gcc/libgo
Ian Lance Taylor 39c0aa5f74 compiler, runtime, reflect: generate unique type descriptors
Currently, the compiler already generates common symbols for type
    descriptors, so the type descriptors are unique. However, when a
    type is created through reflection, it is not deduplicated with
    compiler-generated types. As a consequence, we cannot assume type
    descriptors are unique, and cannot use pointer equality to
    compare them. Also, when constructing a reflect.Type, it has to
    go through a canonicalization map, which introduces overhead to
    reflect.TypeOf, and lock contentions in concurrent programs.
    
    In order for the reflect package to deduplicate types with
    compiler-created types, we register all the compiler-created type
    descriptors at startup time. The reflect package, when it needs
    to create a type, looks up the registry of compiler-created types
    before creates a new one. There is no lock contention since the
    registry is read-only after initialization.
    
    This lets us get rid of the canonicalization map, and also makes
    it possible to compare type descriptors with pointer equality.
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/179598

From-SVN: r271894
2019-06-03 23:37:04 +00:00
..
config
go compiler, runtime, reflect: generate unique type descriptors 2019-06-03 23:37:04 +00:00
misc/cgo libgo: update to Go 1.12.1 2019-03-18 20:27:59 +00:00
runtime libgo: delay applying profile stack-frame skip until fixup 2019-06-03 23:07:54 +00:00
testsuite runtime: drop unused C type reflection code 2019-05-31 21:32:47 +00:00
aclocal.m4 runtime: implement cheaper context switch on Linux/AMD64 2019-05-31 17:56:36 +00:00
check-packages.txt
config.h.in runtime, sync: use __atomic intrinsics instead of __sync 2019-02-01 21:55:38 +00:00
configure runtime: drop unused C type reflection code 2019-05-31 21:32:47 +00:00
configure.ac runtime: implement cheaper context switch on Linux/AMD64 2019-05-31 17:56:36 +00:00
goarch.sh
godeps.sh
gotool-packages.txt
libgo-packages.txt
libgo.imp
LICENSE
Makefile.am runtime: drop unused C type reflection code 2019-05-31 21:32:47 +00:00
Makefile.in runtime: drop unused C type reflection code 2019-05-31 21:32:47 +00:00
match.sh
MERGE libgo: update to Go 1.12.2 2019-04-08 18:36:25 +00:00
merge.sh
mkrsysinfo.sh
mkruntimeinc.sh
mksigtab.sh libgo: add configury and sysinfo support for hurd 2019-02-01 22:46:39 +00:00
mksysinfo.sh libgo: drop Solaris 10 support 2019-05-13 20:26:24 +00:00
mvifdiff.sh
PATENTS
README libgo: add Debugging section to README 2019-05-08 22:07:40 +00:00
README.gcc
sysinfo.c
VERSION libgo: update to Go 1.12.2 2019-04-08 18:36:25 +00:00

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.