffff,%r10d
>   0x00007ff8886e60c4:   or     %r10d,%r11d
>   0x00007ff8886e60c7:   vmovd  %r11d,%xmm0
> _To:_
>   0x00007fc7d94c63ac:   mov    $0x7fffffff,%r10d
>   0x00007fc7d94c63b2:   vmovd  %r10d,%xmm3
>   0x00007fc7d94c63b7:   vpternlogd $0xe4,%xmm3,%xmm1,%xmm0
> 
> #### _**Performance of patch using updated test/micro/org/openjdk/bench/vm/compiler/Signum.java:**_
> #### **BEFORE**
> Signum._5_copySignFloatTest       avgt    5  2.442 ? 0.024  ns/op
> Signum._7_copySignDoubleTest      avgt    5  2.400 ? 0.033  ns/op
> 
> #### **PATCH**
> Signum._5_copySignFloatTest       avgt    5  2.029 ? 0.011  ns/op
> Signum._7_copySignDoubleTest      avgt    5  2.029 ? 0.024  ns/op
> 
> #### **JTREG that covers this case:**
> test/hotspot/jtreg/compiler/intrinsics/math/TestSignumIntrinsic.java
> 
> Signed-off-by: Marcus G K Williams <marcus.williams at intel.com>

Marcus G K Williams has updated the pull request incrementally with one additional commit since the last revision:

  Update x86.ad with #ifdef _LP64 for copySign

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5005/files
  - new: https://git.openjdk.java.net/jdk/pull/5005/files/724410ae..68eb2bc4

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5005&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5005&range=00-01

  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5005.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5005/head:pull/5005

PR: https://git.openjdk.java.net/jdk/pull/5005