Volume 1, Part 1: Application Programming Model
1:55
The 64-bit (
cmp
) and 32-bit (
cmp4
) compare instructions compare two registers, or a
register and an immediate, for one of ten relations (e.g., >, <=). The compare
instructions set two predicate targets according to the result. The
cmp4
instruction
compares the least-significant 32-bits of both sources (the most significant 32-bits are
ignored).
The test bit (
tbit
) instruction sets two predicate registers according to the state of a
single bit in a general register (the position of the bit is specified by an immediate). The
test NaT (
tnat
) instruction sets two predicate registers according to the state of the
NaT bit corresponding to a general register.
The test feature (
tf
) instruction sets two predicate registers according to whether or
not the selected feature is implemented in the processor.
The
fcmp
instruction compares two floating-point registers and sets two predicate
targets according to one of eight relations. The
fclass
instruction sets two predicate
targets according to the classification of the number contained in the floating-point
register source.
The
frcpa
,
fprcpa
,
frsqrta
and
fprsqrta
instructions set a single predicate target if
their floating-point register sources are such that a valid approximation can be
produced, otherwise the predicate target is cleared.
4.3.3
Compare Types
Compare instructions can have as many as five compare types: Normal, Unconditional,
AND, OR, or DeMorgan. The type defines how the instruction writes its target predicate
registers based on the outcome of the comparison and on the qualifying predicate. The
description of these types is contained in
. In the table, “qp” refers to the
value of the qualifying predicate of the compare and “result” refers to the outcome of
the compare relation (one if the compare relation is true and zero if the compare
relation is false).
The Normal compare type simply writes the compare result to the first predicate target
and the complement of the result to the second predicate target.
Table 4-9.
Compare Type Function
Compare Type
Completer
Operation
First Predicate Target
Second Predicate Target
Normal
none
if (qp) {target = result}
if (qp) {target =!result}
Unconditional
unc
if (qp) {target = result}
else {target = 0}
if (qp) {target =!result}
else {target = 0}
AND
and
if (qp &&!result) {target = 0}
if (qp &&!result) {target = 0}
andcm
if (qp && result) {target = 0}
if (qp && result) {target = 0}
OR
or
if (qp && result) {target = 1}
if (qp && result) {target = 1}
orcm
if (qp &&!result) {target = 1}
if (qp &&!result) {target = 1}
DeMorgan
or.andcm
if (qp && result) {target = 1}
if (qp && result) {target = 0}
and.orcm
if (qp &&!result) {target = 0}
if (qp &&!result) {target = 1}
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 ...