static linking on Linux

[Fergus Henderson]

Hi,

Hans Boehm can review this one.

Estimated hours taken: 1

Fix a problem where the new support for Linux ELF shared libraries
in gc 4.11 meant that `ml -static' didn't work on Linux, because
you got unresolved references to _DYNAMIC in dyn_load.o.

boehm_gc/dyn_load.c:
	In GC_FirstDLOpenedLinkMap(), check if the address of _DYNAMIC is 0.
	If so, we've been linked statically, so just return 0.

scripts/ml.in:
	If we're passed `-static' or `--static', then pass
	`-static -Wl,-defsym,_DYNAMIC=0' to gcc, so that gcc
	will pass `-defsym _DYNAMIC=0' to the linker.


Index: mercury/boehm_gc/dyn_load.c
diff -u mercury/boehm_gc/dyn_load.c:1.6 mercury/boehm_gc/dyn_load.c:1.7
--- mercury/boehm_gc/dyn_load.c:1.6	Sun Dec  8 21:34:34 1996
+++ mercury/boehm_gc/dyn_load.c	Sun Feb  9 23:23:28 1997
@@ -279,6 +279,9 @@
     struct r_debug *r;
     static struct link_map *cachedResult = 0;
 
+    if( _DYNAMIC == 0) {
+        return(0);
+    }
     if( cachedResult == 0 ) {
         int tag;
         for( dp = _DYNAMIC; (tag = dp->d_tag) != 0; dp++ ) {
Index: mercury/scripts/ml.in
diff -u mercury/scripts/ml.in:1.24 mercury/scripts/ml.in:1.25
--- mercury/scripts/ml.in:1.24	Sun Feb  9 22:20:02 1997
+++ mercury/scripts/ml.in	Sun Feb  9 23:26:57 1997
@@ -139,7 +139,20 @@
 		shift
 		;;
 	-static|--static)
-		STATIC_OR_SHARED_OPT=-static
+		case $FULLARCH in
+		    *-linux*)
+		    	# On Linux, if we're linking statically, we need to
+		    	# pass `-defsym _DYNAMIC=0' to the linker, to avoid
+		    	# undefined references to _DYNAMIC in
+		    	# boehm_gc/dyn_load.c.
+		    	# (We might eventually need similar treatment
+		    	# for other OSs too)
+			STATIC_OR_SHARED_OPT="-static -Wl,-defsym,_DYNAMIC=0"
+			;;
+		    *)
+			STATIC_OR_SHARED_OPT=-static
+			;;
+		esac
 		case $mercury_libs in shared)
 			mercury_libs=static ;;
 		esac

-- 
Fergus Henderson <fjh at cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3         |     -- the last words of T. S. Garp.