mirror of
https://git.FreeBSD.org/ports.git
synced 2024-11-20 00:21:35 +00:00
0032df7f14
https://gcc.gnu.org/gcc-9/changes.html has a comprehensive overview of many improvements and changes and https://gcc.gnu.org/gcc-8/porting_to.html addresses issues you may encounter porting to this new version, though this release series should have fewer of those than previous ones. To provide a brief overview of some of the more noticable changes: GCC's diagnostics now print source code with a left margin showing line numbers. This is configurable via -fno-diagnostics-show-line-numbers. Plus there have been lots of further improvements around diagnostic messages in general as -fopt-info. As usual a large number of improvements to code generation, including but by far not limited to the following: - Switch expansion (into expressions). - Inliner defaults are tuned to better suit modern C++ codebases, especially when built with link time optimizations. - Hot/cold partitioning is now more precise and aggressive. - Improved scalability for very large translation units. - Link-time optimization improvements including faster compilation. A new option -flive-patching=[inline-only-static|inline-clone] has been introduced to provide a safe compilation for live-patching. A new pair of profiling options -fprofile-filter-files and -fprofile-exclude-files help filter which source files are instrumented. New built-in functions __builtin_expect_with_probability, __builtin_has_attribute, and __builtin_speculation_safe_value. Significant effort has been put into refining existing compiler warnings and adding additional diagnostics. One notable addition is -Wabsolute-value which warns for calls to standard functions that compute the absolute value of an argument when a more appropriate standard function is available. For example, calling abs(3.14) warns because the appropriate function to compute the absolute value of a double argument is fabs. The spelling corrector now considers transposed letters, and the threshold for similarity has been tightened, to avoid nonsensical suggestions. A new option --completion provides better option completion in a shell (such as bash). OpenACC support in C, C++, and Fortran continues to be maintained and improved. Most of the OpenACC 2.5 specification is implemented. Version 5.0 of the OpenMP specification is now partially supported in the C and C++ compilers. There is now experimental support for the upcoming C2X revision of the ISO C standard (via the -std=c2x and similar options). The C++ front end has experimental support for some of the upcoming C++2a draft features, enabled by the -std=c++2a or -std=gnu++2a options. This includes range-based for statements with initializer, default constructible and assignable stateless lambdas, lambdas in unevaluated contexts, language support for empty data members, allowing pack expansion in lambda init-capture, likely and unlikely attributes, class types in non-type template parameters, allowing virtual function calls in constant expressions, explicit(bool), std::is_constant_evaluated, nested inline namespaces, etc. The C++17 implementation is no longer experimental and parallel algorithms and <execution> and <memory_resource> are available. Using the types and functions in <filesystem> does not require linking with -lstdc++fs any more. On the Fortran side asynchronous I/O is now fully supported; FINDLOC and IS_CONTIGUOUS and other intrinsics have been implemented. The MAX and MIN intrinsics are no longer guaranteed to return any particular value in case one of the arguments is a NaN. This conforms with the Fortran standard and what other Fortran compilers do. A new option -fdec-include, set also by -fdec, has been added for compatibility with legacy code. With this option, the INCLUDE directive is parsed also as a statement, which allows it to be written on multiple source lines with line continuations. Support for the Cell Broadband Engine (SPU), and thus powerpcspe on FreeBSD as well, has been removed for lack of upstream maintainership. Also there's been a minor ABI change on arm* targets (that GCC warns about by default, controlled by the -Wpsabi option). Support for the D programming language has been added to GCC, implementing version 2.076 of the language and run-time library, though this port does not enable this yet. Volunteers welcome to test and contribute.
71 lines
2.8 KiB
Plaintext
71 lines
2.8 KiB
Plaintext
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
|