<分区>
我在 Mac OS X 上使用 Java 8 编译了一个简单的 Java 文件以进行汇编。这是 Test.java:
public class Test {
static volatile int a = 1;
public static void main(String[] args) {
a++;
}
}
我输出汇编代码使用:
java -server -Xcomp -XX:+UnlockDiagnosticVMOptions -XX:-Inline -XX:CompileCommand=print,*Test.main Test>Test.asm
这是 Test.asm 输出:
CompilerOracle: print *Test.main
Compiled method (c1) 1733 1750 3 Test::main (9 bytes)
total in heap [0x0000000111848650,0x0000000111848970] = 800
relocation [0x0000000111848778,0x00000001118487a0] = 40
main code [0x00000001118487a0,0x0000000111848860] = 192
stub code [0x0000000111848860,0x00000001118488f0] = 144
oops [0x00000001118488f0,0x00000001118488f8] = 8
metadata [0x00000001118488f8,0x0000000111848900] = 8
scopes data [0x0000000111848900,0x0000000111848918] = 24
scopes pcs [0x0000000111848918,0x0000000111848968] = 80
dependencies [0x0000000111848968,0x0000000111848970] = 8
Loaded disassembler from /Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/hsdis-amd64.dylib
Decoding compiled method 0x0000000111848650:
Code:
[Disassembling for mach='i386:x86-64']
[Entry Point]
[Verified Entry Point]
[Constants]
# {method} {0x000000010e40e240} 'main' '([Ljava/lang/String;)V' in 'Test'
# parm0: rsi:rsi = '[Ljava/lang/String;'
# [sp+0x40] (sp of caller)
0x00000001118487a0: mov %eax,-0x14000(%rsp)
0x00000001118487a7: push %rbp
0x00000001118487a8: sub $0x30,%rsp
0x00000001118487ac: movabs $0x10e40e4d0,%rdi ; {metadata(method data for {method} {0x000000010e40e240} 'main' '([Ljava/lang/String;)V' in 'Test')}
0x00000001118487b6: mov 0xdc(%rdi),%ebx
0x00000001118487bc: add $0x8,%ebx
0x00000001118487bf: mov %ebx,0xdc(%rdi)
0x00000001118487c5: movabs $0x10e40e240,%rdi ; {metadata({method} {0x000000010e40e240} 'main' '([Ljava/lang/String;)V' in 'Test')}
0x00000001118487cf: and $0x0,%ebx
0x00000001118487d2: cmp $0x0,%ebx
0x00000001118487d5: je 0x00000001118487fe
0x00000001118487db: movabs $0x7955fd1e8,%rsi ; {oop(a 'java/lang/Class' = 'Test')}
0x00000001118487e5: mov 0x68(%rsi),%edi ;*getstatic a
; - Test::main@0 (line 6)
0x00000001118487e8: inc %edi
0x00000001118487ea: mov %edi,0x68(%rsi)
0x00000001118487ed: lock addl $0x0,(%rsp) ;*putstatic a
; - Test::main@5 (line 6)
0x00000001118487f2: add $0x30,%rsp
0x00000001118487f6: pop %rbp
0x00000001118487f7: test %eax,-0x5f7f6fd(%rip) # 0x000000010b8c9100
; {poll_return}
0x00000001118487fd: retq
0x00000001118487fe: mov %rdi,0x8(%rsp)
0x0000000111848803: movq $0xffffffffffffffff,(%rsp)
0x000000011184880b: callq 0x0000000111543f60 ; OopMap{rsi=Oop off=112}
;*synchronization entry
; - Test::main@-1 (line 6)
; {runtime_call}
0x0000000111848810: jmp 0x00000001118487db
0x0000000111848812: nop
0x0000000111848813: nop
0x0000000111848814: mov 0x2a8(%r15),%rax
0x000000011184881b: movabs $0x0,%r10
0x0000000111848825: mov %r10,0x2a8(%r15)
0x000000011184882c: movabs $0x0,%r10
0x0000000111848836: mov %r10,0x2b0(%r15)
0x000000011184883d: add $0x30,%rsp
0x0000000111848841: pop %rbp
0x0000000111848842: jmpq 0x00000001114b24a0 ; {runtime_call}
0x0000000111848847: hlt
0x0000000111848848: hlt
0x0000000111848849: hlt
0x000000011184884a: hlt
0x000000011184884b: hlt
0x000000011184884c: hlt
0x000000011184884d: hlt
0x000000011184884e: hlt
0x000000011184884f: hlt
0x0000000111848850: hlt
0x0000000111848851: hlt
0x0000000111848852: hlt
0x0000000111848853: hlt
0x0000000111848854: hlt
0x0000000111848855: hlt
0x0000000111848856: hlt
0x0000000111848857: hlt
0x0000000111848858: hlt
0x0000000111848859: hlt
0x000000011184885a: hlt
0x000000011184885b: hlt
0x000000011184885c: hlt
0x000000011184885d: hlt
0x000000011184885e: hlt
0x000000011184885f: hlt
[Exception Handler]
[Stub Code]
0x0000000111848860: callq 0x00000001115418e0 ; {no_reloc}
0x0000000111848865: mov %rsp,-0x28(%rsp)
0x000000011184886a: sub $0x80,%rsp
0x0000000111848871: mov %rax,0x78(%rsp)
0x0000000111848876: mov %rcx,0x70(%rsp)
0x000000011184887b: mov %rdx,0x68(%rsp)
0x0000000111848880: mov %rbx,0x60(%rsp)
0x0000000111848885: mov %rbp,0x50(%rsp)
0x000000011184888a: mov %rsi,0x48(%rsp)
0x000000011184888f: mov %rdi,0x40(%rsp)
0x0000000111848894: mov %r8,0x38(%rsp)
0x0000000111848899: mov %r9,0x30(%rsp)
0x000000011184889e: mov %r10,0x28(%rsp)
0x00000001118488a3: mov %r11,0x20(%rsp)
0x00000001118488a8: mov %r12,0x18(%rsp)
0x00000001118488ad: mov %r13,0x10(%rsp)
0x00000001118488b2: mov %r14,0x8(%rsp)
0x00000001118488b7: mov %r15,(%rsp)
0x00000001118488bb: movabs $0x10c7d8060,%rdi ; {external_word}
0x00000001118488c5: movabs $0x111848865,%rsi ; {internal_word}
0x00000001118488cf: mov %rsp,%rdx
0x00000001118488d2: and $0xfffffffffffffff0,%rsp
0x00000001118488d6: callq 0x000000010c60361a ; {runtime_call}
0x00000001118488db: hlt
[Deopt Handler Code]
0x00000001118488dc: movabs $0x1118488dc,%r10 ; {section_word}
0x00000001118488e6: push %r10
0x00000001118488e8: jmpq 0x000000011148d3c0 ; {runtime_call}
0x00000001118488ed: hlt
0x00000001118488ee: hlt
0x00000001118488ef: hlt
OopMapSet contains 1 OopMaps
#0
OopMap{rsi=Oop off=112}
Compiled method (c1) 1747 1751 1 Test::main (9 bytes)
total in heap [0x0000000111847250,0x0000000111847518] = 712
relocation [0x0000000111847378,0x00000001118473a0] = 40
main code [0x00000001118473a0,0x0000000111847420] = 128
stub code [0x0000000111847420,0x00000001118474b0] = 144
oops [0x00000001118474b0,0x00000001118474b8] = 8
metadata [0x00000001118474b8,0x00000001118474c0] = 8
scopes data [0x00000001118474c0,0x00000001118474d0] = 16
scopes pcs [0x00000001118474d0,0x0000000111847510] = 64
dependencies [0x0000000111847510,0x0000000111847518] = 8
Decoding compiled method 0x0000000111847250:
Code:
[Entry Point]
[Verified Entry Point]
[Constants]
# {method} {0x000000010e40e240} 'main' '([Ljava/lang/String;)V' in 'Test'
# parm0: rsi:rsi = '[Ljava/lang/String;'
# [sp+0x40] (sp of caller)
0x00000001118473a0: mov %eax,-0x14000(%rsp)
0x00000001118473a7: push %rbp
0x00000001118473a8: sub $0x30,%rsp
0x00000001118473ac: movabs $0x7955fd1e8,%rsi ; {oop(a 'java/lang/Class' = 'Test')}
0x00000001118473b6: mov 0x68(%rsi),%edi ;*getstatic a
; - Test::main@0 (line 6)
0x00000001118473b9: inc %edi
0x00000001118473bb: mov %edi,0x68(%rsi)
0x00000001118473be: lock addl $0x0,(%rsp) ;*putstatic a
; - Test::main@5 (line 6)
0x00000001118473c3: add $0x30,%rsp
0x00000001118473c7: pop %rbp
0x00000001118473c8: test %eax,-0x5f7e2ce(%rip) # 0x000000010b8c9100
; {poll_return}
0x00000001118473ce: retq
0x00000001118473cf: nop
0x00000001118473d0: nop
0x00000001118473d1: mov 0x2a8(%r15),%rax
0x00000001118473d8: movabs $0x0,%r10
0x00000001118473e2: mov %r10,0x2a8(%r15)
0x00000001118473e9: movabs $0x0,%r10
0x00000001118473f3: mov %r10,0x2b0(%r15)
0x00000001118473fa: add $0x30,%rsp
0x00000001118473fe: pop %rbp
0x00000001118473ff: jmpq 0x00000001114b24a0 ; {runtime_call}
0x0000000111847404: hlt
0x0000000111847405: hlt
0x0000000111847406: hlt
0x0000000111847407: hlt
0x0000000111847408: hlt
0x0000000111847409: hlt
0x000000011184740a: hlt
0x000000011184740b: hlt
0x000000011184740c: hlt
0x000000011184740d: hlt
0x000000011184740e: hlt
0x000000011184740f: hlt
0x0000000111847410: hlt
0x0000000111847411: hlt
0x0000000111847412: hlt
0x0000000111847413: hlt
0x0000000111847414: hlt
0x0000000111847415: hlt
0x0000000111847416: hlt
0x0000000111847417: hlt
0x0000000111847418: hlt
0x0000000111847419: hlt
0x000000011184741a: hlt
0x000000011184741b: hlt
0x000000011184741c: hlt
0x000000011184741d: hlt
0x000000011184741e: hlt
0x000000011184741f: hlt
[Exception Handler]
[Stub Code]
0x0000000111847420: callq 0x00000001115418e0 ; {no_reloc}
0x0000000111847425: mov %rsp,-0x28(%rsp)
0x000000011184742a: sub $0x80,%rsp
0x0000000111847431: mov %rax,0x78(%rsp)
0x0000000111847436: mov %rcx,0x70(%rsp)
0x000000011184743b: mov %rdx,0x68(%rsp)
0x0000000111847440: mov %rbx,0x60(%rsp)
0x0000000111847445: mov %rbp,0x50(%rsp)
0x000000011184744a: mov %rsi,0x48(%rsp)
0x000000011184744f: mov %rdi,0x40(%rsp)
0x0000000111847454: mov %r8,0x38(%rsp)
0x0000000111847459: mov %r9,0x30(%rsp)
0x000000011184745e: mov %r10,0x28(%rsp)
0x0000000111847463: mov %r11,0x20(%rsp)
0x0000000111847468: mov %r12,0x18(%rsp)
0x000000011184746d: mov %r13,0x10(%rsp)
0x0000000111847472: mov %r14,0x8(%rsp)
0x0000000111847477: mov %r15,(%rsp)
0x000000011184747b: movabs $0x10c7d8060,%rdi ; {external_word}
0x0000000111847485: movabs $0x111847425,%rsi ; {internal_word}
0x000000011184748f: mov %rsp,%rdx
0x0000000111847492: and $0xfffffffffffffff0,%rsp
0x0000000111847496: callq 0x000000010c60361a ; {runtime_call}
0x000000011184749b: hlt
[Deopt Handler Code]
0x000000011184749c: movabs $0x11184749c,%r10 ; {section_word}
0x00000001118474a6: push %r10
0x00000001118474a8: jmpq 0x000000011148d3c0 ; {runtime_call}
0x00000001118474ad: hlt
0x00000001118474ae: hlt
0x00000001118474af: hlt
OopMapSet contains 0 OopMaps
问题是:为什么生成的汇编代码有两个主要方法，如何让它只有一个？
类classAprivatedeffooputs:fooendpublicdefbarputs:barendprivatedefzimputs:zimendprotecteddefdibputs:dibendendA的实例a=A.new测试a.foorescueputs:faila.barrescueputs:faila.zimrescueputs:faila.dibrescueputs:faila.gazrescueputs:fail测试输出failbarfailfailfail.发送测试[:foo,:bar,:zim,:dib,:gaz].each{|m|a.send(m)resc
我有一个模型:classItem项目有一个属性“商店”基于存储的值，我希望Item对象对特定方法具有不同的行为。Rails中是否有针对此的通用设计模式？如果方法中没有大的if-else语句，这是如何干净利落地完成的？ 最佳答案 通常通过Single-TableInheritance. 关于ruby-on-rails-Rails-子类化模型的设计模式是什么？，我们在StackOverflow上找到一个类似的问题： https://stackoverflow.co
我正在使用的第三方API的文档状态:"[O]urAPIonlyacceptspaddedBase64encodedstrings."什么是“填充的Base64编码字符串”以及如何在Ruby中生成它们。下面的代码是我第一次尝试创建转换为Base64的JSON格式数据。xa=Base64.encode64(a.to_json) 最佳答案 他们说的padding其实就是Base64本身的一部分。它是末尾的“=”和“==”。Base64将3个字节的数据包编码为4个编码字符。所以如果你的输入数据有长度n和n%3=1=>"=="末尾用于填充n%
我主要使用Ruby来执行此操作，但到目前为止我的攻击计划如下:使用gemsrdf、rdf-rdfa和rdf-microdata或mida来解析给定任何URI的数据。我认为最好映射到像schema.org这样的统一模式，例如使用这个yaml文件，它试图描述数据词汇表和opengraph到schema.org之间的转换:#SchemaXtoschema.orgconversion#data-vocabularyDV:name:namestreet-address:streetAddressregion:addressRegionlocality:addressLocalityphoto:i
为什么4.1%2返回0.0999999999999996？但是4.2%2==0.2。 最佳答案 参见此处:WhatEveryProgrammerShouldKnowAboutFloating-PointArithmetic实数是无限的。计算机使用的位数有限(今天是32位、64位)。因此计算机进行的浮点运算不能代表所有的实数。0.1是这些数字之一。请注意，这不是与Ruby相关的问题，而是与所有编程语言相关的问题，因为它来自计算机表示实数的方式。 关于ruby-为什么4.1%2使用Ruby返
它不等于主线程的binding，这个toplevel作用域是什么？此作用域与主线程中的binding有何不同？>ruby-e'putsTOPLEVEL_BINDING===binding'false 最佳答案 事实是，TOPLEVEL_BINDING始终引用Binding的预定义全局实例，而Kernel#binding创建的新实例>Binding每次封装当前执行上下文。在顶层，它们都包含相同的绑定(bind)，但它们不是同一个对象，您无法使用==或===测试它们的绑定(bind)相等性。putsTOPLEVEL_BINDINGput
我可以得到Infinity和NaNn=9.0/0#=>Infinityn.class#=>Floatm=0/0.0#=>NaNm.class#=>Float但是当我想直接访问Infinity或NaN时:Infinity#=>uninitializedconstantInfinity(NameError)NaN#=>uninitializedconstantNaN(NameError)什么是Infinity和NaN？它们是对象、关键字还是其他东西？ 最佳答案 您看到打印为Infinity和NaN的只是Float类的两个特殊实例的字符串
如果您尝试在Ruby中的nil对象上调用方法，则会出现NoMethodError异常并显示消息:"undefinedmethod‘...’fornil:NilClass"然而，有一个tryRails中的方法，如果它被发送到一个nil对象，它只返回nil:require'rubygems'require'active_support/all'nil.try(:nonexisting_method)#noNoMethodErrorexceptionanymore那么try如何在内部工作以防止该异常？ 最佳答案 像Ruby中的所有其他对象
关闭。这个问题需要detailsorclarity.它目前不接受答案。想改进这个问题吗？通过editingthispost添加细节并澄清问题.关闭8年前。Improvethisquestion为什么SecureRandom.uuid创建一个唯一的字符串？SecureRandom.uuid#=>"35cb4e30-54e1-49f9-b5ce-4134799eb2c0"SecureRandom.uuid方法创建的字符串从不重复？
我真的很习惯使用Ruby编写以下代码:my_hash={}my_hash['test']=1Java中对应的数据结构是什么？ 最佳答案 HashMapmap=newHashMap();map.put("test",1);我假设？ 关于java-等价于Java中的RubyHash，我们在StackOverflow上找到一个类似的问题： https://stackoverflow.com/questions/22737685/