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

[Vladimir Ivanov]

>>> 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 
>>>>>>