Ia-32 Application Register Model - Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual

Figure 6-2. IA-32 Application Register Model
General Registers
nats
63 0
gr
0
0
0
gr
1-3
gr
4
gr
7
gr
8
gr
31
gr
32
gr
127
Used by IA-32 execution
Not used by IA-32 execution
Some Itanium registers are modified to an undefined state by hardware as a side-effect
during IA-32 instruction set execution as noted in
Itanium system state is not affected by IA-32 instruction set execution. Itanium
architecture-based code can reference all registers (including IA-32), while IA-32
instruction set references are confined to the IA-32 visible application register state.
Registers are assigned the following conventions during transitions between IA-32 and
Itanium instruction sets.
• IA-32 state: The register contains an IA-32 register during IA-32 instruction set
execution. Expected IA-32 values should be loaded before switching to the IA-32
instruction set. After completion of IA-32 instructions, these registers contain the
results of the execution of IA-32 instructions. These registers may contain any
value during Itanium instruction execution according to Itanium software
conventions. Software should follow IA-32 and Itanium calling conventions for
these registers.
• Undefined: Registers marked as undefined may be used as scratch areas for
execution of IA-32 instructions by the processor and are not ensured to be
preserved across instruction set transitions.
1:114
APPLICATION REGISTER SET
Floating-point Registers
81 0
fr
0.0
0
fr
1.0
1
fr
2-5
fr
6-7
fr
8
fr
31
fr
32
fr
127
Processor Identifiers
63
cpuid
0
cpuid
1
cpuid
n
Volume 1, Part 1: IA-32 Application Execution Model in an Intel
Predicates Branch Registers
63
br
pr
1
0 0
pr
br
1
1
pr
br
2
2
pr
br
15
7
pr
16
Instruction Pointer
63
IP
pr
63
Current Frame Marker
37
CFM
User Mask
5 0
Performance Monitor
Data Registers
0
63
pmd
0
pmd
1
pmd
m
Table 6-1
Application Registers
63 0
0
ar
KR0
0
ar KR7
7
ar
RSC
16
ar
BSP
17
ar BSPSTORE
18
ar
RNAT
19
0
ar
FCR
21
ar
EFLAG
24
ar
CSD
25
0
ar SSD
26
ar
CFLG
27
ar
FSR
28
ar
FIR
29
ar FDR
30
ar
CCV
32
ar
UNAT
36
0
ar
FPSR
40
ar
ITC
44
ar
RUC
45
ar
PFS
64
ar
LC
65
ar
EC
66
ar
127
and Figure 6-2. Generally,
® ®
Itanium System Environment