delay instruction ==>
delayed control-transfer
<SPARC, programming> A technique used on the SPARC to reduce the effect
of pipeline breaks by executing the instruction after a branch instruction (the
"delay instruction" in the "delay slot"). If there is no useful instruction
which can be placed in the delay slot then the "annul bit" on the control
transfer instruction can be set, preventing execution of the delay instruction
(unless the control transfer is conditional and is taken).
Annulled branches are indicated in SPARC assembler language by appending ",A" to
the operation code. For example,
LOOP: ...
CMP %L0,10
BLE,A LOOP
ADD %L2, %L3, #L4
If the delay instruction is also a control transfer instruction then it
gets more complicated. Both control transfer
instructions are executed (but not the following
instruction) and, assuming they are both taken,
control is transferred briefly to the destination of
the first and then immediately to the destination of
the second.
(2001-06-26)
Nearby terms:
dehose « DEK « Delaunay triangulation « delayed
control-transfer » delay instruction » delay
slot » delete
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