2.3. Upgrading a nonwaypoint instruction on an exception

A PTM must trace an exception by upgrading the last successfully executed instruction to be a waypoint instruction, if it was not already a waypoint instruction. How the PTM traces the exception depends on whether the last successfully executed instruction was already a waypoint instruction:

If the last instruction executed was already a waypoint instruction

The PTM outputs an exception branch address packet, indicating the exception taken and the exception vector address.

If the last instruction executed was not already a waypoint instruction

The PTM outputs a packet that indicates the address of this instruction, followed by an exception branch address packet that indicates the exception taken and the exception vector address.

The rest of this specification gives more information about tracing exceptions. In particular, Chapter 5 Tracing Exceptions gives a detailed description of how each type of exception is traced, with examples.

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