llvm-extract was unable to handle aliases. It would leave a copy on the

output of both

llvm-extract foo.ll -func=bar
and
llvm-extract foo.ll -func=bar -delete

so the two new files could not be linked together anymore. With this change
alias are handled almost like functions and global variables. Almost because
with alias we cannot just clear the initializer/body, we have to create a new
declaration and replace the alias with it.

The net result is that now the output of the above commands can be linked
even if foo.ll has aliases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166907 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/ExtractGV.cpp

@@ -79,6 +79,36 @@ namespace {
         I->setLinkage(GlobalValue::ExternalLinkage);
       }
 
+      // Visit the Aliases.
+      for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
+           I != E;) {
+        Module::alias_iterator CurI = I;
+        ++I;
+
+        if (CurI->hasLocalLinkage())
+          CurI->setVisibility(GlobalValue::HiddenVisibility);
+        CurI->setLinkage(GlobalValue::ExternalLinkage);
+
+        if (deleteStuff == (bool)Named.count(CurI)) {
+          Type *Ty =  CurI->getType()->getElementType();
+
+          CurI->removeFromParent();
+          llvm::Value *Declaration;
+          if (FunctionType *FTy = dyn_cast<FunctionType>(Ty)) {
+            Declaration = Function::Create(FTy, GlobalValue::ExternalLinkage,
+                                           CurI->getName(), &M);
+
+          } else {
+            Declaration =
+              new GlobalVariable(M, Ty, false, GlobalValue::ExternalLinkage,
+                                 0, CurI->getName());
+
+          }
+          CurI->replaceAllUsesWith(Declaration);
+          delete CurI;
+        }
+      }
+
       return true;
     }
   };

test/Other/extract-alias.ll

@@ -0,0 +1,40 @@
+; RUN: llvm-extract -func foo -S < %s | FileCheck %s
+; RUN: llvm-extract -delete -func foo -S < %s | FileCheck --check-prefix=DELETE %s
+
+; Both aliases should be converted to declarations
+; CHECK:      @zeda0 = external global i32
+; CHECK:      define i32* @foo() {
+; CHECK-NEXT:  call void @a0bar()
+; CHECK-NEXT:  ret i32* @zeda0
+; CHECK-NEXT: }
+; CHECK:      declare void @a0bar()
+
+; DELETE:      @zed = global i32 0
+; DELETE:      @zeda0 = alias i32* @zed
+; DELETE-NEXT: @a0foo = alias i32* ()* @foo
+; DELETE-NEXT: @a0a0bar = alias void ()* @a0bar
+; DELETE-NEXT: @a0bar = alias void ()* @bar
+; DELETE:      declare i32* @foo()
+; DELETE:      define void @bar() {
+; DELETE-NEXT:  %c = call i32* @foo()
+; DELETE-NEXT:  ret void
+; DELETE-NEXT: }
+
+@zed = global i32 0
+@zeda0 = alias i32* @zed
+
+@a0foo = alias i32* ()* @foo
+
+define i32* @foo() {
+  call void @a0bar()
+  ret i32* @zeda0
+}
+
+@a0a0bar = alias void ()* @a0bar
+
+@a0bar = alias void ()* @bar
+
+define void @bar() {
+  %c = call i32* @foo()
+  ret void
+}