Re: libgo patch committed: Change build procedure to use build tags

[Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>]

On 08/06/2016 02:36 AM, Ian Lance Taylor wrote:
> Go packages use build tags (see the section on Build Constraints at
> https://golang.org/pkg/go/build/) to select which files to build on
> specific systems.
> 
> Previously the libgo Makefile explicitly listed the set of files to
> compile for each package.  For packages that use build tags, this
> required a lot of awkward automake conditionals in the Makefile.
> 
> This patch changes the build to look at the build tags in the files.
> The new shell script libgo/match.sh does the matching.  This required
> adjusting a lot of build tags, and removing some files that are never
> used.  I verified that the exact same sets of files are compiled on
> x86_64-pc-linux-gnu.  I also tested the build on i386-sun-solaris
> (building for both 32-bit and 64-bit).
> 
> Writing match.sh revealed some bugs in the build tag handling that
> already exists, in a slightly different form, in the gotest shell
> script.  This patch fixes those problems as well.
> 
> The old code used automake conditionals to handle systems that were
> missing strerror_r and wait4.  Rather than deal with those in Go,
> those functions are now implemented in runtime/go-nosys.c when
> necessary, so the Go code can simply assume that they exist.
> 
> The os testsuite looked for dir_unix.go, which was never built for
> gccgo and has now been removed.  I changed the testsuite to look for
> dir.go instead.
> 
> Note that if you have an existing build directory, you will have to
> remove all the .dep files in TARGET/libgo after updating to this
> patch.  There isn't anything that will force them to update
> automatically.
> 
> Bootstrapped on x86_64-pc-linux-gnu and i386-sun-solaris.  Ran Go
> testsuite on x86_64-pc-linux-gnu.  Committed to mainline.
> 
> Ian

This appears to break libgo build on s390x:

libtool: compile:  /home3/andreas/clean/gcc-7.0.0-64-clean-build/./gcc/gccgo
-B/home3/andreas/clean/gcc-7.0.0-64-clean-build/./gcc/
-B/home3/andreas/clean/gcc-7.0.0-64-clean-install/s390x-ibm-linux-gnu/bin/ -B/h
ome3/andreas/clean/gcc-7.0.0-64-clean-install/s390x-ibm-linux-gnu/lib/ -isystem
/home3/andreas/clean/gcc-7.0.0-64-clean-install/s390x-ibm-linux-gnu/include -isystem
/home3/andreas/clean/gcc-7.0.0-64-clean-instal
l/s390x-ibm-linux-gnu/sys-include -O2 -g -I . -c -fgo-pkgpath=hash/crc32
/home3/andreas/clean/../gcc/libgo/go/hash/crc32/crc32.go
/home3/andreas/clean/../gcc/libgo/go/hash/crc32/crc32_generic.go /home3/andreas/c
lean/../gcc/libgo/go/hash/crc32/crc32_s390x.go  -fPIC -o hash/.libs/crc32.o
/home3/andreas/clean/../gcc/libgo/go/hash/crc32/crc32_s390x.go:56:1: error: redefinition of
‘updateCastagnoli’
 func updateCastagnoli(crc uint32, p []byte) uint32 {
 ^
/home3/andreas/clean/../gcc/libgo/go/hash/crc32/crc32_generic.go:12:1: note: previous definition of
‘updateCastagnoli’ was here
 func updateCastagnoli(crc uint32, p []byte) uint32 {
 ^
/home3/andreas/clean/../gcc/libgo/go/hash/crc32/crc32_s390x.go:81:1: error: redefinition of ‘updateIEEE’
 func updateIEEE(crc uint32, p []byte) uint32 {
 ^
/home3/andreas/clean/../gcc/libgo/go/hash/crc32/crc32_generic.go:20:1: note: previous definition of
‘updateIEEE’ was here
 func updateIEEE(crc uint32, p []byte) uint32 {
 ^
make[4]: *** [hash/crc32.lo] Error 1
make[4]: *** Waiting for unfinished jobs....


Adding more "build ignore"s does fix the build for me.

However, I'm wondering why we have to disable the asm tuned files for gccgo? For s390 I really would
like to enable them since they make a huge difference.

The same is probably also required in ./hash/crc32/crc32_amd64p32.go
I could add this as well.

Ok to apply?

diff --git a/libgo/go/crypto/aes/cbc_s390x.go b/libgo/go/crypto/aes/cbc_s390x.go
index 427b30b..8346b5e 100644
--- a/libgo/go/crypto/aes/cbc_s390x.go
+++ b/libgo/go/crypto/aes/cbc_s390x.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

+// +build ignore
+
 package aes

 import (
diff --git a/libgo/go/crypto/aes/ctr_s390x.go b/libgo/go/crypto/aes/ctr_s390x.go
index 94dea5c..ae09dba 100644
--- a/libgo/go/crypto/aes/ctr_s390x.go
+++ b/libgo/go/crypto/aes/ctr_s390x.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

+// +build ignore
+
 package aes

 import (
diff --git a/libgo/go/hash/crc32/crc32_s390x.go b/libgo/go/hash/crc32/crc32_s390x.go
index 2f20690..b8a5808 100644
--- a/libgo/go/hash/crc32/crc32_s390x.go
+++ b/libgo/go/hash/crc32/crc32_s390x.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

+// +build ignore
+
 package crc32

 import (