Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3, Manual

Page: 1249 / 1898

3:350 Volume 3: Instruction Formats
4.5.1 Branches
Opcode 0 is used for indirect branch, opcode 1 for indirect call, opcode 4 for IP-relative
branch, and opcode 5 for IP-relative call.
The IP-relative branch instructions encoded within major opcode 4 use a 3-bit opcode
extension field in bits 8:6 (btype) to distinguish the branch types as shown in
Table 4-47 .
The indirect branch, indirect return, and miscellaneous branch-unit instructions are
encoded within major opcode 0 using a 6-bit opcode extension field in bits 32:27 (x
6
).
Table 4-48 summarizes these assignments.
Table 4-47. IP-Relative Branch Types
Opcode
Bits 40:37
btype
Bits 8:6
4
0 br.cond B1
1
e
2 br.wexit B1
3 br.wtop B1
4
e
5 br.cloop B2
6 br.cexit B2
7 br.ctop B2
Table 4-48. Indirect/Miscellaneous Branch Opcode Extensions
Opcode
Bits 40:37
x
6
Bits
30:27
Bits 32:31
0 1 2 3
0
0 break.b B9 epc B8
Indirect Branch
( Table 4-49 )
e
1
e
Indirect Return
( Table 4-50 )
e
2 cover B8
e e e
3
e e e e
4 clrrrb B8
e e e
5 clrrrb.pr B8
e e e
6
e e e e
7
e e e e
8 rfi B8 vmsw.0 B8
e e
9 vmsw.1 B8
e e
A
e e e e
B
e e e e
C bsw.0 B8
e e e
D bsw.1 B8
e e e
E
e e e e
F
e e e e