cctools: support LTO on Darwin

LTO is disabled during bootstrap to keep the bootstrap tools small and
avoid unnecessary LLVM rebuilds, but is enabled in the final stdenv
stage and should be usable by normal packages.

pkgs/development/compilers/llvm/5/llvm.nix

@@ -119,12 +119,14 @@ in stdenv.mkDerivation (rec {
   + stdenv.lib.optionalString enableSharedLibraries ''
     moveToOutput "lib/libLLVM-*" "$lib"
     moveToOutput "lib/libLLVM${stdenv.hostPlatform.extensions.sharedLibrary}" "$lib"
+    moveToOutput "lib/libLTO${stdenv.hostPlatform.extensions.sharedLibrary}" "$lib"
     substituteInPlace "$out/lib/cmake/llvm/LLVMExports-${if debugVersion then "debug" else "release"}.cmake" \
       --replace "\''${_IMPORT_PREFIX}/lib/libLLVM-" "$lib/lib/libLLVM-"
   ''
   + stdenv.lib.optionalString (stdenv.isDarwin && enableSharedLibraries) ''
     substituteInPlace "$out/lib/cmake/llvm/LLVMExports-${if debugVersion then "debug" else "release"}.cmake" \
-      --replace "\''${_IMPORT_PREFIX}/lib/libLLVM.dylib" "$lib/lib/libLLVM.dylib"
+      --replace "\''${_IMPORT_PREFIX}/lib/libLLVM.dylib" "$lib/lib/libLLVM.dylib" \
+      --replace "\''${_IMPORT_PREFIX}/lib/libLTO.dylib" "$lib/lib/libLTO.dylib"
     ln -s $lib/lib/libLLVM.dylib $lib/lib/libLLVM-${shortVersion}.dylib
     ln -s $lib/lib/libLLVM.dylib $lib/lib/libLLVM-${release_version}.dylib
   '';

pkgs/os-specific/darwin/apple-source-releases/ICU/default.nix

@@ -1,8 +1,6 @@
-{ cctools, appleDerivation }:
+{ appleDerivation }:
 
 appleDerivation {
-  nativeBuildInputs = [ cctools ];
-
   patches = [ ./clang-5.patch ];
 
   postPatch = ''

pkgs/os-specific/darwin/apple-source-releases/default.nix

@@ -215,7 +215,7 @@ let
 
     # Splicing is currently broken in Nixpkgs
     # cctools need to be specified manually here to handle this
-    ICU             = applePackage "ICU"               "osx-10.10.5"     "1qihlp42n5g4dl0sn0f9pc0bkxy1452dxzf0vr6y5gqpshlzy03p" { inherit (buildPackages.darwin) cctools; };
+    ICU             = applePackage "ICU"               "osx-10.10.5"     "1qihlp42n5g4dl0sn0f9pc0bkxy1452dxzf0vr6y5gqpshlzy03p" {};
 
     IOKit           = applePackage "IOKit"             "osx-10.11.6"     "0kcbrlyxcyirvg5p95hjd9k8a01k161zg0bsfgfhkb90kh2s8x00" { inherit IOKitSrcs; };
     launchd         = applePackage "launchd"           "osx-10.9.5"      "0w30hvwqq8j5n90s3qyp0fccxflvrmmjnicjri4i1vd2g196jdgj" {};

pkgs/os-specific/darwin/cctools/port.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchFromGitHub, autoconf, automake, libtool_2, autoreconfHook
-, libcxxabi, libuuid
+, libcxxabi, libuuid, llvm
 , libobjc ? null, maloader ? null
 , enableDumpNormalizedLibArgs ? false
 }:
@@ -56,7 +56,7 @@ let
       autoreconfHook
     ];
     buildInputs = [ libuuid ] ++
-      stdenv.lib.optionals stdenv.isDarwin [ libcxxabi libobjc ];
+      stdenv.lib.optionals stdenv.isDarwin [ llvm libcxxabi libobjc ];
 
     patches = [
       ./ld-rpath-nonfinal.patch ./ld-ignore-rpath-link.patch

pkgs/stdenv/darwin/default.nix

@@ -201,6 +201,7 @@ in rec {
       python2 = self.python;
 
       ninja = super.ninja.override { buildDocs = false; };
+      darwin = super.darwin // { cctools = super.darwin.cctools.override { llvm = null; }; };
     };
   in with prevStage; stageFun 1 prevStage {
     extraPreHook = "export NIX_CFLAGS_COMPILE+=\" -F${bootstrapTools}/Library/Frameworks\"";

pkgs/stdenv/darwin/make-bootstrap-tools.nix

@@ -12,6 +12,10 @@ in rec {
     singleBinary = false;
   });
 
+  # We want a version of cctools without LLVM, because the LTO support ends up making
+  # the bootstrap tools huge and isn't really necessary for bootstrap
+  cctools_ = darwin.cctools.override { llvm = null; };
+
   # Avoid debugging larger changes for now.
   bzip2_ = bzip2.override (args: { linkStatic = true; });
 
@@ -95,7 +99,7 @@ in rec {
 
       # Copy binutils.
       for i in as ld ar ranlib nm strip otool install_name_tool dsymutil lipo; do
-        cp ${darwin.cctools}/bin/$i $out/bin
+        cp ${cctools_}/bin/$i $out/bin
       done
 
       cp -rd ${pkgs.darwin.CF}/Library $out
@@ -105,9 +109,9 @@ in rec {
       nuke-refs $out/bin/*
 
       rpathify() {
-        local libs=$(${darwin.cctools}/bin/otool -L "$1" | tail -n +2 | grep -o "$NIX_STORE.*-\S*") || true
+        local libs=$(${cctools_}/bin/otool -L "$1" | tail -n +2 | grep -o "$NIX_STORE.*-\S*") || true
         for lib in $libs; do
-          ${darwin.cctools}/bin/install_name_tool -change $lib "@rpath/$(basename $lib)" "$1"
+          ${cctools_}/bin/install_name_tool -change $lib "@rpath/$(basename $lib)" "$1"
         done
       }