[project @ 2005-01-14 08:01:26 by wolfgang]

Dynamic Linking, Part 2:

Hack the Makefiles to build dynamic libraries.
This allows you to actually use dynamic libraries to greatly reduce binary
sizes on Darwin/PowerPC and on powerpc64-linux (for now).

To use this, add the following to your build.mk

SplitObjs=NO
GhcBuildDylibs=YES
GhcStage2HcOpts=-dynamic
GhcLibHcOpts+=-fPIC -dynamic
GhcRtsHcOpts+=-fPIC -dynamic
GHC_CC_OPTS+=-fPIC

(You can leave out the last three lines on powerpc64-linux).

Then, to compile a program using dynamic libraries, pass the -dynamic option to GHC.
To make GHCi use the dynamic libraries instead of .o files, just delete the HS*.o files.

The dynamic library files are named libHSfoo_dyn.dylib or libHSfoo_dyn.so.

Note that the dynamic and static libraries are build from the same .o files,
but we really want to build the static libraries with SplitObjs and without
-fPIC -dynamic to achieve better code size and performance.

ghc/compiler/ghci/Linker.lhs:
    When looking for a library, look for HSfoo.o first (as before),
    then look for libHSfoo_dyn.[so/dylib] before looking for
    libHSfoo.[so/dylib].

ghc/compiler/main/DriverPipeline.hs:
    Main.dll_o and PrelMain.dll_o are dead, at least for now.

ghc/compiler/main/Packages.lhs:
    When -dynamic is specified, add "_dyn" to all libraries specified in
    hs-libraries (not to the extra-libs).

ghc/lib/compat/Makefile:
    Never build libghccompat as a dynamic lib.

mk/package.mk:
    if GhcBuildDylibs is set to YES, build dynamic libraries.

mk/target.mk:
    When installing .dylibs (Darwin only), update the install_name to point
    to the final location.
    (Somebody please read Apple's documentation on what install_names are,
    and then comment on whether this is a useful feature or whether it should
    be done the "normal" unix way).

1 files changed, 47 insertions, 1 deletions

diff --git a/mk/package.mk b/mk/package.mk
index bff2772058..93fed76075 100644
--- a/mk/package.mk
+++ b/mk/package.mk
@@ -1,5 +1,5 @@
 # -----------------------------------------------------------------------------
-# $Id: package.mk,v 1.42 2004/11/26 16:22:13 simonmar Exp $
+# $Id: package.mk,v 1.43 2005/01/14 08:01:27 wolfgang Exp $
 
 ifneq "$(PACKAGE)" ""
 
@@ -219,6 +219,52 @@ endif # DONT_WANT_STD_GHCI_LIB_RULE
 endif # GhcWithInterpreter
 endif # way
 
+ifeq "$(GhcBuildDylibs)" "YES"
+
+    # Build dynamic libraries.
+    # Currently, this is a hack. Anyone, PLEASE clean it up.
+
+    # For now, we pretend that there are two operating systems in the world;
+    # Darwin, and Everything Else. Furthermore, we pretend that Everything Else
+    # behaves like Linux.
+    
+ifeq "$(darwin_TARGET_OS)" "1"
+    # Darwin: Shared libraries end in .dylib
+DYLD_LIBRARY = $(patsubst %.a,%_dyn.dylib,$(LIBRARY))
+
+    # About the options used for Darwin:
+    # -dynamiclib
+    #   Apple's way of saying -shared
+    # -flat_namespace -undefined suppress:
+    #   Without these options, we'd have to specify the correct dependencies
+    #   for each of the dylibs. Twolevel namespaces are in general a good thing
+    #   (they make things more robust), so we should fix this sooner or later.
+    # -install_name
+    #   Causes the dynamic linker to ignore the DYLD_LIBRARY_PATH when loading
+    #   this lib and instead look for it at its absolute path.
+    #   When installing the .dylibs (see target.mk), we'll change that path to
+    #   point to the place they are installed.
+    #   Note: I'm not yet sure about this, but I think it will be convenient for
+    #         users not to have to set up DYLD_LIBRARY_PATH to point to the GHC
+    #         library dir. -- Wolfgang
+    
+$(DYLD_LIBRARY) : $(LIBOBJS) $(STUBOBJS)
+	$(CC) -dynamiclib -o $@ $(STUBOBJS) $(LIBOBJS) -flat_namespace -undefined suppress -install_name `pwd`/$@
+else
+DYLD_LIBRARY = $(patsubst %.a,%_dyn.so,$(LIBRARY))
+
+$(DYLD_LIBRARY) : $(LIBOBJS) $(STUBOBJS)
+	$(CC) -shared -o $@ $(STUBOBJS) $(LIBOBJS)
+endif
+
+INSTALL_LIBS += $(DYLD_LIBRARY)
+CLEAN_FILES += $(DYLD_LIBRARY)
+
+all :: $(DYLD_LIBRARY)
+
+
+endif
+
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