Under various circumstances, event data can not be mapped to a particular data object. In such cases, the data is mapped to the special data object named <Unknown> and one of its elements as described below.
Module with trigger PC not compiled with -xhwcprof
No event-causing instruction or data object was identified because the object code was not compiled with hardware counter profiling support.
Backtracking failed to find a valid branch target
No event-causing instruction was identified because the hardware profiling support information provided in the compilation object was insufficient to verify the validity of backtracking.
Backtracking traversed a branch target
No event-causing instruction or data object was identified because backtracking encountered a control transfer target in the instruction stream.
No identifying descriptor provided by the compiler
Backtracking determined the likely causal memory-referencing instruction, but its associated data object was not specified by the compiler.
No type information
Backtracking determined the likely event-causing instruction, but the instruction was not identified by the compiler as a memory-referencing instruction.
Not determined from the symbolic information provided by the compiler
Backtracking determined the likely causal memory-referencing instruction, but it was not identified by the compiler and associated data object determination is therefore not possible. Compiler temporaries are generally unidentified.
Backtracking was prevented by a jump or call instruction
No event-causing instructions were identified because backtracking encountered a branch or call instruction in the instruction stream.
Backtracking did not find trigger PC
No event-causing instructions were found within the maximum backtracking range.
Could not determine VA because registers changed after trigger instruction
The virtual address of the data object was not determined because registers were overwritten during hardware counter skid.
Memory-referencing instruction did not specify a valid VA
The virtual address of the data object did not appear to be valid.