Load long
from local variable
Bytecode
For local variable numbers in the range 0-255, use:
Type | Description |
u1 | lload opcode = 0x16 (22) |
u1 | <varnum> |
There is also a wide format for this instruction, which supports access to all local variables from 0 to 65535:
Type | Description |
u1 | wide opcode = 0xC4 (196) |
u1 | lload opcode = 0x16 (22) |
u2 | <varnum> |
Stack ... => ..., value.word1, value.word2
Description
lload retrieves a long integer held in a local variable and
pushes it onto the operand stack.
Since long integers are 64-bits wide, and each local variable only holds up to 32 bits, Java uses two consecutive local variables, <varnum> and <varnum> + 1 to store a long. So lload <varnum> actually places the values of both <varnum> and <varnum> + 1 onto the operand stack.
Both <varnum> and <varnum> + 1 must be valid local variable numbers in the current frame, and together they must be holding a long.
Remember that attempting to treat two-word values as two independent single-word values will produce a verification error. So trying to retrieve either <varnum> or <varnum> + 1 independently (e.g. using iload <varnum>) will produce a verification error. Similarly, if you store a non-long value in <varnum>, then <varnum> + 1 becomes invalidated until a new value is stored in it.
Example
lconst_1 ; push the long integer 1 onto the stack lstore 3 ; pop 1 off of the stack and store in local variables 3 and 4 lload 3 ; push the value from local variables 3 and 4 (the long integer 1) ; back onto the stack
Notes
The lload opcode can be used in conjunction with the wide
instruction to access a local variable using a two-byte unsigned index.