[dpdk-dev] [PATCH v4 01/10] build: add an option to enable LTO build

[Andrzej Ostruszka]

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 <aostruszka at marvell.com>
---
 .travis.yml                                  |  7 ++++
 config/common_base                           |  5 +++
 config/meson.build                           | 13 +++++++
 doc/guides/prog_guide/lto.rst                | 36 ++++++++++++++++++++
 doc/guides/rel_notes/release_19_11.rst       |  8 +++++
 lib/librte_distributor/rte_distributor.c     | 18 +++++-----
 lib/librte_distributor/rte_distributor_v20.c | 18 +++++-----
 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 +++++
 13 files changed, 143 insertions(+), 50 deletions(-)
 create mode 100644 doc/guides/prog_guide/lto.rst

diff --git a/.travis.yml b/.travis.yml
index 781f9f666..70d221852 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,6 +31,7 @@ env:
   - DEF_LIB="static" OPTS="-Denable_kmods=false"
   - DEF_LIB="shared" OPTS="-Denable_kmods=false"
   - DEF_LIB="shared" RUN_TESTS=1 BUILD_DOCS=1
+  - DEF_LIB="shared" OPTS="-Db_lto=true"
 
 matrix:
   include:
@@ -100,6 +101,12 @@ matrix:
       apt:
         packages:
           - *extra_packages
+  - env: DEF_LIB="shared" OPTS="-Db_lto=true" EXTRA_PACKAGES=1
+    compiler: gcc
+    addons:
+      apt:
+        packages:
+          - *extra_packages
 
 
 script: ./.ci/${TRAVIS_OS_NAME}-build.sh
diff --git a/config/common_base b/config/common_base
index 8ef75c203..73a55fdec 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 2bafea530..1a5093118 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -196,3 +196,16 @@ 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/lto.rst b/doc/guides/prog_guide/lto.rst
new file mode 100644
index 000000000..b6daabc86
--- /dev/null
+++ b/doc/guides/prog_guide/lto.rst
@@ -0,0 +1,36 @@
+Link Time Optimization
+======================
+
+The DPDK framework supports compilation with link time optimization
+turned on.  This depends obviously on the capabilities of the compiler
+to do "whole program" optimization at link time and is available only
+for compilers that support that feature (gcc and icc).  To be more
+specific compiler have to support creation of ELF objects containing
+both normal code and internal representation (fat-lto-objects).  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.
+
+Link time optimization can be enabled for whole DPDK framework by
+setting:
+
+.. code-block:: console
+    CONFIG_ENABLE_LTO=y
+
+in config file for the case of make based build and by:
+
+.. code-block:: console
+    meson build -Db_lto=true
+    ninja -C build
+
+for the case of meson based build.
+
+Please note that turning LTO on causes considerable extension of
+compilation time.
diff --git a/doc/guides/rel_notes/release_19_11.rst b/doc/guides/rel_notes/release_19_11.rst
index 8490d897c..97b4f4083 100644
--- a/doc/guides/rel_notes/release_19_11.rst
+++ b/doc/guides/rel_notes/release_19_11.rst
@@ -56,6 +56,14 @@ New Features
      Also, make sure to start the actual text at the margin.
      =========================================================
 
+**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/lib/librte_distributor/rte_distributor.c b/lib/librte_distributor/rte_distributor.c
index 21eb1fb0a..848250f4a 100644
--- a/lib/librte_distributor/rte_distributor.c
+++ b/lib/librte_distributor/rte_distributor.c
@@ -32,7 +32,7 @@ EAL_REGISTER_TAILQ(rte_dist_burst_tailq)
 
 /**** Burst Packet APIs called by workers ****/
 
-void
+void __vsym
 rte_distributor_request_pkt_v1705(struct rte_distributor *d,
 		unsigned int worker_id, struct rte_mbuf **oldpkt,
 		unsigned int count)
@@ -84,7 +84,7 @@ MAP_STATIC_SYMBOL(void rte_distributor_request_pkt(struct rte_distributor *d,
 		unsigned int count),
 		rte_distributor_request_pkt_v1705);
 
-int
+int __vsym
 rte_distributor_poll_pkt_v1705(struct rte_distributor *d,
 		unsigned int worker_id, struct rte_mbuf **pkts)
 {
@@ -124,7 +124,7 @@ MAP_STATIC_SYMBOL(int rte_distributor_poll_pkt(struct rte_distributor *d,
 		unsigned int worker_id, struct rte_mbuf **pkts),
 		rte_distributor_poll_pkt_v1705);
 
-int
+int __vsym
 rte_distributor_get_pkt_v1705(struct rte_distributor *d,
 		unsigned int worker_id, struct rte_mbuf **pkts,
 		struct rte_mbuf **oldpkt, unsigned int return_count)
@@ -159,7 +159,7 @@ MAP_STATIC_SYMBOL(int rte_distributor_get_pkt(struct rte_distributor *d,
 		struct rte_mbuf **oldpkt, unsigned int return_count),
 		rte_distributor_get_pkt_v1705);
 
-int
+int __vsym
 rte_distributor_return_pkt_v1705(struct rte_distributor *d,
 		unsigned int worker_id, struct rte_mbuf **oldpkt, int num)
 {
@@ -335,7 +335,7 @@ release(struct rte_distributor *d, unsigned int wkr)
 
 
 /* process a set of packets to distribute them to workers */
-int
+int __vsym
 rte_distributor_process_v1705(struct rte_distributor *d,
 		struct rte_mbuf **mbufs, unsigned int num_mbufs)
 {
@@ -476,7 +476,7 @@ MAP_STATIC_SYMBOL(int rte_distributor_process(struct rte_distributor *d,
 		rte_distributor_process_v1705);
 
 /* return to the caller, packets returned from workers */
-int
+int __vsym
 rte_distributor_returned_pkts_v1705(struct rte_distributor *d,
 		struct rte_mbuf **mbufs, unsigned int max_mbufs)
 {
@@ -526,7 +526,7 @@ total_outstanding(const struct rte_distributor *d)
  * Flush the distributor, so that there are no outstanding packets in flight or
  * queued up.
  */
-int
+int __vsym
 rte_distributor_flush_v1705(struct rte_distributor *d)
 {
 	unsigned int flushed;
@@ -561,7 +561,7 @@ MAP_STATIC_SYMBOL(int rte_distributor_flush(struct rte_distributor *d),
 		rte_distributor_flush_v1705);
 
 /* clears the internal returns array in the distributor */
-void
+void __vsym
 rte_distributor_clear_returns_v1705(struct rte_distributor *d)
 {
 	unsigned int wkr;
@@ -581,7 +581,7 @@ MAP_STATIC_SYMBOL(void rte_distributor_clear_returns(struct rte_distributor *d),
 		rte_distributor_clear_returns_v1705);
 
 /* creates a distributor instance */
-struct rte_distributor *
+struct rte_distributor * __vsym
 rte_distributor_create_v1705(const char *name,
 		unsigned int socket_id,
 		unsigned int num_workers,
diff --git a/lib/librte_distributor/rte_distributor_v20.c b/lib/librte_distributor/rte_distributor_v20.c
index cdc0969a8..31c766421 100644
--- a/lib/librte_distributor/rte_distributor_v20.c
+++ b/lib/librte_distributor/rte_distributor_v20.c
@@ -27,7 +27,7 @@ EAL_REGISTER_TAILQ(rte_distributor_tailq)
 
 /**** APIs called by workers ****/
 
-void
+void __vsym
 rte_distributor_request_pkt_v20(struct rte_distributor_v20 *d,
 		unsigned worker_id, struct rte_mbuf *oldpkt)
 {
@@ -40,7 +40,7 @@ rte_distributor_request_pkt_v20(struct rte_distributor_v20 *d,
 }
 VERSION_SYMBOL(rte_distributor_request_pkt, _v20, 2.0);
 
-struct rte_mbuf *
+struct rte_mbuf * __vsym
 rte_distributor_poll_pkt_v20(struct rte_distributor_v20 *d,
 		unsigned worker_id)
 {
@@ -54,7 +54,7 @@ rte_distributor_poll_pkt_v20(struct rte_distributor_v20 *d,
 }
 VERSION_SYMBOL(rte_distributor_poll_pkt, _v20, 2.0);
 
-struct rte_mbuf *
+struct rte_mbuf * __vsym
 rte_distributor_get_pkt_v20(struct rte_distributor_v20 *d,
 		unsigned worker_id, struct rte_mbuf *oldpkt)
 {
@@ -66,7 +66,7 @@ rte_distributor_get_pkt_v20(struct rte_distributor_v20 *d,
 }
 VERSION_SYMBOL(rte_distributor_get_pkt, _v20, 2.0);
 
-int
+int __vsym
 rte_distributor_return_pkt_v20(struct rte_distributor_v20 *d,
 		unsigned worker_id, struct rte_mbuf *oldpkt)
 {
@@ -191,7 +191,7 @@ process_returns(struct rte_distributor_v20 *d)
 }
 
 /* process a set of packets to distribute them to workers */
-int
+int __vsym
 rte_distributor_process_v20(struct rte_distributor_v20 *d,
 		struct rte_mbuf **mbufs, unsigned num_mbufs)
 {
@@ -296,7 +296,7 @@ rte_distributor_process_v20(struct rte_distributor_v20 *d,
 VERSION_SYMBOL(rte_distributor_process, _v20, 2.0);
 
 /* return to the caller, packets returned from workers */
-int
+int __vsym
 rte_distributor_returned_pkts_v20(struct rte_distributor_v20 *d,
 		struct rte_mbuf **mbufs, unsigned max_mbufs)
 {
@@ -334,7 +334,7 @@ total_outstanding(const struct rte_distributor_v20 *d)
 
 /* flush the distributor, so that there are no outstanding packets in flight or
  * queued up. */
-int
+int __vsym
 rte_distributor_flush_v20(struct rte_distributor_v20 *d)
 {
 	const unsigned flushed = total_outstanding(d);
@@ -347,7 +347,7 @@ rte_distributor_flush_v20(struct rte_distributor_v20 *d)
 VERSION_SYMBOL(rte_distributor_flush, _v20, 2.0);
 
 /* clears the internal returns array in the distributor */
-void
+void __vsym
 rte_distributor_clear_returns_v20(struct rte_distributor_v20 *d)
 {
 	d->returns.start = d->returns.count = 0;
@@ -358,7 +358,7 @@ rte_distributor_clear_returns_v20(struct rte_distributor_v20 *d)
 VERSION_SYMBOL(rte_distributor_clear_returns, _v20, 2.0);
 
 /* creates a distributor instance */
-struct rte_distributor_v20 *
+struct rte_distributor_v20 * __vsym
 rte_distributor_create_v20(const char *name,
 		unsigned socket_id,
 		unsigned num_workers)
diff --git a/lib/librte_lpm/rte_lpm.c b/lib/librte_lpm/rte_lpm.c
index 3a929a1b1..a2fba8d61 100644
--- a/lib/librte_lpm/rte_lpm.c
+++ b/lib/librte_lpm/rte_lpm.c
@@ -89,7 +89,7 @@ depth_to_range(uint8_t depth)
 /*
  * Find an existing lpm table and return a pointer to it.
  */
-struct rte_lpm_v20 *
+struct rte_lpm_v20 * __vsym
 rte_lpm_find_existing_v20(const char *name)
 {
 	struct rte_lpm_v20 *l = NULL;
@@ -115,7 +115,7 @@ rte_lpm_find_existing_v20(const char *name)
 }
 VERSION_SYMBOL(rte_lpm_find_existing, _v20, 2.0);
 
-struct rte_lpm *
+struct rte_lpm * __vsym
 rte_lpm_find_existing_v1604(const char *name)
 {
 	struct rte_lpm *l = NULL;
@@ -146,7 +146,7 @@ MAP_STATIC_SYMBOL(struct rte_lpm *rte_lpm_find_existing(const char *name),
 /*
  * Allocates memory for LPM object
  */
-struct rte_lpm_v20 *
+struct rte_lpm_v20 * __vsym
 rte_lpm_create_v20(const char *name, int socket_id, int max_rules,
 		__rte_unused int flags)
 {
@@ -219,7 +219,7 @@ rte_lpm_create_v20(const char *name, int socket_id, int max_rules,
 }
 VERSION_SYMBOL(rte_lpm_create, _v20, 2.0);
 
-struct rte_lpm *
+struct rte_lpm * __vsym
 rte_lpm_create_v1604(const char *name, int socket_id,
 		const struct rte_lpm_config *config)
 {
@@ -328,7 +328,7 @@ MAP_STATIC_SYMBOL(
 /*
  * Deallocates memory for given LPM table.
  */
-void
+void __vsym
 rte_lpm_free_v20(struct rte_lpm_v20 *lpm)
 {
 	struct rte_lpm_list *lpm_list;
@@ -357,7 +357,7 @@ rte_lpm_free_v20(struct rte_lpm_v20 *lpm)
 }
 VERSION_SYMBOL(rte_lpm_free, _v20, 2.0);
 
-void
+void __vsym
 rte_lpm_free_v1604(struct rte_lpm *lpm)
 {
 	struct rte_lpm_list *lpm_list;
@@ -1176,7 +1176,7 @@ add_depth_big_v1604(struct rte_lpm *lpm, uint32_t ip_masked, uint8_t depth,
 /*
  * Add a route
  */
-int
+int __vsym
 rte_lpm_add_v20(struct rte_lpm_v20 *lpm, uint32_t ip, uint8_t depth,
 		uint8_t next_hop)
 {
@@ -1217,7 +1217,7 @@ rte_lpm_add_v20(struct rte_lpm_v20 *lpm, uint32_t ip, uint8_t depth,
 }
 VERSION_SYMBOL(rte_lpm_add, _v20, 2.0);
 
-int
+int __vsym
 rte_lpm_add_v1604(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
 		uint32_t next_hop)
 {
@@ -1263,7 +1263,7 @@ MAP_STATIC_SYMBOL(int rte_lpm_add(struct rte_lpm *lpm, uint32_t ip,
 /*
  * Look for a rule in the high-level rules table
  */
-int
+int __vsym
 rte_lpm_is_rule_present_v20(struct rte_lpm_v20 *lpm, uint32_t ip, uint8_t depth,
 uint8_t *next_hop)
 {
@@ -1290,7 +1290,7 @@ uint8_t *next_hop)
 }
 VERSION_SYMBOL(rte_lpm_is_rule_present, _v20, 2.0);
 
-int
+int __vsym
 rte_lpm_is_rule_present_v1604(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
 uint32_t *next_hop)
 {
@@ -1843,7 +1843,7 @@ delete_depth_big_v1604(struct rte_lpm *lpm, uint32_t ip_masked,
 /*
  * Deletes a rule
  */
-int
+int __vsym
 rte_lpm_delete_v20(struct rte_lpm_v20 *lpm, uint32_t ip, uint8_t depth)
 {
 	int32_t rule_to_delete_index, sub_rule_index;
@@ -1897,7 +1897,7 @@ rte_lpm_delete_v20(struct rte_lpm_v20 *lpm, uint32_t ip, uint8_t depth)
 }
 VERSION_SYMBOL(rte_lpm_delete, _v20, 2.0);
 
-int
+int __vsym
 rte_lpm_delete_v1604(struct rte_lpm *lpm, uint32_t ip, uint8_t depth)
 {
 	int32_t rule_to_delete_index, sub_rule_index;
@@ -1956,7 +1956,7 @@ MAP_STATIC_SYMBOL(int rte_lpm_delete(struct rte_lpm *lpm, uint32_t ip,
 /*
  * Delete all rules from the LPM table.
  */
-void
+void __vsym
 rte_lpm_delete_all_v20(struct rte_lpm_v20 *lpm)
 {
 	/* Zero rule information. */
@@ -1973,7 +1973,7 @@ rte_lpm_delete_all_v20(struct rte_lpm_v20 *lpm)
 }
 VERSION_SYMBOL(rte_lpm_delete_all, _v20, 2.0);
 
-void
+void __vsym
 rte_lpm_delete_all_v1604(struct rte_lpm *lpm)
 {
 	/* Zero rule information. */
diff --git a/lib/librte_lpm/rte_lpm6.c b/lib/librte_lpm/rte_lpm6.c
index 9b8aeb972..49a7fea1d 100644
--- a/lib/librte_lpm/rte_lpm6.c
+++ b/lib/librte_lpm/rte_lpm6.c
@@ -811,7 +811,7 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
 /*
  * Add a route
  */
-int
+int __vsym
 rte_lpm6_add_v20(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 		uint8_t next_hop)
 {
@@ -861,7 +861,7 @@ simulate_add(struct rte_lpm6 *lpm, const uint8_t *masked_ip, uint8_t depth)
 	return 0;
 }
 
-int
+int __vsym
 rte_lpm6_add_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 		uint32_t next_hop)
 {
@@ -954,7 +954,7 @@ lookup_step(const struct rte_lpm6 *lpm, const struct rte_lpm6_tbl_entry *tbl,
 /*
  * Looks up an IP
  */
-int
+int __vsym
 rte_lpm6_lookup_v20(const struct rte_lpm6 *lpm, uint8_t *ip, uint8_t *next_hop)
 {
 	uint32_t next_hop32 = 0;
@@ -972,7 +972,7 @@ rte_lpm6_lookup_v20(const struct rte_lpm6 *lpm, uint8_t *ip, uint8_t *next_hop)
 }
 VERSION_SYMBOL(rte_lpm6_lookup, _v20, 2.0);
 
-int
+int __vsym
 rte_lpm6_lookup_v1705(const struct rte_lpm6 *lpm, uint8_t *ip,
 		uint32_t *next_hop)
 {
@@ -1007,7 +1007,7 @@ MAP_STATIC_SYMBOL(int rte_lpm6_lookup(const struct rte_lpm6 *lpm, uint8_t *ip,
 /*
  * Looks up a group of IP addresses
  */
-int
+int __vsym
 rte_lpm6_lookup_bulk_func_v20(const struct rte_lpm6 *lpm,
 		uint8_t ips[][RTE_LPM6_IPV6_ADDR_SIZE],
 		int16_t * next_hops, unsigned n)
@@ -1048,7 +1048,7 @@ rte_lpm6_lookup_bulk_func_v20(const struct rte_lpm6 *lpm,
 }
 VERSION_SYMBOL(rte_lpm6_lookup_bulk_func, _v20, 2.0);
 
-int
+int __vsym
 rte_lpm6_lookup_bulk_func_v1705(const struct rte_lpm6 *lpm,
 		uint8_t ips[][RTE_LPM6_IPV6_ADDR_SIZE],
 		int32_t *next_hops, unsigned int n)
@@ -1098,7 +1098,7 @@ MAP_STATIC_SYMBOL(int rte_lpm6_lookup_bulk_func(const struct rte_lpm6 *lpm,
 /*
  * Look for a rule in the high-level rules table
  */
-int
+int __vsym
 rte_lpm6_is_rule_present_v20(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 		uint8_t *next_hop)
 {
@@ -1118,7 +1118,7 @@ rte_lpm6_is_rule_present_v20(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 }
 VERSION_SYMBOL(rte_lpm6_is_rule_present, _v20, 2.0);
 
-int
+int __vsym
 rte_lpm6_is_rule_present_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 		uint32_t *next_hop)
 {
diff --git a/lib/librte_timer/rte_timer.c b/lib/librte_timer/rte_timer.c
index bdcf05d06..e560ace06 100644
--- a/lib/librte_timer/rte_timer.c
+++ b/lib/librte_timer/rte_timer.c
@@ -131,7 +131,7 @@ rte_timer_data_dealloc(uint32_t id)
 	return 0;
 }
 
-void
+void __vsym
 rte_timer_subsystem_init_v20(void)
 {
 	unsigned lcore_id;
@@ -153,7 +153,7 @@ VERSION_SYMBOL(rte_timer_subsystem_init, _v20, 2.0);
  * secondary processes should be empty, the zeroth entry can be shared by
  * multiple processes.
  */
-int
+int __vsym
 rte_timer_subsystem_init_v1905(void)
 {
 	const struct rte_memzone *mz;
@@ -551,7 +551,7 @@ __rte_timer_reset(struct rte_timer *tim, uint64_t expire,
 }
 
 /* Reset and start the timer associated with the timer handle tim */
-int
+int __vsym
 rte_timer_reset_v20(struct rte_timer *tim, uint64_t ticks,
 		    enum rte_timer_type type, unsigned int tim_lcore,
 		    rte_timer_cb_t fct, void *arg)
@@ -574,7 +574,7 @@ rte_timer_reset_v20(struct rte_timer *tim, uint64_t ticks,
 }
 VERSION_SYMBOL(rte_timer_reset, _v20, 2.0);
 
-int
+int __vsym
 rte_timer_reset_v1905(struct rte_timer *tim, uint64_t ticks,
 		      enum rte_timer_type type, unsigned int tim_lcore,
 		      rte_timer_cb_t fct, void *arg)
@@ -657,14 +657,14 @@ __rte_timer_stop(struct rte_timer *tim, int local_is_locked,
 }
 
 /* Stop the timer associated with the timer handle tim */
-int
+int __vsym
 rte_timer_stop_v20(struct rte_timer *tim)
 {
 	return __rte_timer_stop(tim, 0, &default_timer_data);
 }
 VERSION_SYMBOL(rte_timer_stop, _v20, 2.0);
 
-int
+int __vsym
 rte_timer_stop_v1905(struct rte_timer *tim)
 {
 	return rte_timer_alt_stop(default_data_id, tim);
@@ -817,14 +817,14 @@ __rte_timer_manage(struct rte_timer_data *timer_data)
 	priv_timer[lcore_id].running_tim = NULL;
 }
 
-void
+void __vsym
 rte_timer_manage_v20(void)
 {
 	__rte_timer_manage(&default_timer_data);
 }
 VERSION_SYMBOL(rte_timer_manage, _v20, 2.0);
 
-int
+int __vsym
 rte_timer_manage_v1905(void)
 {
 	struct rte_timer_data *timer_data;
@@ -1074,14 +1074,14 @@ __rte_timer_dump_stats(struct rte_timer_data *timer_data __rte_unused, FILE *f)
 #endif
 }
 
-void
+void __vsym
 rte_timer_dump_stats_v20(FILE *f)
 {
 	__rte_timer_dump_stats(&default_timer_data, f);
 }
 VERSION_SYMBOL(rte_timer_dump_stats, _v20, 2.0);
 
-int
+int __vsym
 rte_timer_dump_stats_v1905(FILE *f)
 {
 	return rte_timer_alt_dump_stats(default_data_id, f);
diff --git a/mk/toolchain/gcc/rte.toolchain-compat.mk b/mk/toolchain/gcc/rte.toolchain-compat.mk
index ea40a11c0..ad4fad83c 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 $(GCC_VERSION) -lt 45 && echo 1), 1)
+		CONFIG_RTE_ENABLE_LTO=n
+	endif
+
 	# Disable thunderx PMD for gcc < 4.7
 	ifeq ($(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