From 5bffa3b88e0d84e45139a891f25169399bfe10cc Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Thu, 28 Feb 2013 13:54:23 -0800
Subject: [PATCH] runtime/cgo: move common symbol overrides into 6c-compiled
 code

There are some function pointers declared by 6c in
package runtime without initialization and then also
declared in package runtime/cgo with initialization,
so that if runtime/cgo is linked in, the function pointers
are non-nil, and otherwise they are nil. We depend on
this property for implementing non-essential cgo hooks
in package runtime.

The declarations in package runtime are 6c-compiled
and end up in .6 files. The declarations in package runtime/cgo
are gcc-compiled and end up in .o files. Since 6l links the .6
and .o files together, this all works.

However, when we switch to "external linking" mode,
6l will not see the .o files, and it would be up to the host linker
to resolve the two into a single initialized symbol.
Not all host linkers will do this (in particular OS X gcc will not).

To fix this, move the cgo declarations into 6c-compiled code,
so that they end up in .6 files, so that 6l gets them no matter what.

R=golang-dev
CC=golang-dev
https://golang.org/cl/7440045
---
 src/pkg/runtime/cgo/callbacks.c         | 16 ++++++++++++++++
 src/pkg/runtime/cgo/gcc_darwin_386.c    |  1 -
 src/pkg/runtime/cgo/gcc_darwin_amd64.c  |  1 -
 src/pkg/runtime/cgo/gcc_freebsd_386.c   |  1 -
 src/pkg/runtime/cgo/gcc_freebsd_amd64.c |  1 -
 src/pkg/runtime/cgo/gcc_freebsd_arm.c   |  5 -----
 src/pkg/runtime/cgo/gcc_linux_386.c     |  1 -
 src/pkg/runtime/cgo/gcc_linux_amd64.c   |  1 -
 src/pkg/runtime/cgo/gcc_linux_arm.c     |  5 -----
 src/pkg/runtime/cgo/gcc_netbsd_386.c    |  1 -
 src/pkg/runtime/cgo/gcc_netbsd_amd64.c  |  1 -
 src/pkg/runtime/cgo/gcc_netbsd_arm.c    |  5 -----
 src/pkg/runtime/cgo/gcc_openbsd_386.c   |  1 -
 src/pkg/runtime/cgo/gcc_openbsd_amd64.c |  1 -
 src/pkg/runtime/cgo/gcc_setenv.c        |  4 +---
 src/pkg/runtime/cgo/gcc_util.c          |  6 ------
 src/pkg/runtime/cgo/gcc_windows_386.c   |  1 -
 src/pkg/runtime/cgo/gcc_windows_amd64.c |  1 -
 src/pkg/runtime/cgo/setenv.c            | 10 ++++++++++
 19 files changed, 27 insertions(+), 36 deletions(-)
 create mode 100644 src/pkg/runtime/cgo/setenv.c

diff --git a/src/pkg/runtime/cgo/callbacks.c b/src/pkg/runtime/cgo/callbacks.c
index cefd67de87..86de808fb1 100644
--- a/src/pkg/runtime/cgo/callbacks.c
+++ b/src/pkg/runtime/cgo/callbacks.c
@@ -77,3 +77,19 @@ _cgo_panic(void *a, int32 n)
 {
 	runtime·cgocallback((void(*)(void))_cgo_panic_internal, a, n);
 }
+
+#pragma cgo_static_import x_cgo_init
+extern void x_cgo_init(G*);
+void (*_cgo_init)(G*) = x_cgo_init;
+
+#pragma cgo_static_import x_cgo_malloc
+extern void x_cgo_malloc(void*);
+void (*_cgo_malloc)(void*) = x_cgo_malloc;
+
+#pragma cgo_static_import x_cgo_free
+extern void x_cgo_free(void*);
+void (*_cgo_free)(void*) = x_cgo_free;
+
+#pragma cgo_static_import x_cgo_thread_start
+extern void x_cgo_thread_start(void*);
+void (*_cgo_thread_start)(void*) = x_cgo_thread_start;
diff --git a/src/pkg/runtime/cgo/gcc_darwin_386.c b/src/pkg/runtime/cgo/gcc_darwin_386.c
index fd4d7a63a9..ad9fb5abf6 100644
--- a/src/pkg/runtime/cgo/gcc_darwin_386.c
+++ b/src/pkg/runtime/cgo/gcc_darwin_386.c
@@ -115,7 +115,6 @@ x_cgo_init(G *g)
 	inittls();
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_darwin_amd64.c b/src/pkg/runtime/cgo/gcc_darwin_amd64.c
index c3519360a4..65d381633d 100644
--- a/src/pkg/runtime/cgo/gcc_darwin_amd64.c
+++ b/src/pkg/runtime/cgo/gcc_darwin_amd64.c
@@ -85,7 +85,6 @@ x_cgo_init(G *g)
 	inittls();
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_freebsd_386.c b/src/pkg/runtime/cgo/gcc_freebsd_386.c
index f22d47b591..7c62a1bc49 100644
--- a/src/pkg/runtime/cgo/gcc_freebsd_386.c
+++ b/src/pkg/runtime/cgo/gcc_freebsd_386.c
@@ -23,7 +23,6 @@ x_cgo_init(G *g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_freebsd_amd64.c b/src/pkg/runtime/cgo/gcc_freebsd_amd64.c
index 27023c3a5e..6be8bd251a 100644
--- a/src/pkg/runtime/cgo/gcc_freebsd_amd64.c
+++ b/src/pkg/runtime/cgo/gcc_freebsd_amd64.c
@@ -23,7 +23,6 @@ x_cgo_init(G *g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_freebsd_arm.c b/src/pkg/runtime/cgo/gcc_freebsd_arm.c
index 9052b63073..3bcb0b2701 100644
--- a/src/pkg/runtime/cgo/gcc_freebsd_arm.c
+++ b/src/pkg/runtime/cgo/gcc_freebsd_arm.c
@@ -55,10 +55,6 @@ x_cgo_save_gm(void)
 	);
 }
 
-// both cgo_tls_{get,set}_gm can be called from runtime
-void (*_cgo_load_gm)(void) = x_cgo_load_gm;
-void (*_cgo_save_gm)(void) = x_cgo_save_gm;
-
 void
 x_cgo_init(G *g)
 {
@@ -72,7 +68,6 @@ x_cgo_init(G *g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_linux_386.c b/src/pkg/runtime/cgo/gcc_linux_386.c
index 0cac96f81f..9357a63f71 100644
--- a/src/pkg/runtime/cgo/gcc_linux_386.c
+++ b/src/pkg/runtime/cgo/gcc_linux_386.c
@@ -21,7 +21,6 @@ x_cgo_init(G *g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_linux_amd64.c b/src/pkg/runtime/cgo/gcc_linux_amd64.c
index 10981d62c5..bc76117d35 100644
--- a/src/pkg/runtime/cgo/gcc_linux_amd64.c
+++ b/src/pkg/runtime/cgo/gcc_linux_amd64.c
@@ -21,7 +21,6 @@ x_cgo_init(G* g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_linux_arm.c b/src/pkg/runtime/cgo/gcc_linux_arm.c
index 93004ddcbc..46a1126ad3 100644
--- a/src/pkg/runtime/cgo/gcc_linux_arm.c
+++ b/src/pkg/runtime/cgo/gcc_linux_arm.c
@@ -55,10 +55,6 @@ x_cgo_save_gm(void)
 	);
 }
 
-// both cgo_tls_{get,set}_gm can be called from runtime
-void (*_cgo_load_gm)(void) = x_cgo_load_gm;
-void (*_cgo_save_gm)(void) = x_cgo_save_gm;
-
 void
 x_cgo_init(G *g)
 {
@@ -72,7 +68,6 @@ x_cgo_init(G *g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_netbsd_386.c b/src/pkg/runtime/cgo/gcc_netbsd_386.c
index 1232541547..09b271df4f 100644
--- a/src/pkg/runtime/cgo/gcc_netbsd_386.c
+++ b/src/pkg/runtime/cgo/gcc_netbsd_386.c
@@ -22,7 +22,6 @@ x_cgo_init(G *g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_netbsd_amd64.c b/src/pkg/runtime/cgo/gcc_netbsd_amd64.c
index bc2e2b9c66..080c59ba49 100644
--- a/src/pkg/runtime/cgo/gcc_netbsd_amd64.c
+++ b/src/pkg/runtime/cgo/gcc_netbsd_amd64.c
@@ -22,7 +22,6 @@ x_cgo_init(G *g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_netbsd_arm.c b/src/pkg/runtime/cgo/gcc_netbsd_arm.c
index 1b9ba39361..d93b531e7b 100644
--- a/src/pkg/runtime/cgo/gcc_netbsd_arm.c
+++ b/src/pkg/runtime/cgo/gcc_netbsd_arm.c
@@ -61,10 +61,6 @@ x_cgo_save_gm(void)
 	);
 }
 
-// both cgo_tls_{get,set}_gm can be called from runtime
-void (*_cgo_load_gm)(void) = x_cgo_load_gm;
-void (*_cgo_save_gm)(void) = x_cgo_save_gm;
-
 void
 x_cgo_init(G *g)
 {
@@ -78,7 +74,6 @@ x_cgo_init(G *g)
 	pthread_attr_destroy(&attr);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_openbsd_386.c b/src/pkg/runtime/cgo/gcc_openbsd_386.c
index c0b90cce69..86c1365adc 100644
--- a/src/pkg/runtime/cgo/gcc_openbsd_386.c
+++ b/src/pkg/runtime/cgo/gcc_openbsd_386.c
@@ -109,7 +109,6 @@ x_cgo_init(G *g)
 	tcb_fixup(1);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_openbsd_amd64.c b/src/pkg/runtime/cgo/gcc_openbsd_amd64.c
index 3984480dfa..d3a5e36b03 100644
--- a/src/pkg/runtime/cgo/gcc_openbsd_amd64.c
+++ b/src/pkg/runtime/cgo/gcc_openbsd_amd64.c
@@ -109,7 +109,6 @@ x_cgo_init(G *g)
 	tcb_fixup(1);
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_setenv.c b/src/pkg/runtime/cgo/gcc_setenv.c
index c99853a0ff..a0938166d1 100644
--- a/src/pkg/runtime/cgo/gcc_setenv.c
+++ b/src/pkg/runtime/cgo/gcc_setenv.c
@@ -1,4 +1,4 @@
-// Copyright 20111 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors.  All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -14,5 +14,3 @@ x_cgo_setenv(char **arg)
 {
 	setenv(arg[0], arg[1], 1);
 }
-
-void (*_cgo_setenv)(char**) = x_cgo_setenv;
diff --git a/src/pkg/runtime/cgo/gcc_util.c b/src/pkg/runtime/cgo/gcc_util.c
index 0e289166fc..20913d7369 100644
--- a/src/pkg/runtime/cgo/gcc_util.c
+++ b/src/pkg/runtime/cgo/gcc_util.c
@@ -16,8 +16,6 @@ x_cgo_malloc(void *p)
 	a->ret = malloc(a->n);
 }
 
-void (*_cgo_malloc)(void*) = x_cgo_malloc;
-
 /* Stub for calling free from Go */
 void
 x_cgo_free(void *p)
@@ -29,8 +27,6 @@ x_cgo_free(void *p)
 	free(a->arg);
 }
 
-void (*_cgo_free)(void*) = x_cgo_free;
-
 /* Stub for creating a new thread */
 void
 x_cgo_thread_start(ThreadStart *arg)
@@ -47,5 +43,3 @@ x_cgo_thread_start(ThreadStart *arg)
 
 	_cgo_sys_thread_start(ts);	/* OS-dependent half */
 }
-
-void (*_cgo_thread_start)(ThreadStart*) = x_cgo_thread_start;
diff --git a/src/pkg/runtime/cgo/gcc_windows_386.c b/src/pkg/runtime/cgo/gcc_windows_386.c
index 5e9d4a94d5..02eab12e59 100644
--- a/src/pkg/runtime/cgo/gcc_windows_386.c
+++ b/src/pkg/runtime/cgo/gcc_windows_386.c
@@ -21,7 +21,6 @@ x_cgo_init(G *g)
 	g->stackguard = (uintptr)&tmp - STACKSIZE + 8*1024;
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/gcc_windows_amd64.c b/src/pkg/runtime/cgo/gcc_windows_amd64.c
index 386e5bbe3a..f7695a1cc2 100644
--- a/src/pkg/runtime/cgo/gcc_windows_amd64.c
+++ b/src/pkg/runtime/cgo/gcc_windows_amd64.c
@@ -21,7 +21,6 @@ x_cgo_init(G *g)
 	g->stackguard = (uintptr)&tmp - STACKSIZE + 8*1024;
 }
 
-void (*_cgo_init)(G*) = x_cgo_init;
 
 void
 _cgo_sys_thread_start(ThreadStart *ts)
diff --git a/src/pkg/runtime/cgo/setenv.c b/src/pkg/runtime/cgo/setenv.c
new file mode 100644
index 0000000000..4c47cdb002
--- /dev/null
+++ b/src/pkg/runtime/cgo/setenv.c
@@ -0,0 +1,10 @@
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin freebsd linux netbsd openbsd
+
+#pragma cgo_import_static x_cgo_setenv
+
+void x_cgo_setenv(char**);
+void (*_cgo_setenv)(char**) = x_cgo_setenv;
-- 
2.48.1