RFR: 8256215: Shenandoah: re-organize saving/restoring machine state in assembler code [v2]

[Zhengyu Gu]

On Wed, 27 Jan 2021 15:26:57 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> $ CONF=linux-x86-server-fastdebug make images run-test TEST=compiler/c1/Test6855215.java TEST_VM_OPTS="-XX:+UseShenandoahGC"
>> 
>> # Internal Error (/home/shade/trunks/jdk/src/hotspot/cpu/x86/assembler_x86.cpp:3047), pid=1427307, tid=1427311
>> # Error: assert(VM_Version::supports_sse2()) failed
>> 
>> V [libjvm.so+0x53f9e8] Assembler::movsd(Address, XMMRegisterImpl*)+0x168
>> V [libjvm.so+0x14647bd] save_xmm_registers(MacroAssembler*)+0x9d
>> V [libjvm.so+0x1465d8f] ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler*, RegisterImpl*, Address, ShenandoahBarrierSet::AccessKind)+0x91f
>> 
>> This only affects x86_32, as x86_64 uses at least UseSSE >= 2 at all times.
>> 
>> Additional testing:
>>  - [ ] `tier1`, Linux x86_64 `-XX:+UseShenandoahGC`
>>  - [ ] `tier1`, Linux x86_32 `-XX:+UseShenandoahGC`
>>  - [ ] `tier1`, Linux x86_32 `-XX:+UseShenandoahGC -XX:UseSSE=0`
>>  - [ ] `tier1`, Linux x86_32 `-XX:+UseShenandoahGC -XX:UseSSE=1`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Drop FP reg saves for arraycopy (current behavior)

Marked as reviewed by zgu (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/1172