if-<test>z
Purpose
Branch to the given destination if the given register's value compares with 0
as specified.
Note: The branch offset may 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.)
Details
| Op & Format |
Mnemonic / Syntax |
Arguments |
| 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) |
Constraints
-
A must be a valid register index for the current stackframe.
-
Register vA must not contain a reference value.
-
Register vA must not be part of a register pair.
-
Register vA must not contain a floating point value (???).
-
B must not be 0.
Behavior
-
The value of register vA is compared to zero according to the <test>
condition. Two results are possible:
-
The condition holds. The value of B is used as a signed offset to the
address of the if-<test>z instruction. Execution continues at the
resulting address.
-
The condition does not hold. Execution continues at the instruction
following the if-<test>z instruction.
Exceptions
None.