Dalvik字节码

总体设计

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• 机器模型和调用约定是近似模仿常见的真实的架构和C风格调用约定。

  • 机器是基于寄存器的，并且框架在被创建的时候是固定大小的。每一框架包含一个特定数量的寄存器（由函数指定）和一些需要执行该函数的附属的数据，例如（但不限制在这些）程序计数器和包含该方法的.dex文件的引用。

  • 当用于位值的时候（例如整数和浮点数），寄存器被认为是32位宽度。相邻的寄存器对被用于64位值。对于寄存器对没有对齐要求。

  • 当用于对象引用的时候，寄存器被认为有足够的宽度来维持整个引用。

  • 在按位表示方面，(Object)null == (int)0。

  • 一个方法的N个参数顺序排列在函数调用框架的后N个寄存器中。长参数消耗两个寄存器。实例函数被传送一个this引用作为他的第一个参数。

• 在指令流中的存储单元是一个16位的无符号数。在一些指令中的一些为被忽略或者必须为０。

• 指令不能被平白限制到一个特定类型。例如，指令在没有解释下移动32位寄存器值不必指定他们移动了整数还是浮点数。

• 有针对字符串，属性，类型和函数引用的分离的枚举和索引的连续的空间。

• 按位文字数据在指令流中代表内嵌的。

• 在实际情况中，因为一个函数需要使用超过16个寄存器是不寻常的，并且因为需要超过8个寄存器是相当普遍的，所以很多指令被限制只能寻址前16个寄存器。当合理的可能的情况下，指令允许寻址达到前256个寄存器。除此之外，有些变型指令允许更多数量的寄存器，包括一对捕捉所有move指令的可以寻址寄存器的范围是v0-v65535。当一个指令变型不能够寻址期望的寄存器，他期望的是，寄存器的内容从原始的寄存器移动到了一个低寄存器上（在操作前）并且/或者从一个低结果寄存器移动到了一个高寄存器上（在操作之后）。

• 有一些”伪指令”，被用于持有可变长度的数据的有效载荷，他们被常规指令引用（例如，fill-array-data）。在执行的正常流中，这样的指令是决不能遇到的。除此之外，指令必须位于偶数字节偏移（也就是。4字节对齐）。为了满足这个要求，dex生成工具必须生成一个额外的nop指令作为一个空格，如果这样一个指令没有被对齐的话。最终，虽然不是必须的，但是大多数工具将会选择在函数的最后提供这些指令，否则可能会需要额外的指令在他们周围分支。

• 在安装到一个运行的系统中的时候，一些指令可能被改变，改变他们的格式，作为一个安装时静态链接优化。一旦链接被知晓，这将会获得更快的执行速度。我们将在后面学习指令格式的相关知识用于”suggested variants”。”suggested”被故意使用。实施这些并不是强制性的。

• 人类语法和记忆：

  • 用于参数的先目的地后源头的排序

  • 一些操作码会有消除歧义的名称后缀来显示他们操作的类型：

    1. 通用型32位操作码是不被标记的。

    2. 通用型64位操作码带有后缀-wide。

    3. 指定类型的操作码使用他们的类型（或者是一个直接的缩略词）作为后缀，例如-boolean -byte -char -short -int -long -float -double -object -string -class -void。

  • 一些操作码有一个消除歧义的后缀去区分那么否则会有相同操作的指令，这些指令有不同的指令布局或选项。这些后缀与主名称之间使用一个斜杠”/”进行分离，并且主要存在与使生成或解释可执行程序的代码中具有静态常亮的一对一映射的地方（这是为了降低人类歧义）。

  • 在这里的解释中，一个值的宽度(一个常亮的范围或者是可能寻址的寄存器数量)被每四位宽度一个字符的使用所强调了。

  • 例如，在指令move-wide/from 16 vAA,vBBBB：

    1. “move”是基础的操作码，代表基本的操作(move是一个寄存器值)。

    2. “wide”是名称后缀，代表他操作宽(64位)数据。

    3. “from 16”是操作码后缀，代表拥有一个16位的寄存器引用的变量作为源。

    4. “vAA”是目的寄存器(由操作指出；规则就是目的参数永远第一个出现)，目的寄存器的范围是v0-v255。

    5. “vBBBB”是源寄存器，他的范围是v0-v65535。

• 在后面的文章”指令格式文档”中，我们将会学习关于变量指令格式的细节，还有一些关于操作码语法的细节。

• 后面文章”.dex文件格式文档”将会学习更多的关于字节码与大环境的适应。

字节码集合的总结

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Op & Format	Mnemonic / Syntax	Arguments	Description
00 10x	nop		Waste cycles. Note: Data-bearing pseudo-instructions are tagged with this opcode, in which case the high-order byte of the opcode unit indicates the nature of the data. See “packed-switch-payload Format”, “sparse-switch-payload Format”, and “fill-array-data-payload Format” below.
01 12x	move vA, vB	A: destination register (4 bits) B: source register (4 bits)	Move the contents of one non-object register to another.
02 22x	move/from16 vAA, vBBBB	A: destination register (8 bits) B: source register (16 bits)	Move the contents of one non-object register to another.
03 32x	move/16 vAAAA, vBBBB	A: destination register (16 bits) B: source register (16 bits)	Move the contents of one non-object register to another.
04 12x	move-wide vA, vB	A: destination register pair (4 bits) B: source register pair (4 bits)	Move the contents of one register-pair to another. Note: It is legal to move from vN to either vN-1 or vN+1, so implementations must arrange for both halves of a register pair to be read before anything is written.
05 22x	move-wide/from16 vAA, vBBBB	A: destination register pair (8 bits) B: source register pair (16 bits)	Move the contents of one register-pair to another. Note: Implementation considerations are the same as move-wide, above.
06 32x	move-wide/16 vAAAA, vBBBB	A: destination register pair (16 bits) B: source register pair (16 bits)	Move the contents of one register-pair to another. Note: Implementation considerations are the same as move-wide, above.
07 12x	move-object vA, vB	A: destination register (4 bits) B: source register (4 bits)	Move the contents of one object-bearing register to another.
08 22x	move-object/from16 vAA, vBBBB	A: destination register (8 bits) B: source register (16 bits)	Move the contents of one object-bearing register to another.
09 32x	move-object/16 vAAAA, vBBBB	A: destination register (16 bits) B: source register (16 bits)	Move the contents of one object-bearing register to another.
0a 11x	move-result vAA	A: destination register (8 bits)	Move the single-word non-object result of the most recent invoke-kind into the indicated register. This must be done as the instruction immediately after an invoke-kind whose (single-word, non-object) result is not to be ignored; anywhere else is invalid.
0b 11x	move-result-wide vAA	A: destination register pair (8 bits)	Move the double-word result of the most recent invoke-kind into the indicated register pair. This must be done as the instruction immediately after an invoke-kind whose (double-word) result is not to be ignored; anywhere else is invalid.
0c 11x	move-result-object vAA	A: destination register (8 bits)	Move the object result of the most recent invoke-kind into the indicated register. This must be done as the instruction immediately after an invoke-kind or filled-new-array whose (object) result is not to be ignored; anywhere else is invalid.
0d 11x	move-exception vAA	A: destination register (8 bits)	Save a just-caught exception into the given register. This must be the first instruction of any exception handler whose caught exception is not to be ignored, and this instruction must only ever occur as the first instruction of an exception handler; anywhere else is invalid.
0e 10x	return-void		Return from a void method.
0f 11x	return vAA	A: return value register (8 bits)	Return from a single-width (32-bit) non-object value-returning method.
10 11x	return-wide vAA	A: return value register-pair (8 bits)	Return from a double-width (64-bit) value-returning method.
11 11x	return-object vAA	A: return value register (8 bits)	Return from an object-returning method.
12 11n	const/4 vA, #+B	A: destination register (4 bits) B: signed int (4 bits)	Move the given literal value (sign-extended to 32 bits) into the specified register.
13 21s	const/16 vAA, #+BBBB	A: destination register (8 bits) B: signed int (16 bits)	Move the given literal value (sign-extended to 32 bits) into the specified register.
14 31i	const vAA, #+BBBBBBBB	A: destination register (8 bits) B: arbitrary 32-bit constant	Move the given literal value into the specified register.
15 21h	const/high16 vAA, #+BBBB0000	A: destination register (8 bits) B: signed int (16 bits)	Move the given literal value (right-zero-extended to 32 bits) into the specified register.
16 21s	const-wide/16 vAA, #+BBBB	A: destination register (8 bits) B: signed int (16 bits)	Move the given literal value (sign-extended to 64 bits) into the specified register-pair.
17 31i	const-wide/32 vAA, #+BBBBBBBB	A: destination register (8 bits) B: signed int (32 bits)	Move the given literal value (sign-extended to 64 bits) into the specified register-pair.
18 51l	const-wide vAA, #+BBBBBBBBBBBBBBBB	A: destination register (8 bits) B: arbitrary double-width (64-bit) constant	Move the given literal value into the specified register-pair.
19 21h	const-wide/high16 vAA, #+BBBB000000000000	A: destination register (8 bits) B: signed int (16 bits)	Move the given literal value (right-zero-extended to 64 bits) into the specified register-pair.
1a 21c	const-string vAA, string@BBBB	A: destination register (8 bits) B: string index	Move a reference to the string specified by the given index into the specified register.
1b 31c	const-string/jumbo vAA, string@BBBBBBBB	A: destination register (8 bits) B: string index	Move a reference to the string specified by the given index into the specified register.
1c 21c	const-class vAA, type@BBBB	A: destination register (8 bits) B: type index	Move a reference to the class specified by the given index into the specified register. In the case where the indicated type is primitive, this will store a reference to the primitive type’s degenerate class.
1d 11x	monitor-enter vAA	A: reference-bearing register (8 bits)	Acquire the monitor for the indicated object.
1e 11x	monitor-exit vAA	A: reference-bearing register (8 bits)	Release the monitor for the indicated object. Note: If this instruction needs to throw an exception, it must do so as if the pc has already advanced past the instruction. It may be useful to think of this as the instruction successfully executing (in a sense), and the exception getting thrown after the instruction but before the next one gets a chance to run. This definition makes it possible for a method to use a monitor cleanup catch-all (e.g., finally) block as the monitor cleanup for that block itself, as a way to handle the arbitrary exceptions that might get thrown due to the historical implementation of Thread.stop(), while still managing to have proper monitor hygiene.
1f 21c	check-cast vAA, type@BBBB	A: reference-bearing register (8 bits) B: type index (16 bits)	Throw a ClassCastException if the reference in the given register cannot be cast to the indicated type. Note: Since A must always be a reference (and not a primitive value), this will necessarily fail at runtime (that is, it will throw an exception) if B refers to a primitive type.
20 22c	instance-of vA, vB, type@CCCC	A: destination register (4 bits) B: reference-bearing register (4 bits) C: type index (16 bits)	Store in the given destination register 1 if the indicated reference is an instance of the given type, or 0 if not. Note: Since B must always be a reference (and not a primitive value), this will always result in 0 being stored if C refers to a primitive type.
21 12x	array-length vA, vB	A: destination register (4 bits) B: array reference-bearing register (4 bits)	Store in the given destination register the length of the indicated array, in entries
22 21c	new-instance vAA, type@BBBB	A: destination register (8 bits) B: type index	Construct a new instance of the indicated type, storing a reference to it in the destination. The type must refer to a non-array class.
23 22c	new-array vA, vB, type@CCCC	A: destination register (4 bits) B: size register C: type index	Construct a new array of the indicated type and size. The type must be an array type.
24 35c	filled-new-array {vC, vD, vE, vF, vG}, type@BBBB	A: array size and argument word count (4 bits) B: type index (16 bits) C..G: argument registers (4 bits each)	Construct an array of the given type and size, filling it with the supplied contents. The type must be an array type. The array’s contents must be single-word (that is, no arrays of long or double, but reference types are acceptable). The constructed instance is stored as a “result” in the same way that the method invocation instructions store their results, so the constructed instance must be moved to a register with an immediately subsequent move-result-object instruction (if it is to be used).
25 3rc	filled-new-array/range {vCCCC .. vNNNN}, type@BBBB	A: array size and argument word count (8 bits) B: type index (16 bits) C: first argument register (16 bits) N = A + C - 1	Construct an array of the given type and size, filling it with the supplied contents. Clarifications and restrictions are the same as filled-new-array, described above.
26 31t	fill-array-data vAA, +BBBBBBBB (with supplemental data as specified below in “fill-array-data-payload Format”)	A: array reference (8 bits) B: signed “branch” offset to table data pseudo-instruction (32 bits)	Fill the given array with the indicated data. The reference must be to an array of primitives, and the data table must match it in type and must contain no more elements than will fit in the array. That is, the array may be larger than the table, and if so, only the initial elements of the array are set, leaving the remainder alone.
27 11x	throw vAA	A: exception-bearing register (8 bits)	Throw the indicated exception.
28 10t	goto +AA	A: signed branch offset (8 bits)	Unconditionally jump to the indicated instruction. Note: The branch offset must not be 0. (A spin loop may be legally constructed either with goto/32 or by including a nop as a target before the branch.)
29 20t	goto/16 +AAAA	A: signed branch offset (16 bits)	Unconditionally jump to the indicated instruction. Note: The branch offset must not be 0. (A spin loop may be legally constructed either with goto/32 or by including a nop as a target before the branch.)
2a 30t	goto/32 +AAAAAAAA	A: signed branch offset (32 bits)	Unconditionally jump to the indicated instruction.
2b 31t	packed-switch vAA, +BBBBBBBB (with supplemental data as specified below in “packed-switch-payload Format”)	A: register to test B: signed “branch” offset to table data pseudo-instruction (32 bits)	Jump to a new instruction based on the value in the given register, using a table of offsets corresponding to each value in a particular integral range, or fall through to the next instruction if there is no match.
2c 31t	sparse-switch vAA, +BBBBBBBB (with supplemental data as specified below in “sparse-switch-payload Format”)	A: register to test B: signed “branch” offset to table data pseudo-instruction (32 bits)	Jump to a new instruction based on the value in the given register, using an ordered table of value-offset pairs, or fall through to the next instruction if there is no match.
2d..31 23x	cmpkind vAA, vBB, vCC 2d: cmpl-float (lt bias) 2e: cmpg-float (gt bias) 2f: cmpl-double (lt bias) 30: cmpg-double (gt bias) 31: cmp-long	A: destination register (8 bits) B: first source register or pair C: second source register or pair	Perform the indicated floating point or long comparison, setting a to 0 if b == c, 1 if b > c, or -1 if b < c. The “bias” listed for the floating point operations indicates how NaN comparisons are treated: “gt bias” instructions return 1 for NaN comparisons, and “lt bias” instructions return -1. For example, to check to see if floating point x < y it is advisable to use cmpg-float; a result of -1 indicates that the test was true, and the other values indicate it was false either due to a valid comparison or because one of the values was NaN.
32..37 22t	if-test vA, vB, +CCCC 32: if-eq 33: if-ne 34: if-lt 35: if-ge 36: if-gt 37: if-le	A: first register to test (4 bits) B: second register to test (4 bits) C: signed branch offset (16 bits)	Branch to the given destination if the given two registers’ values compare as specified. Note: The branch offset must not be 0. (A spin loop may be legally constructed either by branching around a backward goto or by including a nop as a target before the branch.)
38..3d 21t	if-testz vAA, +BBBB 38: if-eqz 39: if-nez 3a: if-ltz 3b: if-gez 3c: if-gtz 3d: if-lez	A: register to test (8 bits) B: signed branch offset (16 bits)	Branch to the given destination if the given register’s value compares with 0 as specified. Note: The branch offset must not be 0. (A spin loop may be legally constructed either by branching around a backward goto or by including a nop as a target before the branch.)
3e..43 10x	(unused)		(unused)
44..51 23x	arrayop vAA, vBB, vCC 44: aget 45: aget-wide 46: aget-object 47: aget-boolean 48: aget-byte 49: aget-char 4a: aget-short 4b: aput 4c: aput-wide 4d: aput-object 4e: aput-boolean 4f: aput-byte 50: aput-char 51: aput-short	A: value register or pair; may be source or dest (8 bits) B: array register (8 bits) C: index register (8 bits)	Perform the identified array operation at the identified index of the given array, loading or storing into the value register.
52..5f 22c	iinstanceop vA, vB, field@CCCC 52: iget 53: iget-wide 54: iget-object 55: iget-boolean 56: iget-byte 57: iget-char 58: iget-short 59: iput 5a: iput-wide 5b: iput-object 5c: iput-boolean 5d: iput-byte 5e: iput-char 5f: iput-short	A: value register or pair; may be source or dest (4 bits) B: object register (4 bits) C: instance field reference index (16 bits)	Perform the identified object instance field operation with the identified field, loading or storing into the value register. Note: These opcodes are reasonable candidates for static linking, altering the field argument to be a more direct offset.
60..6d 21c	sstaticop vAA, field@BBBB 60: sget 61: sget-wide 62: sget-object 63: sget-boolean 64: sget-byte 65: sget-char 66: sget-short 67: sput 68: sput-wide 69: sput-object 6a: sput-boolean 6b: sput-byte 6c: sput-char 6d: sput-short	A: value register or pair; may be source or dest (8 bits) B: static field reference index (16 bits)	Perform the identified object static field operation with the identified static field, loading or storing into the value register. Note: These opcodes are reasonable candidates for static linking, altering the field argument to be a more direct offset.
6e..72 35c	invoke-kind {vC, vD, vE, vF, vG}, meth@BBBB 6e: invoke-virtual 6f: invoke-super 70: invoke-direct 71: invoke-static 72: invoke-interface	A: argument word count (4 bits) B: method reference index (16 bits) C..G: argument registers (4 bits each)	Call the indicated method. The result (if any) may be stored with an appropriate move-result* variant as the immediately subsequent instruction. invoke-virtual is used to invoke a normal virtual method (a method that is not private, static, or final, and is also not a constructor). When the method_id references a method of a non-interface class, invoke-super is used to invoke the closest superclass’s virtual method (as opposed to the one with the same method_id in the calling class). The same method restrictions hold as for invoke-virtual. In Dex files version 037 or later, if the method_id refers to an interface method, invoke-super is used to invoke the most specific, non-overridden version of that method defined on that interface. The same method restrictions hold as for invoke-virtual. In Dex files prior to version 037, having an interface method_id is illegal and undefined. invoke-direct is used to invoke a non-static direct method (that is, an instance method that is by its nature non-overridable, namely either a private instance method or a constructor). invoke-static is used to invoke a static method (which is always considered a direct method). invoke-interface is used to invoke an interface method, that is, on an object whose concrete class isn’t known, using a method_id that refers to an interface. Note: These opcodes are reasonable candidates for static linking, altering the method argument to be a more direct offset (or pair thereof).
73 10x	(unused)		(unused)
74..78 3rc	invoke-kind/range {vCCCC .. vNNNN}, meth@BBBB 74: invoke-virtual/range 75: invoke-super/range 76: invoke-direct/range 77: invoke-static/range 78: invoke-interface/range	A: argument word count (8 bits) B: method reference index (16 bits) C: first argument register (16 bits) N = A + C - 1	Call the indicated method. See first invoke-kind description above for details, caveats, and suggestions.
79..7a 10x	(unused)		(unused)
7b..8f 12x	unop vA, vB 7b: neg-int 7c: not-int 7d: neg-long 7e: not-long 7f: neg-float 80: neg-double 81: int-to-long 82: int-to-float 83: int-to-double 84: long-to-int 85: long-to-float 86: long-to-double 87: float-to-int 88: float-to-long 89: float-to-double 8a: double-to-int 8b: double-to-long 8c: double-to-float 8d: int-to-byte 8e: int-to-char 8f: int-to-short	A: destination register or pair (4 bits) B: source register or pair (4 bits)	Perform the identified unary operation on the source register, storing the result in the destination register.
90..af 23x	binop vAA, vBB, vCC 90: add-int 91: sub-int 92: mul-int 93: div-int 94: rem-int 95: and-int 96: or-int 97: xor-int 98: shl-int 99: shr-int 9a: ushr-int 9b: add-long 9c: sub-long 9d: mul-long 9e: div-long 9f: rem-long a0: and-long a1: or-long a2: xor-long a3: shl-long a4: shr-long a5: ushr-long a6: add-float a7: sub-float a8: mul-float a9: div-float aa: rem-float ab: add-double ac: sub-double ad: mul-double ae: div-double af: rem-double	A: destination register or pair (8 bits) B: first source register or pair (8 bits) C: second source register or pair (8 bits)	Perform the identified binary operation on the two source registers, storing the result in the destination register. Note: Contrary to other -long mathematical operations (which take register pairs for both their first and their second source), shl-long, shr-long, and ushr-long take a register pair for their first source (the value to be shifted), but a single register for their second source (the shifting distance).
b0..cf 12x	binop/2addr vA, vB b0: add-int/2addr b1: sub-int/2addr b2: mul-int/2addr b3: div-int/2addr b4: rem-int/2addr b5: and-int/2addr b6: or-int/2addr b7: xor-int/2addr b8: shl-int/2addr b9: shr-int/2addr ba: ushr-int/2addr bb: add-long/2addr bc: sub-long/2addr bd: mul-long/2addr be: div-long/2addr bf: rem-long/2addr c0: and-long/2addr c1: or-long/2addr c2: xor-long/2addr c3: shl-long/2addr c4: shr-long/2addr c5: ushr-long/2addr c6: add-float/2addr c7: sub-float/2addr c8: mul-float/2addr c9: div-float/2addr ca: rem-float/2addr cb: add-double/2addr cc: sub-double/2addr cd: mul-double/2addr ce: div-double/2addr cf: rem-double/2addr	A: destination and first source register or pair (4 bits) B: second source register or pair (4 bits)	Perform the identified binary operation on the two source registers, storing the result in the first source register. Note: Contrary to other -long/2addr mathematical operations (which take register pairs for both their destination/first source and their second source), shl-long/2addr, shr-long/2addr, and ushr-long/2addr take a register pair for their destination/first source (the value to be shifted), but a single register for their second source (the shifting distance).
d0..d7 22s	binop/lit16 vA, vB, #+CCCC d0: add-int/lit16 d1: rsub-int (reverse subtract) d2: mul-int/lit16 d3: div-int/lit16 d4: rem-int/lit16 d5: and-int/lit16 d6: or-int/lit16 d7: xor-int/lit16	A: destination register (4 bits) B: source register (4 bits) C: signed int constant (16 bits)	Perform the indicated binary op on the indicated register (first argument) and literal value (second argument), storing the result in the destination register. Note: rsub-int does not have a suffix since this version is the main opcode of its family. Also, see below for details on its semantics.
d8..e2 22b	binop/lit8 vAA, vBB, #+CC d8: add-int/lit8 d9: rsub-int/lit8 da: mul-int/lit8 db: div-int/lit8 dc: rem-int/lit8 dd: and-int/lit8 de: or-int/lit8 df: xor-int/lit8 e0: shl-int/lit8 e1: shr-int/lit8 e2: ushr-int/lit8	A: destination register (8 bits) B: source register (8 bits) C: signed int constant (8 bits)	Perform the indicated binary op on the indicated register (first argument) and literal value (second argument), storing the result in the destination register. Note: See below for details on the semantics of rsub-int.
e3..f9 10x	(unused)		(unused)
fa 45cc	invoke-polymorphic {vC, vD, vE, vF, vG}, meth@BBBB, proto@HHHH	A: argument word count (4 bits) B: method reference index (16 bits) C: method handle reference to invoke (16 bits) D..G: argument registers (4 bits each) H: prototype reference index (16 bits)	Invoke the indicated method handle. The result (if any) may be stored with an appropriate move-result* variant as the immediately subsequent instruction. The method reference must be to java.lang.invoke.MethodHandle.invoke or java.lang.invoke.MethodHandle.invokeExact. The prototype reference describes the argument types provided and the expected return type. The invoke-polymorphic bytecode may raise exceptions when it executes. The exceptions are described in the API documentation for java.lang.invoke.MethodHandle.invoke and java.lang.invoke.MethodHandle.invokeExact. Present in Dex files from version 038 onwards.
fb 4rcc	invoke-polymorphic/range {vCCCC .. vNNNN}, meth@BBBB, proto@HHHH	A: argument word count (8 bits) B: method reference index (16 bits) C: method handle reference to invoke (16 bits) H: prototype reference index (16 bits) N = A + C - 1	Invoke the indicated method handle. See the invoke-polymorphic description above for details. Present in Dex files from version 038 onwards.
fc 35c	invoke-custom {vC, vD, vE, vF, vG}, call_site@BBBB	A: argument word count (4 bits) B: call site reference index (16 bits) C..G: argument registers (4 bits each)	Resolves and invokes the indicated call site. The result from the invocation (if any) may be stored with an appropriate move-result* variant as the immediately subsequent instruction. This instruction executes in two phases: call site resolution and call site invocation. Call site resolution checks whether the indicated call site has an associated java.lang.invoke.CallSite instance. If not, the bootstrap linker method for the indicated call site is invoked using arguments present in the DEX file (see call_site_item). The bootstrap linker method returns a java.lang.invoke.CallSite instance that will then be associated with the indicated call site if no association exists. Another thread may have already made the association first, and if so execution of the instruction continues with the first associated java.lang.invoke.CallSite instance. Call site invocation is made on the java.lang.invoke.MethodHandle target of the resolved java.lang.invoke.CallSite instance. The target is invoked as if executing invoke-polymorphic (described above) using the method handle and arguments to the invoke-custom instruction as the arguments to an exact method handle invocation. Exceptions raised by the bootstrap linker method are wrapped in a java.lang.BootstrapMethodError. A BootstrapMethodError is also raised if: the bootstrap linker method fails to return a java.lang.invoke.CallSite instance. the returned java.lang.invoke.CallSite has a null method handle target. the method handle target is not of the requested type. Present in Dex files from version 038 onwards.
fd 3rc	invoke-custom/range {vCCCC .. vNNNN}, call_site@BBBB	A: argument word count (8 bits) B: call site reference index (16 bits) C: first argument register (16-bits) N = A + C - 1	Resolve and invoke a call site. See the invoke-custom description above for details. Present in Dex files from version 038 onwards.
fe..ff 10x	(unused)		(unused)

压缩开关有效载荷格式

---

Name	Format	Description
ident	ushort = 0x0100	identifying pseudo-opcode
size	ushort	number of entries in the table
first_key	int	first (and lowest) switch case value
targets	int[]	list of size relative branch targets. The targets are relative to the address of the switch opcode, not of this table.

注意：这个表中每一个实例的编码单元的总数为`(size * 2) + 4`。

稀疏开关有效载荷格式

---

Name	Format	Description
ident	ushort = 0x0200	identifying pseudo-opcode
size	ushort	number of entries in the table
keys	int[]	list of size key values, sorted low-to-high
targets	int[]	list of size relative branch targets, each corresponding to the key value at the same index. The targets are relative to the address of the switch opcode, not of this table.

注意：这个表中每一个实例的编码单元的总数为`(size * 4) + 2`。

填充数组数据有效载荷格式

---

Name	Format	Description
ident	ushort = 0x0300	identifying pseudo-opcode
element_width	ushort	number of bytes in each element
size	uint	number of elements in the table
data	ubyte[]	data values

注意：这个表中每一个实例的编码单元的总数为`(size * element_width + 1)  / 2 + 4`。

数学操作细节

---

注意：浮点操作必须要遵守IEEE 754规则，使用舍入到最接近的和渐进下溢算法，除非在哪里明确指出。

Opcode	C Semantics	Notes
neg-int	int32 a; int32 result = -a;	Unary twos-complement.
not-int	int32 a; int32 result = ~a;	Unary ones-complement.
neg-long	int64 a; int64 result = -a;	Unary twos-complement.
not-long	int64 a; int64 result = ~a;	Unary ones-complement.
neg-float	float a; float result = -a;	Floating point negation.
neg-double	double a; double result = -a;	Floating point negation.
int-to-long	int32 a; int64 result = (int64) a;	Sign extension of int32 into int64.
int-to-float	int32 a; float result = (float) a;	Conversion of int32 to float, using round-to-nearest. This loses precision for some values.
int-to-double	int32 a; double result = (double) a;	Conversion of int32 to double.
long-to-int	int64 a; int32 result = (int32) a;	Truncation of int64 into int32.
long-to-float	int64 a; float result = (float) a;	Conversion of int64 to float, using round-to-nearest. This loses precision for some values.
long-to-double	int64 a; double result = (double) a;	Conversion of int64 to double, using round-to-nearest. This loses precision for some values.
float-to-int	float a; int32 result = (int32) a;	Conversion of float to int32, using round-toward-zero. NaN and -0.0 (negative zero) convert to the integer 0. Infinities and values with too large a magnitude to be represented get converted to either 0x7fffffff or -0x80000000 depending on sign.
float-to-long	float a; int64 result = (int64) a;	Conversion of float to int64, using round-toward-zero. The same special case rules as for float-to-int apply here, except that out-of-range values get converted to either 0x7fffffffffffffff or -0x8000000000000000 depending on sign.
float-to-double	float a; double result = (double) a;	Conversion of float to double, preserving the value exactly.
double-to-int	double a; int32 result = (int32) a;	Conversion of double to int32, using round-toward-zero. The same special case rules as for float-to-int apply here.
double-to-long	double a; int64 result = (int64) a;	Conversion of double to int64, using round-toward-zero. The same special case rules as for float-to-long apply here.
double-to-float	double a; float result = (float) a;	Conversion of double to float, using round-to-nearest. This loses precision for some values.
int-to-byte	int32 a; int32 result = (a << 24) >> 24;	Truncation of int32 to int8, sign extending the result.
int-to-char	int32 a; int32 result = a & 0xffff;	Truncation of int32 to uint16, without sign extension.
int-to-short	int32 a; int32 result = (a << 16) >> 16;	Truncation of int32 to int16, sign extending the result.
add-int	int32 a, b; int32 result = a + b;	Twos-complement addition.
sub-int	int32 a, b; int32 result = a - b;	Twos-complement subtraction.
rsub-int	int32 a, b; int32 result = b - a;	Twos-complement reverse subtraction.
mul-int	int32 a, b; int32 result = a * b;	Twos-complement multiplication.
div-int	int32 a, b; int32 result = a / b;	Twos-complement division, rounded towards zero (that is, truncated to integer). This throws ArithmeticException if b == 0.
rem-int	int32 a, b; int32 result = a % b;	Twos-complement remainder after division. The sign of the result is the same as that of a, and it is more precisely defined as result == a - (a / b) * b. This throws ArithmeticException if b == 0.
and-int	int32 a, b; int32 result = a & b;	Bitwise AND.
or-int	int32 a, b; int32 result = a | b;	Bitwise OR.
xor-int	int32 a, b; int32 result = a ^ b;	Bitwise XOR.
shl-int	int32 a, b; int32 result = a << (b & 0x1f);	Bitwise shift left (with masked argument).
shr-int	int32 a, b; int32 result = a >> (b & 0x1f);	Bitwise signed shift right (with masked argument).
ushr-int	uint32 a, b; int32 result = a >> (b & 0x1f);	Bitwise unsigned shift right (with masked argument).
add-long	int64 a, b; int64 result = a + b;	Twos-complement addition.
sub-long	int64 a, b; int64 result = a - b;	Twos-complement subtraction.
mul-long	int64 a, b; int64 result = a * b;	Twos-complement multiplication.
div-long	int64 a, b; int64 result = a / b;	Twos-complement division, rounded towards zero (that is, truncated to integer). This throws ArithmeticException if b == 0.
rem-long	int64 a, b; int64 result = a % b;	Twos-complement remainder after division. The sign of the result is the same as that of a, and it is more precisely defined as result == a - (a / b) * b. This throws ArithmeticException if b == 0.
and-long	int64 a, b; int64 result = a & b;	Bitwise AND.
or-long	int64 a, b; int64 result = a | b;	Bitwise OR.
xor-long	int64 a, b; int64 result = a ^ b;	Bitwise XOR.
shl-long	int64 a; int32 b; int64 result = a << (b & 0x3f);	Bitwise shift left (with masked argument).
shr-long	int64 a; int32 b; int64 result = a >> (b & 0x3f);	Bitwise signed shift right (with masked argument).
ushr-long	uint64 a; int32 b; int64 result = a >> (b & 0x3f);	Bitwise unsigned shift right (with masked argument).
add-float	float a, b; float result = a + b;	Floating point addition.
sub-float	float a, b; float result = a - b;	Floating point subtraction.
mul-float	float a, b; float result = a * b;	Floating point multiplication.
div-float	float a, b; float result = a / b;	Floating point division.
rem-float	float a, b; float result = a % b;	Floating point remainder after division. This function is different than IEEE 754 remainder and is defined as result == a - roundTowardZero(a / b) * b.
add-double	double a, b; double result = a + b;	Floating point addition.
sub-double	double a, b; double result = a - b;	Floating point subtraction.
mul-double	double a, b; double result = a * b;	Floating point multiplication.
div-double	double a, b; double result = a / b;	Floating point division.
rem-double	double a, b; double result = a % b;	Floating point remainder after division. This function is different than IEEE 754 remainder and is defined as result == a - roundTowardZero(a / b) * b.