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GET /api/patches/58626/?format=api
{ "id": 58626, "url": "http://patches.dpdk.org/api/patches/58626/?format=api", "web_url": "http://patches.dpdk.org/project/dpdk/patch/20190905093239.27187-2-amo@semihalf.com/", "project": { "id": 1, "url": "http://patches.dpdk.org/api/projects/1/?format=api", "name": "DPDK", "link_name": "dpdk", "list_id": "dev.dpdk.org", "list_email": "dev@dpdk.org", "web_url": "http://core.dpdk.org", "scm_url": "git://dpdk.org/dpdk", "webscm_url": "http://git.dpdk.org/dpdk", "list_archive_url": "https://inbox.dpdk.org/dev", "list_archive_url_format": "https://inbox.dpdk.org/dev/{}", "commit_url_format": "" }, "msgid": "<20190905093239.27187-2-amo@semihalf.com>", "list_archive_url": "https://inbox.dpdk.org/dev/20190905093239.27187-2-amo@semihalf.com", "date": "2019-09-05T09:32:30", "name": "[01/10] build: add an option to enable LTO build", "commit_ref": null, "pull_url": null, "state": "superseded", "archived": true, "hash": "1dd043d6ebaa0d6813758ae2955e0e9290c76830", "submitter": { "id": 1112, "url": "http://patches.dpdk.org/api/people/1112/?format=api", "name": "Andrzej Ostruszka", "email": "amo@semihalf.com" }, "delegate": { "id": 1, "url": "http://patches.dpdk.org/api/users/1/?format=api", "username": "tmonjalo", "first_name": "Thomas", "last_name": "Monjalon", "email": "thomas@monjalon.net" }, "mbox": "http://patches.dpdk.org/project/dpdk/patch/20190905093239.27187-2-amo@semihalf.com/mbox/", "series": [ { "id": 6250, "url": "http://patches.dpdk.org/api/series/6250/?format=api", "web_url": "http://patches.dpdk.org/project/dpdk/list/?series=6250", "date": "2019-09-05T09:32:29", "name": "Add an option to use LTO for DPDK build", "version": 1, "mbox": "http://patches.dpdk.org/series/6250/mbox/" } ], "comments": "http://patches.dpdk.org/api/patches/58626/comments/", "check": "warning", "checks": "http://patches.dpdk.org/api/patches/58626/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<dev-bounces@dpdk.org>", "X-Original-To": "patchwork@dpdk.org", "Delivered-To": "patchwork@dpdk.org", "Received": [ "from [92.243.14.124] (localhost [127.0.0.1])\n\tby dpdk.org (Postfix) with ESMTP id DF0CD1EDD5;\n\tThu, 5 Sep 2019 11:32:44 +0200 (CEST)", "from mail-lf1-f50.google.com (mail-lf1-f50.google.com\n\t[209.85.167.50]) by dpdk.org (Postfix) with ESMTP id E25721ED83\n\tfor <dev@dpdk.org>; Thu, 5 Sep 2019 11:32:41 +0200 (CEST)", "by mail-lf1-f50.google.com with SMTP id q27so1397469lfo.10\n\tfor <dev@dpdk.org>; Thu, 05 Sep 2019 02:32:41 -0700 (PDT)", "from localhost.localdomain (31-172-191-173.noc.fibertech.net.pl.\n\t[31.172.191.173]) by smtp.googlemail.com with ESMTPSA id\n\tb25sm363060lfa.90.2019.09.05.02.32.40\n\t(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n\tThu, 05 Sep 2019 02:32:40 -0700 (PDT)" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=semihalf-com.20150623.gappssmtp.com; s=20150623;\n\th=from:to:cc:subject:date:message-id:in-reply-to:references;\n\tbh=KulmLa3F+a4DpXJD5buRRIWy22ZnJT2reFnr1o2Owho=;\n\tb=k3RVkfSVPaOf2Q8BFEvzrEOxxHzh+tzBKF1hUzYoyYMG20BCivxF7HTwRc+7JUgATc\n\tTsh3HNzs7wcAffTDPNwckVX6K3Vp+2+ZNRUZtcyaqaC4yCjADsI5mKzWqeYJSg5vtyng\n\tI3u6iOPCfbMYnOa/fC1+Sc2Wrrp7gKecCXSHrgwAFYl0A3mxfNMqZV7+uYhR3F/oTWd+\n\t8+/DyOzamGpnQM/AeEk2BQXrO+MfBHFLgWimq8urUX3zptoBhatmeYOSaYPmwOh0t3ag\n\t+SkPWRz1p6FhK5RE9EgFW5tV49j/Gp20N/Rh71CLW8dDIqFE8bVGovsssGJYZIZa8WaL\n\tOjrg==", "X-Google-DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=1e100.net; s=20161025;\n\th=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to\n\t:references;\n\tbh=KulmLa3F+a4DpXJD5buRRIWy22ZnJT2reFnr1o2Owho=;\n\tb=eHAPkMNNACngRR3ovfbh11vr+S3HMk0S6LVsb4tWUSBU1AM+zFBaw4bM7edlb4DAF4\n\tKuWRO33Kl9IcI5Y4mJpVEu6giBd42idofLFL+xaeAPGPgBkO7a9FtqSk8f8lmolDDAcm\n\toyYpdKzi+uKMR6lH08eT+YQNyFDaRlJ3t4EZPMKmEb6AH5KYqSbCvAeBUTF1UC3S7H2t\n\tFHc4pabvLMzluFHgDrlWd9fArQhTvA6xHO1q3f1FcFgd9or/gmblmtMLLPxr9idA8Y1V\n\ttxFk+CnjYZf0gfgdEfj1oxtkAUtGW95g/gNoWag0n4nL4p0kU9QFAlSG4IJZzFoqHA19\n\t0/IA==", "X-Gm-Message-State": "APjAAAVwp+X7jC+8hArU63XsW0kNr9fw2WlxKIYQuHoCIKqSqwRMmP8s\n\t9bXEMctDgL+03LLIPPIIn+7gALG4HFCtAQ==", "X-Google-Smtp-Source": "APXvYqwvgKs6g1tVyeK5nWSlRp6M4sR+nPedea7HespU5I3Y0VQzibNY1VdKJRijiXlfPZLOIiDeWQ==", "X-Received": "by 2002:a19:ee02:: with SMTP id g2mr1655804lfb.113.1567675961254;\n\tThu, 05 Sep 2019 02:32:41 -0700 (PDT)", "From": "Andrzej Ostruszka <amo@semihalf.com>", "To": "dev@dpdk.org", "Cc": "Andrzej Ostruszka <aostruszka@marvell.com>", "Date": "Thu, 5 Sep 2019 11:32:30 +0200", "Message-Id": "<20190905093239.27187-2-amo@semihalf.com>", "X-Mailer": "git-send-email 2.17.1", "In-Reply-To": "<20190905093239.27187-1-amo@semihalf.com>", "References": "<20190905093239.27187-1-amo@semihalf.com>", "Subject": "[dpdk-dev] [PATCH 01/10] 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 <dev.dpdk.org>", "List-Unsubscribe": "<https://mails.dpdk.org/options/dev>,\n\t<mailto:dev-request@dpdk.org?subject=unsubscribe>", "List-Archive": "<http://mails.dpdk.org/archives/dev/>", "List-Post": "<mailto:dev@dpdk.org>", "List-Help": "<mailto:dev-request@dpdk.org?subject=help>", "List-Subscribe": "<https://mails.dpdk.org/listinfo/dev>,\n\t<mailto:dev-request@dpdk.org?subject=subscribe>", "Errors-To": "dev-bounces@dpdk.org", "Sender": "\"dev\" <dev-bounces@dpdk.org>" }, "content": "This patch adds an option to enable link time optimization. In addition\nto LTO option itself (-flto) fat-lto-objects are being used. This is\nbecause during the build pmdinfogen scans the generated ELF objects to\nfind this_pmd_name* symbol in symbol table. Without fat-lto-objects gcc\nproduces ELF only with extra symbols for internal use during linking and\nclang does not produce ELF at all (only LLVM IR bitcode).\n\nSigned-off-by: Andrzej Ostruszka <aostruszka@marvell.com>\n---\n .travis.yml | 7 +++++\n config/common_base | 5 +++\n config/meson.build | 9 ++++++\n doc/guides/prog_guide/lto.rst | 36 ++++++++++++++++++++++\n doc/guides/rel_notes/release_19_11.rst | 8 +++++\n meson_options.txt | 2 ++\n mk/toolchain/clang/rte.toolchain-compat.mk | 4 +++\n mk/toolchain/clang/rte.vars.mk | 8 +++++\n mk/toolchain/gcc/rte.toolchain-compat.mk | 4 +++\n mk/toolchain/gcc/rte.vars.mk | 12 ++++++++\n mk/toolchain/icc/rte.vars.mk | 8 +++++\n 11 files changed, 103 insertions(+)\n create mode 100644 doc/guides/prog_guide/lto.rst", "diff": "diff --git a/.travis.yml b/.travis.yml\nindex 781f9f666..a9506b13a 100644\n--- a/.travis.yml\n+++ b/.travis.yml\n@@ -31,6 +31,7 @@ env:\n - DEF_LIB=\"static\" OPTS=\"-Denable_kmods=false\"\n - DEF_LIB=\"shared\" OPTS=\"-Denable_kmods=false\"\n - DEF_LIB=\"shared\" RUN_TESTS=1 BUILD_DOCS=1\n+ - DEF_LIB=\"static\" OPTS=\"-Denable_lto=true\"\n \n matrix:\n include:\n@@ -100,6 +101,12 @@ matrix:\n apt:\n packages:\n - *extra_packages\n+ - env: DEF_LIB=\"static\" OPTS=\"-Denable_lto=true\" EXTRA_PACKAGES=1\n+ compiler: gcc\n+ addons:\n+ apt:\n+ packages:\n+ - *extra_packages\n \n \n script: ./.ci/${TRAVIS_OS_NAME}-build.sh\ndiff --git a/config/common_base b/config/common_base\nindex 8ef75c203..73a55fdec 100644\n--- a/config/common_base\n+++ b/config/common_base\n@@ -49,6 +49,11 @@ CONFIG_RTE_FORCE_INTRINSICS=n\n #\n CONFIG_RTE_ARCH_STRICT_ALIGN=n\n \n+#\n+# Enable link time optimization\n+#\n+CONFIG_RTE_ENABLE_LTO=n\n+\n #\n # Compile to share library\n #\ndiff --git a/config/meson.build b/config/meson.build\nindex 2bafea530..b224d0cb8 100644\n--- a/config/meson.build\n+++ b/config/meson.build\n@@ -196,3 +196,12 @@ add_project_arguments('-D_GNU_SOURCE', language: 'c')\n if is_freebsd\n \tadd_project_arguments('-D__BSD_VISIBLE', language: 'c')\n endif\n+\n+if get_option('enable_lto')\n+\tif cc.has_argument('-flto -ffat-lto-objects')\n+\t\tadd_project_arguments('-flto -ffat-lto-objects', language: 'c')\n+\t\tadd_project_link_arguments('-flto', language: 'c')\n+\telse\n+\t\tmessage('compiler does not support LTO')\n+\tendif\n+endif\ndiff --git a/doc/guides/prog_guide/lto.rst b/doc/guides/prog_guide/lto.rst\nnew file mode 100644\nindex 000000000..effa0fcc3\n--- /dev/null\n+++ b/doc/guides/prog_guide/lto.rst\n@@ -0,0 +1,36 @@\n+Link Time Optimization\n+======================\n+\n+The DPDK framework supports compilation with link time optimization\n+turned on. This depends obviously on the capabilities of the compiler\n+to do \"whole program\" optimization at link time and is available only\n+for compilers that support that feature (gcc, clang and icc). To be\n+more specific compiler have to support creation of ELF objects\n+containing both normal code and internal representation\n+(fat-lto-objects). This is required since during build some code is\n+generated by parsing produced ELF objects (pmdinfogen).\n+\n+The amount of performance gain that one can get from LTO depends on the\n+compiler and the code that is being compiled. However LTO is also\n+useful for additional code analysis done by the compiler. In particular\n+due to interprocedural analysis compiler can produce additional warnings\n+about variables that might be used uninitialized. Some of these\n+warnings might be \"false positives\" though and you might need to\n+explicitly initialize variable in order to silence the compiler.\n+\n+Link time optimization can be enabled for whole DPDK framework by\n+setting:\n+\n+.. code-block:: console\n+ CONFIG_ENABLE_LTO=y\n+\n+in config file for the case of make based build and by:\n+\n+.. code-block:: console\n+ meson build -Denable_lto=true\n+ ninja -C build\n+\n+for the case of meson based build.\n+\n+Please note that turning LTO on causes considerable extension of\n+compilation time.\ndiff --git a/doc/guides/rel_notes/release_19_11.rst b/doc/guides/rel_notes/release_19_11.rst\nindex 27cfbd9e3..639b7ed53 100644\n--- a/doc/guides/rel_notes/release_19_11.rst\n+++ b/doc/guides/rel_notes/release_19_11.rst\n@@ -56,6 +56,14 @@ New Features\n Also, make sure to start the actual text at the margin.\n =========================================================\n \n+**Added build support for Link Time Optimization.**\n+\n+ LTO is an optimization technique used by the compiler to perform whole\n+ program analysis and optimization at link time. In order to do that\n+ compilers store their internal representation of the source code that\n+ the linker uses at the final stage of compilation process.\n+\n+ See :doc:`../prog_guide/lto` for more information:\n \n Removed Items\n -------------\ndiff --git a/meson_options.txt b/meson_options.txt\nindex 448f3e63d..a315e0f82 100644\n--- a/meson_options.txt\n+++ b/meson_options.txt\n@@ -6,6 +6,8 @@ option('drivers_install_subdir', type: 'string', value: 'dpdk/pmds-<VERSION>',\n \tdescription: 'Subdirectory of libdir where to install PMDs. Defaults to using a versioned subdirectory.')\n option('enable_docs', type: 'boolean', value: false,\n \tdescription: 'build documentation')\n+option('enable_lto', type: 'boolean', value: false,\n+\tdescription: 'Enable link time optimization')\n option('enable_kmods', type: 'boolean', value: true,\n \tdescription: 'build kernel modules')\n option('examples', type: 'string', value: '',\ndiff --git a/mk/toolchain/clang/rte.toolchain-compat.mk b/mk/toolchain/clang/rte.toolchain-compat.mk\nindex e6189b498..78f96c648 100644\n--- a/mk/toolchain/clang/rte.toolchain-compat.mk\n+++ b/mk/toolchain/clang/rte.toolchain-compat.mk\n@@ -20,3 +20,7 @@ CLANG_MINOR_VERSION := $(shell echo $(CLANG_VERSION) | cut -f2 -d.)\n ifeq ($(shell test $(CLANG_MAJOR_VERSION)$(CLANG_MINOR_VERSION) -lt 35 && echo 1), 1)\n \tCC_SUPPORTS_Z := false\n endif\n+\n+ifeq ($(shell test $(CLANG_MAJOR_VERSION)$(CLANG_MINOR_VERSION) -lt 60 && echo 1), 1)\n+\tCONFIG_RTE_ENABLE_LTO=n\n+endif\ndiff --git a/mk/toolchain/clang/rte.vars.mk b/mk/toolchain/clang/rte.vars.mk\nindex 3c49dc568..3b1fa05f9 100644\n--- a/mk/toolchain/clang/rte.vars.mk\n+++ b/mk/toolchain/clang/rte.vars.mk\n@@ -48,6 +48,14 @@ endif\n # process cpu flags\n include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk\n \n+ifeq ($(CONFIG_RTE_ENABLE_LTO),y)\n+# 'fat-lto' is used since pmdinfogen needs to have 'this_pmd_nameX'\n+# exported in symbol table and without this option only internal\n+# representation is present.\n+TOOLCHAIN_CFLAGS += -flto -ffat-lto-objects\n+TOOLCHAIN_LDFLAGS += -flto\n+endif\n+\n # workaround clang bug with warning \"missing field initializer\" for \"= {0}\"\n WERROR_FLAGS += -Wno-missing-field-initializers\n \ndiff --git a/mk/toolchain/gcc/rte.toolchain-compat.mk b/mk/toolchain/gcc/rte.toolchain-compat.mk\nindex ea40a11c0..ad4fad83c 100644\n--- a/mk/toolchain/gcc/rte.toolchain-compat.mk\n+++ b/mk/toolchain/gcc/rte.toolchain-compat.mk\n@@ -88,6 +88,10 @@ else\n \t\tMACHINE_CFLAGS := $(filter-out -march% -mtune% -msse%,$(MACHINE_CFLAGS))\n \tendif\n \n+\tifeq ($(shell test $(GCC_VERSION) -lt 45 && echo 1), 1)\n+\t\tCONFIG_RTE_ENABLE_LTO=n\n+\tendif\n+\n \t# Disable thunderx PMD for gcc < 4.7\n \tifeq ($(shell test $(GCC_VERSION) -lt 47 && echo 1), 1)\n \t\tCONFIG_RTE_LIBRTE_THUNDERX_NICVF_PMD=d\ndiff --git a/mk/toolchain/gcc/rte.vars.mk b/mk/toolchain/gcc/rte.vars.mk\nindex b852fcfd7..9fc704193 100644\n--- a/mk/toolchain/gcc/rte.vars.mk\n+++ b/mk/toolchain/gcc/rte.vars.mk\n@@ -62,6 +62,18 @@ endif\n # process cpu flags\n include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk\n \n+ifeq ($(CONFIG_RTE_ENABLE_LTO),y)\n+# 'fat-lto' is used since pmdinfogen needs to have 'this_pmd_nameX'\n+# exported in symbol table and without this option only internal\n+# representation is present.\n+TOOLCHAIN_CFLAGS += -flto -ffat-lto-objects\n+TOOLCHAIN_LDFLAGS += -flto\n+# workaround for GCC bug 81440\n+ifeq ($(shell test $(GCC_VERSION) -lt 80 && echo 1), 1)\n+WERROR_FLAGS += -Wno-lto-type-mismatch\n+endif\n+endif\n+\n # workaround GCC bug with warning \"missing initializer\" for \"= {0}\"\n ifeq ($(shell test $(GCC_VERSION) -lt 47 && echo 1), 1)\n WERROR_FLAGS += -Wno-missing-field-initializers\ndiff --git a/mk/toolchain/icc/rte.vars.mk b/mk/toolchain/icc/rte.vars.mk\nindex aa1422bf1..8aa87aa1e 100644\n--- a/mk/toolchain/icc/rte.vars.mk\n+++ b/mk/toolchain/icc/rte.vars.mk\n@@ -54,5 +54,13 @@ endif\n # process cpu flags\n include $(RTE_SDK)/mk/toolchain/$(RTE_TOOLCHAIN)/rte.toolchain-compat.mk\n \n+ifeq ($(CONFIG_RTE_ENABLE_LTO),y)\n+# 'fat-lto' is used since pmdinfogen needs to have 'this_pmd_nameX'\n+# exported in symbol table and without this option only internal\n+# representation is present.\n+TOOLCHAIN_CFLAGS += -flto -ffat-lto-objects\n+TOOLCHAIN_LDFLAGS += -flto\n+endif\n+\n export CC AS AR LD OBJCOPY OBJDUMP STRIP READELF\n export TOOLCHAIN_CFLAGS TOOLCHAIN_LDFLAGS TOOLCHAIN_ASFLAGS\n", "prefixes": [ "01/10" ] }