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P.4.4 expected software handling of ade trap, Expected software handling of ade trap 171, P.4.4 expected software handling of – FUJITSU Implementation Supplement Fujitsu SPARC64 V User Manual

Page 182: Trap

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Release 1.0, 1 July 2002

F. Chapter P

Error Handling

171

TABLE P-14

defines each instruction end-method after an

ADE

trap.

P.4.4

Expected Software Handling of

ADE

Trap

The expected software handling of an

ADE

trap is described by the pseudo C code

below. The main purpose of this flow is to recover from the following errors as much
as possible:

An error in the CPU internal RAM or register file

An error in the accumulator

An error in the CPU internal temporary registers and data bus

TABLE P-14

Instruction End-Method After

async_data_error

Exception

Precise

Retryable But Not Precise

Not Retryable

Instructions executed after
the last

ADE

,

IAE

, or

DAE

trap and before the trapped
instruction referenced by

TPC

.

Ended (Committed).
The instructions without

UGE

complete as defined in the architecture. The

instruction with

UGE

was unpredictable value to its output (destination register or,

in the case of a store instruction, destination memory location).

The trapped instruction
referenced by

TPC

Not executed. The output of the instruction is

incomplete.
Part of the output may be
changed, or the invalid value
may be written to the instruction
output. However, the
modification to the invalid target
that is not defined as instruction
output is not executed.
The following modifications are
not executed:

• Store to the cacheable area

including cache.

• Store to the noncacheable area.
• Output to the source register of

the instruction (destructive
overlap)

The output of the instruction is
incomplete.
Part of the output may be
changed, or the invalid value
may be written to the instruction
output. However, the
modification to the invalid target
that is not defined as instruction
output is not executed.
A store to an invalid address is
not executed. (Store to a valid
address with uncorrected data
may be executed.)

Instructions to be executed
after the instruction
referenced by

TPC

Not executed. Not executed.

Not executed.

The possibility of resuming
the trapped program by
executing the

RETRY

instruction to the

%tpc

when the trapped program
is not damaged at the
single-

ADE

trap

Possible.

Possible.

Impossible.