From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id F3289A034E; Thu, 7 Nov 2019 16:03:50 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 49E811BF52; Thu, 7 Nov 2019 16:03:34 +0100 (CET) Received: from mx0b-0016f401.pphosted.com (mx0a-0016f401.pphosted.com [67.231.148.174]) by dpdk.org (Postfix) with ESMTP id 7F3D31BF4A for ; Thu, 7 Nov 2019 16:03:31 +0100 (CET) Received: from pps.filterd (m0045849.ppops.net [127.0.0.1]) by mx0a-0016f401.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xA7EskbE023769; Thu, 7 Nov 2019 07:03:30 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=marvell.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=pfpt0818; bh=pFJrhBHsqWbpdefVdj3HhunWGxclN2jUR7Ik4T0j3bU=; b=yZM96aM2tVIQta9AkRi+6p8iIhcWPGfmJ4MgmMgccHmVy8QVjsPzy1sVZQlDR8++ku8X Lvy3snclWXt+CwYVYhP+HFJ90uDktj2ut0U79NrAQn6MWnMFuSqR4kI+ns1sQ1dk8pbV ejNLA0/0vWahX4vwbZt4smhMQH61dbgJklOI5ol2mOL4xkVYyvydw4NTAYqXaH29yfes uz0MlfeWYeLCMAYEfzxjpnIzMTgQ2VaKeCZ5a1TB/3zRVc8GaZpOyw9x8yMAXAyA2ZnK AdFRd6Tw/3qlNySv76IJvfizsWMzOPzuE3Ii9DshrAJjmCvwYJ9mxTRB+pMkooPkscqF iQ== Received: from sc-exch01.marvell.com ([199.233.58.181]) by mx0a-0016f401.pphosted.com with ESMTP id 2w41uwvrdk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT); Thu, 07 Nov 2019 07:03:30 -0800 Received: from SC-EXCH01.marvell.com (10.93.176.81) by SC-EXCH01.marvell.com (10.93.176.81) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Thu, 7 Nov 2019 07:03:29 -0800 Received: from maili.marvell.com (10.93.176.43) by SC-EXCH01.marvell.com (10.93.176.81) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Thu, 7 Nov 2019 07:03:29 -0800 Received: from amok.marvell.com (unknown [10.95.130.48]) by maili.marvell.com (Postfix) with ESMTP id 398FE3F703F; Thu, 7 Nov 2019 07:03:27 -0800 (PST) From: Andrzej Ostruszka To: , Aaron Conole , Michael Santana , Thomas Monjalon , John McNamara , Marko Kovacevic CC: , Date: Thu, 7 Nov 2019 16:03:09 +0100 Message-ID: <20191107150318.3677-4-aostruszka@marvell.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191107150318.3677-1-aostruszka@marvell.com> References: <20191029141212.4907-1-aostruszka@marvell.com> <20191107150318.3677-1-aostruszka@marvell.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-11-07_05:2019-11-07,2019-11-07 signatures=0 Subject: [dpdk-dev] [PATCH v7 03/12] build: add an option to enable LTO build X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" This patch adds an option to enable link time optimization. In addition to LTO option itself (-flto) fat-lto-objects are being used. This is because during the build pmdinfogen scans the generated ELF objects to find this_pmd_name* symbol in symbol table. Without fat-lto-objects gcc produces ELF only with extra symbols for internal use during linking. Signed-off-by: Andrzej Ostruszka Acked-by: Bruce Richardson --- .travis.yml | 9 ++++++ config/common_base | 5 +++ config/meson.build | 13 ++++++++ doc/guides/prog_guide/index.rst | 1 + doc/guides/prog_guide/lto.rst | 40 ++++++++++++++++++++++++ doc/guides/rel_notes/release_19_11.rst | 9 ++++++ mk/toolchain/gcc/rte.toolchain-compat.mk | 4 +++ mk/toolchain/gcc/rte.vars.mk | 12 +++++++ mk/toolchain/icc/rte.vars.mk | 8 +++++ 9 files changed, 101 insertions(+) create mode 100644 doc/guides/prog_guide/lto.rst diff --git a/.travis.yml b/.travis.yml index 3d6ef2959..a1c31d407 100644 --- a/.travis.yml +++ b/.travis.yml @@ -105,6 +105,15 @@ matrix: apt: packages: - *extra_packages + - env: DEF_LIB="static" OPTS="-Db_lto=true" EXTRA_PACKAGES=1 CC=gcc-7 + compiler: gcc + addons: + apt: + sources: + - ubuntu-toolchain-r-test + packages: + - *extra_packages + - gcc-7 script: ./.ci/${TRAVIS_OS_NAME}-build.sh diff --git a/config/common_base b/config/common_base index b2be3d96a..0d1207166 100644 --- a/config/common_base +++ b/config/common_base @@ -49,6 +49,11 @@ CONFIG_RTE_FORCE_INTRINSICS=n # CONFIG_RTE_ARCH_STRICT_ALIGN=n +# +# Enable link time optimization +# +CONFIG_RTE_ENABLE_LTO=n + # # Compile to share library # diff --git a/config/meson.build b/config/meson.build index e1ebdad26..2b1cb92e7 100644 --- a/config/meson.build +++ b/config/meson.build @@ -225,3 +225,16 @@ add_project_arguments('-D_GNU_SOURCE', language: 'c') if is_freebsd add_project_arguments('-D__BSD_VISIBLE', language: 'c') endif + +if get_option('b_lto') + if cc.has_argument('-ffat-lto-objects') + add_project_arguments('-ffat-lto-objects', language: 'c') + else + error('compiler does not support fat LTO objects - please turn LTO off') + endif + # workaround for gcc bug 81440 + if cc.get_id() == 'gcc' and cc.version().version_compare('<8.0') + add_project_arguments('-Wno-lto-type-mismatch', language: 'c') + add_project_link_arguments('-Wno-lto-type-mismatch', language: 'c') + endif +endif diff --git a/doc/guides/prog_guide/index.rst b/doc/guides/prog_guide/index.rst index 692409af8..dc4851c57 100644 --- a/doc/guides/prog_guide/index.rst +++ b/doc/guides/prog_guide/index.rst @@ -65,5 +65,6 @@ Programmer's Guide ext_app_lib_make_help perf_opt_guidelines writing_efficient_code + lto profile_app glossary diff --git a/doc/guides/prog_guide/lto.rst b/doc/guides/prog_guide/lto.rst new file mode 100644 index 000000000..50aecc9e5 --- /dev/null +++ b/doc/guides/prog_guide/lto.rst @@ -0,0 +1,40 @@ +.. SPDX-License-Identifier: BSD-3-Clause + Copyright(c) 2019 Marvell International Ltd. + +Link Time Optimization +====================== + +The DPDK supports compilation with link time optimization turned on. +This depends obviously on the ability of the compiler to do "whole +program" optimization at link time and is available only for compilers +that support that feature. +To be more specific, compiler (in addition to performing LTO) have to +support creation of ELF objects containing both normal code and internal +representation (called fat-lto-objects in gcc and icc). +This is required since during build some code is generated by parsing +produced ELF objects (pmdinfogen). + +The amount of performance gain that one can get from LTO depends on the +compiler and the code that is being compiled. +However LTO is also useful for additional code analysis done by the +compiler. +In particular due to interprocedural analysis compiler can produce +additional warnings about variables that might be used uninitialized. +Some of these warnings might be "false positives" though and you might +need to explicitly initialize variable in order to silence the compiler. + +Please note that turning LTO on causes considerable extension of +build time. + +When using make based build, link time optimization can be enabled for +the whole DPDK by setting: + +.. code-block:: console + CONFIG_ENABLE_LTO=y + +in config file. +For the meson based build it can be enabled by setting meson built-in +'b_lto' option: + +.. code-block:: console + meson build -Db_lto=true diff --git a/doc/guides/rel_notes/release_19_11.rst b/doc/guides/rel_notes/release_19_11.rst index ae8e7b2f0..b11abe2fe 100644 --- a/doc/guides/rel_notes/release_19_11.rst +++ b/doc/guides/rel_notes/release_19_11.rst @@ -231,6 +231,15 @@ New Features * Added a console command to testpmd app, ``show port (port_id) ptypes`` which gives ability to print port supported ptypes in different protocol layers. +* **Added build support for Link Time Optimization.** + + LTO is an optimization technique used by the compiler to perform whole + program analysis and optimization at link time. In order to do that + compilers store their internal representation of the source code that + the linker uses at the final stage of compilation process. + + See :doc:`../prog_guide/lto` for more information: + Removed Items ------------- diff --git a/mk/toolchain/gcc/rte.toolchain-compat.mk b/mk/toolchain/gcc/rte.toolchain-compat.mk index ea40a11c0..69a53e5d0 100644 --- a/mk/toolchain/gcc/rte.toolchain-compat.mk +++ b/mk/toolchain/gcc/rte.toolchain-compat.mk @@ -88,6 +88,10 @@ else MACHINE_CFLAGS := $(filter-out -march% -mtune% -msse%,$(MACHINE_CFLAGS)) endif + ifeq ($(shell test $(GCC_VERSION) -lt 74 && echo 1), 1) + CONFIG_RTE_ENABLE_LTO=n + endif + # Disable thunderx PMD for gcc < 4.7 ifeq ($(shell test $(GCC_VERSION) -lt 47 && echo 1), 1) CONFIG_RTE_LIBRTE_THUNDERX_NICVF_PMD=d diff --git a/mk/toolchain/gcc/rte.vars.mk b/mk/toolchain/gcc/rte.vars.mk index b852fcfd7..9fc704193 100644 --- a/mk/toolchain/gcc/rte.vars.mk +++ b/mk/toolchain/gcc/rte.vars.mk @@ -62,6 +62,18 @@ endif # process cpu flags include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk +ifeq ($(CONFIG_RTE_ENABLE_LTO),y) +# 'fat-lto' is used since pmdinfogen needs to have 'this_pmd_nameX' +# exported in symbol table and without this option only internal +# representation is present. +TOOLCHAIN_CFLAGS += -flto -ffat-lto-objects +TOOLCHAIN_LDFLAGS += -flto +# workaround for GCC bug 81440 +ifeq ($(shell test $(GCC_VERSION) -lt 80 && echo 1), 1) +WERROR_FLAGS += -Wno-lto-type-mismatch +endif +endif + # workaround GCC bug with warning "missing initializer" for "= {0}" ifeq ($(shell test $(GCC_VERSION) -lt 47 && echo 1), 1) WERROR_FLAGS += -Wno-missing-field-initializers diff --git a/mk/toolchain/icc/rte.vars.mk b/mk/toolchain/icc/rte.vars.mk index aa1422bf1..8aa87aa1e 100644 --- a/mk/toolchain/icc/rte.vars.mk +++ b/mk/toolchain/icc/rte.vars.mk @@ -54,5 +54,13 @@ endif # process cpu flags include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk +ifeq ($(CONFIG_RTE_ENABLE_LTO),y) +# 'fat-lto' is used since pmdinfogen needs to have 'this_pmd_nameX' +# exported in symbol table and without this option only internal +# representation is present. +TOOLCHAIN_CFLAGS += -flto -ffat-lto-objects +TOOLCHAIN_LDFLAGS += -flto +endif + export CC AS AR LD OBJCOPY OBJDUMP STRIP READELF export TOOLCHAIN_CFLAGS TOOLCHAIN_LDFLAGS TOOLCHAIN_ASFLAGS -- 2.17.1