..
  Copyright 1988-2022 Free Software Foundation, Inc.
  This is part of the GCC manual.
  For copying conditions, see the copyright.rst file.

.. index:: profiling, code generation

.. _profiling:

Generating Code for Profiling
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

These macros will help you generate code for profiling.

.. c:macro:: FUNCTION_PROFILER (file, labelno)

  A C statement or compound statement to output to :samp:`{file}` some
  assembler code to call the profiling subroutine ``mcount``.

  .. index:: mcount

  The details of how ``mcount`` expects to be called are determined by
  your operating system environment, not by GCC.  To figure them out,
  compile a small program for profiling using the system's installed C
  compiler and look at the assembler code that results.

  Older implementations of ``mcount`` expect the address of a counter
  variable to be loaded into some register.  The name of this variable is
  :samp:`LP` followed by the number :samp:`{labelno}`, so you would generate
  the name using :samp:`LP%d` in a ``fprintf``.

.. c:macro:: PROFILE_HOOK

  A C statement or compound statement to output to :samp:`{file}` some assembly
  code to call the profiling subroutine ``mcount`` even the target does
  not support profiling.

.. c:macro:: NO_PROFILE_COUNTERS

  Define this macro to be an expression with a nonzero value if the
  ``mcount`` subroutine on your system does not need a counter variable
  allocated for each function.  This is true for almost all modern
  implementations.  If you define this macro, you must not use the
  :samp:`{labelno}` argument to ``FUNCTION_PROFILER``.

.. c:macro:: PROFILE_BEFORE_PROLOGUE

  Define this macro if the code for function profiling should come before
  the function prologue.  Normally, the profiling code comes after.

.. include:: ../tm.rst.in
  :start-after: [TARGET_KEEP_LEAF_WHEN_PROFILED]
  :end-before: [TARGET_KEEP_LEAF_WHEN_PROFILED]