split-obj: disable split-objects on Windows.

A change has caused GHC to generate excessive specializations.
This is making GHC generate 1800 splits for a simple GHC.Prim module,
which means 1800 fork/exec calls.

Due to this compilation times on Windows with split-objs on take over
24 hours to complete depending on your disk speed.  Also the end
compiler
compiling medium to large project is also much slower.

So I think we need to just disable split-objects. As there's nothing
that
can be done about this.

Test Plan: ./validate

Reviewers: bgamari

Subscribers: tdammers, rwbarton, thomie, erikd, carter

GHC Trac Issues: #15051

Differential Revision: https://phabricator.haskell.org/D4915

1 files changed, 6 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index ac464b6d2f..2b05535e20 100644
--- a/configure.ac
+++ b/configure.ac
@@ -710,6 +710,12 @@ cygwin32|mingw32)
   else
     AC_PATH_PROG([PerlCmd],[perl])
   fi
+  # because of Trac #15051 SplitObjs is useless on Windows.  It regresses
+  # build times to days for a build, and this effect is also there for end users
+  # of GHC.  So unfortunately we have to disable it, even without having
+  # split-sections.  Though the compile time hit for split-sections should be
+  # tiny compared to this so maybe we should enable it for x86_64.
+  SplitObjsBroken=YES
   ;;
 *)
     AC_PATH_PROG([PerlCmd],[perl])