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In a computer instruction set architecture (ISA), an execute instruction is a machine language instruction which treats data as a machine instruction and executes it. It can be considered a fourth mode of instruction sequencing after ordinary sequential execution , branching , and interrupting . [ 1 ]
[a] Branch (or branching, branched) may also refer to the act of switching execution to a different instruction sequence as a result of executing a branch instruction. Branch instructions are used to implement control flow in program loops and conditionals (i.e., executing a particular sequence of instructions only if certain conditions are ...
An indirect branch (also known as a computed jump, indirect jump and register-indirect jump) is a type of program control instruction present in some machine language instruction sets. Rather than specifying the address of the next instruction to execute , as in a direct branch , the argument specifies where the address is located.
Thus, instead of using a conditional branch to select an instruction or a sequence of instructions to execute based on the predicate that controls whether the branch occurs, the instructions to be executed are associated with that predicate, so that they will be executed, or not executed, based on whether that predicate is true or false. [1]
This sometimes involves an addition of the offset onto the program counter register (unless, in some instruction sets, the branch instruction allows an extra index register). This final address usually points to one of a sequence of unconditional branch instructions, or the instruction immediately beyond them (saving one entry in the table).
The programmer can load the base register from a register known to contain the entry point address, typically R15, or can use the BALR (Branch And Link, Register form) instruction (with a R2 Value of 0) to store the next sequential instruction's address into the base register, which was then coded explicitly or implicitly in each instruction ...
If it is zero, execution continues with the next instruction. One more sequencing option allowed on a branch instruction is the execute (XQ) option. When specified, the single instruction at the branch address is executed, but then execution continues after the original branch instruction. The IX option can be used with the XQ option.
In computer architecture, a branch target predictor is the part of a processor that predicts the target, i.e., the address of the instruction that is executed next, of a taken conditional branch or unconditional branch instruction before the target of the branch instruction is computed by the execution unit of the processor. Branch target ...