4:484
Volume 4: IA-32 SSE Instruction Reference
4.11
Reserved Behavior and Software Compatibility
In many register and memory layout descriptions, certain bits are marked as
reserved
.
When bits are marked as reserved, it is essential for compatibility with future
processors that software treat these bits as having a future, though unknown, effect.
The behavior of reserved bits should be regarded as not only reserved, but
unpredictable. In general, reserved behavior may also be applied in other areas.
Software should follow these guidelines in dealing with reserved behavior:
• Do not depend on the states of any reserved fields when testing the values of
registers which contain such bits. Mask out the reserved fields before testing.
• Do not depend on the states of any reserved fields when storing to memory or to a
register.
• Do not depend on the ability to retain information written into any reserved fields.
• When loading a register, always load the reserved fields with the values indicated in
the documentation, if any, or reload them with values previously read from the
same register.
Note:
Avoid any software dependency upon the reserved state/behavior. Depending
upon reserved behavior will make the software dependent upon the unspecified
manner in which the processor handles this behavior and risks incompatibility
with future processors.
4.12
Notations
Besides opcodes, two kinds of notations are found which both describe information
found in the ModR/M byte:
1.
/digit:
(digit between 0 and 7) indicates that the instruction uses only the r/m
(register and memory) operand. The reg field contains the digit that provides an
extension to the instruction's opcode.
2.
/r
: indicates that the ModR/M byte of an instruction contains both a register
operand and an r/m operand.
In addition, the following abbreviations are used:
•
r32
:
Intel architecture 32-bit integer register.
•
xmm/m128
:Indicates a 128-bit multimedia register or a 128-bit memory location.
•
xmm/m64
: Indicates a 128-bit multimedia register or a 64-bit memory location.
•
xmm/m32:
Indicates a 128-bit multimedia register or a 32-bit memory location.
•
mm/m64
:
Indicates a 64-bit multimedia register or a 64-bit memory location.
Segment Override
(2EH,36H,3EH,26H,64H,65H)
Affects cacheability control instructions with mem. operand
Ignored by cacheability control instruction without mem operand
Repeat Prefix(F3H)
Reserved and may result in unpredictable behavior.
Repeat NE Prefix(F2H)
Reserved and may result in unpredictable behavior.
Lock Prefix (0F0H)
Generates an invalid opcode exception for all cacheability
instructions.
Table 4-8.
Cacheability Control Instruction Behavior with Prefixes
Prefix Type
Effect on SSE Instructions
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 ...