dload : retrieve double from local variable : index : visitVarInsn()

Description

dload retrieves a double-precision floating point number held in local variable and pushes it onto the operand stack.

Since double-precision floats 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 double. So dload <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 double.

Remember that attempting to treat two-word values as two independent single-word values will produce a verification error. So trying to retrieve <varnum> or <varnum> + 1 independently (e.g. iload <varnum>) will produce a verification error. Similarly, if you store a non-double value in <varnum>, then <varnum> + 1 becomes invalidated until a new value is stored in it.

Example

dload 2         ; push the double held in local variables 2 and 3 onto the stack

See also

fload iload aload lload wide

Stack

Before	After
...	result-word1
	result-word2
	...

Bytecode

Type	Description
u1	dload opcode = 0x18 (24)
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	dload opcode = 0x18 (24)
u2	<varnum>