@Aleksey,
1. Why do you find it is a bug in tierred compilation machinery? It is not
on my eye. The compilation level is: C2, level 4
2. I have still a doubt: why profiling counter is not synchronized. What if
2 or more threads executing a function
simple()
Can you explain?
W dniu niedziela, 4 lutego 2018 00:31:28 UTC+1 użytkownik John Hening
napisał:
>
> public static int dontOptimize;
>
>
> public static int simple(){
> return dontOptimize;
> }
>
> And JITed version of that:
>
>
> 0x00007fdc75112aa0: mov %eax,-0x14000(%rsp)
> 0x00007fdc75112aa7: push %rbp
> 0x00007fdc75112aa8: sub $0x30,%rsp
> *0x00007fdc75112aac*: mov $0x7fdc7443be90,%rax ; {metadata(method
> data for {method} {0x00007fdc7443bb30} 'simple' '()I' in 'Main')}
> 0x00007fdc75112ab6: mov 0xdc(%rax),%esi
> 0x00007fdc75112abc: add $0x8,%esi
> 0x00007fdc75112abf: mov %esi,0xdc(%rax)
> 0x00007fdc75112ac5: mov $0x7fdc7443bb30,%rax ; {metadata({method}
> {0x00007fdc7443bb30} 'simple' '()I' in 'Main')}
> 0x00007fdc75112acf: and $0x1ff8,%esi
> 0x00007fdc75112ad5: cmp $0x0,%esi
> *0x00007fdc75112ad8*: je 0x00007fdc75112af7
> 0x00007fdc75112ade: mov $0x76d2414f0,%rax ; {oop(a
> 'java/lang/Class' = 'Main')}
> 0x00007fdc75112ae8: mov 0x68(%rax),%eax ;*getstatic dontOptimize
> ; - Main::simple@0 (line
> 11)
>
> 0x00007fdc75112aeb: add $0x30,%rsp
> 0x00007fdc75112aef: pop %rbp
> 0x00007fdc75112af0: test %eax,0x1861060a(%rip) #
> 0x00007fdc8d723100
> ; {poll_return}
> 0x00007fdc75112af6: retq
>
>
>
>
>
> Though I know assembly I cannot understand a such simple code. Especially,
> what does lines between 0x00007fdc75112aac-*0x00007fdc75112ad8* means? I
> highlighted it.
>
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