[dpdk-dev] [PATCH v7 00/12] Add an option to use LTO for DPDK build

[Andrzej Ostruszka <aostruszka@marvell.com>]

This patch series adds an option to make use of link time optimization
(if compiler has support for it).  It is split as follows:
- 1st patch is just a minor doc fix for versioning macros
- 2nd patch fixes missing __vsym annotations (needed for LTO)
- 3rd is the LTO enablement
- remaining patches are fixes for the warnings produced by the compiler
  and they are split by directory/subsystem so their maintainers can
  easily find and verify the changes - please note that there are two
  groups:
  * errors (or possible errors) - with title "fix possible use ..."
  * false positives - warnings that _I_ think are not valid and the
    changes are made only to silence the compiler.

v7 Changes:
-----------
- dpaa2:
  - reverted some changes in dpaa2 that were not required to silence gcc
    warning
  - added extra check to avoid possible array overrun
- updated travis:
  - removed entry in "env"
  - use gcc-7 to make build with LTO:
    this is because in reproduced CI environment only gcc-7 package from
    ubuntu-toolchain-r/test PPA could finish the build without any
    warnings
- change the gcc version to 7.4 in rte.toolchain-compat.mk

v6 Changes:
-----------
- yet another split of the patch: this time from __vsym one minor doc
  fix to versioning macros has been moved to another patch
- net/ifc - fixed initialization of vring in m_ifcvf_start():
  after rebase definition rte_vhost_vring has changed and now simple
  '{ 0 }' produces proper warning - however instead of '{ { 0 } }'
  I went with memset() because I could not get gcc to be quiet about
  "missing initializer" (IMHO "{{0}}" is a correct initialization but
  gcc required me to spell out initializers to all members which looked
  ugly and would require update on further changes to vring)
- I've been suggested (offlist) to mark the patches that were previously
  "reviewed/acked" so I've added some "Reviewed|Acked-by" tags (if the
  ack was sent to a patch that was later split the tag is placed in
  both patches).

v5 Changes:
-----------
- rebased to the v19.11 (one additional warning silenced in net/qede)
- initial patch has been split into two:
  - one adding '__vsym' annotations and clarifying versioning docs
  - another adding the actual LTO enablement
- addressed various documentation flaws pointed during review

v4 Changes:
-----------
- merge nested conditionals in config/meson.build into one

v3 Changes:
-----------
- removed support for clang (only gcc and icc remain):
  - it turned out that 'fat-lto-objects' is not really supported - it is
    accepted as a flag but ignored e.g. clang v6.0:
      clang: error: optimization flag '-ffat-lto-objects' is not supported
      [-Werror,-Wignored-optimization-argument]
    this was probably masked previously by playing around with meson and
    testing for the availability of this flag and dropping LTO if not
    supported.
- improved commit messages:
  - added 'Fixes' tags where appropriate
  - included snippets of compiler warnings
- changed commit names for the commits cleaning up 'false positive'
  compiler warnings - these are not really 'fixes' for the code, just
  workarounds for compiler shortcomings and check-git-log.sh was
  complaining about missing 'Fixes' tag.

v2 Changes:
-----------
- fixed building of shared libraries:
  - gcc does not scan top level assembler statements so it missed that
    function implementations for specific versions were being used and
    was removing them
- fixed meson.build config files:
  - moved from 'enable_lto' project option to built-in 'b_lto'
  - documented that 'default_library' should be 'shared':
    with 'default_library=static' (the default) the meson build with LTO
    is broken - this is because, SHARED_LIB is fixed in rte_config.h
    used by meson which leads to no alias for default version in
    generated static libraries (MAP_STATIC_SYMBOL() is empty)
- app/test: added log for failed bonding "config get"

Andrzej Ostruszka (12):
  doc: fix description of versioning macros
  build: annotate versioned symbols with __vsym macro
  build: add an option to enable LTO build
  eventdev: fix possible use of uninitialized var
  app/eventdev: clean LTO build warnings (maybe-uninitialized)
  event/octeontx2: clean LTO build warnings (maybe-uninitialized)
  app/test: clean LTO build warnings (maybe-uninitialized)
  net/dpaa2: fix possible use of uninitialized vars
  net/e1000: clean LTO build warnings (maybe-uninitialized)
  net/i40e: clean LTO build warnings (maybe-uninitialized)
  net/ifc: clean LTO build warnings (maybe-uninitialized)
  net/qede: clean LTO build warnings (maybe-uninitialized)

 .travis.yml                                   |  9 +++++
 app/test-eventdev/test_perf_common.c          |  2 +-
 app/test-eventdev/test_pipeline_common.c      |  4 +-
 app/test/test_hash_readwrite.c                |  2 +-
 app/test/test_link_bonding_mode4.c            |  8 +++-
 app/test/test_memzone.c                       |  3 +-
 config/common_base                            |  5 +++
 config/meson.build                            | 13 ++++++
 doc/guides/contributing/versioning.rst        | 18 ++++++---
 doc/guides/prog_guide/index.rst               |  1 +
 doc/guides/prog_guide/lto.rst                 | 40 +++++++++++++++++++
 doc/guides/rel_notes/release_19_11.rst        |  9 +++++
 drivers/event/octeontx2/otx2_tim_worker.h     |  2 +-
 drivers/net/dpaa2/base/dpaa2_hw_dpni.c        |  1 +
 drivers/net/dpaa2/mc/dpkg.c                   |  5 ++-
 drivers/net/e1000/base/e1000_82543.c          |  2 +-
 drivers/net/e1000/base/e1000_ich8lan.c        |  2 +-
 drivers/net/e1000/base/e1000_phy.c            |  2 +-
 drivers/net/i40e/i40e_ethdev.c                |  2 +-
 drivers/net/ifc/ifcvf_vdpa.c                  | 14 +++++--
 drivers/net/qede/base/ecore_mcp.c             | 15 +++----
 lib/librte_distributor/rte_distributor.c      | 18 ++++-----
 lib/librte_distributor/rte_distributor_v20.c  | 18 ++++-----
 .../common/include/rte_function_versioning.h  | 11 ++++-
 lib/librte_eventdev/rte_event_timer_adapter.c |  8 ++--
 lib/librte_lpm/rte_lpm.c                      | 28 ++++++-------
 lib/librte_lpm/rte_lpm6.c                     | 16 ++++----
 lib/librte_timer/rte_timer.c                  | 20 +++++-----
 mk/toolchain/gcc/rte.toolchain-compat.mk      |  4 ++
 mk/toolchain/gcc/rte.vars.mk                  | 12 ++++++
 mk/toolchain/icc/rte.vars.mk                  |  8 ++++
 31 files changed, 217 insertions(+), 85 deletions(-)
 create mode 100644 doc/guides/prog_guide/lto.rst

-- 
2.17.1