[15] RFR (L): 7175279: Don't use x87 FPU on x86-64

[Vladimir Kozlov]

Good 

Thanks
Vladimir

> On Dec 19, 2019, at 1:58 PM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:
> 
> 
>>>> Make ConversionStub x86_32-specific only if possible. From what I see it is only LIR_OpConvert in c1_LIR.hpp we have to deal with. I actually can't see how it could be only 32-specific. Hmm?
>>> 
>>> I experimented with it, but it requires #ifdefs in c1_LIR.cpp/hpp which I don't like. So, I don't consider it as an  > option right now.
>> Okay, NOT_IA32( ShouldNotReachHere() ) with comment in c1_CodeStubs.hpp should be enough for now.
> 
> Incremental diff:
>  http://cr.openjdk.java.net/~vlivanov/7175279/webrev.01-00/
> 
> Best regards,
> Vladimir Ivanov
> 
>>>>>> c1_LinearScan.cpp - I think IA64 is used for Itanium. For 64-bit x86 we use AMD64:
>>>>>> 
>>>>>> https://hg.openjdk.java.net/jdk/jdk/file/cfaa2457a60a/src/hotspot/share/utilities/macros.hpp#l456 
>>>>> 
>>>>> 
>>>>> 
>>>>> Yes, you are right. Good catch! :-)
>>>>> 
>>>>> Best regards,
>>>>> Vladimir Ivanov
>>>>> 
>>>>>> On 12/17/19 4:50 AM, Vladimir Ivanov wrote:
>>>>>>> http://cr.openjdk.java.net/~vlivanov/7175279/webrev.00/
>>>>>>> https://bugs.openjdk.java.net/browse/JDK-7175279
>>>>>>> 
>>>>>>> There was a major rewrite of math intrinsics which in 9 time frame which almost completely eliminated x87 code in x86-64 code base.
>>>>>>> 
>>>>>>> Proposed patch removes the rest and makes x86-64 code x87-free.
>>>>>>> 
>>>>>>> The main motivation for the patch is to completely eliminate non-strictfp behaving code in order to prepare the JVM for JEP 306 [1] and related enhancements [2].
>>>>>>> 
>>>>>>> Most of the changes are in C1, but there is one case in template interpreter (java_lang_math_abs) which now uses StubRoutines::x86::double_sign_mask(). It forces its initialization to be moved to StubRoutines::initialize1().
>>>>>>> 
>>>>>>> x87 instructions are made available only on x86-32.
>>>>>>> 
>>>>>>> C1 changes involve removing FPU support on x86-64 and effectively make x86-specific support in linear scan allocator [2] x86-32-only.
>>>>>>> 
>>>>>>> Testing: tier1-6, build on x86-23, linux-aarch64, linux-arm32.
>>>>>>> 
>>>>>>> Best regards,
>>>>>>> Vladimir Ivanov
>>>>>>> 
>>>>>>> [1] https://bugs.openjdk.java.net/browse/JDK-8175916
>>>>>>> 
>>>>>>> [2] https://bugs.openjdk.java.net/browse/JDK-8136414
>>>>>>> 
>>>>>>> [3] http://hg.openjdk.java.net/jdk/jdk/file/ff7cd49f2aef/src/hotspot/cpu/x86/c1_LinearScan_x86.cpp