VM Spec

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A B C D F G I J L M N P R S T W

## d2f

Operation

> Convert `double` to `float`

Format

> d2f

Forms

> d2f = 144 (0x90)

Operand Stack

> ..., value ..., result

Description

> The value on the top of the operand stack must be of type `double`. It is popped from the operand stack and undergoes value set conversion (§3.8.3) resulting in value'. Then value' is converted to a `float` result using IEEE 754 round to nearest mode. The result is pushed onto the operand stack.

> Where an d2f instruction is FP-strict (§3.8.2), the result of the conversion is always rounded to the nearest representable value in the float value set (§3.3.2).

> Where an d2f instruction is not FP-strict, the result of the conversion may be taken from the float-extended-exponent value set (§3.3.2); it is not necessarily rounded to the nearest representable value in the float value set.

> A finite value' too small to be represented as a `float` is converted to a zero of the same sign; a finite value' too large to be represented as a `float` is converted to an infinity of the same sign. A `double` NaN is converted to a `float` NaN.

Notes

> The d2f instruction performs a narrowing primitive conversion (§2.6.3). It may lose information about the overall magnitude of value' and may also lose precision.

## d2i

Operation

> Convert `double` to `int`

Format

> d2i

Forms

> d2i = 142 (0x8e)

Operand Stack

> ..., value ..., result

Description

> The value on the top of the operand stack must be of type `double`. It is popped from the operand stack and undergoes value set conversion (§3.8.3) resulting in value'. Then value' is converted to an `int`. The result is pushed onto the operand stack:

- If the value' is NaN, the result of the conversion is an `int` 0.

- Otherwise, if the value' is not an infinity, it is rounded to an integer value V, rounding towards zero using IEEE 754 round towards zero mode. If this integer value V can be represented as an `int`, then the result is the `int` value V.

- Otherwise, either the value' must be too small (a negative value of large magnitude or negative infinity), and the result is the smallest representable value of type `int`, or the value' must be too large (a positive value of large magnitude or positive infinity), and the result is the largest representable value of type `int`.

Notes

> The d2i instruction performs a narrowing primitive conversion (§2.6.3). It may lose information about the overall magnitude of value' and may also lose precision.

## d2l

Operation

> Convert `double` to `long`

Format

> d2l

Forms

> d2l = 143 (0x8f)

Operand Stack

> ..., value ..., result

Description

> The value on the top of the operand stack must be of type `double`. It is popped from the operand stack and undergoes value set conversion (§3.8.3) resulting in value'. Then value' is converted to a `long`. The result is pushed onto the operand stack:

- If the value' is NaN, the result of the conversion is a `long` 0.

- Otherwise, if the value' is not an infinity, it is rounded to an integer value V, rounding towards zero using IEEE 754 round towards zero mode. If this integer value V can be represented as a `long`, then the result is the `long` value V.

- Otherwise, either the value' must be too small (a negative value of large magnitude or negative infinity), and the result is the smallest representable value of type `long`, or the value' must be too large (a positive value of large magnitude or positive infinity), and the result is the largest representable value of type `long`.

Notes

> The d2l instruction performs a narrowing primitive conversion (§2.6.3). It may lose information about the overall magnitude of value' and may also lose precision.

## dadd

Operation

> Add `double`

Format

> dadd

Forms

> dadd = 99 (0x63)

Operand Stack

> ..., value1, value2 ..., result

Description

> Both value1 and value2 must be of type `double`. The values are popped from the operand stack and undergo value set conversion (§3.8.3), resulting in value1' and value2'. The `double` result is value1' + value2'. The result is pushed onto the operand stack.

> The result of a dadd instruction is governed by the rules of IEEE arithmetic:

- If either value1' or value2' is NaN, the result is NaN.

- The sum of two infinities of opposite sign is NaN.

- The sum of two infinities of the same sign is the infinity of that sign.

- The sum of an infinity and any finite value is equal to the infinity.

- The sum of two zeroes of opposite sign is positive zero.

- The sum of two zeroes of the same sign is the zero of that sign.

- The sum of a zero and a nonzero finite value is equal to the nonzero value.

- The sum of two nonzero finite values of the same magnitude and opposite sign is positive zero.

- In the remaining cases, where neither operand is an infinity, a zero, or NaN and the values have the same sign or have different magnitudes, the sum is computed and rounded to the nearest representable value using IEEE 754 round to nearest mode. If the magnitude is too large to represent as a `double`, we say the operation overflows; the result is then an infinity of appropriate sign. If the magnitude is too small to represent as a `double`, we say the operation underflows; the result is then a zero of appropriate sign.

> The Java virtual machine requires support of gradual underflow as defined by IEEE 754. Despite the fact that overflow, underflow, or loss of precision may occur, execution of a dadd instruction never throws a runtime exception.

## daload

Operation

> Load `double` from array

Format

> daload

Forms

> daload = 49 (0x31)

Operand Stack

> ..., arrayref, index ..., value

Description

> The arrayref must be of type `reference` and must refer to an array whose components are of type `double`. The index must be of type `int`. Both arrayref and index are popped from the operand stack. The `double` value in the component of the array at index is retrieved and pushed onto the operand stack.

Runtime Exceptions

> If arrayref is `null`, daload throws a `NullPointerException`.

> Otherwise, if index is not within the bounds of the array referenced by arrayref, the daload instruction throws an `ArrayIndexOutOfBoundsException`.

## dastore

Operation

> Store into `double` array

Format

> dastore

Forms

> dastore = 82 (0x52)

Operand Stack

> ..., arrayref, index, value ...

Description

> The arrayref must be of type `reference` and must refer to an array whose components are of type `double`. The index must be of type `int`, and value must be of type `double`. The arrayref, index, and value are popped from the operand stack. The `double` value undergoes value set conversion (§3.8.3), resulting in value', which is stored as the component of the array indexed by index.

Runtime Exceptions

> If arrayref is `null`, dastore throws a `NullPointerException`.

> Otherwise, if index is not within the bounds of the array referenced by arrayref, the dastore instruction throws an `ArrayIndexOutOfBounds` `Exception`.

## dcmp<op>

Operation

> Compare `double`

Format

> dcmp<op>

Forms

> dcmpg = 152 (0x98) dcmpl = 151 (0x97)

Operand Stack

> ..., value1, value2 ..., result

Description

> Both value1 and value2 must be of type `double`. The values are popped from the operand stack and undergo value set conversion (§3.8.3), resulting in value1' and value2'. A floating-point comparison is performed:

- If value1' is greater than value2', the `int` value 1 is pushed onto the operand stack.

- Otherwise, if value1' is equal to value2', the `int` value 0 is pushed onto the operand stack.

- Otherwise, if value1' is less than value2', the `int` value -1 is pushed onto the operand stack.

· Otherwise, at least one of value1' or value2' is NaN. The dcmpg instruction pushes the `int` value 1 onto the operand stack and the dcmpl instruction pushes the `int` value -1 onto the operand stack.

> Floating-point comparison is performed in accordance with IEEE 754. All values other than NaN are ordered, with negative infinity less than all finite values and positive infinity greater than all finite values. Positive zero and negative zero are considered equal.

Notes

> The dcmpg and dcmpl instructions differ only in their treatment of a comparison involving NaN. NaN is unordered, so any `double` comparison fails if either or both of its operands are NaN. With both dcmpg and dcmpl available, any `double` comparison may be compiled to push the same result onto the operand stack whether the comparison fails on non-NaN values or fails because it encountered a NaN. For more information, see Section 7.5, "More Control Examples."

## dconst_<d>

Operation

> Push `double`

Format

> dconst_<d>

Forms

> dconst_0 = 14 (0xe) dconst_1 = 15 (0xf)

Operand Stack

> ... ..., <d>

Description

> Push the `double` constant <d> (0.0 or 1.0) onto the operand stack.

## ddiv

Operation

> Divide `double`

Format

> ddiv

Forms

> ddiv = 111 (0x6f)

Operand Stack

> ..., value1, value2 ..., result

Description

> Both value1 and value2 must be of type `double`. The values are popped from the operand stack and undergo value set conversion (§3.8.3), resulting in value1' and value2'. The `double` result is value1' / value2'. The result is pushed onto the operand stack.

> The result of a ddiv instruction is governed by the rules of IEEE arithmetic:

- If either value1' or value2' is NaN, the result is NaN.

- If neither value1' nor value2' is NaN, the sign of the result is positive if both values have the same sign, negative if the values have different signs.

- Division of an infinity by an infinity results in NaN.

- Division of an infinity by a finite value results in a signed infinity, with the sign-producing rule just given.

- Division of a finite value by an infinity results in a signed zero, with the sign-producing rule just given.

- Division of a zero by a zero results in NaN; division of zero by any other finite value results in a signed zero, with the sign-producing rule just given.

- Division of a nonzero finite value by a zero results in a signed infinity, with the sign-producing rule just given.

- In the remaining cases, where neither operand is an infinity, a zero, or NaN, the quotient is computed and rounded to the nearest `double` using IEEE 754 round to nearest mode. If the magnitude is too large to represent as a `double`, we say the operation overflows; the result is then an infinity of appropriate sign. If the magnitude is too small to represent as a `double`, we say the operation underflows; the result is then a zero of appropriate sign.

> The Java virtual machine requires support of gradual underflow as defined by IEEE 754. Despite the fact that overflow, underflow, division by zero, or loss of precision may occur, execution of a ddiv instruction never throws a runtime exception.

## dload

Operation

> Load `double` from local variable

Format

> dload
> index

Forms

> dload = 24 (0x18)

Operand Stack

> ... ..., value

Description

> The index is an unsigned byte. Both index and index + 1 must be indices into the local variable array of the current frame (§3.6). The local variable at index must contain a `double`. The value of the local variable at index is pushed onto the operand stack.

Notes

> The dload opcode can be used in conjunction with the wide instruction to access a local variable using a two-byte unsigned index.

## dload_<n>

Operation

> Load `double` from local variable

Format

> dload_<n>

Forms

> dload_0 = 38 (0x26) dload_1 = 39 (0x27) dload_2 = 40 (0x28) dload_3 = 41 (0x29)

Operand Stack

> ... ..., value

Description

> Both <n> and <n> + 1 must be indices into the local variable array of the current frame (§3.6). The local variable at <n> must contain a `double`. The value of the local variable at <n> is pushed onto the operand stack.

Notes

> Each of the dload_<n> instructions is the same as dload with an index of <n>, except that the operand <n> is implicit.

## dmul

Operation

> Multiply `double`

Format

> dmul

Forms

> dmul = 107 (0x6b)

Operand Stack

> ..., value1, value2 ..., result

Description

> Both value1 and value2 must be of type `double`. The values are popped from the operand stack and undergo value set conversion (§3.8.3), resulting in value1' and value2'. The `double` result is value1' * value2'. The result is pushed onto the operand stack.

> The result of a dmul instruction is governed by the rules of IEEE arithmetic:

- If either value1' or value2' is NaN, the result is NaN.

- If neither value1' nor value2' is NaN, the sign of the result is positive if both values have the same sign and negative if the values have different signs.

- Multiplication of an infinity by a zero results in NaN.

- Multiplication of an infinity by a finite value results in a signed infinity, with the sign-producing rule just given.

- In the remaining cases, where neither an infinity nor NaN is involved, the product is computed and rounded to the nearest representable value using IEEE 754 round to nearest mode. If the magnitude is too large to represent as a `double`, we say the operation overflows; the result is then an infinity of appropriate sign. If the magnitude is too small to represent as a `double`, we say the operation underflows; the result is then a zero of appropriate sign.

> The Java virtual machine requires support of gradual underflow as defined by IEEE 754. Despite the fact that overflow, underflow, or loss of precision may occur, execution of a dmul instruction never throws a runtime exception.

## dneg

Operation

> Negate `double`

Format

> dneg

Forms

> dneg = 119 (0x77)

Operand Stack

> ..., value ..., result

Description

> The value must be of type `double`. It is popped from the operand stack and undergoes value set conversion (§3.8.3), resulting in value'. The `double` result is the arithmetic negation of value'. The result is pushed onto the operand stack.

> For `double` values, negation is not the same as subtraction from zero. If `x` is +`0.0`, then `0.0`-`x` equals +`0.0`, but -`x` equals -`0.0`. Unary minus merely inverts the sign of a `double`.

> Special cases of interest:

- If the operand is NaN, the result is NaN (recall that NaN has no sign).

- If the operand is an infinity, the result is the infinity of opposite sign.

- If the operand is a zero, the result is the zero of opposite sign.

## drem

Operation

> Remainder `double`

Format

> drem

Forms

> drem = 115 (0x73)

Operand Stack

> ..., value1, value2 ..., result

Description

> Both value1 and value2 must be of type `double`. The values are popped from the operand stack and undergo value set conversion (§3.8.3), resulting in value1' and value2'. The result is calculated and pushed onto the operand stack as a `double`.

> The result of a drem instruction is not the same as that of the so-called remainder operation defined by IEEE 754. The IEEE 754 "remainder" operation computes the remainder from a rounding division, not a truncating division, and so its behavior is not analogous to that of the usual integer remainder operator. Instead, the Java virtual machine defines drem to behave in a manner analogous to that of the Java virtual machine integer remainder instructions (irem and lrem); this may be compared with the C library function `fmod`.

> The result of a drem instruction is governed by these rules:

- If either value1' or value2' is NaN, the result is NaN.

- If neither value1' nor value2' is NaN, the sign of the result equals the sign of the dividend.

- If the dividend is an infinity or the divisor is a zero or both, the result is NaN.

- If the dividend is finite and the divisor is an infinity, the result equals the dividend.

- If the dividend is a zero and the divisor is finite, the result equals the dividend.

- In the remaining cases, where neither operand is an infinity, a zero, or NaN, the floating-point remainder result from a dividend value1' and a divisor value2' is defined by the mathematical relation result = value1' - (value2' * q), where q is an integer that is negative only if value1' / value2' is negative, and positive only if value1' / value2' is positive, and whose magnitude is as large as possible without exceeding the magnitude of the true mathematical quotient of value1' and value2'.

> Despite the fact that division by zero may occur, evaluation of a drem instruction never throws a runtime exception. Overflow, underflow, or loss of precision cannot occur.

Notes

> The IEEE 754 remainder operation may be computed by the library routine `Math.IEEEremainder`.

## dreturn

Operation

> Return `double` from method

Format

> dreturn

Forms

> dreturn = 175 (0xaf)

Operand Stack

> ..., value [empty]

Description

> The current method must have return type `double`. The value must be of type `double`. If the current method is a `synchronized` method, the monitor acquired or reentered on invocation of the method is released or exited (respectively) as if by execution of a monitorexit instruction. If no exception is thrown, value is popped from the operand stack of the current frame (§3.6) and undergoes value set conversion (§3.8.3), resulting in value'. The value' is pushed onto the operand stack of the frame of the invoker. Any other values on the operand stack of the current method are discarded.

> The interpreter then returns control to the invoker of the method, reinstating the frame of the invoker.

Runtime Exceptions

> If the current method is a `synchronized` method and the current thread is not the owner of the monitor acquired or reentered on invocation of the method, dreturn throws an `IllegalMonitorStateException`. This can happen, for example, if a `synchronized` method contains a monitorexit instruction, but no monitorenter instruction, on the object on which the method is synchronized.

> Otherwise, if the virtual machine implementation enforces the rules on structured use of locks described in §8.13 and if the first of those rules is violated during invocation of the current method, then dreturn throws an `IllegalMonitorStateException`.

## dstore

Operation

> Store `double` into local variable

Format

> dstore
> index

Forms

> dstore = 57 (0x39)

Operand Stack

> ..., value ...

Description

> The index is an unsigned byte. Both index and index + 1 must be indices into the local variable array of the current frame (§3.6). The value on the top of the operand stack must be of type `double`. It is popped from the operand stack and undergoes value set conversion (§3.8.3), resulting in value'. The local variables at index and index + 1 are set to value'.

Notes

> The dstore opcode can be used in conjunction with the wide instruction to access a local variable using a two-byte unsigned index.

## dstore_<n>

Operation

> Store `double` into local variable

Format

> dstore_<n>

Forms

> dstore_0 = 71 (0x47) dstore_1 = 72 (0x48) dstore_2 = 73 (0x49) dstore_3 = 74 (0x4a)

Operand Stack

> ..., value ...

Description

> Both <n> and <n> + 1 must be indices into the local variable array of the current frame (§3.6). The value on the top of the operand stack must be of type `double`. It is popped from the operand stack and undergoes value set conversion (§3.8.3), resulting in value'. The local variables at <n> and <n> + 1 are set to value'.

Notes

> Each of the dstore_<n> instructions is the same as dstore with an index of <n>, except that the operand <n> is implicit.

## dsub

Operation

> Subtract `double`

Format

> dsub

Forms

> dsub = 103 (0x67)

Operand Stack

> ..., value1, value2 ..., result

Description

> Both value1 and value2 must be of type `double`. The values are popped from the operand stack and undergo value set conversion (§3.8.3), resulting in value1' and value2'. The `double` result is value1' - value2'. The result is pushed onto the operand stack.

> For `double` subtraction, it is always the case that `a`-`b` produces the same result as `a`+(-`b`). However, for the dsub instruction, subtraction from zero is not the same as negation, because if `x` is +`0.0`, then `0.0`-`x` equals +`0.0`, but -`x` equals -`0.0`.

> The Java virtual machine requires support of gradual underflow as defined by IEEE 754. Despite the fact that overflow, underflow, or loss of precision may occur, execution of a dsub instruction never throws a runtime exception.

## dup

Operation

> Duplicate the top operand stack value

Format

> dup

Forms

> dup = 89 (0x59)

Operand Stack

> ..., value ..., value, value

Description

> Duplicate the top value on the operand stack and push the duplicated value onto the operand stack.

> The dup instruction must not be used unless value is a value of a category 1 computational type (§3.11.1).

## dup_x1

Operation

> Duplicate the top operand stack value and insert two values down

Format

> dup_x1

Forms

> dup_x1 = 90 (0x5a)

Operand Stack

> ..., value2, value1 ..., value1, value2, value1

Description

> Duplicate the top value on the operand stack and insert the duplicated value two values down in the operand stack.

> The dup_x1 instruction must not be used unless both value1 and value2 are values of a category 1 computational type (§3.11.1).

## dup_x2

Operation

> Duplicate the top operand stack value and insert two or three values down

Format

> dup_x2

Forms

> dup_x2 = 91 (0x5b)

Operand Stack

> Form 1:

> ..., value3, value2, value1 ..., value1, value3, value2, value1

> where value1, value2, and value3 are all values of a category 1 computational type (§3.11.1).

> Form 2:

> ..., value2, value1 ..., value1, value2, value1

> where value1 is a value of a category 1 computational type and value2 is a value of a category 2 computational type (§3.11.1).

Description

> Duplicate the top value on the operand stack and insert the duplicated value two or three values down in the operand stack.

## dup2

Operation

> Duplicate the top one or two operand stack values

Format

> dup2

Forms

> dup2 = 92 (0x5c)

Operand Stack

> Form 1:

> ..., value2, value1 ..., value2, value1, value2, value1

> where both value1 and value2 are values of a category 1 computational type (§3.11.1).

> Form 2:

> ..., value ..., value, value

> where value is a value of a category 2 computational type (§3.11.1).

Description

> Duplicate the top one or two values on the operand stack and push the duplicated value or values back onto the operand stack in the original order.

## dup2_x1

Operation

> Duplicate the top one or two operand stack values and insert two or three values down

Format

> dup2_x1

Forms

> dup2_x1 = 93 (0x5d)

Operand Stack

> Form 1:

> ..., value3, value2, value1 ..., value2, value1, value3, value2, value1

> where value1, value2, and value3 are all values of a category 1 computational type (§3.11.1).

> Form 2:

> ..., value2, value1 ..., value1, value2, value1

> where value1 is a value of a category 2 computational type and value2 is a value of a category 1 computational type (§3.11.1).

Description

> Duplicate the top one or two values on the operand stack and insert the duplicated values, in the original order, one value beneath the original value or values in the operand stack.

## dup2_x2

Operation

> Duplicate the top one or two operand stack values and insert two, three, or four values down

Format

> dup2_x2

Forms

> dup2_x2 = 94 (0x5e)

Operand Stack

> Form 1:

> ..., value4, value3, value2, value1 ..., value2, value1, value4, value3, value2, value1

> where value1, value2, value3, and value4 are all values of a category 1 computational type (§3.11.1).

> Form 2:

> ..., value3, value2, value1 ..., value1, value3, value2, value1

> where value1 is a value of a category 2 computational type and value2 and value3 are both values of a category 1 computational type (§3.11.1).

> Form 3:

> ..., value3, value2, value1 ..., value2, value1, value3, value2, value1

> where value1 and value2 are both values of a category 1 computational type and value3 is a value of a category 2 computational type (§3.11.1).

> Form 4:

> ..., value2, value1 ..., value1, value2, value1

> where value1 and value2 are both values of a category 2 computational type (§3.11.1).

Description

> Duplicate the top one or two values on the operand stack and insert the duplicated values, in the original order, into the operand stack.

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The JavaTM Virtual Machine Specification
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