Volume 3: Instruction Reference
3:145
hint
hint — Performance Hint
Format:
(
qp
) hint
imm
21
pseudo-op
(
qp
) hint.i
imm
21
i_unit_form
(
qp
) hint.b
imm
21
b_unit_form
(
qp
) hint.m
imm
21
m_unit_form
(
qp
) hint.f
imm
21
f_unit_form
(
qp
) hint.x
imm
62
x_unit_form
Description:
Provides a performance hint to the processor about the program being executed. It has
no effect on architectural machine state, and operates as a
nop
instruction except for its
performance effects.
The immediate,
imm
21
or
imm
62
, specifies the hint. For the x_unit_form, the L slot of the
bundle contains the upper 41 bits of
imm
62
.
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.
Operation:
if (PR[
qp
]) {
if (x_unit_form)
hint =
imm
62
;
else // i_unit_form || b_unit_form || b_unit_form || f_unit_form
hint =
imm
21
;
if (is_supported_hint(hint))
execute_hint(hint);
}
Interruptions:
None
Table 2-31.
Hint Immediates
imm
21
or imm
62
Mnemonic
Hint
0x0
@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.
0x1
@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.
0x02-0x3f
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.
other
Implementation specific. Performs an implementation-specific hint action.
Consult processor model-specific documentation for details.
Summary of Contents for ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Page 1: ......
Page 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Page 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Page 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Page 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
Page 230: ......
Page 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Page 380: ...2 132 Volume 2 Part 1 Interruptions ...
Page 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Page 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Page 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Page 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Page 808: ...2 560 Volume 2 Part 2 Context Management ...
Page 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Page 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Page 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Page 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
Page 891: ......
Page 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Page 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Page 1296: ......
Page 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...