X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTarget%2FARM%2FARMTargetMachine.cpp;h=0778ec372a8ee1bd0d1f43897df162b895887996;hb=d44dd1789ad34be8e9537f544fd3e815d7a4b721;hp=93495d66ae70d9d4a613e5d449f70249a82ac90c;hpb=24a1fec2a7eb592b27a90ada293a8960cbdd7128;p=oota-llvm.git

diff --git a/lib/Target/ARM/ARMTargetMachine.cpp b/lib/Target/ARM/ARMTargetMachine.cpp
index 93495d66ae7..0778ec372a8 100644
--- a/lib/Target/ARM/ARMTargetMachine.cpp
+++ b/lib/Target/ARM/ARMTargetMachine.cpp
@@ -348,7 +348,13 @@ bool ARMPassConfig::addPreISel() {
     // tricky when doing code gen per function.
     bool OnlyOptimizeForSize = (TM->getOptLevel() < CodeGenOpt::Aggressive) &&
                                (EnableGlobalMerge == cl::BOU_UNSET);
-    addPass(createGlobalMergePass(TM, 127, OnlyOptimizeForSize));
+    // Merging of extern globals is enabled by default on non-Mach-O as we
+    // expect it to be generally either beneficial or harmless. On Mach-O it
+    // is disabled as we emit the .subsections_via_symbols directive which
+    // means that merging extern globals is not safe.
+    bool MergeExternalByDefault = !TM->getTargetTriple().isOSBinFormatMachO();
+    addPass(createGlobalMergePass(TM, 127, OnlyOptimizeForSize,
+                                  MergeExternalByDefault));
   }
 
   return false;