Intel Itanium 9150M, Manual

Page: 43 / 420

3:34 Volume 3: Instruction Reference
bsw
bsw — Bank Switch
Format: bsw.0 zero_form B8
bsw.1 one_form B8
Description:
This instruction switches to the specified register bank. The zero_form specifies Bank 0
for GR16 to GR31. The one_form specifies Bank 1 for GR16 to GR31. After the bank
switch the previous register bank is no longer accessible but does retain its current
state. If the new and old register banks are the same,
bsw
is effectively a
nop
, although
there may be a performance degradation.
A
bsw
instruction must be the last instruction in an instruction group; otherwise,
operation is undefined. Instructions in the same instruction group that access GR16 to
GR31 reference the previous register bank. Subsequent instruction groups reference
the new register bank.
This instruction can only be executed at the most privileged level, and when PSR.vm is
0.
This instruction cannot be predicated.
Operation: if (!followed_by_stop())
undefined_behavior();
if (PSR.cpl != 0)
privileged_operation_fault(0);
if (PSR.vm == 1)
virtualization_fault();
if (zero_form)
PSR.bn = 0;
else // one_form
PSR.bn = 1;
Interruptions:
Privileged Operation fault Virtualization fault
Serialization:
This instruction does not require any additional instruction or data serialization
operation. The bank switch occurs synchronously with its execution.