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| author | Andres Freund <andres@anarazel.de> | 2022-07-17 17:49:51 -0700 |
|---|---|---|
| committer | Andres Freund <andres@anarazel.de> | 2022-07-17 17:49:51 -0700 |
| commit | 089480c077056fc20fa8d8f5a3032a9dcf5ed812 (patch) | |
| tree | e5b2ad0c9a66073ea08306e5539e0f3b4df159ba /src/Makefile.shlib | |
| parent | fd4bad1655391582f639527c325fc4a99680cc64 (diff) | |
| download | postgresql-089480c077056fc20fa8d8f5a3032a9dcf5ed812.tar.gz | |
Default to hidden visibility for extension libraries where possible
Until now postgres built extension libraries with global visibility, i.e.
exporting all symbols. On the one platform where that behavior is not
natively available, namely windows, we emulate it by analyzing the input files
to the shared library and exporting all the symbols therein.
Not exporting all symbols is actually desirable, as it can improve loading
speed, reduces the likelihood of symbol conflicts and can improve intra
extension library function call performance. It also makes the non-windows
builds more similar to windows builds.
Additionally, with meson implementing the export-all-symbols behavior for
windows, turns out to be more verbose than desirable.
This patch adds support for hiding symbols by default and, to counteract that,
explicit symbol visibility annotation for compilers that support
__attribute__((visibility("default"))) and -fvisibility=hidden. That is
expected to be most, if not all, compilers except msvc (for which we already
support explicit symbol export annotations).
Now that extension library symbols are explicitly exported, we don't need to
export all symbols on windows anymore, hence remove that behavior from
src/tools/msvc. The supporting code can't be removed, as we still need to
export all symbols from the main postgres binary.
Author: Andres Freund <andres@anarazel.de>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/20211101020311.av6hphdl6xbjbuif@alap3.anarazel.de
Diffstat (limited to 'src/Makefile.shlib')
| -rw-r--r-- | src/Makefile.shlib | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/Makefile.shlib b/src/Makefile.shlib index 6df96c634b..2396bc247e 100644 --- a/src/Makefile.shlib +++ b/src/Makefile.shlib @@ -218,6 +218,19 @@ ifeq ($(PORTNAME), win32) endif +# If the shared library doesn't have an export file, mark all symbols not +# explicitly exported using PGDLLEXPORT as hidden. We can't pass these flags +# when building a library with explicit exports, as the symbols would be +# hidden before the linker script / exported symbol list takes effect. +# +# This is duplicated in pgxs.mk for MODULES style libraries. +ifeq ($(SHLIB_EXPORTS),) + # LDFLAGS_SL addition not strictly needed, CFLAGS used everywhere, but ... + override LDFLAGS_SL += $(CFLAGS_SL_MODULE) + override CFLAGS += $(CFLAGS_SL_MODULE) + override CXXFLAGS += $(CXXFLAGS_SL_MODULE) +endif + ## ## BUILD |