Intel Itanium 9150M, Manual, Page: 49 / 420

3:40 Volume 3: Instruction Reference
cmp
simply uses the negative relation with an implemented type. The implemented relations
and how the pseudo-ops map onto them are shown in
Table 2-16 (for normal and unc
type compares), and Table 2-17 (for parallel type compares).
The parallel compare types can be used only with a restricted set of relations and
operands. They can be used with equal and not-equal comparisons between two
registers or between a register and an immediate, or they can be used with inequality
comparisons between a register and GR 0. Unsigned relations are not provided, since
they are not of much use when one of the operands is zero. For the parallel inequality
comparisons, hardware only directly implements the ones where the first operand (GR
r
2
) is GR 0. Comparisons where the second operand is GR 0 are pseudo-ops for which
the assembler switches the register specifiers and uses the opposite relation.
Table 2-16. 64-bit Comparison Relations for Normal and unc Compares
crel
Compare Relation
( a rel b )
Register Form is a
pseudo-op of
Immediate Form is a
pseudo-op of
Immediate Range
eq a == b -128 .. 127
ne a != b eq p
1

p
2
eq p
1

p
2
-128 .. 127
lt a < b signed -128 .. 127
le a <= b lt a

b p
1

p
2
lt a-1 -127 .. 128
gt a > b lt a

b lt a-1 p
1

p
2
-127 .. 128
ge a >= b lt p
1

p
2
lt p
1

p
2
-128 .. 127
ltu a < b unsigned 0 .. 127,
2
64
-128 .. 2
64
-1
leu a <= b ltu a

b p
1

p
2
ltu a-1 1 .. 128,
2
64
-127 .. 2
64
gtu a > b ltu a

b ltu a-1 p
1

p
2
1 .. 128,
2
64
-127 .. 2
64
geu a >= b ltu p
1

p
2
ltu p
1

p
2
0 .. 127,
2
64
-128 .. 2
64
-1
Table 2-17. 64-bit Comparison Relations for Parallel Compares
crel
Compare Relation
( a rel b )
Register Form is a
pseudo-op of
Immediate Range
eq a == b -128 .. 127
ne a != b -128 .. 127
lt 0 < b signed no immediate forms
lt a < 0 gt a

b
le 0 <= b
le a <= 0 ge a

b
gt 0 > b
gt a > 0 lt a

b
ge 0 >= b
ge a >= 0 le a

b