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Volume 1, Part 1: Application Programming Model
4.8.2
Bit Strings
The population count instruction (
popcnt
) writes the number of bits that have a value
of 1 in the source register into the target register. The count leading zeros instruction
(
clz
) writes the number of leading zero bits in the source register into the target
register; coupled with complement,
clz
can also perform count leading ones
functionality as well.
4.9
Privilege Level Transfer
Three instructions may cause a privilege level change: break (
break
), enter privileged
code (
epc
) and branch return (
br.ret
). The
break
instruction is defined to cause a
Break Instruction fault which can be used to transfer privilege levels. The
break
instruction contains an immediate which is made available to a dedicated fault handler.
The
epc
instruction increases the privilege level without causing an interruption or a
control flow transfer. The new privilege level is specified by the TLB entry for the page
containing the
epc
, if virtual address translation for instruction fetches is enabled. If the
privilege level specified by PFS.ppl (in the Previous Function State application register)
is lower than the current privilege level (as specified by PSR.cpl in the Processor Status
Register)
epc
raises an Illegal Operation fault. The
br.ret
instruction is defined to
demote the privilege level if PFS.ppl is lower than PSR.cpl. A
br.ret
will never increase
privilege level.
§
Table 4-33.
String Support Instructions
Mnemonic
Operation
1-byte
2-byte
czx.l
Locate first zero element, left to right
x
x
czx.r
Locate first zero element, right to left
x
x
Table 4-34.
Bit Support Instructions
Mnemonic
Operation
popcnt
Count number of ones in source register
clz
Count number of leading zeros in source register
Содержание ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
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Страница 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
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Страница 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Страница 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Страница 749: ...2 501 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part II System Programmer s Guide ...
Страница 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Страница 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Страница 808: ...2 560 Volume 2 Part 2 Context Management ...
Страница 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Страница 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Страница 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
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Страница 941: ...3 42 Volume 3 Instruction Reference cmp illegal_operation_fault PR p1 0 PR p2 0 Interruptions Illegal Operation fault ...
Страница 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
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Страница 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Страница 1564: ...4 262 Volume 4 Base IA 32 Instruction Reference LES Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1565: ...Volume 4 Base IA 32 Instruction Reference 4 263 LFS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1568: ...4 266 Volume 4 Base IA 32 Instruction Reference LGS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1583: ...Volume 4 Base IA 32 Instruction Reference 4 281 LSS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Страница 1663: ...Volume 4 Base IA 32 Instruction Reference 4 361 SHL SHR Shift Instructions See entry for SAL SAR SHL SHR ...
Страница 1668: ...4 366 Volume 4 Base IA 32 Instruction Reference SIDT Store Interrupt Descriptor Table Register See entry for SGDT SIDT ...
Страница 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Страница 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Страница 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...