Date: Sat, 27 Apr 2019 14:47:53 +0000 (UTC) From: Gerald Pfeifer <gerald@FreeBSD.org> To: ports-committers@freebsd.org, svn-ports-all@freebsd.org, svn-ports-branches@freebsd.org Subject: svn commit: r500211 - in branches/2019Q2/lang/gcc8: . files Message-ID: <201904271447.x3RElr9f092395@repo.freebsd.org>
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Author: gerald Date: Sat Apr 27 14:47:53 2019 New Revision: 500211 URL: https://svnweb.freebsd.org/changeset/ports/500211 Log: MFH: r499061 Approved by: portmgr (miwi) GCC has two runtime libraries: The static library libgcc.a (-lgcc) and the shared library libgcc_s.so (-lgcc_s). Both implement many of the same functions but they also each have their unique functions. When GCC links programs and libraries there are three possibilities: 1. gcc -static-libgcc or gcc -static: -lgcc => Just use libgcc.a. 2. gcc -shared-libgcc: -lgcc_s -lgcc => Link with libgcc_s first, so libgcc.a is only used for its unique functions. 3. gcc: -lgcc -Wl,--as-needed -lgcc_s -Wl,--no-as-needed => Link with libgcc.a first so libgcc_s is only used for its unique functions (_Unwind_* functions). Approach 3 is the default for gcc and it's also what clang and clang++ use; approach 2 is the default for gfortran, g++ and probably other front ends. This patch makes 3 the default for gfortran. It significantly reduces the use of libgcc_s. The _Unwind_* functions are also available in the old base system libgcc_s which means this reduces the need for -rpath /usr/local/lib/gccN in ports that depend on libraries built with gfortran. Consider a dependency tree like this: prog -> libA -> libgcc_s (old base system libgcc_s is fine) -> libB -> libgcc_s (libB built with gfortran, needs new libgcc_s) Here prog needs to be linked with -rpath /usr/local/lib/gccN even if it's a normal C program compiled with clang. Without -rpath it will fail to start because it loads old libgcc_s first as a dependency of libA and then it fails to load libB. With this patch libB works with old base system libgcc_s or may not need libgcc_s at all, so prog does not need to be linked with -rpath. PR: 208120 Submitted by: tijl Added: branches/2019Q2/lang/gcc8/files/patch-gfortran-libgcc - copied unchanged from r499061, head/lang/gcc8/files/patch-gfortran-libgcc Modified: branches/2019Q2/lang/gcc8/Makefile Directory Properties: branches/2019Q2/ (props changed) Modified: branches/2019Q2/lang/gcc8/Makefile ============================================================================== --- branches/2019Q2/lang/gcc8/Makefile Sat Apr 27 14:06:13 2019 (r500210) +++ branches/2019Q2/lang/gcc8/Makefile Sat Apr 27 14:47:53 2019 (r500211) @@ -3,7 +3,7 @@ PORTNAME= gcc PORTVERSION= 8.3.0 -PORTREVISION= 1 +PORTREVISION= 2 CATEGORIES= lang MASTER_SITES= GCC PKGNAMESUFFIX= ${SUFFIX} Copied: branches/2019Q2/lang/gcc8/files/patch-gfortran-libgcc (from r499061, head/lang/gcc8/files/patch-gfortran-libgcc) ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ branches/2019Q2/lang/gcc8/files/patch-gfortran-libgcc Sat Apr 27 14:47:53 2019 (r500211, copy of r499061, head/lang/gcc8/files/patch-gfortran-libgcc) @@ -0,0 +1,70 @@ +GCC has two runtime libraries: The static library libgcc.a (-lgcc) and +the shared library libgcc_s.so (-lgcc_s). Both implement many of the +same functions but they also each have their unique functions. When +gcc links programs and libraries there are three possibilities: + +1. gcc -static-libgcc or gcc -static: -lgcc + => Just use libgcc.a. + +2. gcc -shared-libgcc: -lgcc_s -lgcc + => Link with libgcc_s first, so libgcc.a is only used for its unique + functions. + +3. gcc: -lgcc -Wl,--as-needed -lgcc_s -Wl,--no-as-needed + => Link with libgcc.a first so libgcc_s is only used for its unique + functions (_Unwind_* functions). + +Approach 3 is the default for gcc and it's also what clang and clang++ use; +approach 2 is the default for gfortran, g++ and probably other front ends. + +This patch makes 3 the default for gfortran. It significantly reduces +the use of libgcc_s. The _Unwind_* functions are also available in the +old base system libgcc_s which means this reduces the need for +-rpath /usr/local/lib/gccN in ports that depend on libraries built with +gfortran. Consider a dependency tree like this: + + prog -> libA -> libgcc_s (old base system libgcc_s is fine) + -> libB -> libgcc_s (libB built with gfortran, needs new libgcc_s) + +Here prog needs to be linked with -rpath /usr/local/lib/gccN even if it's +a normal C program compiled with clang. Without -rpath it will fail to +start because it loads old libgcc_s first as a dependency of libA and then +it fails to load libB. With this patch libB works with old base system +libgcc_s or may not need libgcc_s at all, so prog does not need to be +linked with -rpath. + +Upstream is unlikely accept a patch like this because libgfortran calls +some _Unwind_* functions and so always needs libgcc_s. Also because +every Fortran program and library links to libgfortran it makes sense +that option 2 above is the default. On FreeBSD where clang and GCC +compiled code can be mixed and where multiple libgcc_s may be installed, +option 3 is just a lot easier to deal with. + +The bug that sparked this is PR 208120 (but note there's a lot of +misleading information in that bug. CMake is not actually doing +anything wrong.) + +--- UTC +--- gcc/fortran/gfortranspec.c.orig 2015-06-26 17:47:23 UTC ++++ gcc/fortran/gfortranspec.c +@@ -404,7 +404,7 @@ For more information about these matters + } + } + +-#ifdef ENABLE_SHARED_LIBGCC ++#if 0 + if (library) + { + unsigned int i; + +--- libgfortran/Makefile.in.orig 2019-02-22 14:22:13.000000000 +0000 ++++ libgfortran/Makefile.in 2019-02-27 16:27:08.856408000 +0000 +@@ -625,7 +625,7 @@ + $(LTLDFLAGS) $(LIBQUADLIB) ../libbacktrace/libbacktrace.la \ + $(HWCAP_LDFLAGS) \ + -lm $(extra_ldflags_libgfortran) \ +- $(version_arg) -Wc,-shared-libgcc ++ $(version_arg) + + libgfortran_la_DEPENDENCIES = $(version_dep) libgfortran.spec $(LIBQUADLIB_DEP) + cafexeclib_LTLIBRARIES = libcaf_single.la
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