Add gen-dll as replacement for dll-split

Summary:
This tool can be used to generate dll's for any list of object files
given to it. It will then repartition them automatically to fit within
a dll and generates as many dll's as needed to do this. Cyclic dependencies
between these generated dlls are handle automatically so there is no need
to tell it how to partition.

It is also a lot more general than `dll-split` as it is able to split any
package not just `libGHC`. It also uses a trick using GNU style import libraries
to hide the splitting from the rest of the pipeline. Which means come linking time
you don't need to know which dll contains what symbol or how many split dlls were
created.

The import libraries are by default created with libtool. However since libtool is BFD
based it is very slow. So if present and detected by configure the `genlib` tool
from the msys2 project is used. This makes a difference of about ~45 minutes when compiling.

To install `genlib` run `pacman -Sy mingw-w64-$(uname -m)-tools-git`.

More detailed explaination of the process can be found here
https://ghc.haskell.org/trac/ghc/wiki/WindowsDynamicLinking

Test Plan: ./validate

Reviewers: austin, hvr, bgamari, erikd, simonmar

Reviewed By: bgamari

Subscribers: snowleopard, rwbarton, thomie, erikd, #ghc_windows_task_force

GHC Trac Issues: #5987

Differential Revision: https://phabricator.haskell.org/D3883

1 files changed, 19 insertions, 5 deletions

diff --git a/rts/ghc.mk b/rts/ghc.mk
index e3de93dc49..ed1b89c0f4 100644
--- a/rts/ghc.mk
+++ b/rts/ghc.mk
@@ -207,11 +207,25 @@ ifneq "$$(findstring dyn, $1)" ""
 ifeq "$$(TargetOS_CPP)" "mingw32"
 $$(rts_$1_LIB) : $$(rts_$1_OBJS) $$(ALL_RTS_DEF_LIBS) rts/dist/libs.depend rts/dist/build/$$(LIBFFI_DLL)
 	"$$(RM)" $$(RM_OPTS) $$@
-	"$$(rts_dist_HC)" -this-unit-id rts -shared -dynamic -dynload deploy \
-	  -no-auto-link-packages -Lrts/dist/build -l$$(LIBFFI_NAME) \
-         `cat rts/dist/libs.depend` $$(rts_$1_OBJS) $$(ALL_RTS_DEF_LIBS) \
-         $$(rts_dist_$1_GHC_LD_OPTS) \
-         -o $$@
+	# Call out to the shell script to decide how to build the dll.
+	# Making a shared library for the RTS.
+	# $$1  = dir
+	# $$2  = distdir
+	# $$3  = way
+	# $$4  = extra flags
+	# $$5  = extra libraries to link
+	# $$6  = object files to link
+	# $$7  = output filename
+	# $$8  = link command
+	# $$9  = create delay load import lib
+	# $$10 = SxS Name
+	# $$11 = SxS Version
+	$$(gen-dll_INPLACE) link "rts/dist/build" "rts/dist/build" "" "" "$$(ALL_RTS_DEF_LIBS)" "$$(rts_$1_OBJS)" "$$@" "$$(rts_dist_HC) -this-unit-id rts -no-hs-main -shared -dynamic -dynload deploy \
+         -no-auto-link-packages -Lrts/dist/build -l$$(LIBFFI_NAME) \
+         `cat rts/dist/libs.depend | tr '\n' ' '` \
+         $$(rts_dist_$1_GHC_LD_OPTS)" "NO" \
+         "$(rts_INSTALL_INFO)-$(subst dyn,,$(subst _dyn,,$(subst v,,$1)))" "$(ProjectVersion)"
+
 else
 ifneq "$$(UseSystemLibFFI)" "YES"
 LIBFFI_LIBS = -Lrts/dist/build -l$$(LIBFFI_NAME)