dream.in.java

來自我的<計算機組成與體系結構>關于JVM的一些語句摘錄[原]

今天晚上在看<計算機組成與體系結構>的時候，很巧遇上了JVM這一章節，于是自己作了個總結，供大家參考下。因為課本是英文原版的，我在這里摘錄了一些語句，就不翻譯了~~有什么錯誤請各位指出~~~
A  virtual machine is a software emulation( 仿真) of a real machine.
It's the JVM's responsibility to load, check, find, and execute btyecodes at the runtime.
JVM acts as an interpreter, taking Java bytecodes and interpreting them into underlying machine instruction.
Compling a C++ program results in an assembly language program that is translated to machine code.
C++ is complied lanuage while Java ,Perl and Python are P-codes, which execute from 5 to 10 times more slowly than C++;
Java's bytecodes is a stack-based language, partially composed of zero address intructoin.要查看字節碼是基于棧的話,可以用 javap -c命令來查看,這個鏈接是我在UC發的一個貼，是關于javap -c 和bytecodes is a stack-based language的：http://www.unix-center.net/bbs/viewthread.php?tid=12799&page=1&extra=page%3D1
Java uses two's complement to represent signed integers but does not allow for unsigned integers.請看截圖:

Table 5-1. Ranges of the Java Virtual Machineís data types(來自 inside Java virtual Machine 一書)

Type	Range
byte	8-bit signed two's complement integer (-27 to 27 - 1, inclusive)
short	16-bit signed two's complement integer (-215 to 215 - 1, inclusive)
int	32-bit signed two's complement integer (-231 to 231 - 1, inclusive)
long	64-bit signed two's complement integer (-263 to 263 - 1, inclusive)
char	16-bit unsigned Unicode character (0 to 216 - 1, inclusive)
float	32-bit IEEE 754 single-precision float
double	64-bit IEEE 754 double-precision float
returnValue	address of an opcode within the same method
reference	reference to an object on the heap, or null

從數的表示范圍(-2 ^n-1 ---- 2 ^n-1-1)可以看出，是用補碼保存的,
Java has four registers, which provide access to five different main memory regions.

JVM的內部組成：




JVM工作環境：
Figure 1-4, native methods are the connection between a Java program and an underlying host operating system.

最后給出一些Java 虛擬機規范定義的字節代碼指令:

Opcode Mnemonic by Function Group

 

Stack Operations (Chapter 10)

Instructions that push a constant onto the stack

aconst_null	Push null object reference
iconst_m1	Push int constant -1
iconst_0	Push int constant 0
iconst_1	Push int constant 1
iconst_2	Push int constant 2
iconst_3	Push int constant 3
iconst_4	Push int constant 4
iconst_5	Push int constant 5
lconst_0	Push long constant 0
lconst_1	Push long constant 1
fconst_0	Push float constant 0.0
fconst_1	Push float constant 1.0
fconst_2	Push float constant 2.0
dconst_0	Push double constant 0.0
dconst_1	Push double constant 1.0
bipush	Push 8-bit signed integer
sipush	Push 16-bit signed integer
ldc	Push item from constant pool
ldcw	Push item from constant pool (wide index)
ldc2_w	Push long or double from constant pool (wide index)

Instructions that load a local variable onto the stack

iload	Load int from local variable
lload	Load long from local variable
fload	Load float from local variable
dload	Load double from local variable
aload	Load reference from local variable
iload_0	Load int from local variable 0
iload_1	Load int from local variable 1
iload_2	Load int from local variable 2
iload_3	Load int from local variable 3
lload_0	Load long from local variable 0
lload_1	Load long from local variable 1
lload_2	Load long from local variable 2
lload_3	Load long from local variable 3
fload_0	Load float from local variable 0
fload_1	Load float from local variable 1
fload_2	Load float from local variable 2
fload_3	Load float from local variable 3
dload_0	Load double from local variable 0
dload_1	Load double from local variable 1
dload_2	Load double from local variable 2
dload_3	Load double from local variable 3
aload_0	Load reference from local variable 0
aload_1	Load reference from local variable 1
aload_2	Load reference from local variable 2
aload_3	Load reference from local variable 3
iaload	Load int from array
laload	Load long from array
faload	Load float from array
daload	Load double from array
aaload	Load reference from array
baload	Load byte or boolean from array
caload	Load char from array
saload	Load short from array

Instructions that store a value from the stack into a local variable

istore	Store int into local variable
lstore	Store long into local variable
fstore	Store float into local variable
dstore	Store double into local variable
astore	Store reference or returnAddress into local variable
istore_0	Store int into local variable 0
istore_1	Store int into local variable 1
istore_2	Store int into local variable 2
istore_3	Store int into local variable 3
lstore_0	Store long into local variable 0
lstore_1	Store long into local variable 1
lstore_2	Store long into local variable 2
lstore_3	Store long into local variable 3
fstore_0	Store float into local variable 0
fstore_1	Store float into local variable 1
fstore_2	Store float into local variable 2
fstore_3	Store float into local variable 3
dstore_0	Store double into local variable 0
dstore_1	Store double into local variable 1
dstore_2	Store double into local variable 2
dstore_3	Store double into local variable 3
astore_0	Store reference or returnAddress into local variable 0
astore_1	Store reference or returnAddress into local variable 1
astore_2	Store reference or returnAddress into local variable 2
astore_3	Store reference or returnAddress into local variable 3
iastore	Store into int array
lastore	Store into long array
fastore	Store into float array
dastore	Store into double array
aastore	Store into reference array
bastore	Store into byte or boolean array
castore	Store into char array
sastore	Store into short array

The wide instruction

wide	Extend a local variable index with additional bytes

Generic (typeless) stack operations

nop	Do nothing
pop	Pop top stack word
pop2	Pop top two stack words
dup	Duplicate top stack word
dup_x1	Duplicate top stack word and put two down
dup_x2	Duplicate top stack word and put three down
dup2	Duplicate top two stack words
dup2_x1	Duplicate top two stack words and put two down
dup2_x2	Duplicate top two stack words and put three down
swap	Swap top two stack words

Type Conversion (Chapter 11)

i2l	Convert int to long
i2f	Convert int to float
i2d	Convert int to double
l2i	Convert long to int
l2f	Convert long to float
l2d	Convert long to double
f2i	Convert float to int
f2l	Convert float to long
f2d	Convert float to double
d2i	Convert double to int
d2l	Convert double to long
d2f	Convert double to float
i2b	Convert int to byte
i2c	Convert int to char
i2s	Convert int to short

Integer Arithmetic (Chapter 12)

iadd	Add ints
ladd	Add longs
isub	Subtract ints
lsub	Subtract longs
imul	Multiply ints
lmul	Multiply longs
idiv	Divide ints
ldiv	Divide longs
irem	Calculate remainder of division of ints
lrem	Calculate remainder of division of longs
ineg	Negate int
lneg	Negate long
iinc	Increment int local variable by constant

Logic (Chapter 13)

Shift operations

ishl	Perform left shift on int
lshl	Perform left shift on long
ishr	Perform arithmetic right shift on int
lshr	Perform arithmetic right shift on long
iushr	Perform logical right shift on int
lushr	Perform logical right shift on long

Bitwise boolean operations

iand	Perform boolean AND on ints
land	Perform boolean AND on longs
ior	Perform boolean OR on ints
lor	Perform boolean OR on longs
ixor	Perform boolean XOR on ints
lxor	Perform boolean XOR on longs

Floating Point Arithmetic (Chapter 14)

fadd	Add floats
dadd	Add doubles
fsub	Subtract floats
dsub	Subtract doubles
fmul	Multiply floats
dmul	Multiply doubles
fdiv	Divide floats
ddiv	Divide doubles
frem	Calculate remainder of division of floats
drem	Calculate remainder of division of doubles
fneg	Negate float
dneg	Negate double

Objects and Arrays (Chapter 15)

Instructions that deal with objects

new	Create a new object
checkcast	Make sure object is of a given type
getfield	Fetch field from object
putfield	Set field in object
getstatic	Fetch static field from class
putstatic	Set static field in class
instanceof	Determine if an object is of a given type

Instructions that deal with arrays

newarray	Allocate new array of primitive type components
anewarray	Allocate new array of reference type components
arraylength	Get length of an array
multianewarray	Allocate a new multi-dimensional array

Control Flow (Chapter 16)

Conditional branch instructions

ifeq	Branch if equal to 0
ifne	Branch if not equal to 0
iflt	Branch if less than 0
ifge	Branch if greater than or equal to 0
ifgt	Branch if greater than 0
ifle	Branch if less than or equal to 0
if_icmpeq	Branch if ints equal
if_icmpne	Branch if ints not equal
if_icmplt	Branch if int less than other int
if_icmpge	Branch if int greater than or equal to other int
if_icmpgt	Branch if int greater than other int
if_icmple	Branch if int less than or equal to other int
ifnull	Branch if null
ifnonnull	Branch if not null
if_acmpeq	Branch if object references are equal
if_acmpne	Branch if object references not equal

Comparison instructions

lcmp	Compare longs
fcmpl	Compare floats (-1 on NaN)
fcmpg	Compare floats (1 on NaN)
dcmpl	Compare doubles (-1 on NaN)
dcmpg	Compare doubles (1 on NaN)

Unconditional branch instructions

goto	Branch always
goto_w	Branch always (wide index)

Table jumping instructions

tableswitch	Access jump table by index and jump
lookupswitch	Access jump table by key match and jump

Exceptions (Chapter 17)

athrow

Throw exception or error

Finally Clauses (Chapter 18)

jsr	Jump to subroutine
jsr_w	Jump to subroutine (wide index)
ret	Return from subroutine

Method Invocation and Return (Chapter 19)

Method invocation instructions

invokevirtual	Invoke instance method, dispatch based on run-time type
invokespecial	Invoke instance method, dispatching based on compile-time type
invokestatic	Invoke a class (static) method
invokeinterface	Invoke interface method

Method return instructions

ireturn	Return int from method
lreturn	Return long from method
freturn	Return float from method
dreturn	Return double from method
areturn	Return reference from method
return	Return (void) from method

posted on 2009-04-13 01:37 YXY 閱讀(408) 評論(0)  編輯  收藏