gcc/libgo
Nikhil Benesch 0cdde1e7ae libgo: handle linking to NetBSD's versioned symbols
On NetBSD, for backwards compatibility, various libc symbols are
renamed to a symbol with a version suffix. For example, this is the
(abbreviated) definition of sigaction:

    int sigaction(...) __asm__ ("__sigaction14")

This poses a challenge for libgo, which attempts to link sigaction by
way of an "//extern" comment:

    //extern sigaction
    func sigaction(...)

This results in a reference to the deprecated compatibility symbol
"sigaction", rather than the desired "__sigaction14" symbol.

This patch introduces a new "//extern-sysinfo" comment to handle this
situation. The new mklinknames.awk script scans a package for these
comments and outputs a "//go:linkname" directive that links the wrapper
to the correct versioned symbol, as determined by parsing the __asm__
annotation on the function's declaration in gen-sysinfo.go.

For now, only the following packages are scanned by mklinknames.awk:

    os
    os/user
    runtime
    syscall

gotools/:
	* Makefile.am (check-runtime): Add runtime_linknames.go to
	--extrafiles.
	* Makefile.in: Regenerate.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/265125
2020-10-28 18:20:50 -07:00
..
config
go libgo: handle linking to NetBSD's versioned symbols 2020-10-28 18:20:50 -07:00
misc/cgo
runtime
testsuite
aclocal.m4
check-packages.txt
config.h.in libgo: handle linking to NetBSD's versioned symbols 2020-10-28 18:20:50 -07:00
configure libgo: handle linking to NetBSD's versioned symbols 2020-10-28 18:20:50 -07:00
configure.ac libgo: handle linking to NetBSD's versioned symbols 2020-10-28 18:20:50 -07:00
goarch.sh
godeps.sh
gotool-packages.txt
libgo-packages.txt
libgo.imp
LICENSE
Makefile.am libgo: handle linking to NetBSD's versioned symbols 2020-10-28 18:20:50 -07:00
Makefile.in libgo: handle linking to NetBSD's versioned symbols 2020-10-28 18:20:50 -07:00
match.sh
MERGE
merge.sh
mklinknames.awk libgo: handle linking to NetBSD's versioned symbols 2020-10-28 18:20:50 -07:00
mkrsysinfo.sh
mkruntimeinc.sh
mksigtab.sh
mksysinfo.sh
mvifdiff.sh
PATENTS
README
README.gcc
sysinfo.c libgo: handle linking to NetBSD's versioned symbols 2020-10-28 18:20:50 -07:00
VERSION

See ../README.

This is the runtime support library for the Go programming language.
This library is intended for use with the Go frontend.

This library should not be stripped when it is installed.  Go code
relies on being able to look up file/line information, which comes
from the debugging info using the libbacktrace library.

The library has only been tested on GNU/Linux using glibc, and on
Solaris.  It should not be difficult to port to other operating
systems.

Directories:

go
  A copy of the Go library from http://golang.org/, with several
  changes for gccgo.

runtime
  Runtime functions, written in C, which are called directly by the
  compiler or by the library.

Contributing
============

To contribute patches to the files in this directory, please see
http://golang.org/doc/gccgo_contribute.html .

The master copy of these files is hosted at
http://code.google.com/p/gofrontend .  Changes to these files require
signing a Google contributor license agreement.  If you are the
copyright holder, you will need to agree to the individual contributor
license agreement at
http://code.google.com/legal/individual-cla-v1.0.html.  This agreement
can be completed online.

If your organization is the copyright holder, the organization will
need to agree to the corporate contributor license agreement at
http://code.google.com/legal/corporate-cla-v1.0.html.

If the copyright holder for your code has already completed the
agreement in connection with another Google open source project, it
does not need to be completed again.

Debugging
=========

This describes how to test libgo when built as part of gccgo.

To test a specific package, cd to the libgo build directory
(TARGET/libgo) and run `make PKG/check`.  For example, `make
bytes/check`.

To see the exact commands that it runs, including how the compiler is
invoked, run `make GOTESTFLAGS=--trace bytes/check`.  This will
display the commands if the test fails.  If the test passes, the
commands and other output will be visible in a file named
check-testlog in a subdirectory with the name of the package being
checked.  In the case of bytes/check, this will create
bytes/check-testlog.

To leave the test program behind, run `make GOTESTFLAGS=--keep
bytes/check`.  That will leave a gotestNNNN/test directory in the
libgo build directory.  In that directory you can run
`LD_LIBRARY_PATH=../../.libs ./a.out -test.short` to run the tests.
You can run specific failing tests using a -test.run option.  You can
see the tests being run with the -test.v option.  You can run the
program under a debugger such as gdb.