[commit: ghc] master: -dead_strip is now the default on Darwin (0a6c257)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/0a6c257de5c217436ec61fdf4b06bca059181f83/ghc

>---------------------------------------------------------------

commit 0a6c257de5c217436ec61fdf4b06bca059181f83
Author: Demi Obenour <demiobenour at gmail.com>
Date:   Thu Jan 5 17:06:26 2017 -0500

    -dead_strip is now the default on Darwin
    
    This enables subsections-via-symbols (-dead_strip) by default on Darwin.
    The Static Reference Table (SRT) needs to be split in order for
    -dead_strip to be helpful, so this commit always splits it on Darwin
    systems.
    
    Test Plan: GHC CI on Darwin
    
    Reviewers: erikd, austin, bgamari
    
    Reviewed By: erikd, bgamari
    
    Subscribers: erikd, thomie
    
    Differential Revision: https://phabricator.haskell.org/D2911
    
    GHC Trac Issues: #11040, #13049


>---------------------------------------------------------------

0a6c257de5c217436ec61fdf4b06bca059181f83
 compiler/main/DriverPipeline.hs | 24 ++++++++++++++----------
 compiler/main/HscMain.hs        |  4 +++-
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/compiler/main/DriverPipeline.hs b/compiler/main/DriverPipeline.hs
index 133bdde..a62233d 100644
--- a/compiler/main/DriverPipeline.hs
+++ b/compiler/main/DriverPipeline.hs
@@ -1794,6 +1794,9 @@ linkBinary' staticLink dflags o_files dep_packages = do
               in ["-L" ++ l] ++ ["-Wl,-rpath", "-Wl," ++ libpath]
          | otherwise = ["-L" ++ l]
 
+    let dead_strip = if osMachOTarget (platformOS platform)
+                      then ["-Wl,-dead_strip"]
+                      else []
     let lib_paths = libraryPaths dflags
     let lib_path_opts = map ("-L"++) lib_paths
 
@@ -1808,16 +1811,17 @@ linkBinary' staticLink dflags o_files dep_packages = do
                                  -- HS packages, because libtool doesn't accept other options.
                                  -- In the case of iOS these need to be added by hand to the
                                  -- final link in Xcode.
-            else other_flags ++ package_hs_libs ++ extra_libs -- -Wl,-u,<sym> contained in other_flags
-                                                              -- needs to be put before -l<package>,
-                                                              -- otherwise Solaris linker fails linking
-                                                              -- a binary with unresolved symbols in RTS
-                                                              -- which are defined in base package
-                                                              -- the reason for this is a note in ld(1) about
-                                                              -- '-u' option: "The placement of this option
-                                                              -- on the command line is significant.
-                                                              -- This option must be placed before the library
-                                                              -- that defines the symbol."
+            else other_flags ++ dead_strip ++ package_hs_libs ++ extra_libs
+                 -- -Wl,-u,<sym> contained in other_flags
+                 -- needs to be put before -l<package>,
+                 -- otherwise Solaris linker fails linking
+                 -- a binary with unresolved symbols in RTS
+                 -- which are defined in base package
+                 -- the reason for this is a note in ld(1) about
+                 -- '-u' option: "The placement of this option
+                 -- on the command line is significant.
+                 -- This option must be placed before the library
+                 -- that defines the symbol."
 
     -- frameworks
     pkg_framework_opts <- getPkgFrameworkOpts dflags platform dep_packages
diff --git a/compiler/main/HscMain.hs b/compiler/main/HscMain.hs
index 7d80912..12e8a1d 100644
--- a/compiler/main/HscMain.hs
+++ b/compiler/main/HscMain.hs
@@ -137,6 +137,7 @@ import Maybes
 
 import DynFlags
 import ErrUtils
+import Platform ( platformOS, OS(OSDarwin) )
 
 import Outputable
 import NameEnv
@@ -1392,7 +1393,8 @@ doCodeGen hsc_env this_mod data_tycons
     -- we generate one SRT for the whole module.
     let
      pipeline_stream
-      | gopt Opt_SplitObjs dflags || gopt Opt_SplitSections dflags
+      | gopt Opt_SplitObjs dflags || gopt Opt_SplitSections dflags ||
+        platformOS (targetPlatform dflags) == OSDarwin
         = {-# SCC "cmmPipeline" #-}
           let run_pipeline us cmmgroup = do
                 let (topSRT', us') = initUs us emptySRT