Teach GlobalOpt to delete aliases with internal linkage (after
forwarding any uses). GlobalDCE can also do this, but is only
run at -O3.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90850 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 4635d0e..1793bbf 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2493,29 +2493,28 @@
Changed = true;
}
- // If the aliasee has internal linkage, give it the name and linkage
- // of the alias, and delete the alias. This turns:
- // define internal ... @f(...)
- // @a = alias ... @f
- // into:
- // define ... @a(...)
- if (!Target->hasLocalLinkage())
- continue;
+ // If the alias is externally visible, we may still be able to simplify it.
+ if (!J->hasLocalLinkage()) {
+ // If the aliasee has internal linkage, give it the name and linkage
+ // of the alias, and delete the alias. This turns:
+ // define internal ... @f(...)
+ // @a = alias ... @f
+ // into:
+ // define ... @a(...)
+ if (!Target->hasLocalLinkage())
+ continue;
- // The transform is only useful if the alias does not have internal linkage.
- if (J->hasLocalLinkage())
- continue;
+ // Do not perform the transform if multiple aliases potentially target the
+ // aliasee. This check also ensures that it is safe to replace the section
+ // and other attributes of the aliasee with those of the alias.
+ if (!hasOneUse)
+ continue;
- // Do not perform the transform if multiple aliases potentially target the
- // aliasee. This check also ensures that it is safe to replace the section
- // and other attributes of the aliasee with those of the alias.
- if (!hasOneUse)
- continue;
-
- // Give the aliasee the name, linkage and other attributes of the alias.
- Target->takeName(J);
- Target->setLinkage(J->getLinkage());
- Target->GlobalValue::copyAttributesFrom(J);
+ // Give the aliasee the name, linkage and other attributes of the alias.
+ Target->takeName(J);
+ Target->setLinkage(J->getLinkage());
+ Target->GlobalValue::copyAttributesFrom(J);
+ }
// Delete the alias.
M.getAliasList().erase(J);