Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1044

hint — Performance Hint
( ) hint
Format: qp imm
(qp) hint.i
(qp) hint.b
(qp) hint.m
(qp) hint.f
(qp) hint.x
Provides a performance hint to the processor about the program being executed. It has
Description:
no effect on architectural machine state, and operates as a nop instruction except for its
performance effects.
The immediate,
bundle contains the upper 41 bits of
This instruction has five forms, each of which can be executed only on a particular
execution unit type. The pseudo-op can be used if the unit type to execute on is
unimportant.
Table 2-31.
imm or imm
21
0x0
0x1
0x02-0x3f
other
Operation: if (PR[qp]) {
if (x_unit_form)
hint = imm
else // i_unit_form || b_unit_form || b_unit_form || f_unit_form
hint = imm
if (is_supported_hint(hint))
execute_hint(hint);
}
None
Interruptions:
Volume 3: Instruction Reference
21
imm
21
imm
21
imm
21
imm
21
imm
62
or , specifies the hint. For the x_unit_form, the L slot of the
imm imm
21 62
Hint Immediates
Mnemonic
62
@pause Indicates to the processor that the currently executing stream is waiting,
spinning, or performing low priority tasks. This hint can be used by the
processor to allocate more resources or time to another executing stream
on the same processor. For the case where the currently executing stream
is spinning or otherwise waiting for a particular address in memory to
change, an advanced load to that address should be done before
executing a hint @pause ; this hint can be used by the processor to
resume normal allocation of resources or time to the currently executing
stream at the point when some other stream stores to that address.
@priority Indicates to the processor that the currently executing stream is performing
a high priority task. This hint can be used by the processor to allocate more
resources or time to this stream. Implementations will ensure that such
increased allocation is only temporary, and that repeated use of this hint
will not impair longer-term fairness of allocation.
These values are available for future architected extensions and will
execute as a nop on all current processors. Use of these values may
cause unexpected performance issues on future processors and should
not be used.
Implementation specific. Performs an implementation-specific hint action.
Consult processor model-specific documentation for details.
;
62
;
21
.
imm
62
Hint
hint
pseudo-op
i_unit_form I18
b_unit_form B9
m_unit_form M48
f_unit_form F16
x_unit_form X5
3:145