Merging r195477:

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r195477 | rafael | 2013-11-22 09:58:12 -0800 (Fri, 22 Nov 2013) | 13 lines

Add a fixed version of r195470 back.

The fix is simply to use CurI instead of I when handling aliases to
avoid accessing a invalid iterator.

original message:

Convert linkonce* to weak* instead of strong.

Also refactor the logic into a helper function. This is an important improve
on mingw where the linker complains about mixed weak and strong symbols.
Converting to weak ensures that the symbol is not dropped, but keeps in a
comdat, making the linker happy.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@195603 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 37 insertions, 17 deletions

diff --git a/lib/Transforms/IPO/ExtractGV.cpp b/lib/Transforms/IPO/ExtractGV.cpp
index fa3d72d..50fb3e6 100644
--- a/lib/Transforms/IPO/ExtractGV.cpp
+++ b/lib/Transforms/IPO/ExtractGV.cpp
@@ -21,6 +21,38 @@
 #include <algorithm>
 using namespace llvm;
 
+/// Make sure GV is visible from both modules. Delete is true if it is
+/// being deleted from this module.
+/// This also makes sure GV cannot be dropped so that references from
+/// the split module remain valid.
+static void makeVisible(GlobalValue &GV, bool Delete) {
+  bool Local = GV.hasLocalLinkage();
+  if (Local)
+    GV.setVisibility(GlobalValue::HiddenVisibility);
+
+  if (Local || Delete) {
+    GV.setLinkage(GlobalValue::ExternalLinkage);
+    return;
+  }
+
+  if (!GV.hasLinkOnceLinkage()) {
+    assert(!GV.isDiscardableIfUnused());
+    return;
+  }
+
+  // Map linkonce* to weak* so that llvm doesn't drop this GV.
+  switch(GV.getLinkage()) {
+  default:
+    llvm_unreachable("Unexpected linkage");
+  case GlobalValue::LinkOnceAnyLinkage:
+    GV.setLinkage(GlobalValue::WeakAnyLinkage);
+    return;
+  case GlobalValue::LinkOnceODRLinkage:
+    GV.setLinkage(GlobalValue::WeakODRLinkage);
+    return;
+  }
+}
+
 namespace {
   /// @brief A pass to extract specific functions and their dependencies.
   class GVExtractorPass : public ModulePass {
@@ -60,12 +92,7 @@ namespace {
             continue;
         }
 
-        bool Local = I->isDiscardableIfUnused();
-        if (Local)
-          I->setVisibility(GlobalValue::HiddenVisibility);
-
-        if (Local || Delete)
-          I->setLinkage(GlobalValue::ExternalLinkage);
+	makeVisible(*I, Delete);
 
         if (Delete)
           I->setInitializer(0);
@@ -80,12 +107,7 @@ namespace {
             continue;
         }
 
-        bool Local = I->isDiscardableIfUnused();
-        if (Local)
-          I->setVisibility(GlobalValue::HiddenVisibility);
-
-        if (Local || Delete)
-          I->setLinkage(GlobalValue::ExternalLinkage);
+	makeVisible(*I, Delete);
 
         if (Delete)
           I->deleteBody();
@@ -97,12 +119,10 @@ namespace {
         Module::alias_iterator CurI = I;
         ++I;
 
-        if (CurI->isDiscardableIfUnused()) {
-          CurI->setVisibility(GlobalValue::HiddenVisibility);
-          CurI->setLinkage(GlobalValue::ExternalLinkage);
-        }
+	bool Delete = deleteStuff == (bool)Named.count(CurI);
+	makeVisible(*CurI, Delete);
 
-        if (deleteStuff == (bool)Named.count(CurI)) {
+        if (Delete) {
           Type *Ty =  CurI->getType()->getElementType();
 
           CurI->removeFromParent();