Instruction Formats; Bundle Format; Relationship Between Instruction Type And Execution Unit Type - Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 3 REV 2.3 Manual

Instruction Formats

Each Itanium instruction is categorized into one of six types; each instruction type may
be executed on one or more execution unit types.
and the execution unit type on which they are executed:
Table 4-1.
a. L+X Major Opcodes 0 - 7 execute on an I-unit. L+X Major Opcodes 8 - F execute on a B-unit.
Three instructions are grouped together into 128-bit sized and aligned containers called
bundles. Each bundle contains three 41-bit instruction slots and a 5-bit template
field. The format of a bundle is depicted in
Figure 4-1.
127
instruction slot 2
The template field specifies two properties: stops within the current bundle, and the
mapping of instruction slots to execution unit types. Not all combinations of these two
properties are allowed -
rightmost columns correspond to the three instruction slots in a bundle; listed within
each column is the execution unit type controlled by that instruction slot for each
encoding of the template field. A double line to the right of an instruction slot indicates
that a stop occurs at that point within the current bundle. See
Overview" on page 1:38
proceeds from slot 0 to slot 2. Unused template values (appearing as empty rows in
Table 4-2) are reserved and cause an Illegal Operation fault.
Extended instructions, used for long immediate integer and long branch instructions,
occupy two instruction slots. Depending on the major opcode, extended instructions
execute on a B-unit (long branch/call) or an I-unit (all other L+X instructions).
Volume 3: Instruction Formats

Relationship between Instruction Type and Execution Unit Type

Instruction
Type
A Integer ALU
I Non-ALU integer
M Memory
F Floating-point
B Branch
L+X Extended

Bundle Format

87 86
41
Table 4-2
for the definition of a stop. Within a bundle, execution order
Table 4-1
Description
Figure 4-1.
46 45
instruction slot 1
41
indicates the defined combinations. The three
lists the instruction types
Execution Unit Type
I-unit or M-unit
I-unit
M-unit
F-unit
B-unit
a
I-unit/B-unit
5 4
instruction slot 0 template
41
"Instruction Encoding
4
0
5
3:293