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#### 9.29.6 Profiling Capability

It is a performance hit to use gcc's profiling approach for this tiny target. Even more – jtag hardware facility does not perform any profiling functions. However we've got gdb's built-in simulator where we can do anything.

We define new section ‘`.profiler`’ which holds all profiling information. We define new pseudo operation ‘`.profiler`’ which will instruct assembler to add new profile entry to the object file. Profile should take place at the present address.

Pseudo operation format:

‘`.profiler flags,function_to_profile [, cycle_corrector, extra]`’

where:

‘`flags`’ is a combination of the following characters:
`s`
  function entry
`x`
  function exit
`i`
  function is in init section
`f`
  function is in fini section
`l`
  library call
`c`
  libc standard call
`d`
  stack value demand
`I`
  interrupt service routine
`P`
  prologue start
`p`
  prologue end
`E`
  epilogue start
`e`
  epilogue end
`j`
  long jump / sjlj unwind
`a`
  an arbitrary code fragment
`t`
  extra parameter saved (a constant value like frame size)

`function_to_profile`
  a function address
`cycle_corrector`
  a value which should be added to the cycle counter, zero if omitted.
`extra`
  any extra parameter, zero if omitted.

For example:

         .global fxx
         .type fxx,@function
         fxx:
         .LFrameOffset_fxx=0x08
         .profiler "scdP", fxx     ; function entry.
         			  ; we also demand stack value to be saved
           push r11
           push r10
           push r9
           push r8
         .profiler "cdpt",fxx,0, .LFrameOffset_fxx  ; check stack value at this point
         					  ; (this is a prologue end)
         					  ; note, that spare var filled with
         					  ; the farme size
           mov r15,r8
         ...
         .profiler cdE,fxx         ; check stack
           pop r8
           pop r9
           pop r10
           pop r11
         .profiler xcde,fxx,3      ; exit adds 3 to the cycle counter
           ret                     ; cause 'ret' insn takes 3 cycles