JVM Instructions

The JVM specification defines nearly 200+ instructions, as shown in the table below:

op	Syntax	Stack	Description
0x00	nop	No change	Do nothing
0x01	aconst_null	... → ...,null	Push null reference onto the stack[^1] top
0x02	iconst_m1	... → ...,-1	Push int constant -1 onto the stack top
0x03	iconst_0	.. . → ...,0	Push int constant 0 onto the stack top
0x04	iconst_1	... → ...,1	Push int constant 1 onto the stack top
0x05	iconst_2	... → ...,2	Push int constant 2 onto the stack top
0x06	iconst_3	... → ...,3	Push int constant 3 onto the stack top
0x07	iconst_4	... → ...,4	Push int constant 4 onto the stack top
0x08	iconst_5	... → ...,5	Push int constant 5 onto the stack top
0x09	lconst_0	... → ...,0L	Push long constant 0L onto the stack top
0x0a	lconst_1	... → ...,1L	Push long constant 1L onto the stack top
0x0b	fconst_0	... → ...,0.0f	Push float constant 0.0f onto the stack top
0x0c	fconst_1	... → ...,1.0f	Push float constant 1.0f onto the stack top
0x0d	fconst_2	... → ...,2.0f	Push float constant 1.0f onto the stack top
0x0e	dconst_0	... → ...,0.0	Push double constant 0.0 onto the stack top
0x0f	dconst_1	... → ...,1.0	Push double constant 1.0 onto the stack top
0x10	bipush,AA[^2]	... → ...,v	Push immediate[^3] value AA onto the stack top
0x11	sipush,AAAA[^4]	... → ...,v	Push immediate value AAAA onto the stack top
0x12	ldc,AA	... → ...,v	Push constant at index AA in constant pool onto the stack top
0x13	ldc_w,AAAA	... → ...,v	Push constant at index AAAA in constant pool onto the stack top
0x14	ldc2_w,AAAA	... → ...,v	Push long or double constant at index AAAA in constant pool onto the stack top
0x15	iload,AA	... → ...,v	Push int variable at index AA in local variable table onto the stack top
0x16	lload,AA	... → ...,v	Push long variable at index AA in local variable table onto the stack top
0x17	fload,AA	... → ...,v	Push float variable at index AA in local variable table onto the stack top
0x18	dload,AA	... → ...,v	Push double variable at index AA in local variable table onto the stack top
0x19	aload,AA	... → ...,v	Push aref at index AA in local variable table onto the stack top
0x1a	iload_0	... → ...,0	Push int variable at index 0 in local variable table onto the stack top
0x1b	iload_1	... → ...,1	Push int variable at index 1 in local variable table onto the stack top
0x1c	iload_2	... → ...,2	Push int variable at index 2 in local variable table onto the stack top
0x1d	iload_3	... → ...,3	Push int variable at index 3 in local variable table onto the stack top
0x1e	lload_0	... → ...,0L	Push long variable at index 0 in local variable table onto the stack top
0x1f	lload_1	... → ...,1L	Push long variable at index 1 in local variable table onto the stack top
0x20	lload_2	... → ...,2L	Push long variable at index 2 in local variable table onto the stack top
0x21	lload_3	... → ...,3L	Push long variable at index 3 in local variable table onto the stack top
0x22	fload_0	... → ...,0.0f	Push float variable at index 0 in local variable table onto the stack top
0x23	fload_1	... → ...,1.0f	Push float variable at index 1 in local variable table onto the stack top
0x24	fload_2	... → ...,2.0f	Push float variable at index 2 in local variable table onto the stack top
0x25	fload_3	... → ...,3.0f	Push float variable at index 3 in local variable table onto the stack top
0x26	dload_0	... → ...,0.0	Push double variable at index 0 in local variable table onto the stack top
0x27	dload_1	... → ...,1.0	Push double variable at index 1 in local variable table onto the stack top
0x28	dload_2	... → ...,2.0	Push double variable at index 2 in local variable table onto the stack top
0x29	dload_3	... → ...,3.0	Push double variable at index 3 in local variable table onto the stack top
0x2a	aload_0	... → ...,aref	Push aref at index 0 in local variable table onto the stack top
0x2b	aload_1	... → ...,aref	Push aref at index 1 in local variable table onto the stack top
0x2c	aload_2	... → ...,aref	Push aref at index 2 in local variable table onto the stack top
0x2d	aload_3	... → ...,aref	Push aref at index 3 in local variable table onto the stack top
0x2e	iaload*	...,aaref,index → ...,v	Push int value at index (int) in array aaref onto the stack top
0x2f	laload	...,aaref,index → ...,v	Push long value at index (int) in array aaref onto the stack top
0x30	faload	...,aaref,index → ...,v	Push float value at index (int) in array aaref onto the stack top
0x31	daload	...,aaref,index → ...,v	Push double value at index (int) in array aaref onto the stack top
0x32	aaload	...,aaref,index → ...,v	Push reference value at index (int) in array aaref onto the stack top
0x33	baload	...,aaref,index → ...,v	Push byte or boolean value at index (int) in array aaref onto the stack top
0x34	caload	...,aaref,index → ...,v	Push char value at index (int) in array aaref onto the stack top
0x35	saload	...,aaref,index → ...,v	Push short value at index (int) in array aaref onto the stack top
0x36	istore,AA	...,v → ...,	Pop int value from stack top and store to local variable at index AA
0x37	lstore,AA	...,v → ...,	Pop long value from stack top and store to local variable at index AA
0x38	fstore,AA	...,v → ...,	Pop float value from stack top and store to local variable at index AA
0x39	dstore,AA	...,v → ...,	Pop double value from stack top and store to local variable at index AA
0x3a	astore,AA	...,v → ...,	Pop reference value from stack top and store to local variable at index AA
0x3b	istore_0	...,v → ...,	Pop int value from stack top and store to local variable at index 0
0x3c	istore_1	...,v → ...,	Pop int value from stack top and store to local variable at index 1
0x3d	istore_2	...,v → ...,	Pop int value from stack top and store to local variable at index 2
0x3e	istore_3	...,v → ...,	Pop int value from stack top and store to local variable at index 3
0x3f	lstore_0	...,v → ...,	Pop long value from stack top and store to local variable at index 0
0x40	lstore_1	...,v → ...,	Pop long value from stack top and store to local variable at index 1
0x41	lstore_2	...,v → ...,	Pop long value from stack top and store to local variable at index 2
0x42	lstore_3	...,v → ...,	Pop long value from stack top and store to local variable at index 3
0x43	fstore_0	...,v → ...,	Pop float value from stack top and store to local variable at index 0
0x44	fstore_1	...,v → ...,	Pop float value from stack top and store to local variable at index 1
0x45	fstore_2	...,v → ...,	Pop float value from stack top and store to local variable at index 2
0x46	fstore_3	...,v → ...,	Pop float value from stack top and store to local variable at index 3
0x47	dstore_0	...,v → ...,	Pop double value from stack top and store to local variable at index 0
0x48	dstore_1	...,v → ...,	Pop double value from stack top and store to local variable at index 1
0x49	dstore_2	...,v → ...,	Pop double value from stack top and store to local variable at index 2
0x4a	dstore_3	...,v → ...,	Pop double value from stack top and store to local variable at index 3
0x4b	astore_0	...,aref → ...,	Pop reference value from stack top and store to local variable at index 0
0x4c	astore_1	...,aref → ...,	Pop reference value from stack top and store to local variable at index 1
0x4d	astore_2	...,aref → ...,	Pop reference value from stack top and store to local variable at index 2
0x4e	astore_3	...,aref → ...,	Pop reference value from stack top and store to local variable at index 3
0x4f	iastore	...,aaref,index,v → ...,	Pop aaref, index (int), v (int) from stack top and store v into aaref[index]
0x50	lastore	...,aaref,index,v → ...,	Pop aaref, index (int), v (long) from stack top and store v into aaref[index]
0x51	fastore	...,aaref,index,v → ...,	Pop aaref, index (int), v (float) from stack top and store v into aaref[index]
0x52	dastore	...,aaref,index,v → ...,	Pop aaref, index (int), v (double) from stack top and store v into aaref[index]
0x53	aastore	...,aaref,index,v → ...,	Pop aaref, index (int), v (reference) from stack top and store v into aaref[index]
0x54	bastore	...,aaref,index,v → ...,	Pop aaref, index (int), v (byte) from stack top and store v into aaref[index]
0x55	castore	...,aaref,index,v → ...,	Pop aaref, index (int), v (char) from stack top and store v into aaref[index]
0x56	sastore	...,aaref,index,v → ...,	Pop aaref, index (int), v (short) from stack top and store v into aaref[index]
0x57	pop	...,v → ...,	Pop the top value from the stack
0x58	pop2	...,v2,v1 → ...,	Pop 1 or 2 values from the stack top
0x59	dup	...,v → ...,v,v	Duplicate the top value and push the duplicate onto the stack top
0x5a	dup_x1	...,v2,v1 → ...,v1,v2,v1	Duplicate the top value and insert the duplicate at the 2nd position from the top
0x5b	dup_x2	...,v3,v2,v1 → ...,v1,v3,v2,v1	Duplicate the top value and insert the duplicate at the 2nd or 3rd position from the top
0x5c	dup2	...,v2,v1 → ...,v2,v1,v2,v1	Duplicate the top 1 or 2 values and push the duplicates onto the stack in original order
0x5d	dup2_x1	...,v3,v2,v1 → ...,v2,v1,v3,v2,v1	Duplicate the top 1 or 2 values and insert the duplicates at the 2nd or 3rd position from the top in original order
0x5e	dup2_x2	...,v4,v3,v2,v1 → ...,v2,v1,v4,v3,v2,v1	Duplicate the top 1 or 2 values and insert the duplicates at the 2nd, 3rd, or 4th position from the top in original order
0x5f	swap	...,v2,v1 → ...,v1,v2	Swap the top two values on the stack
0x60	iadd	...,v1,v2 → ...,result	Add the top two int values and push the result onto the stack top
0x61	ladd	...,v1,v2 → ...,result	Add the top two long values and push the result onto the stack top
0x62	fadd	...,v1,v2 → ...,result	Add the top two float values and push the result onto the stack top
0x63	dadd	...,v1,v2 → ...,result	Add the top two double values and push the result onto the stack top
0x64	isub	...,v1,v2 → ...,result	Subtract the top int value from the second top int value and push the result onto the stack top
0x65	lsub	...,v1,v2 → ...,result
0x66	fsub	...,v1,v2 → ...,result
0x67	dsub	...,v1,v2 → ...,result
0x68	imul	...,v1,v2 → ...,result
0x69	lmul	...,v1,v2 → ...,result
0x6a	fmul	...,v1,v2 → ...,result
0x6b	dmul	...,v1,v2 → ...,result
0x6c	idiv	...,v1,v2 → ...,result
0x6d	ldiv	...,v1,v2 → ...,result
0x6e	fdiv	...,v1,v2 → ...,result
0x6f	ddiv	...,v1,v2 → ...,result
0x70	irem	...,v1,v2 → ...,result
0x71	lrem	...,v1,v2 → ...,result
0x72	frem	...,v1,v2 → ...,result
0x73	drem	...,v1,v2 → ...,result
0x74	ineg	...,v1,v2 → ...,result
0x75	lneg	...,v1,v2 → ...,result
0x76	fneg	...,v1,v2 → ...,result
0x77	dneg	...,v1,v2 → ...,result
0x78	ishl	...,v1,v2 → ...,result
0x79	lshl	...,v1,v2 → ...,result
0x7a	ishr	...,v1,v2 → ...,result
0x7b	lshr	...,v1,v2 → ...,result
0x7c	iushr	...,v1,v2 → ...,result
0x7d	lushr	...,v1,v2 → ...,result
0x7e	iand	...,v1,v2 → ...,result
0x7f	land	...,v1,v2 → ...,result
0x80	ior	...,v1,v2 → ...,result
0x81	lor	...,v1,v2 → ...,result
0x82	ixor	...,v1,v2 → ...,result
0x83	lxor	...,v1,v2 → ...,result
0x84	iinc,AA,+BB[^5]	...,v → ...,result
0x85	i2l	...,v → ...,result
0x86	i2f	...,v → ...,result
0x87	i2d	...,v → ...,result
0x88	l2i	...,v → ...,result
0x89	l2f	...,v → ...,result
0x8a	l2d	...,v → ...,result
0x8b	f2i	...,v → ...,result
0x8c	f2l	...,v → ...,result
0x8d	f2d	...,v → ...,result
0x8e	d2i	...,v → ...,result
0x8f	d2l	...,v → ...,result
0x90	d2f	...,v → ...,result
0x91	i2b	...,v → ...,result
0x92	i2c	...,v → ...,result
0x93	i2s	...,v → ...,result
0x94	lcmp	...,v1,v2 → ...,result
0x95	fcmpl	...,v1,v2 → ...,result
0x96	fcmpg	...,v1,v2 → ...,result
0x97	dcmpl	...,v1,v2 → ...,result
0x98	dcmpg	...,v1,v2 → ...,result
0x99	ifeq,+AAAA	...,v1,v2 → ...,result
0x9a	ifne,+AAAA	...,v1,v2 → ...,result
0x9b	iflt,+AAAA	...,v1,v2 → ...,result
0x9c	ifge,+AAAA	...,v1,v2 → ...,result
0x9d	ifgt,+AAAA	...,v1,v2 → ...,result
0x9e	ifle,+AAAA	...,v1,v2 → ...,result
0x9f	if_icmpeq,+AAAA	...,v1,v2 → ...,result
0xa7	goto,+AAAA
0xa0	if_icmpne,+AAAA	...,v1,v2 → ...,result
0xa1	if_icmplt,+AAAA	...,v1,v2 → ...,result
0xa2	if_icmpge,+AAAA	...,v1,v2 → ...,result
0xa3	if_icmpgt,+AAAA	...,v1,v2 → ...,result
0xa4	if_icmple,+AAAA	...,v1,v2 → ...,result
0xa5	if_acmpeq,+AAAA	...,v1,v2 → ...,result
0xa6	if_acmpne,+AAAA	...,v1,v2 → ...,result
0xa8	jsr,+AAAA	... → ...,address
0xa9	ret,AA	No change
0xaa	tableswitch [0]{0,3} +AAAAAAAA +BBBBBBBB +CCCCCCCC {+DDDDDDDD..+NNNNNNNN}	...,index → ...
0xab	lookupswitch [0]{0,3} +AAAAAAAA +BBBBBBBB +CCCCCCCC {+DDDDDDDD..+NNNNNNNN}	...,key → ...
0xac	ireturn	...,v → [empty]
0xad	lreturn	...,v → [empty]
0xae	freturn	...,v → [empty]
0xaf	dreturn	...,v → [empty]
0xb0	areturn	...,v → [empty]
0xb1	return	...,v → [empty]
0xb2	getstatic,AAAA	... → ...,v
0xb3	putstatic,AAAA	... → ...,v
0xb4	getfield,AAAA	...,aref → ...,v
0xb5	putfield,AAAA	...,aref → ...,v
0xb6	invokevirtual,AAAA	...,aref,[arg1,[arg2...]] → ...
0xb7	invokespecial,AAAA	...,aref,[arg1,[arg2...]] → ...
0xb8	invokestatic,AAAA	...,[arg1,[arg2...]] → ...
0xb9	invokeinterface,AAAA,BB,00	...,aref,[arg1,[arg2...]] → ...
0xba	invokedynamic,AAAA,00,00	...,[arg1,[arg2...]] → ...
0xbb	new,AAAA	... → ...,aref
0xbc	newarray,AA	...,count → ...,aaref
0xbd	anewarray,AAAA	...,count → ...,aaref
0xbe	arraylength	...,aaref → ...,length
0xbf	athrow	...,aref → ...,aref
0xc0	checkcast,AAAA	...,aref → ...,aref
0xc1	instanceof,AAAA	...,aref → ...,result
0xc2	monitorenter	...,aref → ...
0xc3	monitorexit	...,aref → ...
0xc4	wide,<opcode>,AAAA,[BBBB]	Same as original instruction
0xc5	multianewarray,AAAA,BB	...,count1,[count2,...] → ...,aaref
0xc6	ifnull,+AAAA	...,v → ...
0xc7	ifnonnull,+AAAA	...,v → ...
0xc8	goto_w,+AAAAAAAA	No change
0xc9	jsr_w,+AAAAAAAA	... → ...,address
0xca	breakpoint		Reserved for Java debugger
0xcb	...		Reserved
...	...		Reserved
0xfd	...		Reserved
0xfe	impdep1		Reserved for debugger
0xff	impdep2		Reserved for debugger

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[^1]: A stack structure used for storing operands. JVM instructions take operands from the stack during execution and push results back to the stack top. The stack is also used to store method parameters (the first parameter of non-static methods is the this reference) and method return results. [^2]: AA represents 1 unsigned byte (unsigned byte) [^3]: Data that is directly encoded in the instruction and used as an operand. For example: bipush 0x10, where 0x10 is directly encoded into the instruction sequence, which is an immediate value. [^4]: AAAA represents 1 unsigned 16-bit integer (unsigned 16-bit int) [^5]: +BB represents 1 signed byte (signed byte)